Merge remote-tracking branch 'origin/embedded-vnc' into claude/vnc-udp-feasibility-6KB1U

.github/pull_request_template.md

@@ -12,7 +12,6 @@
 - [ ] Is a feature enhancement
 - [ ] It is a refactor
 - [ ] Created tests that fail without the change (if possible)
-- [ ] This change does **not** modify the public API, gRPC protocols, functionality behavior, CLI / service flags, or introduce a new feature — **OR** I have discussed it with the NetBird team beforehand (link the issue / Slack thread in the description). See [CONTRIBUTING.md](https://github.com/netbirdio/netbird/blob/main/CONTRIBUTING.md#discuss-changes-with-the-netbird-team-first).
 
 > By submitting this pull request, you confirm that you have read and agree to the terms of the [Contributor License Agreement](https://github.com/netbirdio/netbird/blob/main/CONTRIBUTOR_LICENSE_AGREEMENT.md).
 

.github/workflows/wasm-build-validation.yml

@@ -61,8 +61,8 @@ jobs:
 
           echo "Size: ${SIZE} bytes (${SIZE_MB} MB)"
 
-          if [ ${SIZE} -gt 58720256 ]; then
-            echo "Wasm binary size (${SIZE_MB}MB) exceeds 56MB limit!"
+          if [ ${SIZE} -gt 62914560 ]; then
+            echo "Wasm binary size (${SIZE_MB}MB) exceeds 60MB limit!"
             exit 1
           fi
 

CONTRIBUTING.md

@@ -15,7 +15,6 @@ If you haven't already, join our slack workspace [here](https://docs.netbird.io/
 - [Contributing to NetBird](#contributing-to-netbird)
     - [Contents](#contents)
     - [Code of conduct](#code-of-conduct)
-    - [Discuss changes with the NetBird team first](#discuss-changes-with-the-netbird-team-first)
     - [Directory structure](#directory-structure)
     - [Development setup](#development-setup)
         - [Requirements](#requirements)
@@ -34,14 +33,6 @@ Conduct which can be found in the file [CODE_OF_CONDUCT.md](CODE_OF_CONDUCT.md).
 By participating, you are expected to uphold this code. Please report
 unacceptable behavior to community@netbird.io.
 
-## Discuss changes with the NetBird team first
-
-Changes to the **public API**, **gRPC protocols**, **functionality behavior**, **CLI / service flags**, or **new features** should be discussed with the NetBird team before you start the work. These surfaces are part of NetBird's contract with operators, self-hosters, and downstream integrators, and changes to them have compatibility, security, and release-planning implications that benefit from an early conversation.
-
-Open an issue or reach out on [Slack](https://docs.netbird.io/slack-url) to talk through what you have in mind. We'll help shape the change, flag any constraints we know about, and confirm the direction so the PR review can focus on implementation rather than design.
-
-Typical bug fixes, internal refactors, documentation updates, and tests do not need pre-discussion — open the PR directly.
-
 ## Directory structure
 
 The NetBird project monorepo is organized to maintain most of its individual dependencies code within their directories, except for a few auxiliary or shared packages.

README.md

@@ -1,134 +1,147 @@
 
 <div align="center">
-  <p align="center">
-    <img width="234" src="docs/media/logo-full.png" alt="NetBird logo"/>
-  </p>
-  <p align="center">
-    <a href="https://sonarcloud.io/dashboard?id=netbirdio_netbird">
-      <img src="https://sonarcloud.io/api/project_badges/measure?project=netbirdio_netbird&metric=alert_status" alt="SonarCloud alert status"/>
-    </a>
-    <a href="https://github.com/netbirdio/netbird/blob/main/LICENSE">
-      <img src="https://img.shields.io/badge/license-BSD--3-blue" alt="BSD-3 License"/>
-    </a>
+<br/>
+  <br/>
+<p align="center">
+  <img width="234" src="docs/media/logo-full.png"/>
+</p>
+  <p>
+   <a href="https://img.shields.io/badge/license-BSD--3-blue)">
+       <img src="https://sonarcloud.io/api/project_badges/measure?project=netbirdio_netbird&metric=alert_status" />
+     </a> 
+     <a href="https://github.com/netbirdio/netbird/blob/main/LICENSE">
+       <img src="https://img.shields.io/badge/license-BSD--3-blue" />
+     </a> 
+    <br>
     <a href="https://docs.netbird.io/slack-url">
-      <img src="https://img.shields.io/badge/slack-@netbird-red.svg?logo=slack" alt="NetBird Slack"/>
-    </a>
+        <img src="https://img.shields.io/badge/slack-@netbird-red.svg?logo=slack"/>
+     </a>
     <a href="https://forum.netbird.io">
-      <img src="https://img.shields.io/badge/community%20forum-@netbird-red.svg?logo=discourse" alt="Community forum"/>
-    </a>
+        <img src="https://img.shields.io/badge/community forum-@netbird-red.svg?logo=discourse"/>
+     </a>  
+     <br>
     <a href="https://gurubase.io/g/netbird">
-      <img src="https://img.shields.io/badge/Gurubase-Ask%20NetBird%20Guru-006BFF" alt="Gurubase: Ask NetBird Guru"/>
-    </a>
+        <img src="https://img.shields.io/badge/Gurubase-Ask%20NetBird%20Guru-006BFF"/>
+     </a>    
   </p>
 </div>
 
+
 <p align="center">
-  <strong>
-    Start using NetBird at <a href="https://netbird.io/pricing">netbird.io</a>
-    <br/>
-    See <a href="https://netbird.io/docs/">Documentation</a>
-    <br/>
-    Join our <a href="https://docs.netbird.io/slack-url">Slack channel</a> or our <a href="https://forum.netbird.io">Community forum</a>
-  </strong>
+<strong>
+  Start using NetBird at <a href="https://netbird.io/pricing">netbird.io</a>
   <br/>
+  See <a href="https://netbird.io/docs/">Documentation</a>
   <br/>
-  <strong>
-    🚀 <a href="https://careers.netbird.io">We are hiring! Join us at careers.netbird.io</a>
-  </strong>
+   Join our <a href="https://docs.netbird.io/slack-url">Slack channel</a> or our <a href="https://forum.netbird.io">Community forum</a>
+  <br/>
+ 
+</strong>
+<br>
+<strong>
+  🚀 <a href="https://careers.netbird.io">We are hiring! Join us at careers.netbird.io</a>
+</strong>
+<br>
+<br>
+<a href="https://registry.terraform.io/providers/netbirdio/netbird/latest">
+    New: NetBird terraform provider
+  </a> 
 </p>
 
+<br>
+
 **NetBird combines a configuration-free peer-to-peer private network and a centralized access control system in a single platform, making it easy to create secure private networks for your organization or home.**
 
 **Connect.** NetBird creates a WireGuard-based overlay network that automatically connects your machines over an encrypted tunnel, leaving behind the hassle of opening ports, complex firewall rules, VPN gateways, and so forth.
 
 **Secure.** NetBird enables secure remote access by applying granular access policies while allowing you to manage them intuitively from a single place. Works universally on any infrastructure.
 
+### Open Source Network Security in a Single Platform
+
 https://github.com/user-attachments/assets/10cec749-bb56-4ab3-97af-4e38850108d2
 
-### Self-host NetBird (video)
-
+### Self-Host NetBird (Video)
 [![Watch the video](https://img.youtube.com/vi/bZAgpT6nzaQ/0.jpg)](https://youtu.be/bZAgpT6nzaQ)
 
 ### Key features
 
-| Connectivity | Management | Security | Automation | Platforms |
-|---|---|---|---|---|
-| ✓ [Kernel WireGuard](https://docs.netbird.io/about-netbird/why-wireguard-with-netbird) | ✓ [Admin Web UI](https://github.com/netbirdio/dashboard) | ✓ [SSO & MFA support](https://docs.netbird.io/how-to/installation#running-net-bird-with-sso-login) | ✓ [Public API](https://docs.netbird.io/api) | ✓ [Linux](https://docs.netbird.io/get-started/install/linux) |
-| ✓ [Peer-to-peer connections](https://docs.netbird.io/about-netbird/how-netbird-works) | ✓ Auto peer discovery and configuration | ✓ [Access control: groups & rules](https://docs.netbird.io/how-to/manage-network-access) | ✓ [Setup keys for bulk provisioning](https://docs.netbird.io/how-to/register-machines-using-setup-keys) | ✓ [macOS](https://docs.netbird.io/get-started/install/macos) |
-| ✓ Connection relay fallback | ✓ [IdP integrations](https://docs.netbird.io/selfhosted/identity-providers) | ✓ [Activity logging](https://docs.netbird.io/how-to/audit-events-logging) | ✓ [Self-hosting quickstart script](https://docs.netbird.io/selfhosted/selfhosted-quickstart) | ✓ [Windows](https://docs.netbird.io/get-started/install/windows) |
-| ✓ [Routes to external networks](https://docs.netbird.io/how-to/routing-traffic-to-private-networks) | ✓ [Private DNS](https://docs.netbird.io/how-to/manage-dns-in-your-network) | ✓ [Traffic events](https://docs.netbird.io/manage/activity/traffic-events-logging) | ✓ [IdP groups sync with JWT](https://docs.netbird.io/manage/team/idp-sync) | ✓ [Android](https://docs.netbird.io/get-started/install/android) |
-| ✓ [Domain-based DNS routes](https://docs.netbird.io/manage/dns/dns-aliases-for-routed-networks) | ✓ [Custom DNS zones](https://docs.netbird.io/manage/dns/custom-zones) | ✓ [Device posture checks](https://docs.netbird.io/how-to/manage-posture-checks) | ✓ [Terraform provider](https://registry.terraform.io/providers/netbirdio/netbird/latest) | ✓ [Android TV](https://docs.netbird.io/get-started/install/android-tv) |
-| ✓ [Exit nodes](https://docs.netbird.io/manage/network-routes/use-cases/exit-nodes) | ✓ [Multiuser support](https://docs.netbird.io/how-to/add-users-to-your-network) | ✓ Peer-to-peer encryption | ✓ [Ansible collection](https://github.com/netbirdio/ansible-netbird) | ✓ [iOS](https://docs.netbird.io/get-started/install/ios) |
-| ✓ [IPv6 dual-stack overlay](https://docs.netbird.io/manage/settings/ipv6) | ✓ [Multi-account profile switching](https://docs.netbird.io/client/profiles) | ✓ [SSH with central access policies](https://docs.netbird.io/manage/peers/ssh) | | ✓ [Apple TV](https://docs.netbird.io/get-started/install/tvos) |
-| ✓ [Browser SSH & RDP](https://docs.netbird.io/manage/peers/browser-client) | | ✓ [Quantum-resistance with Rosenpass](https://netbird.io/knowledge-hub/the-first-quantum-resistant-mesh-vpn) | | ✓ FreeBSD |
-| ✓ [Reverse proxy with auto-TLS](https://docs.netbird.io/manage/reverse-proxy) | | ✓ [Periodic re-authentication](https://docs.netbird.io/how-to/enforce-periodic-user-authentication) | | ✓ [pfSense](https://docs.netbird.io/get-started/install/pfsense) |
-| | | | | ✓ [OPNsense](https://docs.netbird.io/get-started/install/opnsense) |
-| | | | | ✓ [MikroTik RouterOS](https://docs.netbird.io/use-cases/homelab/client-on-mikrotik-router) |
-| | | | | ✓ OpenWRT |
-| | | | | ✓ [Synology](https://docs.netbird.io/get-started/install/synology) |
-| | | | | ✓ [TrueNAS](https://docs.netbird.io/get-started/install/truenas) |
-| | | | | ✓ [Proxmox](https://docs.netbird.io/get-started/install/proxmox-ve) |
-| | | | | ✓ [Raspberry Pi](https://docs.netbird.io/get-started/install/raspberrypi) |
-| | | | | ✓ [Serverless](https://docs.netbird.io/how-to/netbird-on-faas) |
-| | | | | ✓ [Container](https://docs.netbird.io/get-started/install/docker) |
+| Connectivity | Management | Security | Automation| Platforms |
+|----|----|----|----|----|
+| <ul><li>- \[x] Kernel WireGuard</ul></li> | <ul><li>- \[x] [Admin Web UI](https://github.com/netbirdio/dashboard)</ul></li> | <ul><li>- \[x] [SSO & MFA support](https://docs.netbird.io/how-to/installation#running-net-bird-with-sso-login)</ul></li> | <ul><li>- \[x] [Public API](https://docs.netbird.io/api)</ul></li> | <ul><li>- \[x] Linux</ul></li> |
+| <ul><li>- \[x] Peer-to-peer connections</ul></li> | <ul><li>- \[x] Auto peer discovery and configuration</ui></li> | <ul><li>- \[x] [Access control - groups & rules](https://docs.netbird.io/how-to/manage-network-access)</ui></li> | <ul><li>- \[x] [Setup keys for bulk network provisioning](https://docs.netbird.io/how-to/register-machines-using-setup-keys)</ui></li> | <ul><li>- \[x] Mac</ui></li> |
+| <ul><li>- \[x] Connection relay fallback</ui></li> | <ul><li>- \[x] [IdP integrations](https://docs.netbird.io/selfhosted/identity-providers)</ui></li> | <ul><li>- \[x] [Activity logging](https://docs.netbird.io/how-to/audit-events-logging)</ui></li> | <ul><li>- \[x] [Self-hosting quickstart script](https://docs.netbird.io/selfhosted/selfhosted-quickstart)</ui></li> | <ul><li>- \[x] Windows</ui></li> |
+| <ul><li>- \[x] [Routes to external networks](https://docs.netbird.io/how-to/routing-traffic-to-private-networks)</ui></li> | <ul><li>- \[x] [Private DNS](https://docs.netbird.io/how-to/manage-dns-in-your-network)</ui></li> | <ul><li>- \[x] [Device posture checks](https://docs.netbird.io/how-to/manage-posture-checks)</ui></li> | <ul><li>- \[x] IdP groups sync with JWT</ui></li> | <ul><li>- \[x] Android</ui></li> |
+| <ul><li>- \[x] NAT traversal with BPF</ui></li> | <ul><li>- \[x] [Multiuser support](https://docs.netbird.io/how-to/add-users-to-your-network)</ui></li> | <ul><li>- \[x] Peer-to-peer encryption</ui></li> || <ul><li>- \[x] iOS</ui></li> |
+||| <ul><li>- \[x] [Quantum-resistance with Rosenpass](https://netbird.io/knowledge-hub/the-first-quantum-resistant-mesh-vpn)</ui></li> || <ul><li>- \[x] OpenWRT</ui></li> |
+||| <ul><li>- \[x] [Periodic re-authentication](https://docs.netbird.io/how-to/enforce-periodic-user-authentication)</ui></li> || <ul><li>- \[x] [Serverless](https://docs.netbird.io/how-to/netbird-on-faas)</ui></li> |
+||||| <ul><li>- \[x] Docker</ui></li> |
 
 ### Quickstart with NetBird Cloud
 
-- Download and install NetBird at [https://app.netbird.io/install](https://app.netbird.io/install).
-- Follow the steps to sign up with Google, Microsoft, GitHub or your email address.
-- Check the NetBird [admin UI](https://app.netbird.io/).
+- Download and install NetBird at [https://app.netbird.io/install](https://app.netbird.io/install)
+- Follow the steps to sign-up with Google, Microsoft, GitHub or your email address.
+- Check NetBird [admin UI](https://app.netbird.io/).
+- Add more machines.
 
 ### Quickstart with self-hosted NetBird
 
-This is the quickest way to try self-hosted NetBird. It should take around 5 minutes to get started if you already have a public domain and a VM. Follow the [Advanced guide with a custom identity provider](https://docs.netbird.io/selfhosted/selfhosted-guide#advanced-guide-with-a-custom-identity-provider) for installations with different IdPs.
+> This is the quickest way to try self-hosted NetBird. It should take around 5 minutes to get started if you already have a public domain and a VM.
+Follow the [Advanced guide with a custom identity provider](https://docs.netbird.io/selfhosted/selfhosted-guide#advanced-guide-with-a-custom-identity-provider) for installations with different IDPs.
 
 **Infrastructure requirements:**
-- A Linux VM with at least **1 CPU** and **2 GB** of memory.
-- The VM should be publicly accessible on TCP ports **80** and **443** and UDP port **3478**.
-- A **public domain** name pointing to the VM.
+- A Linux VM with at least **1CPU** and **2GB** of memory.
+- The VM should be publicly accessible on TCP ports **80** and **443** and UDP port: **3478**.
+- **Public domain** name pointing to the VM.
 
 **Software requirements:**
-- Docker with the Compose plugin (Compose v2 or higher). See the [Docker installation guide](https://docs.docker.com/engine/install/).
+- Docker installed on the VM with the docker-compose plugin ([Docker installation guide](https://docs.docker.com/engine/install/)) or docker with docker-compose in version 2 or higher.
+- [jq](https://jqlang.github.io/jq/) installed. In most distributions
+  Usually available in the official repositories and can be installed with `sudo apt install jq` or `sudo yum install jq`
+- [curl](https://curl.se/) installed.
+  Usually available in the official repositories and can be installed with `sudo apt install curl` or `sudo yum install curl`
 
 **Steps**
 - Download and run the installation script:
 ```bash
 export NETBIRD_DOMAIN=netbird.example.com; curl -fsSL https://github.com/netbirdio/netbird/releases/latest/download/getting-started.sh | bash
 ```
+- Once finished, you can manage the resources via `docker-compose`
 
 ### A bit on NetBird internals
-- Every machine in the network runs the [NetBird agent](client/), which manages WireGuard.
-- Every agent connects to the [Management Service](management/), which holds network state, manages peer IPs, and distributes updates to agents.
-- Agents use ICE (via [pion/ice](https://github.com/pion/ice)) to discover connection candidates for peer-to-peer connections.
-- Candidates are discovered with the help of [STUN](https://en.wikipedia.org/wiki/STUN) servers.
-- Agents negotiate a connection through the [Signal Service](signal/), exchanging end-to-end encrypted messages with candidates.
-- When NAT traversal fails (e.g. mobile carrier-grade NAT) and a direct p2p connection isn't possible, the system falls back to a [Relay Service](relay/) and a secure WireGuard tunnel is established through it.
+-  Every machine in the network runs [NetBird Agent (or Client)](client/) that manages WireGuard.
+-  Every agent connects to [Management Service](management/) that holds network state, manages peer IPs, and distributes network updates to agents (peers).
+-  NetBird agent uses WebRTC ICE implemented in [pion/ice library](https://github.com/pion/ice) to discover connection candidates when establishing a peer-to-peer connection between machines.
+-  Connection candidates are discovered with the help of [STUN](https://en.wikipedia.org/wiki/STUN) servers.
+-  Agents negotiate a connection through [Signal Service](signal/) passing p2p encrypted messages with candidates.
+-  Sometimes the NAT traversal is unsuccessful due to strict NATs (e.g. mobile carrier-grade NAT) and a p2p connection isn't possible. When this occurs the system falls back to a relay server called [TURN](https://en.wikipedia.org/wiki/Traversal_Using_Relays_around_NAT), and a secure WireGuard tunnel is established via the TURN server. 
+ 
+[Coturn](https://github.com/coturn/coturn) is the one that has been successfully used for STUN and TURN in NetBird setups.
 
 <p float="left" align="middle">
-  <img src="https://docs.netbird.io/docs-static/img/about-netbird/high-level-dia.png" width="700" alt="NetBird high-level architecture diagram"/>
+  <img src="https://docs.netbird.io/docs-static/img/about-netbird/high-level-dia.png" width="700"/>
 </p>
 
 See a complete [architecture overview](https://docs.netbird.io/about-netbird/how-netbird-works#architecture) for details.
 
 ### Community projects
-- [NetBird installer script](https://github.com/physk/netbird-installer)
-- [netbird-tui](https://github.com/n0pashkov/netbird-tui) - terminal UI for managing NetBird peers, routes, and settings
-- [caddy-netbird](https://github.com/lixmal/caddy-netbird) - Caddy plugin that embeds a NetBird client for proxying HTTP and TCP/UDP traffic through NetBird networks
+-  [NetBird installer script](https://github.com/physk/netbird-installer)
+-  [NetBird ansible collection by Dominion Solutions](https://galaxy.ansible.com/ui/repo/published/dominion_solutions/netbird/)
+-  [netbird-tui](https://github.com/n0pashkov/netbird-tui) — terminal UI for managing NetBird peers, routes, and settings
 
 **Note**: The `main` branch may be in an *unstable or even broken state* during development.
 For stable versions, see [releases](https://github.com/netbirdio/netbird/releases).
 
 ### Support acknowledgement
 
-In November 2022, NetBird joined the [StartUpSecure program](https://www.forschung-it-sicherheit-kommunikationssysteme.de/foerderung/bekanntmachungen/startup-secure) sponsored by the Federal Ministry of Education and Research of the Federal Republic of Germany. Together with the [CISPA Helmholtz Center for Information Security](https://cispa.de/en), NetBird brings security best practices and simplicity to private networking.
+In November 2022, NetBird joined the [StartUpSecure program](https://www.forschung-it-sicherheit-kommunikationssysteme.de/foerderung/bekanntmachungen/startup-secure) sponsored by The Federal Ministry of Education and Research of The Federal Republic of Germany. Together with [CISPA Helmholtz Center for Information Security](https://cispa.de/en) NetBird brings the security best practices and simplicity to private networking.
 
 ![CISPA_Logo_BLACK_EN_RZ_RGB (1)](https://user-images.githubusercontent.com/700848/203091324-c6d311a0-22b5-4b05-a288-91cbc6cdcc46.png)
 
-### Acknowledgements
-We build on open-source technologies like [WireGuard®](https://www.wireguard.com/), [Pion ICE](https://github.com/pion/ice), and [Rosenpass](https://rosenpass.eu). We greatly appreciate the work these projects are doing, and we'd love it if you could support them too (e.g., by starring or contributing).
+### Testimonials
+We use open-source technologies like [WireGuard®](https://www.wireguard.com/), [Pion ICE (WebRTC)](https://github.com/pion/ice), [Coturn](https://github.com/coturn/coturn), and [Rosenpass](https://rosenpass.eu). We very much appreciate the work these guys are doing and we'd greatly appreciate if you could support them in any way (e.g., by giving a star or a contribution).
 
 ### Legal
-This repository is licensed under the BSD-3-Clause license, which applies to all parts of the repository except for the directories management/, signal/ and relay/.
+This repository is licensed under BSD-3-Clause license that applies to all parts of the repository except for the directories management/, signal/ and relay/.
 Those directories are licensed under the GNU Affero General Public License version 3.0 (AGPLv3). See the respective LICENSE files inside each directory.
 
 _WireGuard_ and the _WireGuard_ logo are [registered trademarks](https://www.wireguard.com/trademark-policy/) of Jason A. Donenfeld.

client/cmd/up.go

@@ -361,6 +361,9 @@ func setupSetConfigReq(customDNSAddressConverted []byte, cmd *cobra.Command, pro
 	if cmd.Flag(serverSSHAllowedFlag).Changed {
 		req.ServerSSHAllowed = &serverSSHAllowed
 	}
+	if cmd.Flag(serverVNCAllowedFlag).Changed {
+		req.ServerVNCAllowed = &serverVNCAllowed
+	}
 	if cmd.Flag(enableSSHRootFlag).Changed {
 		req.EnableSSHRoot = &enableSSHRoot
 	}
@@ -467,6 +470,9 @@ func setupConfig(customDNSAddressConverted []byte, cmd *cobra.Command, configFil
 	if cmd.Flag(serverSSHAllowedFlag).Changed {
 		ic.ServerSSHAllowed = &serverSSHAllowed
 	}
+	if cmd.Flag(serverVNCAllowedFlag).Changed {
+		ic.ServerVNCAllowed = &serverVNCAllowed
+	}
 
 	if cmd.Flag(enableSSHRootFlag).Changed {
 		ic.EnableSSHRoot = &enableSSHRoot
@@ -595,6 +601,9 @@ func setupLoginRequest(providedSetupKey string, customDNSAddressConverted []byte
 	if cmd.Flag(serverSSHAllowedFlag).Changed {
 		loginRequest.ServerSSHAllowed = &serverSSHAllowed
 	}
+	if cmd.Flag(serverVNCAllowedFlag).Changed {
+		loginRequest.ServerVNCAllowed = &serverVNCAllowed
+	}
 
 	if cmd.Flag(enableSSHRootFlag).Changed {
 		loginRequest.EnableSSHRoot = &enableSSHRoot

client/cmd/vnc_agent.go

@@ -0,0 +1,67 @@
+//go:build windows
+
+package cmd
+
+import (
+	"fmt"
+	"net/netip"
+	"os"
+
+	log "github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+
+	vncserver "github.com/netbirdio/netbird/client/vnc/server"
+)
+
+var vncAgentPort string
+
+func init() {
+	vncAgentCmd.Flags().StringVar(&vncAgentPort, "port", "15900", "Port for the VNC agent to listen on")
+	rootCmd.AddCommand(vncAgentCmd)
+}
+
+// vncAgentCmd runs a VNC server in the current user session, listening on
+// localhost. It is spawned by the NetBird service (Session 0) via
+// CreateProcessAsUser into the interactive console session.
+var vncAgentCmd = &cobra.Command{
+	Use:    "vnc-agent",
+	Short:  "Run VNC capture agent (internal, spawned by service)",
+	Hidden: true,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		// Agent's stderr is piped to the service which relogs it.
+		// Use JSON format with caller info for structured parsing.
+		log.SetReportCaller(true)
+		log.SetFormatter(&log.JSONFormatter{})
+		log.SetOutput(os.Stderr)
+
+		sessionID := vncserver.GetCurrentSessionID()
+		log.Infof("VNC agent starting on 127.0.0.1:%s (session %d)", vncAgentPort, sessionID)
+
+		token := os.Getenv("NB_VNC_AGENT_TOKEN")
+		if token == "" {
+			return fmt.Errorf("NB_VNC_AGENT_TOKEN not set; agent requires a token from the service")
+		}
+
+		capturer := vncserver.NewDesktopCapturer()
+		injector := vncserver.NewWindowsInputInjector()
+		srv := vncserver.New(capturer, injector, "")
+		srv.SetDisableAuth(true)
+		srv.SetAgentToken(token)
+
+		port, err := netip.ParseAddrPort("127.0.0.1:" + vncAgentPort)
+		if err != nil {
+			return fmt.Errorf("parse listen addr: %w", err)
+		}
+
+		loopback := netip.PrefixFrom(netip.AddrFrom4([4]byte{127, 0, 0, 0}), 8)
+		if err := srv.Start(cmd.Context(), port, loopback); err != nil {
+			return fmt.Errorf("start vnc server: %w", err)
+		}
+		log.Infof("vnc-agent listening on 127.0.0.1:%s, ready", vncAgentPort)
+
+		<-cmd.Context().Done()
+		log.Info("vnc-agent context cancelled, shutting down")
+		return srv.Stop()
+	},
+	SilenceUsage: true,
+}

client/cmd/vnc_flags.go

@@ -0,0 +1,9 @@
+package cmd
+
+const serverVNCAllowedFlag = "allow-server-vnc"
+
+var serverVNCAllowed bool
+
+func init() {
+	upCmd.PersistentFlags().BoolVar(&serverVNCAllowed, serverVNCAllowedFlag, false, "Allow embedded VNC server on peer")
+}

client/firewall/iptables/dnat_refcount_linux_test.go

@@ -1,199 +0,0 @@
-package iptables
-
-import (
-	"net/netip"
-	"testing"
-
-	"github.com/stretchr/testify/require"
-
-	fw "github.com/netbirdio/netbird/client/firewall/manager"
-	"github.com/netbirdio/netbird/client/iface"
-	"github.com/netbirdio/netbird/client/iface/wgaddr"
-)
-
-func iptRefcountIfaceV4() *iFaceMock {
-	return &iFaceMock{
-		NameFunc: func() string { return "wt-refcount" },
-		AddressFunc: func() wgaddr.Address {
-			return wgaddr.Address{
-				IP:      netip.MustParseAddr("10.20.0.1"),
-				Network: netip.MustParsePrefix("10.20.0.0/24"),
-			}
-		},
-	}
-}
-
-func iptRefcountIfaceDual() *iFaceMock {
-	return &iFaceMock{
-		NameFunc: func() string { return "wt-refcount" },
-		AddressFunc: func() wgaddr.Address {
-			return wgaddr.Address{
-				IP:      netip.MustParseAddr("10.20.0.1"),
-				Network: netip.MustParsePrefix("10.20.0.0/24"),
-				IPv6:    netip.MustParseAddr("fd00::1"),
-				IPv6Net: netip.MustParsePrefix("fd00::/64"),
-			}
-		},
-	}
-}
-
-func newIptRefcountManager(t *testing.T, dual bool) *Manager {
-	t.Helper()
-	var ifMock *iFaceMock
-	if dual {
-		ifMock = iptRefcountIfaceDual()
-	} else {
-		ifMock = iptRefcountIfaceV4()
-	}
-	m, err := Create(ifMock, iface.DefaultMTU)
-	require.NoError(t, err, "create manager")
-	require.NoError(t, m.Init(nil), "init manager")
-	t.Cleanup(func() {
-		require.NoError(t, m.Close(nil), "close manager")
-	})
-	return m
-}
-
-func iptDnatV4(port uint16) fw.ForwardRule {
-	return fw.ForwardRule{
-		Protocol:          fw.ProtocolTCP,
-		DestinationPort:   fw.Port{Values: []uint16{port}},
-		TranslatedAddress: netip.MustParseAddr("10.20.0.2"),
-		TranslatedPort:    fw.Port{Values: []uint16{80}},
-	}
-}
-
-func iptDnatV6(port uint16) fw.ForwardRule {
-	return fw.ForwardRule{
-		Protocol:          fw.ProtocolTCP,
-		DestinationPort:   fw.Port{Values: []uint16{port}},
-		TranslatedAddress: netip.MustParseAddr("fd00::2"),
-		TranslatedPort:    fw.Port{Values: []uint16{80}},
-	}
-}
-
-// TestIptablesDNAT_RefcountBalancedV4 covers a Balanced Add/Delete pair on v4.
-func TestIptablesDNAT_RefcountBalancedV4(t *testing.T) {
-	m := newIptRefcountManager(t, false)
-	state := m.router.ipFwdState
-
-	r1, err := m.AddDNATRule(iptDnatV4(7081))
-	require.NoError(t, err, "add v4 dnat 1")
-	v4, v6 := state.Counts()
-	require.Equal(t, 1, v4, "v4 refcount after first add")
-	require.Equal(t, 0, v6, "v6 refcount unchanged")
-
-	r2, err := m.AddDNATRule(iptDnatV4(7082))
-	require.NoError(t, err, "add v4 dnat 2")
-	v4, v6 = state.Counts()
-	require.Equal(t, 2, v4, "v4 refcount after second add")
-	require.Equal(t, 0, v6, "v6 refcount unchanged")
-
-	require.NoError(t, m.DeleteDNATRule(r1))
-	v4, v6 = state.Counts()
-	require.Equal(t, 1, v4, "v4 refcount after first delete")
-	require.Equal(t, 0, v6, "v6 refcount unchanged")
-
-	require.NoError(t, m.DeleteDNATRule(r2))
-	v4, v6 = state.Counts()
-	require.Equal(t, 0, v4, "v4 refcount after second delete")
-	require.Equal(t, 0, v6, "v6 refcount unchanged")
-}
-
-// TestIptablesDNAT_RefcountBalancedV6 checks the v6 path increments v6 only and
-// decrements back to zero.
-func TestIptablesDNAT_RefcountBalancedV6(t *testing.T) {
-	m := newIptRefcountManager(t, true)
-	require.NotNil(t, m.router6, "v6 router")
-	require.Same(t, m.router.ipFwdState, m.router6.ipFwdState, "shared state")
-	state := m.router.ipFwdState
-
-	r1, err := m.AddDNATRule(iptDnatV6(9081))
-	require.NoError(t, err, "add v6 dnat 1")
-	v4, v6 := state.Counts()
-	require.Equal(t, 0, v4)
-	require.Equal(t, 1, v6, "v6 refcount after first add")
-
-	r2, err := m.AddDNATRule(iptDnatV6(9082))
-	require.NoError(t, err, "add v6 dnat 2")
-	v4, v6 = state.Counts()
-	require.Equal(t, 0, v4, "v4 refcount unchanged")
-	require.Equal(t, 2, v6, "v6 refcount after second add")
-
-	require.NoError(t, m.DeleteDNATRule(r1))
-	v4, v6 = state.Counts()
-	require.Equal(t, 0, v4, "v4 refcount unchanged")
-	require.Equal(t, 1, v6, "v6 refcount after first delete")
-
-	require.NoError(t, m.DeleteDNATRule(r2))
-	v4, v6 = state.Counts()
-	require.Equal(t, 0, v4)
-	require.Equal(t, 0, v6, "v6 refcount after second delete")
-}
-
-// TestIptablesDNAT_DuplicateAddNoLeak verifies the duplicate-rule path returns
-// without bumping the refcount.
-func TestIptablesDNAT_DuplicateAddNoLeak(t *testing.T) {
-	m := newIptRefcountManager(t, true)
-	state := m.router.ipFwdState
-
-	rule := iptDnatV4(7083)
-	r1, err := m.AddDNATRule(rule)
-	require.NoError(t, err)
-	v4, _ := state.Counts()
-	require.Equal(t, 1, v4)
-
-	_, err = m.AddDNATRule(rule)
-	require.NoError(t, err, "duplicate add")
-	v4, _ = state.Counts()
-	require.Equal(t, 1, v4, "duplicate add must not increment")
-
-	require.NoError(t, m.DeleteDNATRule(r1))
-	v4, _ = state.Counts()
-	require.Equal(t, 0, v4, "single delete must drop to zero")
-}
-
-// TestIptablesDNAT_DeleteMissingNoUnderflow verifies Delete on an unknown rule
-// neither errors nor releases the refcount.
-func TestIptablesDNAT_DeleteMissingNoUnderflow(t *testing.T) {
-	m := newIptRefcountManager(t, true)
-	state := m.router.ipFwdState
-
-	phantom := iptDnatV4(7099)
-	require.NoError(t, m.DeleteDNATRule(&phantom), "delete missing v4")
-	v4, v6 := state.Counts()
-	require.Equal(t, 0, v4)
-	require.Equal(t, 0, v6)
-
-	phantom6 := iptDnatV6(9099)
-	require.NoError(t, m.DeleteDNATRule(&phantom6), "delete missing v6")
-	v4, v6 = state.Counts()
-	require.Equal(t, 0, v4)
-	require.Equal(t, 0, v6)
-
-	r1, err := m.AddDNATRule(iptDnatV4(7100))
-	require.NoError(t, err)
-	v4, _ = state.Counts()
-	require.Equal(t, 1, v4, "real add still increments after phantom delete")
-	require.NoError(t, m.DeleteDNATRule(r1))
-}
-
-// TestIptablesDNAT_DoubleDeleteNoUnderflow verifies a second Delete on the same
-// rule is a no-op.
-func TestIptablesDNAT_DoubleDeleteNoUnderflow(t *testing.T) {
-	m := newIptRefcountManager(t, true)
-	state := m.router.ipFwdState
-
-	r1, err := m.AddDNATRule(iptDnatV6(9083))
-	require.NoError(t, err)
-	_, v6 := state.Counts()
-	require.Equal(t, 1, v6)
-
-	require.NoError(t, m.DeleteDNATRule(r1), "first delete")
-	_, v6 = state.Counts()
-	require.Equal(t, 0, v6)
-
-	require.NoError(t, m.DeleteDNATRule(r1), "second delete must be no-op")
-	_, v6 = state.Counts()
-	require.Equal(t, 0, v6, "double delete must not underflow")
-}

client/firewall/iptables/manager_linux.go

@@ -89,7 +89,7 @@ func (m *Manager) createIPv6Components(wgIface iFaceMapper, mtu uint16) error {
 	}
 
 	// Share the same IP forwarding state with the v4 router, since
-	// Forwarding refcounter is per-family but shared between v4 and v6 routers.
+	// EnableIPForwarding controls both v4 and v6 sysctls.
 	m.router6.ipFwdState = m.router.ipFwdState
 
 	m.aclMgr6, err = newAclManager(ip6Client, wgIface)
@@ -402,33 +402,17 @@ func (m *Manager) SetLogLevel(log.Level) {
 }
 
 func (m *Manager) EnableRouting() error {
-	if err := m.router.ipFwdState.RequestForwarding(false); err != nil {
-		return fmt.Errorf("enable IPv4 forwarding: %w", err)
-	}
-	// v6 only when the overlay actually has v6.
-	if m.router6 == nil {
-		return nil
-	}
-	if err := m.router.ipFwdState.RequestForwarding(true); err != nil {
-		if rerr := m.router.ipFwdState.ReleaseForwarding(false); rerr != nil {
-			log.Warnf("rollback v4 forwarding: %v", rerr)
-		}
-		return fmt.Errorf("enable IPv6 forwarding: %w", err)
+	if err := m.router.ipFwdState.RequestForwarding(); err != nil {
+		return fmt.Errorf("enable IP forwarding: %w", err)
 	}
 	return nil
 }
 
 func (m *Manager) DisableRouting() error {
-	var merr *multierror.Error
-	if err := m.router.ipFwdState.ReleaseForwarding(false); err != nil {
-		merr = multierror.Append(merr, fmt.Errorf("disable IPv4 forwarding: %w", err))
+	if err := m.router.ipFwdState.ReleaseForwarding(); err != nil {
+		return fmt.Errorf("disable IP forwarding: %w", err)
 	}
-	if m.router6 != nil {
-		if err := m.router.ipFwdState.ReleaseForwarding(true); err != nil {
-			merr = multierror.Append(merr, fmt.Errorf("disable IPv6 forwarding: %w", err))
-		}
-	}
-	return nberrors.FormatErrorOrNil(merr)
+	return nil
 }
 
 // AddDNATRule adds a DNAT rule

client/firewall/iptables/router_linux.go

@@ -101,7 +101,7 @@ func newRouter(iptablesClient *iptables.IPTables, wgIface iFaceMapper, mtu uint1
 		wgIface:        wgIface,
 		mtu:            mtu,
 		v6:             iptablesClient.Proto() == iptables.ProtocolIPv6,
-		ipFwdState:     ipfwdstate.NewIPForwardingState(wgIface.Name()),
+		ipFwdState:     ipfwdstate.NewIPForwardingState(),
 	}
 
 	r.ipsetCounter = refcounter.New(
@@ -763,6 +763,10 @@ func (r *router) updateState() {
 }
 
 func (r *router) AddDNATRule(rule firewall.ForwardRule) (firewall.Rule, error) {
+	if err := r.ipFwdState.RequestForwarding(); err != nil {
+		return nil, err
+	}
+
 	ruleKey := rule.ID()
 	if _, exists := r.rules[ruleKey+dnatSuffix]; exists {
 		return rule, nil
@@ -837,16 +841,6 @@ func (r *router) AddDNATRule(rule firewall.ForwardRule) (firewall.Rule, error) {
 		r.rules[key] = ruleInfo.rule
 	}
 
-	if err := r.ipFwdState.RequestForwarding(r.v6); err != nil {
-		if rollbackErr := r.rollbackRules(rules); rollbackErr != nil {
-			log.Errorf("rollback failed: %v", rollbackErr)
-		}
-		for key := range rules {
-			delete(r.rules, key)
-		}
-		return nil, fmt.Errorf("enable forwarding: %w", err)
-	}
-
 	r.updateState()
 	return rule, nil
 }
@@ -867,15 +861,12 @@ func (r *router) rollbackRules(rules map[string]ruleInfo) error {
 }
 
 func (r *router) DeleteDNATRule(rule firewall.Rule) error {
-	ruleKey := rule.ID()
-
-	_, hadDNAT := r.rules[ruleKey+dnatSuffix]
-	_, hadSNAT := r.rules[ruleKey+snatSuffix]
-	_, hadFWD := r.rules[ruleKey+fwdSuffix]
-	if !hadDNAT && !hadSNAT && !hadFWD {
-		return nil
+	if err := r.ipFwdState.ReleaseForwarding(); err != nil {
+		log.Errorf("%v", err)
 	}
 
+	ruleKey := rule.ID()
+
 	var merr *multierror.Error
 	if dnatRule, exists := r.rules[ruleKey+dnatSuffix]; exists {
 		if err := r.iptablesClient.Delete(tableNat, chainRTRDR, dnatRule...); err != nil {
@@ -898,10 +889,6 @@ func (r *router) DeleteDNATRule(rule firewall.Rule) error {
 		delete(r.rules, ruleKey+fwdSuffix)
 	}
 
-	if err := r.ipFwdState.ReleaseForwarding(r.v6); err != nil {
-		log.Errorf("%v", err)
-	}
-
 	r.updateState()
 	return nberrors.FormatErrorOrNil(merr)
 }

client/firewall/nftables/dnat_refcount_linux_test.go

@@ -1,208 +0,0 @@
-package nftables
-
-import (
-	"net/netip"
-	"testing"
-
-	"github.com/stretchr/testify/require"
-
-	fw "github.com/netbirdio/netbird/client/firewall/manager"
-	"github.com/netbirdio/netbird/client/iface"
-	"github.com/netbirdio/netbird/client/iface/wgaddr"
-)
-
-func nftRefcountIfaceV4() *iFaceMock {
-	return &iFaceMock{
-		NameFunc: func() string { return "wt-refcount" },
-		AddressFunc: func() wgaddr.Address {
-			return wgaddr.Address{
-				IP:      netip.MustParseAddr("100.96.0.1"),
-				Network: netip.MustParsePrefix("100.96.0.0/16"),
-			}
-		},
-	}
-}
-
-func nftRefcountIfaceDual() *iFaceMock {
-	return &iFaceMock{
-		NameFunc: func() string { return "wt-refcount" },
-		AddressFunc: func() wgaddr.Address {
-			return wgaddr.Address{
-				IP:      netip.MustParseAddr("100.96.0.1"),
-				Network: netip.MustParsePrefix("100.96.0.0/16"),
-				IPv6:    netip.MustParseAddr("fd00::1"),
-				IPv6Net: netip.MustParsePrefix("fd00::/64"),
-			}
-		},
-	}
-}
-
-func newNftRefcountManager(t *testing.T, dual bool) *Manager {
-	t.Helper()
-	if check() != NFTABLES {
-		t.Skip("nftables not supported on this system")
-	}
-	var ifMock *iFaceMock
-	if dual {
-		ifMock = nftRefcountIfaceDual()
-	} else {
-		ifMock = nftRefcountIfaceV4()
-	}
-	m, err := Create(ifMock, iface.DefaultMTU)
-	require.NoError(t, err, "create manager")
-	require.NoError(t, m.Init(nil), "init manager")
-	t.Cleanup(func() {
-		require.NoError(t, m.Close(nil), "close manager")
-	})
-	return m
-}
-
-func dnatV4(port uint16) fw.ForwardRule {
-	return fw.ForwardRule{
-		Protocol:          fw.ProtocolTCP,
-		DestinationPort:   fw.Port{Values: []uint16{port}},
-		TranslatedAddress: netip.MustParseAddr("100.96.0.2"),
-		TranslatedPort:    fw.Port{Values: []uint16{80}},
-	}
-}
-
-func dnatV6(port uint16) fw.ForwardRule {
-	return fw.ForwardRule{
-		Protocol:          fw.ProtocolTCP,
-		DestinationPort:   fw.Port{Values: []uint16{port}},
-		TranslatedAddress: netip.MustParseAddr("fd00::2"),
-		TranslatedPort:    fw.Port{Values: []uint16{80}},
-	}
-}
-
-// TestNftablesDNAT_RefcountBalancedV4 verifies that Add/Delete pairs leave the
-// v4 refcount at zero.
-func TestNftablesDNAT_RefcountBalancedV4(t *testing.T) {
-	m := newNftRefcountManager(t, false)
-	state := m.router.ipFwdState
-
-	r1, err := m.AddDNATRule(dnatV4(8081))
-	require.NoError(t, err, "add v4 dnat 1")
-	v4, v6 := state.Counts()
-	require.Equal(t, 1, v4, "v4 refcount after first add")
-	require.Equal(t, 0, v6, "v6 refcount unchanged")
-
-	r2, err := m.AddDNATRule(dnatV4(8082))
-	require.NoError(t, err, "add v4 dnat 2")
-	v4, v6 = state.Counts()
-	require.Equal(t, 2, v4, "v4 refcount after second add")
-	require.Equal(t, 0, v6, "v6 refcount unchanged")
-
-	require.NoError(t, m.DeleteDNATRule(r1), "delete v4 dnat 1")
-	v4, v6 = state.Counts()
-	require.Equal(t, 1, v4, "v4 refcount after first delete")
-	require.Equal(t, 0, v6, "v6 refcount unchanged")
-
-	require.NoError(t, m.DeleteDNATRule(r2), "delete v4 dnat 2")
-	v4, v6 = state.Counts()
-	require.Equal(t, 0, v4, "v4 refcount after second delete")
-	require.Equal(t, 0, v6, "v6 refcount unchanged")
-}
-
-// TestNftablesDNAT_RefcountBalancedV6 verifies the v6 path increments v6 only
-// and decrements back to zero on Delete.
-func TestNftablesDNAT_RefcountBalancedV6(t *testing.T) {
-	m := newNftRefcountManager(t, true)
-	require.NotNil(t, m.router6, "v6 router")
-	require.Same(t, m.router.ipFwdState, m.router6.ipFwdState, "shared state")
-	state := m.router.ipFwdState
-
-	r1, err := m.AddDNATRule(dnatV6(9091))
-	require.NoError(t, err, "add v6 dnat 1")
-	v4, v6 := state.Counts()
-	require.Equal(t, 0, v4, "v4 refcount unchanged")
-	require.Equal(t, 1, v6, "v6 refcount after first add")
-
-	r2, err := m.AddDNATRule(dnatV6(9092))
-	require.NoError(t, err, "add v6 dnat 2")
-	v4, v6 = state.Counts()
-	require.Equal(t, 0, v4)
-	require.Equal(t, 2, v6, "v6 refcount after second add")
-
-	require.NoError(t, m.DeleteDNATRule(r1), "delete v6 dnat 1")
-	v4, v6 = state.Counts()
-	require.Equal(t, 0, v4, "v4 refcount unchanged")
-	require.Equal(t, 1, v6, "v6 refcount after first delete")
-
-	require.NoError(t, m.DeleteDNATRule(r2), "delete v6 dnat 2")
-	v4, v6 = state.Counts()
-	require.Equal(t, 0, v4)
-	require.Equal(t, 0, v6, "v6 refcount after second delete")
-}
-
-// TestNftablesDNAT_DuplicateAddNoLeak verifies that a duplicate Add (same
-// ForwardRule) does not double-increment the refcount.
-func TestNftablesDNAT_DuplicateAddNoLeak(t *testing.T) {
-	m := newNftRefcountManager(t, true)
-	state := m.router.ipFwdState
-
-	rule := dnatV4(8083)
-	r1, err := m.AddDNATRule(rule)
-	require.NoError(t, err, "add v4 dnat")
-	v4, _ := state.Counts()
-	require.Equal(t, 1, v4)
-
-	// duplicate add: same rule ID, must be a no-op for the refcount.
-	_, err = m.AddDNATRule(rule)
-	require.NoError(t, err, "duplicate add")
-	v4, _ = state.Counts()
-	require.Equal(t, 1, v4, "duplicate add must not increment")
-
-	require.NoError(t, m.DeleteDNATRule(r1), "delete v4 dnat")
-	v4, _ = state.Counts()
-	require.Equal(t, 0, v4, "single delete must drop to zero")
-}
-
-// TestNftablesDNAT_DeleteMissingNoUnderflow verifies deleting a rule that was
-// never added does not underflow the refcount.
-func TestNftablesDNAT_DeleteMissingNoUnderflow(t *testing.T) {
-	m := newNftRefcountManager(t, true)
-	state := m.router.ipFwdState
-
-	// Construct a Rule reference for something never added. The router stores
-	// rules by ID(), and DeleteDNATRule looks them up in r.rules; a missing
-	// entry must be a no-op rather than calling Release.
-	phantom := dnatV4(8099)
-	require.NoError(t, m.DeleteDNATRule(&phantom), "delete missing v4 dnat")
-	v4, v6 := state.Counts()
-	require.Equal(t, 0, v4, "v4 refcount unaffected by missing delete")
-	require.Equal(t, 0, v6, "v6 refcount unaffected")
-
-	phantom6 := dnatV6(9099)
-	require.NoError(t, m.DeleteDNATRule(&phantom6), "delete missing v6 dnat")
-	v4, v6 = state.Counts()
-	require.Equal(t, 0, v4)
-	require.Equal(t, 0, v6, "v6 refcount unaffected by missing delete")
-
-	// And after a phantom delete, a real add still results in count=1.
-	r1, err := m.AddDNATRule(dnatV4(8100))
-	require.NoError(t, err, "add v4 dnat after phantom delete")
-	v4, _ = state.Counts()
-	require.Equal(t, 1, v4, "real add still increments after phantom delete")
-	require.NoError(t, m.DeleteDNATRule(r1))
-}
-
-// TestNftablesDNAT_DoubleDeleteNoUnderflow verifies that deleting the same rule
-// twice does not underflow the refcount (the second delete is a no-op).
-func TestNftablesDNAT_DoubleDeleteNoUnderflow(t *testing.T) {
-	m := newNftRefcountManager(t, true)
-	state := m.router.ipFwdState
-
-	r1, err := m.AddDNATRule(dnatV6(9093))
-	require.NoError(t, err)
-	_, v6 := state.Counts()
-	require.Equal(t, 1, v6)
-
-	require.NoError(t, m.DeleteDNATRule(r1), "first delete")
-	_, v6 = state.Counts()
-	require.Equal(t, 0, v6)
-
-	require.NoError(t, m.DeleteDNATRule(r1), "second delete must be no-op")
-	_, v6 = state.Counts()
-	require.Equal(t, 0, v6, "double delete must not underflow")
-}

client/firewall/nftables/external_chain_monitor_linux.go

@@ -52,10 +52,9 @@ func (m *externalChainMonitor) start() {
 
 	ctx, cancel := context.WithCancel(context.Background())
 	m.cancel = cancel
-	done := make(chan struct{})
-	m.done = done
+	m.done = make(chan struct{})
 
-	go m.run(ctx, done)
+	go m.run(ctx)
 }
 
 func (m *externalChainMonitor) stop() {
@@ -73,8 +72,8 @@ func (m *externalChainMonitor) stop() {
 	<-done
 }
 
-func (m *externalChainMonitor) run(ctx context.Context, done chan struct{}) {
-	defer close(done)
+func (m *externalChainMonitor) run(ctx context.Context) {
+	defer close(m.done)
 
 	bo := &backoff.ExponentialBackOff{
 		InitialInterval:     externalMonitorInitInterval,

client/firewall/nftables/manager_linux.go

@@ -105,8 +105,8 @@ func (m *Manager) createIPv6Components(tableName string, wgIface iFaceMapper, mt
 		return fmt.Errorf("create v6 router: %w", err)
 	}
 
-	// Share the per-family forwarding refcounter with the v4 router so a v4
-	// rule and a v6 rule against the same state machine cooperate cleanly.
+	// Share the same IP forwarding state with the v4 router, since
+	// EnableIPForwarding controls both v4 and v6 sysctls.
 	m.router6.ipFwdState = m.router.ipFwdState
 
 	m.aclManager6, err = newAclManager(workTable6, wgIface, chainNameRoutingFw)
@@ -530,33 +530,17 @@ func (m *Manager) SetLogLevel(log.Level) {
 }
 
 func (m *Manager) EnableRouting() error {
-	if err := m.router.ipFwdState.RequestForwarding(false); err != nil {
-		return fmt.Errorf("enable IPv4 forwarding: %w", err)
-	}
-	// v6 only when the overlay actually has v6.
-	if m.router6 == nil {
-		return nil
-	}
-	if err := m.router.ipFwdState.RequestForwarding(true); err != nil {
-		if rerr := m.router.ipFwdState.ReleaseForwarding(false); rerr != nil {
-			log.Warnf("rollback v4 forwarding: %v", rerr)
-		}
-		return fmt.Errorf("enable IPv6 forwarding: %w", err)
+	if err := m.router.ipFwdState.RequestForwarding(); err != nil {
+		return fmt.Errorf("enable IP forwarding: %w", err)
 	}
 	return nil
 }
 
 func (m *Manager) DisableRouting() error {
-	var merr *multierror.Error
-	if err := m.router.ipFwdState.ReleaseForwarding(false); err != nil {
-		merr = multierror.Append(merr, fmt.Errorf("disable IPv4 forwarding: %w", err))
+	if err := m.router.ipFwdState.ReleaseForwarding(); err != nil {
+		return fmt.Errorf("disable IP forwarding: %w", err)
 	}
-	if m.router6 != nil {
-		if err := m.router.ipFwdState.ReleaseForwarding(true); err != nil {
-			merr = multierror.Append(merr, fmt.Errorf("disable IPv6 forwarding: %w", err))
-		}
-	}
-	return nberrors.FormatErrorOrNil(merr)
+	return nil
 }
 
 // Flush rule/chain/set operations from the buffer

client/firewall/nftables/router_linux.go

@@ -93,7 +93,7 @@ func newRouter(workTable *nftables.Table, wgIface iFaceMapper, mtu uint16) (*rou
 		rules:      make(map[string]*nftables.Rule),
 		af:         familyForAddr(workTable.Family == nftables.TableFamilyIPv4),
 		wgIface:    wgIface,
-		ipFwdState: ipfwdstate.NewIPForwardingState(wgIface.Name()),
+		ipFwdState: ipfwdstate.NewIPForwardingState(),
 		mtu:        mtu,
 	}
 
@@ -1550,6 +1550,10 @@ func (r *router) refreshRulesMap() error {
 }
 
 func (r *router) AddDNATRule(rule firewall.ForwardRule) (firewall.Rule, error) {
+	if err := r.ipFwdState.RequestForwarding(); err != nil {
+		return nil, err
+	}
+
 	ruleKey := rule.ID()
 	if _, exists := r.rules[ruleKey+dnatSuffix]; exists {
 		return rule, nil
@@ -1560,18 +1564,7 @@ func (r *router) AddDNATRule(rule firewall.ForwardRule) (firewall.Rule, error) {
 		return nil, fmt.Errorf("convert protocol to number: %w", err)
 	}
 
-	// Request forwarding before queueing rules: addDnatRedirect/addDnatMasq
-	// buffer netlink messages on r.conn that the next caller's Flush would
-	// commit if we returned without flushing them ourselves.
-	v6 := r.af.tableFamily == nftables.TableFamilyIPv6
-	if err := r.ipFwdState.RequestForwarding(v6); err != nil {
-		return nil, fmt.Errorf("enable forwarding: %w", err)
-	}
-
 	if err := r.addDnatRedirect(rule, protoNum, ruleKey); err != nil {
-		if rerr := r.ipFwdState.ReleaseForwarding(v6); rerr != nil {
-			log.Warnf("rollback forwarding refcount: %v", rerr)
-		}
 		return nil, err
 	}
 
@@ -1583,11 +1576,6 @@ func (r *router) AddDNATRule(rule firewall.ForwardRule) (firewall.Rule, error) {
 	// TODO: find chains with drop policies and add rules there
 
 	if err := r.conn.Flush(); err != nil {
-		if rerr := r.ipFwdState.ReleaseForwarding(v6); rerr != nil {
-			log.Warnf("rollback forwarding refcount: %v", rerr)
-		}
-		delete(r.rules, ruleKey+dnatSuffix)
-		delete(r.rules, ruleKey+snatSuffix)
 		return nil, fmt.Errorf("flush rules: %w", err)
 	}
 
@@ -1790,18 +1778,16 @@ func (r *router) addDnatMasq(rule firewall.ForwardRule, protoNum uint8, ruleKey
 }
 
 func (r *router) DeleteDNATRule(rule firewall.Rule) error {
+	if err := r.ipFwdState.ReleaseForwarding(); err != nil {
+		log.Errorf("%v", err)
+	}
+
 	ruleKey := rule.ID()
 
 	if err := r.refreshRulesMap(); err != nil {
 		return fmt.Errorf(refreshRulesMapError, err)
 	}
 
-	_, hadDNAT := r.rules[ruleKey+dnatSuffix]
-	_, hadSNAT := r.rules[ruleKey+snatSuffix]
-	if !hadDNAT && !hadSNAT {
-		return nil
-	}
-
 	var merr *multierror.Error
 	var needsFlush bool
 
@@ -1838,10 +1824,6 @@ func (r *router) DeleteDNATRule(rule firewall.Rule) error {
 		delete(r.rules, ruleKey+snatSuffix)
 	}
 
-	if err := r.ipFwdState.ReleaseForwarding(r.af.tableFamily == nftables.TableFamilyIPv6); err != nil {
-		log.Errorf("%v", err)
-	}
-
 	return nberrors.FormatErrorOrNil(merr)
 }
 

client/installer.nsis

@@ -260,15 +260,23 @@ WriteRegStr ${REG_ROOT} "${UNINSTALL_PATH}"  "Publisher" "${COMP_NAME}"
 
 WriteRegStr ${REG_ROOT} "${UI_REG_APP_PATH}" "" "$INSTDIR\${UI_APP_EXE}"
 
-; Create autostart registry entry based on checkbox
+; Drop Run, App Paths and Uninstall entries left in the 32-bit registry view
+; or HKCU by legacy installers.
+DetailPrint "Cleaning legacy 32-bit / HKCU entries..."
+DeleteRegValue HKCU "${AUTOSTART_REG_KEY}" "${APP_NAME}"
+SetRegView 32
+DeleteRegValue HKLM "${AUTOSTART_REG_KEY}" "${APP_NAME}"
+DeleteRegKey HKLM "${REG_APP_PATH}"
+DeleteRegKey HKLM "${UI_REG_APP_PATH}"
+DeleteRegKey HKLM "${UNINSTALL_PATH}"
+SetRegView 64
+
 DetailPrint "Autostart enabled: $AutostartEnabled"
 ${If} $AutostartEnabled == "1"
     WriteRegStr HKLM "${AUTOSTART_REG_KEY}" "${APP_NAME}" '"$INSTDIR\${UI_APP_EXE}.exe"'
     DetailPrint "Added autostart registry entry: $INSTDIR\${UI_APP_EXE}.exe"
 ${Else}
     DeleteRegValue HKLM "${AUTOSTART_REG_KEY}" "${APP_NAME}"
-    ; Legacy: pre-HKLM installs wrote to HKCU; clean that up too.
-    DeleteRegValue HKCU "${AUTOSTART_REG_KEY}" "${APP_NAME}"
     DetailPrint "Autostart not enabled by user"
 ${EndIf}
 
@@ -299,11 +307,16 @@ ExecWait '"$INSTDIR\${MAIN_APP_EXE}" service uninstall'
 DetailPrint "Terminating Netbird UI process..."
 ExecWait `taskkill /im ${UI_APP_EXE}.exe /f`
 
-; Remove autostart registry entry
+; Remove autostart entries from every view a previous installer may have used.
 DetailPrint "Removing autostart registry entry if exists..."
 DeleteRegValue HKLM "${AUTOSTART_REG_KEY}" "${APP_NAME}"
-; Legacy: pre-HKLM installs wrote to HKCU; clean that up too.
 DeleteRegValue HKCU "${AUTOSTART_REG_KEY}" "${APP_NAME}"
+SetRegView 32
+DeleteRegValue HKLM "${AUTOSTART_REG_KEY}" "${APP_NAME}"
+DeleteRegKey HKLM "${REG_APP_PATH}"
+DeleteRegKey HKLM "${UI_REG_APP_PATH}"
+DeleteRegKey HKLM "${UNINSTALL_PATH}"
+SetRegView 64
 
 ; Handle data deletion based on checkbox
 DetailPrint "Checking if user requested data deletion..."

client/internal/auth/auth.go

@@ -315,6 +315,7 @@ func (a *Auth) setSystemInfoFlags(info *system.Info) {
 		a.config.RosenpassEnabled,
 		a.config.RosenpassPermissive,
 		a.config.ServerSSHAllowed,
+		a.config.ServerVNCAllowed,
 		a.config.DisableClientRoutes,
 		a.config.DisableServerRoutes,
 		a.config.DisableDNS,

client/internal/connect.go

@@ -562,6 +562,7 @@ func createEngineConfig(key wgtypes.Key, config *profilemanager.Config, peerConf
 		RosenpassEnabled:              config.RosenpassEnabled,
 		RosenpassPermissive:           config.RosenpassPermissive,
 		ServerSSHAllowed:              util.ReturnBoolWithDefaultTrue(config.ServerSSHAllowed),
+		ServerVNCAllowed:              config.ServerVNCAllowed != nil && *config.ServerVNCAllowed,
 		EnableSSHRoot:                 config.EnableSSHRoot,
 		EnableSSHSFTP:                 config.EnableSSHSFTP,
 		EnableSSHLocalPortForwarding:  config.EnableSSHLocalPortForwarding,
@@ -644,6 +645,7 @@ func loginToManagement(ctx context.Context, client mgm.Client, pubSSHKey []byte,
 		config.RosenpassEnabled,
 		config.RosenpassPermissive,
 		config.ServerSSHAllowed,
+		config.ServerVNCAllowed,
 		config.DisableClientRoutes,
 		config.DisableServerRoutes,
 		config.DisableDNS,

client/internal/debug/debug.go

@@ -636,6 +636,9 @@ func (g *BundleGenerator) addCommonConfigFields(configContent *strings.Builder)
 	if g.internalConfig.SSHJWTCacheTTL != nil {
 		configContent.WriteString(fmt.Sprintf("SSHJWTCacheTTL: %d\n", *g.internalConfig.SSHJWTCacheTTL))
 	}
+	if g.internalConfig.ServerVNCAllowed != nil {
+		configContent.WriteString(fmt.Sprintf("ServerVNCAllowed: %v\n", *g.internalConfig.ServerVNCAllowed))
+	}
 
 	configContent.WriteString(fmt.Sprintf("DisableClientRoutes: %v\n", g.internalConfig.DisableClientRoutes))
 	configContent.WriteString(fmt.Sprintf("DisableServerRoutes: %v\n", g.internalConfig.DisableServerRoutes))

client/internal/debug/debug_linux.go

@@ -844,10 +844,6 @@ func collectSysctls() string {
 		[]string{"net.ipv4.conf.all.src_valid_mark", "net.ipv4.conf.default.src_valid_mark"},
 		listInterfaceSysctls("ipv4", "src_valid_mark")...,
 	))
-	writeSysctlGroup(&builder, "accept_ra", append(
-		[]string{"net.ipv6.conf.all.accept_ra", "net.ipv6.conf.default.accept_ra"},
-		listInterfaceSysctls("ipv6", "accept_ra")...,
-	))
 	writeSysctlGroup(&builder, "conntrack", []string{
 		"net.netfilter.nf_conntrack_acct",
 		"net.netfilter.nf_conntrack_tcp_loose",

client/internal/debug/debug_test.go

@@ -862,6 +862,7 @@ func TestAddConfig_AllFieldsCovered(t *testing.T) {
 		RosenpassEnabled:              true,
 		RosenpassPermissive:           true,
 		ServerSSHAllowed:              &bTrue,
+		ServerVNCAllowed:              &bTrue,
 		EnableSSHRoot:                 &bTrue,
 		EnableSSHSFTP:                 &bTrue,
 		EnableSSHLocalPortForwarding:  &bTrue,

client/internal/engine.go

@@ -123,6 +123,7 @@ type EngineConfig struct {
 	RosenpassPermissive bool
 
 	ServerSSHAllowed              bool
+	ServerVNCAllowed              bool
 	EnableSSHRoot                 *bool
 	EnableSSHSFTP                 *bool
 	EnableSSHLocalPortForwarding  *bool
@@ -205,6 +206,7 @@ type Engine struct {
 	networkMonitor *networkmonitor.NetworkMonitor
 
 	sshServer sshServer
+	vncSrv    vncServer
 
 	statusRecorder *peer.Status
 
@@ -320,6 +322,10 @@ func (e *Engine) Stop() error {
 		log.Warnf("failed to stop SSH server: %v", err)
 	}
 
+	if err := e.stopVNCServer(); err != nil {
+		log.Warnf("failed to stop VNC server: %v", err)
+	}
+
 	e.cleanupSSHConfig()
 
 	if e.ingressGatewayMgr != nil {
@@ -1010,6 +1016,7 @@ func (e *Engine) updateChecksIfNew(checks []*mgmProto.Checks) error {
 		e.config.RosenpassEnabled,
 		e.config.RosenpassPermissive,
 		&e.config.ServerSSHAllowed,
+		&e.config.ServerVNCAllowed,
 		e.config.DisableClientRoutes,
 		e.config.DisableServerRoutes,
 		e.config.DisableDNS,
@@ -1057,6 +1064,10 @@ func (e *Engine) updateConfig(conf *mgmProto.PeerConfig) error {
 		}
 	}
 
+	if err := e.updateVNC(conf.GetSshConfig()); err != nil {
+		log.Warnf("failed handling VNC server setup: %v", err)
+	}
+
 	state := e.statusRecorder.GetLocalPeerState()
 	state.IP = e.wgInterface.Address().String()
 	state.IPv6 = e.wgInterface.Address().IPv6String()
@@ -1182,6 +1193,7 @@ func (e *Engine) receiveManagementEvents() {
 			e.config.RosenpassEnabled,
 			e.config.RosenpassPermissive,
 			&e.config.ServerSSHAllowed,
+			&e.config.ServerVNCAllowed,
 			e.config.DisableClientRoutes,
 			e.config.DisableServerRoutes,
 			e.config.DisableDNS,
@@ -1371,6 +1383,11 @@ func (e *Engine) updateNetworkMap(networkMap *mgmProto.NetworkMap) error {
 		e.updateSSHServerAuth(networkMap.GetSshAuth())
 	}
 
+	// VNC auth: always sync, including nil so cleared auth on the management
+	// side is applied locally, and so it isn't skipped on the RemotePeersIsEmpty
+	// cleanup path.
+	e.updateVNCServerAuth(networkMap.GetVncAuth())
+
 	// must set the exclude list after the peers are added. Without it the manager can not figure out the peers parameters from the store
 	excludedLazyPeers := e.toExcludedLazyPeers(forwardingRules, remotePeers)
 	e.connMgr.SetExcludeList(e.ctx, excludedLazyPeers)
@@ -1826,6 +1843,7 @@ func (e *Engine) readInitialSettings() ([]*route.Route, *nbdns.Config, bool, err
 		e.config.RosenpassEnabled,
 		e.config.RosenpassPermissive,
 		&e.config.ServerSSHAllowed,
+		&e.config.ServerVNCAllowed,
 		e.config.DisableClientRoutes,
 		e.config.DisableServerRoutes,
 		e.config.DisableDNS,

client/internal/engine_vnc.go

@@ -0,0 +1,243 @@
+package internal
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/netip"
+
+	log "github.com/sirupsen/logrus"
+
+	firewallManager "github.com/netbirdio/netbird/client/firewall/manager"
+	nftypes "github.com/netbirdio/netbird/client/internal/netflow/types"
+	sshauth "github.com/netbirdio/netbird/client/ssh/auth"
+	vncserver "github.com/netbirdio/netbird/client/vnc/server"
+	mgmProto "github.com/netbirdio/netbird/shared/management/proto"
+	sshuserhash "github.com/netbirdio/netbird/shared/sshauth"
+)
+
+const (
+	vncExternalPort uint16 = 5900
+	vncInternalPort uint16 = 25900
+)
+
+type vncServer interface {
+	Start(ctx context.Context, addr netip.AddrPort, network netip.Prefix) error
+	Stop() error
+	ActiveSessions() []vncserver.ActiveSessionInfo
+}
+
+func (e *Engine) setupVNCPortRedirection() error {
+	if e.firewall == nil || e.wgInterface == nil {
+		return nil
+	}
+
+	localAddr := e.wgInterface.Address().IP
+	if !localAddr.IsValid() {
+		return errors.New("invalid local NetBird address")
+	}
+
+	if err := e.firewall.AddInboundDNAT(localAddr, firewallManager.ProtocolTCP, vncExternalPort, vncInternalPort); err != nil {
+		return fmt.Errorf("add VNC port redirection: %w", err)
+	}
+	log.Infof("VNC port redirection: %s:%d -> %s:%d", localAddr, vncExternalPort, localAddr, vncInternalPort)
+
+	return nil
+}
+
+func (e *Engine) cleanupVNCPortRedirection() error {
+	if e.firewall == nil || e.wgInterface == nil {
+		return nil
+	}
+
+	localAddr := e.wgInterface.Address().IP
+	if !localAddr.IsValid() {
+		return errors.New("invalid local NetBird address")
+	}
+
+	if err := e.firewall.RemoveInboundDNAT(localAddr, firewallManager.ProtocolTCP, vncExternalPort, vncInternalPort); err != nil {
+		return fmt.Errorf("remove VNC port redirection: %w", err)
+	}
+
+	return nil
+}
+
+// updateVNC handles starting/stopping the VNC server based on the config flag.
+// sshConf provides the JWT identity provider config (shared with SSH).
+func (e *Engine) updateVNC(sshConf *mgmProto.SSHConfig) error {
+	if !e.config.ServerVNCAllowed {
+		if e.vncSrv != nil {
+			log.Info("VNC server disabled, stopping")
+		}
+		return e.stopVNCServer()
+	}
+
+	if e.config.BlockInbound {
+		log.Info("VNC server disabled because inbound connections are blocked")
+		return e.stopVNCServer()
+	}
+
+	if e.vncSrv != nil {
+		// Update JWT config on existing server in case management sent new config.
+		e.updateVNCServerJWT(sshConf)
+		return nil
+	}
+
+	return e.startVNCServer(sshConf)
+}
+
+func (e *Engine) startVNCServer(sshConf *mgmProto.SSHConfig) error {
+	if e.wgInterface == nil {
+		return errors.New("wg interface not initialized")
+	}
+
+	capturer, injector, ok := newPlatformVNC()
+	if !ok {
+		log.Debug("VNC server not supported on this platform")
+		return nil
+	}
+
+	netbirdIP := e.wgInterface.Address().IP
+
+	srv := vncserver.New(capturer, injector, "")
+	if vncNeedsServiceMode() {
+		log.Info("VNC: running in Session 0, enabling service mode (agent proxy)")
+		srv.SetServiceMode(true)
+	}
+
+	if protoJWT := sshConf.GetJwtConfig(); protoJWT != nil {
+		audiences := protoJWT.GetAudiences()
+		if len(audiences) == 0 && protoJWT.GetAudience() != "" {
+			audiences = []string{protoJWT.GetAudience()}
+		}
+		srv.SetJWTConfig(&vncserver.JWTConfig{
+			Issuer:       protoJWT.GetIssuer(),
+			Audiences:    audiences,
+			KeysLocation: protoJWT.GetKeysLocation(),
+			MaxTokenAge:  protoJWT.GetMaxTokenAge(),
+		})
+		log.Debugf("VNC: JWT authentication configured (issuer=%s)", protoJWT.GetIssuer())
+	}
+
+	if netstackNet := e.wgInterface.GetNet(); netstackNet != nil {
+		srv.SetNetstackNet(netstackNet)
+	}
+
+	listenAddr := netip.AddrPortFrom(netbirdIP, vncInternalPort)
+	network := e.wgInterface.Address().Network
+	if err := srv.Start(e.ctx, listenAddr, network); err != nil {
+		return fmt.Errorf("start VNC server: %w", err)
+	}
+
+	e.vncSrv = srv
+
+	if registrar, ok := e.firewall.(interface {
+		RegisterNetstackService(protocol nftypes.Protocol, port uint16)
+	}); ok {
+		registrar.RegisterNetstackService(nftypes.TCP, vncInternalPort)
+		log.Debugf("registered VNC service for TCP:%d", vncInternalPort)
+	}
+
+	if err := e.setupVNCPortRedirection(); err != nil {
+		log.Warnf("setup VNC port redirection: %v", err)
+	}
+
+	log.Info("VNC server enabled")
+	return nil
+}
+
+// updateVNCServerJWT configures the JWT validation for the VNC server using
+// the same JWT config as SSH (same identity provider).
+func (e *Engine) updateVNCServerJWT(sshConf *mgmProto.SSHConfig) {
+	if e.vncSrv == nil {
+		return
+	}
+
+	vncSrv, ok := e.vncSrv.(*vncserver.Server)
+	if !ok {
+		return
+	}
+
+	protoJWT := sshConf.GetJwtConfig()
+	if protoJWT == nil {
+		return
+	}
+
+	audiences := protoJWT.GetAudiences()
+	if len(audiences) == 0 && protoJWT.GetAudience() != "" {
+		audiences = []string{protoJWT.GetAudience()}
+	}
+
+	vncSrv.SetJWTConfig(&vncserver.JWTConfig{
+		Issuer:       protoJWT.GetIssuer(),
+		Audiences:    audiences,
+		KeysLocation: protoJWT.GetKeysLocation(),
+		MaxTokenAge:  protoJWT.GetMaxTokenAge(),
+	})
+}
+
+// updateVNCServerAuth updates VNC fine-grained access control from management.
+func (e *Engine) updateVNCServerAuth(vncAuth *mgmProto.VNCAuth) {
+	if vncAuth == nil || e.vncSrv == nil {
+		return
+	}
+
+	vncSrv, ok := e.vncSrv.(*vncserver.Server)
+	if !ok {
+		return
+	}
+
+	protoUsers := vncAuth.GetAuthorizedUsers()
+	authorizedUsers := make([]sshuserhash.UserIDHash, len(protoUsers))
+	for i, hash := range protoUsers {
+		if len(hash) != 16 {
+			log.Warnf("invalid VNC auth hash length %d, expected 16", len(hash))
+			return
+		}
+		authorizedUsers[i] = sshuserhash.UserIDHash(hash)
+	}
+
+	machineUsers := make(map[string][]uint32)
+	for osUser, indexes := range vncAuth.GetMachineUsers() {
+		machineUsers[osUser] = indexes.GetIndexes()
+	}
+
+	vncSrv.UpdateVNCAuth(&sshauth.Config{
+		UserIDClaim:     vncAuth.GetUserIDClaim(),
+		AuthorizedUsers: authorizedUsers,
+		MachineUsers:    machineUsers,
+	})
+}
+
+// GetVNCServerStatus returns whether the VNC server is running and the list
+// of active VNC sessions.
+func (e *Engine) GetVNCServerStatus() (enabled bool, sessions []vncserver.ActiveSessionInfo) {
+	if e.vncSrv == nil {
+		return false, nil
+	}
+	return true, e.vncSrv.ActiveSessions()
+}
+
+func (e *Engine) stopVNCServer() error {
+	if e.vncSrv == nil {
+		return nil
+	}
+
+	if err := e.cleanupVNCPortRedirection(); err != nil {
+		log.Warnf("cleanup VNC port redirection: %v", err)
+	}
+
+	if registrar, ok := e.firewall.(interface {
+		UnregisterNetstackService(protocol nftypes.Protocol, port uint16)
+	}); ok {
+		registrar.UnregisterNetstackService(nftypes.TCP, vncInternalPort)
+	}
+
+	log.Info("stopping VNC server")
+	err := e.vncSrv.Stop()
+	e.vncSrv = nil
+	if err != nil {
+		return fmt.Errorf("stop VNC server: %w", err)
+	}
+	return nil
+}

client/internal/engine_vnc_console_freebsd.go

@@ -0,0 +1,31 @@
+//go:build freebsd
+
+package internal
+
+import (
+	"fmt"
+
+	log "github.com/sirupsen/logrus"
+
+	vncserver "github.com/netbirdio/netbird/client/vnc/server"
+)
+
+// newConsoleVNC builds the FreeBSD console fallback: vt(4) framebuffer
+// for capture, /dev/uinput for input. The uinput device requires the
+// `uinput` kernel module (`kldload uinput`); without it, input init
+// fails and we drop to a stub injector so the user still gets a
+// view-only screen mirror.
+func newConsoleVNC() (vncserver.ScreenCapturer, vncserver.InputInjector, error) {
+	poller := vncserver.NewFBPoller("")
+	w, h := poller.Width(), poller.Height()
+	if w == 0 || h == 0 {
+		poller.Close()
+		return nil, nil, fmt.Errorf("vt framebuffer init failed (vt may not allow mmap on this driver)")
+	}
+	if inj, err := vncserver.NewUInputInjector(w, h); err == nil {
+		return poller, inj, nil
+	} else {
+		log.Infof("VNC console: uinput unavailable (%v); view-only mode. Run `kldload uinput` to enable input.", err)
+		return poller, &vncserver.StubInputInjector{}, nil
+	}
+}

client/internal/engine_vnc_console_linux.go

@@ -0,0 +1,30 @@
+//go:build linux && !android
+
+package internal
+
+import (
+	"fmt"
+
+	log "github.com/sirupsen/logrus"
+
+	vncserver "github.com/netbirdio/netbird/client/vnc/server"
+)
+
+// newConsoleVNC builds a framebuffer + uinput VNC backend for boxes
+// without a running X server. Used as the auto-fallback when
+// newPlatformVNC can't reach X. Returns an error when /dev/fb0 or
+// /dev/uinput aren't usable so the caller can drop back to a stub.
+func newConsoleVNC() (vncserver.ScreenCapturer, vncserver.InputInjector, error) {
+	poller := vncserver.NewFBPoller("")
+	w, h := poller.Width(), poller.Height()
+	if w == 0 || h == 0 {
+		poller.Close()
+		return nil, nil, fmt.Errorf("framebuffer capturer init failed (is /dev/fb0 readable?)")
+	}
+	inj, err := vncserver.NewUInputInjector(w, h)
+	if err != nil {
+		log.Debugf("uinput unavailable, falling back to view-only VNC: %v", err)
+		return poller, &vncserver.StubInputInjector{}, nil
+	}
+	return poller, inj, nil
+}

client/internal/engine_vnc_darwin.go

@@ -0,0 +1,23 @@
+//go:build darwin && !ios
+
+package internal
+
+import (
+	log "github.com/sirupsen/logrus"
+
+	vncserver "github.com/netbirdio/netbird/client/vnc/server"
+)
+
+func newPlatformVNC() (vncserver.ScreenCapturer, vncserver.InputInjector, bool) {
+	capturer := vncserver.NewMacPoller()
+	injector, err := vncserver.NewMacInputInjector()
+	if err != nil {
+		log.Debugf("VNC: macOS input injector: %v", err)
+		return capturer, &vncserver.StubInputInjector{}, true
+	}
+	return capturer, injector, true
+}
+
+func vncNeedsServiceMode() bool {
+	return false
+}

client/internal/engine_vnc_stub.go

@@ -0,0 +1,13 @@
+//go:build (!windows && !darwin && !freebsd && !(linux && !android)) || (darwin && ios)
+
+package internal
+
+import vncserver "github.com/netbirdio/netbird/client/vnc/server"
+
+func newPlatformVNC() (vncserver.ScreenCapturer, vncserver.InputInjector, bool) {
+	return nil, nil, false
+}
+
+func vncNeedsServiceMode() bool {
+	return false
+}

client/internal/engine_vnc_windows.go

@@ -0,0 +1,13 @@
+//go:build windows
+
+package internal
+
+import vncserver "github.com/netbirdio/netbird/client/vnc/server"
+
+func newPlatformVNC() (vncserver.ScreenCapturer, vncserver.InputInjector, bool) {
+	return vncserver.NewDesktopCapturer(), vncserver.NewWindowsInputInjector(), true
+}
+
+func vncNeedsServiceMode() bool {
+	return vncserver.GetCurrentSessionID() == 0
+}

client/internal/engine_vnc_x11.go

@@ -0,0 +1,35 @@
+//go:build (linux && !android) || freebsd
+
+package internal
+
+import (
+	log "github.com/sirupsen/logrus"
+
+	vncserver "github.com/netbirdio/netbird/client/vnc/server"
+)
+
+func newPlatformVNC() (vncserver.ScreenCapturer, vncserver.InputInjector, bool) {
+	// Prefer X11 when an X server is reachable. NewX11InputInjector probes
+	// DISPLAY (and /proc) eagerly, so a non-nil error here means no X.
+	injector, err := vncserver.NewX11InputInjector("")
+	if err == nil {
+		return vncserver.NewX11Poller(""), injector, true
+	}
+	log.Debugf("VNC: X11 not available: %v", err)
+
+	// Fallback for headless / pre-X states (kernel console, login manager
+	// without X, physical server in recovery): stream the framebuffer and
+	// inject input via /dev/uinput.
+	consoleCap, consoleInj, err := newConsoleVNC()
+	if err == nil {
+		log.Infof("VNC: using framebuffer console capture (%dx%d)", consoleCap.Width(), consoleCap.Height())
+		return consoleCap, consoleInj, true
+	}
+	log.Debugf("VNC: framebuffer console fallback unavailable: %v", err)
+
+	return &vncserver.StubCapturer{}, &vncserver.StubInputInjector{}, false
+}
+
+func vncNeedsServiceMode() bool {
+	return false
+}

client/internal/profilemanager/config.go

@@ -65,6 +65,7 @@ type ConfigInput struct {
 	StateFilePath                 string
 	PreSharedKey                  *string
 	ServerSSHAllowed              *bool
+	ServerVNCAllowed              *bool
 	EnableSSHRoot                 *bool
 	EnableSSHSFTP                 *bool
 	EnableSSHLocalPortForwarding  *bool
@@ -116,6 +117,7 @@ type Config struct {
 	RosenpassEnabled              bool
 	RosenpassPermissive           bool
 	ServerSSHAllowed              *bool
+	ServerVNCAllowed              *bool
 	EnableSSHRoot                 *bool
 	EnableSSHSFTP                 *bool
 	EnableSSHLocalPortForwarding  *bool
@@ -418,6 +420,21 @@ func (config *Config) apply(input ConfigInput) (updated bool, err error) {
 		updated = true
 	}
 
+	if input.ServerVNCAllowed != nil {
+		if config.ServerVNCAllowed == nil || *input.ServerVNCAllowed != *config.ServerVNCAllowed {
+			if *input.ServerVNCAllowed {
+				log.Infof("enabling VNC server")
+			} else {
+				log.Infof("disabling VNC server")
+			}
+			config.ServerVNCAllowed = input.ServerVNCAllowed
+			updated = true
+		}
+	} else if config.ServerVNCAllowed == nil {
+		config.ServerVNCAllowed = util.True()
+		updated = true
+	}
+
 	if input.EnableSSHRoot != nil && input.EnableSSHRoot != config.EnableSSHRoot {
 		if *input.EnableSSHRoot {
 			log.Infof("enabling SSH root login")

client/internal/routemanager/ipfwdstate/ipfwdstate.go

@@ -2,109 +2,54 @@ package ipfwdstate
 
 import (
 	"fmt"
-	"sync"
 
 	log "github.com/sirupsen/logrus"
 
 	"github.com/netbirdio/netbird/client/internal/routemanager/systemops"
 )
 
-// IPForwardingState tracks v4 and v6 IP-forwarding sysctl enables with
-// independent refcounts so a v4-only routing setup doesn't flip v6 sysctls.
+// IPForwardingState is a struct that keeps track of the IP forwarding state.
+// todo: read initial state of the IP forwarding from the system and reset the state based on it.
+// todo: separate v4/v6 forwarding state, since the sysctls are independent
+// (net.ipv4.ip_forward vs net.ipv6.conf.all.forwarding). Currently the nftables
+// manager shares one instance between both routers, which works only because
+// EnableIPForwarding enables both sysctls in a single call.
 type IPForwardingState struct {
-	mu sync.Mutex
-
-	v4Count int
-	v6Count int
-
-	wgIfaceName string
-	v6Saved     map[string]int
+	enabledCounter int
 }
 
-func NewIPForwardingState(wgIfaceName string) *IPForwardingState {
-	return &IPForwardingState{wgIfaceName: wgIfaceName}
+func NewIPForwardingState() *IPForwardingState {
+	return &IPForwardingState{}
 }
 
-// Counts returns the current v4 and v6 refcounts. Intended for diagnostics
-// and tests.
-func (f *IPForwardingState) Counts() (v4, v6 int) {
-	f.mu.Lock()
-	defer f.mu.Unlock()
-	return f.v4Count, f.v6Count
-}
-
-// RequestForwarding enables the family's forwarding sysctl on first request.
-func (f *IPForwardingState) RequestForwarding(v6 bool) error {
-	f.mu.Lock()
-	defer f.mu.Unlock()
-
-	if v6 {
-		return f.requestV6()
-	}
-	return f.requestV4()
-}
-
-// ReleaseForwarding decrements the family counter. The last v6 release restores
-// what enable captured. v4 stays on: net.ipv4.ip_forward is co-owned by other
-// tooling (docker, k8s, libvirt).
-func (f *IPForwardingState) ReleaseForwarding(v6 bool) error {
-	f.mu.Lock()
-	defer f.mu.Unlock()
-
-	if v6 {
-		return f.releaseV6()
-	}
-	f.releaseV4()
-	return nil
-}
-
-func (f *IPForwardingState) requestV4() error {
-	if f.v4Count == 0 {
-		if err := systemops.EnableV4IPForwarding(); err != nil {
-			return fmt.Errorf("enable IPv4 forwarding: %w", err)
-		}
-		log.Info("IPv4 forwarding enabled")
-	}
-	f.v4Count++
-	return nil
-}
-
-func (f *IPForwardingState) releaseV4() {
-	if f.v4Count > 0 {
-		f.v4Count--
-	}
-}
-
-func (f *IPForwardingState) requestV6() error {
-	if f.v6Count == 0 {
-		saved, err := systemops.EnableV6IPForwarding(f.wgIfaceName)
-		if err != nil {
-			if rerr := systemops.DisableV6IPForwarding(saved); rerr != nil {
-				log.Warnf("rollback partial v6 sysctls: %v", rerr)
-			}
-			return fmt.Errorf("enable IPv6 forwarding: %w", err)
-		}
-		f.v6Saved = saved
-		log.Info("IPv6 forwarding enabled")
-	}
-	f.v6Count++
-	return nil
-}
-
-func (f *IPForwardingState) releaseV6() error {
-	if f.v6Count == 0 {
-		return nil
-	}
-	f.v6Count--
-	if f.v6Count > 0 {
+func (f *IPForwardingState) RequestForwarding() error {
+	if f.enabledCounter != 0 {
+		f.enabledCounter++
 		return nil
 	}
 
-	saved := f.v6Saved
-	f.v6Saved = nil
-	if err := systemops.DisableV6IPForwarding(saved); err != nil {
-		return fmt.Errorf("disable IPv6 forwarding: %w", err)
+	if err := systemops.EnableIPForwarding(); err != nil {
+		return fmt.Errorf("failed to enable IP forwarding with sysctl: %w", err)
 	}
-	log.Info("IPv6 forwarding disabled")
+	f.enabledCounter = 1
+	log.Info("IP forwarding enabled")
+
+	return nil
+}
+
+func (f *IPForwardingState) ReleaseForwarding() error {
+	if f.enabledCounter == 0 {
+		return nil
+	}
+
+	if f.enabledCounter > 1 {
+		f.enabledCounter--
+		return nil
+	}
+
+	// if failed to disable IP forwarding we anyway decrement the counter
+	f.enabledCounter = 0
+
+	// todo call systemops.DisableIPForwarding()
 	return nil
 }

client/internal/routemanager/systemops/systemops_android.go

@@ -32,17 +32,8 @@ func (r *SysOps) removeFromRouteTable(netip.Prefix, Nexthop) error {
 	return nil
 }
 
-func EnableV4IPForwarding() error {
-	log.Infof("Enable IPv4 forwarding is not implemented on %s", runtime.GOOS)
-	return nil
-}
-
-func EnableV6IPForwarding(string) (map[string]int, error) {
-	log.Infof("Enable IPv6 forwarding is not implemented on %s", runtime.GOOS)
-	return map[string]int{}, nil
-}
-
-func DisableV6IPForwarding(map[string]int) error {
+func EnableIPForwarding() error {
+	log.Infof("Enable IP forwarding is not implemented on %s", runtime.GOOS)
 	return nil
 }
 

client/internal/routemanager/systemops/systemops_ios.go

@@ -58,17 +58,8 @@ func (r *SysOps) removeFromRouteTable(netip.Prefix, Nexthop) error {
 	return nil
 }
 
-func EnableV4IPForwarding() error {
-	log.Infof("Enable IPv4 forwarding is not implemented on %s", runtime.GOOS)
-	return nil
-}
-
-func EnableV6IPForwarding(string) (map[string]int, error) {
-	log.Infof("Enable IPv6 forwarding is not implemented on %s", runtime.GOOS)
-	return map[string]int{}, nil
-}
-
-func DisableV6IPForwarding(map[string]int) error {
+func EnableIPForwarding() error {
+	log.Infof("Enable IP forwarding is not implemented on %s", runtime.GOOS)
 	return nil
 }
 

client/internal/routemanager/systemops/systemops_linux.go

@@ -763,10 +763,13 @@ func flushRoutes(tableID, family int) error {
 	return nberrors.FormatErrorOrNil(result)
 }
 
-func EnableV4IPForwarding() error {
+func EnableIPForwarding() error {
 	if _, err := sysctl.Set(ipv4ForwardingPath, 1, false); err != nil {
 		return err
 	}
+	if _, err := sysctl.Set(ipv6ForwardingPath, 1, false); err != nil {
+		log.Warnf("failed to enable IPv6 forwarding: %v", err)
+	}
 	return nil
 }
 

client/internal/routemanager/systemops/systemops_nonlinux.go

@@ -43,17 +43,8 @@ func (r *SysOps) RemoveVPNRoute(prefix netip.Prefix, intf *net.Interface) error
 	return r.genericRemoveVPNRoute(prefix, intf)
 }
 
-func EnableV4IPForwarding() error {
-	log.Infof("Enable IPv4 forwarding is not implemented on %s", runtime.GOOS)
-	return nil
-}
-
-func EnableV6IPForwarding(string) (map[string]int, error) {
-	log.Infof("Enable IPv6 forwarding is not implemented on %s", runtime.GOOS)
-	return map[string]int{}, nil
-}
-
-func DisableV6IPForwarding(map[string]int) error {
+func EnableIPForwarding() error {
+	log.Infof("Enable IP forwarding is not implemented on %s", runtime.GOOS)
 	return nil
 }
 

client/internal/routemanager/systemops/v6forwarding_linux.go

@@ -1,82 +0,0 @@
-//go:build !android
-
-package systemops
-
-import (
-	"fmt"
-	"net"
-	"os"
-
-	"github.com/hashicorp/go-multierror"
-	log "github.com/sirupsen/logrus"
-
-	nberrors "github.com/netbirdio/netbird/client/errors"
-	"github.com/netbirdio/netbird/client/internal/routemanager/sysctl"
-)
-
-const (
-	// 1 (default) accepts RAs only while forwarding is off; 2 keeps RA
-	// acceptance on regardless, so RA-installed host defaults survive our
-	// v6 forwarding flip.
-	acceptRAInterfacePath  = "net.ipv6.conf.%s.accept_ra"
-	acceptRAProcPathFormat = "/proc/sys/net/ipv6/conf/%s/accept_ra"
-)
-
-// EnableV6IPForwarding bumps accept_ra=2 on host v6 interfaces before flipping
-// forwarding=1, so RA-installed host defaults survive. Returns the prior values
-// of sysctls we actually changed; entries already at the target are omitted.
-func EnableV6IPForwarding(wgIfaceName string) (map[string]int, error) {
-	saved := map[string]int{}
-	bumpAcceptRA(saved, wgIfaceName)
-
-	oldVal, err := sysctl.Set(ipv6ForwardingPath, 1, false)
-	if err != nil {
-		return saved, err
-	}
-	if oldVal != 1 {
-		saved[ipv6ForwardingPath] = oldVal
-	}
-	return saved, nil
-}
-
-// DisableV6IPForwarding restores what EnableV6IPForwarding captured.
-func DisableV6IPForwarding(saved map[string]int) error {
-	var result *multierror.Error
-	for key, value := range saved {
-		if _, err := sysctl.Set(key, value, false); err != nil {
-			result = multierror.Append(result, fmt.Errorf("restore %s: %w", key, err))
-		}
-	}
-	return nberrors.FormatErrorOrNil(result)
-}
-
-func bumpAcceptRA(saved map[string]int, wgIfaceName string) {
-	interfaces, err := net.Interfaces()
-	if err != nil {
-		log.Warnf("list interfaces for accept_ra: %v", err)
-		return
-	}
-	for _, intf := range interfaces {
-		if intf.Name == "lo" || intf.Name == wgIfaceName {
-			continue
-		}
-		bumpAcceptRAForInterface(saved, intf.Name)
-	}
-}
-
-func bumpAcceptRAForInterface(saved map[string]int, name string) {
-	key := fmt.Sprintf(acceptRAInterfacePath, name)
-	// Build procfs path from name, not the dotted key: VLAN names like eth0.100.
-	if _, err := os.Stat(fmt.Sprintf(acceptRAProcPathFormat, name)); err != nil {
-		return
-	}
-	// onlyIfOne=true: leave admin overrides (0, 2) alone.
-	oldVal, err := sysctl.Set(key, 2, true)
-	if err != nil {
-		log.Warnf("bump %s: %v", key, err)
-		return
-	}
-	if oldVal != 2 {
-		saved[key] = oldVal
-	}
-}

client/internal/sleep/detector_darwin.go

@@ -188,9 +188,7 @@ func (d *Detector) triggerCallback(event EventType, cb func(event EventType), do
 	}
 
 	doneChan := make(chan struct{})
-	// macOS forces sleep ~30s after kIOMessageSystemWillSleep, so block long
-	// enough for teardown to finish while staying under that deadline.
-	timeout := time.NewTimer(20 * time.Second)
+	timeout := time.NewTimer(500 * time.Millisecond)
 	defer timeout.Stop()
 
 	go func() {

client/internal/statemanager/manager.go

@@ -74,6 +74,14 @@ func New(filePath string) *Manager {
 	}
 }
 
+// FilePath returns the path of the underlying state file.
+func (m *Manager) FilePath() string {
+	if m == nil {
+		return ""
+	}
+	return m.filePath
+}
+
 // Start starts the state manager periodic save routine
 func (m *Manager) Start() {
 	if m == nil {

client/netbird.wxs

@@ -64,6 +64,13 @@
 					<RegistryValue Name="InstalledByMSI" Type="integer" Value="1" KeyPath="yes" />
 				</RegistryKey>
 			</Component>
+			<!-- Drop the HKCU Run\Netbird value written by legacy NSIS installers. -->
+			<Component Id="NetbirdLegacyHKCUCleanup" Guid="*">
+				<RegistryValue Root="HKCU" Key="Software\NetBird GmbH\Installer"
+					Name="LegacyHKCUCleanup" Type="integer" Value="1" KeyPath="yes" />
+				<RemoveRegistryValue Root="HKCU"
+					Key="Software\Microsoft\Windows\CurrentVersion\Run" Name="Netbird" />
+			</Component>
 		</StandardDirectory>
 
 		<StandardDirectory Id="CommonAppDataFolder">
@@ -76,10 +83,28 @@
 			</Directory>
 		</StandardDirectory>
 
+		<!-- Drop Run, App Paths and Uninstall entries written by legacy NSIS
+		     installers into the 32-bit registry view (HKLM\Software\Wow6432Node). -->
+		<Component Id="NetbirdLegacyWow6432Cleanup" Directory="NetbirdInstallDir"
+			Guid="bda5d628-16bd-4086-b2c1-5099d8d51763" Bitness="always32">
+			<RegistryValue Root="HKLM" Key="Software\NetBird GmbH\Installer"
+				Name="LegacyWow6432Cleanup" Type="integer" Value="1" KeyPath="yes" />
+			<RemoveRegistryValue Root="HKLM"
+				Key="Software\Microsoft\Windows\CurrentVersion\Run" Name="Netbird" />
+			<RemoveRegistryKey Action="removeOnInstall" Root="HKLM"
+				Key="Software\Microsoft\Windows\CurrentVersion\App Paths\Netbird" />
+			<RemoveRegistryKey Action="removeOnInstall" Root="HKLM"
+				Key="Software\Microsoft\Windows\CurrentVersion\App Paths\Netbird-ui" />
+			<RemoveRegistryKey Action="removeOnInstall" Root="HKLM"
+				Key="Software\Microsoft\Windows\CurrentVersion\Uninstall\Netbird" />
+		</Component>
+
 		<ComponentGroup Id="NetbirdFilesComponent">
 			<ComponentRef Id="NetbirdFiles" />
 			<ComponentRef Id="NetbirdAumidRegistry" />
 			<ComponentRef Id="NetbirdAutoStart" />
+			<ComponentRef Id="NetbirdLegacyHKCUCleanup" />
+			<ComponentRef Id="NetbirdLegacyWow6432Cleanup" />
 		</ComponentGroup>
 
 		<util:CloseApplication Id="CloseNetBird" CloseMessage="no" Target="netbird.exe" RebootPrompt="no" />

client/proto/daemon.proto

@@ -205,6 +205,8 @@ message LoginRequest {
   optional bool disableSSHAuth = 38;
   optional int32 sshJWTCacheTTL = 39;
   optional bool disable_ipv6 = 40;
+
+  optional bool serverVNCAllowed = 41;
 }
 
 message LoginResponse {
@@ -314,6 +316,8 @@ message GetConfigResponse {
   int32 sshJWTCacheTTL = 26;
 
   bool disable_ipv6 = 27;
+
+  bool serverVNCAllowed = 28;
 }
 
 // PeerState contains the latest state of a peer
@@ -394,6 +398,20 @@ message SSHServerState {
   repeated SSHSessionInfo sessions = 2;
 }
 
+// VNCSessionInfo contains information about an active VNC session
+message VNCSessionInfo {
+  string remoteAddress = 1;
+  string mode = 2;
+  string username = 3;
+  string jwtUsername = 4;
+}
+
+// VNCServerState contains the latest state of the VNC server
+message VNCServerState {
+  bool enabled = 1;
+  repeated VNCSessionInfo sessions = 2;
+}
+
 // FullStatus contains the full state held by the Status instance
 message FullStatus {
   ManagementState managementState = 1;
@@ -408,6 +426,7 @@ message FullStatus {
 
   bool lazyConnectionEnabled = 9;
   SSHServerState sshServerState = 10;
+  VNCServerState vncServerState = 11;
 }
 
 // Networks
@@ -678,6 +697,8 @@ message SetConfigRequest {
   optional bool disableSSHAuth = 33;
   optional int32 sshJWTCacheTTL = 34;
   optional bool disable_ipv6 = 35;
+
+  optional bool serverVNCAllowed = 36;
 }
 
 message SetConfigResponse{}

client/server/server.go

@@ -376,6 +376,7 @@ func (s *Server) SetConfig(callerCtx context.Context, msg *proto.SetConfigReques
 	config.RosenpassPermissive = msg.RosenpassPermissive
 	config.DisableAutoConnect = msg.DisableAutoConnect
 	config.ServerSSHAllowed = msg.ServerSSHAllowed
+	config.ServerVNCAllowed = msg.ServerVNCAllowed
 	config.NetworkMonitor = msg.NetworkMonitor
 	config.DisableClientRoutes = msg.DisableClientRoutes
 	config.DisableServerRoutes = msg.DisableServerRoutes
@@ -1136,6 +1137,7 @@ func (s *Server) Status(
 		pbFullStatus := fullStatus.ToProto()
 		pbFullStatus.Events = s.statusRecorder.GetEventHistory()
 		pbFullStatus.SshServerState = s.getSSHServerState()
+		pbFullStatus.VncServerState = s.getVNCServerState()
 		statusResponse.FullStatus = pbFullStatus
 	}
 
@@ -1175,6 +1177,37 @@ func (s *Server) getSSHServerState() *proto.SSHServerState {
 	return sshServerState
 }
 
+// getVNCServerState retrieves the current VNC server state.
+func (s *Server) getVNCServerState() *proto.VNCServerState {
+	s.mutex.Lock()
+	connectClient := s.connectClient
+	s.mutex.Unlock()
+
+	if connectClient == nil {
+		return nil
+	}
+
+	engine := connectClient.Engine()
+	if engine == nil {
+		return nil
+	}
+
+	enabled, sessions := engine.GetVNCServerStatus()
+	pbSessions := make([]*proto.VNCSessionInfo, 0, len(sessions))
+	for _, sess := range sessions {
+		pbSessions = append(pbSessions, &proto.VNCSessionInfo{
+			RemoteAddress: sess.RemoteAddress,
+			Mode:          sess.Mode,
+			Username:      sess.Username,
+			JwtUsername:   sess.JWTUsername,
+		})
+	}
+	return &proto.VNCServerState{
+		Enabled:  enabled,
+		Sessions: pbSessions,
+	}
+}
+
 // GetPeerSSHHostKey retrieves SSH host key for a specific peer
 func (s *Server) GetPeerSSHHostKey(
 	ctx context.Context,
@@ -1531,6 +1564,7 @@ func (s *Server) GetConfig(ctx context.Context, req *proto.GetConfigRequest) (*p
 		Mtu:                           int64(cfg.MTU),
 		DisableAutoConnect:            cfg.DisableAutoConnect,
 		ServerSSHAllowed:              *cfg.ServerSSHAllowed,
+		ServerVNCAllowed:              cfg.ServerVNCAllowed != nil && *cfg.ServerVNCAllowed,
 		RosenpassEnabled:              cfg.RosenpassEnabled,
 		RosenpassPermissive:           cfg.RosenpassPermissive,
 		LazyConnectionEnabled:         cfg.LazyConnectionEnabled,

client/server/setconfig_test.go

@@ -58,6 +58,7 @@ func TestSetConfig_AllFieldsSaved(t *testing.T) {
 	rosenpassEnabled := true
 	rosenpassPermissive := true
 	serverSSHAllowed := true
+	serverVNCAllowed := true
 	interfaceName := "utun100"
 	wireguardPort := int64(51820)
 	preSharedKey := "test-psk"
@@ -83,6 +84,7 @@ func TestSetConfig_AllFieldsSaved(t *testing.T) {
 		RosenpassEnabled:      &rosenpassEnabled,
 		RosenpassPermissive:   &rosenpassPermissive,
 		ServerSSHAllowed:      &serverSSHAllowed,
+		ServerVNCAllowed:      &serverVNCAllowed,
 		InterfaceName:         &interfaceName,
 		WireguardPort:         &wireguardPort,
 		OptionalPreSharedKey:  &preSharedKey,
@@ -127,6 +129,8 @@ func TestSetConfig_AllFieldsSaved(t *testing.T) {
 	require.Equal(t, rosenpassPermissive, cfg.RosenpassPermissive)
 	require.NotNil(t, cfg.ServerSSHAllowed)
 	require.Equal(t, serverSSHAllowed, *cfg.ServerSSHAllowed)
+	require.NotNil(t, cfg.ServerVNCAllowed)
+	require.Equal(t, serverVNCAllowed, *cfg.ServerVNCAllowed)
 	require.Equal(t, interfaceName, cfg.WgIface)
 	require.Equal(t, int(wireguardPort), cfg.WgPort)
 	require.Equal(t, preSharedKey, cfg.PreSharedKey)
@@ -179,6 +183,7 @@ func verifyAllFieldsCovered(t *testing.T, req *proto.SetConfigRequest) {
 		"RosenpassEnabled":              true,
 		"RosenpassPermissive":           true,
 		"ServerSSHAllowed":              true,
+		"ServerVNCAllowed":              true,
 		"InterfaceName":                 true,
 		"WireguardPort":                 true,
 		"OptionalPreSharedKey":          true,
@@ -240,6 +245,7 @@ func TestCLIFlags_MappedToSetConfig(t *testing.T) {
 		"enable-rosenpass":                  "RosenpassEnabled",
 		"rosenpass-permissive":              "RosenpassPermissive",
 		"allow-server-ssh":                  "ServerSSHAllowed",
+		"allow-server-vnc":                  "ServerVNCAllowed",
 		"interface-name":                    "InterfaceName",
 		"wireguard-port":                    "WireguardPort",
 		"preshared-key":                     "OptionalPreSharedKey",

client/ssh/server/executor_windows.go

@@ -200,8 +200,8 @@ func newLsaString(s string) lsaString {
 	}
 }
 
-// generateS4UUserToken creates a Windows token using S4U authentication
-// This is the exact approach OpenSSH for Windows uses for public key authentication
+// generateS4UUserToken creates a Windows token using S4U authentication.
+// This is the same approach OpenSSH for Windows uses for public key authentication.
 func generateS4UUserToken(logger *log.Entry, username, domain string) (windows.Handle, error) {
 	userCpn := buildUserCpn(username, domain)
 

client/ssh/server/server.go

@@ -551,27 +551,7 @@ func (s *Server) checkTokenAge(token *gojwt.Token, jwtConfig *JWTConfig) error {
 		maxTokenAge = DefaultJWTMaxTokenAge
 	}
 
-	claims, ok := token.Claims.(gojwt.MapClaims)
-	if !ok {
-		userID := extractUserID(token)
-		return fmt.Errorf("token has invalid claims format (user=%s)", userID)
-	}
-
-	iat, ok := claims["iat"].(float64)
-	if !ok {
-		userID := extractUserID(token)
-		return fmt.Errorf("token missing iat claim (user=%s)", userID)
-	}
-
-	issuedAt := time.Unix(int64(iat), 0)
-	tokenAge := time.Since(issuedAt)
-	maxAge := time.Duration(maxTokenAge) * time.Second
-	if tokenAge > maxAge {
-		userID := getUserIDFromClaims(claims)
-		return fmt.Errorf("token expired for user=%s: age=%v, max=%v", userID, tokenAge, maxAge)
-	}
-
-	return nil
+	return jwt.CheckTokenAge(token, time.Duration(maxTokenAge)*time.Second)
 }
 
 func (s *Server) extractAndValidateUser(token *gojwt.Token) (*auth.UserAuth, error) {
@@ -602,27 +582,7 @@ func (s *Server) hasSSHAccess(userAuth *auth.UserAuth) bool {
 }
 
 func extractUserID(token *gojwt.Token) string {
-	if token == nil {
-		return "unknown"
-	}
-	claims, ok := token.Claims.(gojwt.MapClaims)
-	if !ok {
-		return "unknown"
-	}
-	return getUserIDFromClaims(claims)
-}
-
-func getUserIDFromClaims(claims gojwt.MapClaims) string {
-	if sub, ok := claims["sub"].(string); ok && sub != "" {
-		return sub
-	}
-	if userID, ok := claims["user_id"].(string); ok && userID != "" {
-		return userID
-	}
-	if email, ok := claims["email"].(string); ok && email != "" {
-		return email
-	}
-	return "unknown"
+	return jwt.UserIDFromToken(token)
 }
 
 func (s *Server) parseTokenWithoutValidation(tokenString string) (map[string]interface{}, error) {

client/status/status.go

@@ -131,6 +131,18 @@ type SSHServerStateOutput struct {
 	Sessions []SSHSessionOutput `json:"sessions" yaml:"sessions"`
 }
 
+type VNCSessionOutput struct {
+	RemoteAddress string `json:"remoteAddress" yaml:"remoteAddress"`
+	Mode          string `json:"mode" yaml:"mode"`
+	Username      string `json:"username,omitempty" yaml:"username,omitempty"`
+	JWTUsername   string `json:"jwtUsername,omitempty" yaml:"jwtUsername,omitempty"`
+}
+
+type VNCServerStateOutput struct {
+	Enabled  bool               `json:"enabled" yaml:"enabled"`
+	Sessions []VNCSessionOutput `json:"sessions" yaml:"sessions"`
+}
+
 type OutputOverview struct {
 	Peers                   PeersStateOutput           `json:"peers" yaml:"peers"`
 	CliVersion              string                     `json:"cliVersion" yaml:"cliVersion"`
@@ -153,6 +165,7 @@ type OutputOverview struct {
 	LazyConnectionEnabled   bool                       `json:"lazyConnectionEnabled" yaml:"lazyConnectionEnabled"`
 	ProfileName             string                     `json:"profileName" yaml:"profileName"`
 	SSHServerState          SSHServerStateOutput       `json:"sshServer" yaml:"sshServer"`
+	VNCServerState          VNCServerStateOutput       `json:"vncServer" yaml:"vncServer"`
 }
 
 // ConvertToStatusOutputOverview converts protobuf status to the output overview.
@@ -173,6 +186,7 @@ func ConvertToStatusOutputOverview(pbFullStatus *proto.FullStatus, opts ConvertO
 
 	relayOverview := mapRelays(pbFullStatus.GetRelays())
 	sshServerOverview := mapSSHServer(pbFullStatus.GetSshServerState())
+	vncServerOverview := mapVNCServer(pbFullStatus.GetVncServerState())
 	peersOverview := mapPeers(pbFullStatus.GetPeers(), opts.StatusFilter, opts.PrefixNamesFilter, opts.PrefixNamesFilterMap, opts.IPsFilter, opts.ConnectionTypeFilter)
 
 	overview := OutputOverview{
@@ -197,6 +211,7 @@ func ConvertToStatusOutputOverview(pbFullStatus *proto.FullStatus, opts ConvertO
 		LazyConnectionEnabled:   pbFullStatus.GetLazyConnectionEnabled(),
 		ProfileName:             opts.ProfileName,
 		SSHServerState:          sshServerOverview,
+		VNCServerState:          vncServerOverview,
 	}
 
 	if opts.Anonymize {
@@ -271,6 +286,25 @@ func mapSSHServer(sshServerState *proto.SSHServerState) SSHServerStateOutput {
 	}
 }
 
+func mapVNCServer(state *proto.VNCServerState) VNCServerStateOutput {
+	if state == nil {
+		return VNCServerStateOutput{Sessions: []VNCSessionOutput{}}
+	}
+	sessions := make([]VNCSessionOutput, 0, len(state.GetSessions()))
+	for _, sess := range state.GetSessions() {
+		sessions = append(sessions, VNCSessionOutput{
+			RemoteAddress: sess.GetRemoteAddress(),
+			Mode:          sess.GetMode(),
+			Username:      sess.GetUsername(),
+			JWTUsername:   sess.GetJwtUsername(),
+		})
+	}
+	return VNCServerStateOutput{
+		Enabled:  state.GetEnabled(),
+		Sessions: sessions,
+	}
+}
+
 func mapPeers(
 	peers []*proto.PeerState,
 	statusFilter string,
@@ -533,6 +567,34 @@ func (o *OutputOverview) GeneralSummary(showURL bool, showRelays bool, showNameS
 		}
 	}
 
+	vncServerStatus := "Disabled"
+	if o.VNCServerState.Enabled {
+		vncSessionCount := len(o.VNCServerState.Sessions)
+		if vncSessionCount > 0 {
+			sessionWord := "session"
+			if vncSessionCount > 1 {
+				sessionWord = "sessions"
+			}
+			vncServerStatus = fmt.Sprintf("Enabled (%d active %s)", vncSessionCount, sessionWord)
+		} else {
+			vncServerStatus = "Enabled"
+		}
+
+		if showSSHSessions && vncSessionCount > 0 {
+			for _, sess := range o.VNCServerState.Sessions {
+				var line string
+				if sess.JWTUsername != "" {
+					line = fmt.Sprintf("[%s@%s -> %s] mode=%s",
+						sess.JWTUsername, sess.RemoteAddress, sess.Username, sess.Mode)
+				} else {
+					line = fmt.Sprintf("[%s] mode=%s user=%s",
+						sess.RemoteAddress, sess.Mode, sess.Username)
+				}
+				vncServerStatus += "\n  " + line
+			}
+		}
+	}
+
 	peersCountString := fmt.Sprintf("%d/%d Connected", o.Peers.Connected, o.Peers.Total)
 
 	var forwardingRulesString string
@@ -563,6 +625,7 @@ func (o *OutputOverview) GeneralSummary(showURL bool, showRelays bool, showNameS
 			"Quantum resistance: %s\n"+
 			"Lazy connection: %s\n"+
 			"SSH Server: %s\n"+
+			"VNC Server: %s\n"+
 			"Networks: %s\n"+
 			"%s"+
 			"Peers count: %s\n",
@@ -581,6 +644,7 @@ func (o *OutputOverview) GeneralSummary(showURL bool, showRelays bool, showNameS
 		rosenpassEnabledStatus,
 		lazyConnectionEnabledStatus,
 		sshServerStatus,
+		vncServerStatus,
 		networks,
 		forwardingRulesString,
 		peersCountString,
@@ -960,6 +1024,19 @@ func anonymizeOverview(a *anonymize.Anonymizer, overview *OutputOverview) {
 		overview.Relays.Details[i] = detail
 	}
 
+	anonymizeNSServerGroups(a, overview)
+
+	for i, route := range overview.Networks {
+		overview.Networks[i] = a.AnonymizeRoute(route)
+	}
+
+	overview.FQDN = a.AnonymizeDomain(overview.FQDN)
+
+	anonymizeEvents(a, overview)
+	anonymizeServerSessions(a, overview)
+}
+
+func anonymizeNSServerGroups(a *anonymize.Anonymizer, overview *OutputOverview) {
 	for i, nsGroup := range overview.NSServerGroups {
 		for j, domain := range nsGroup.Domains {
 			overview.NSServerGroups[i].Domains[j] = a.AnonymizeDomain(domain)
@@ -971,13 +1048,9 @@ func anonymizeOverview(a *anonymize.Anonymizer, overview *OutputOverview) {
 			}
 		}
 	}
+}
 
-	for i, route := range overview.Networks {
-		overview.Networks[i] = a.AnonymizeRoute(route)
-	}
-
-	overview.FQDN = a.AnonymizeDomain(overview.FQDN)
-
+func anonymizeEvents(a *anonymize.Anonymizer, overview *OutputOverview) {
 	for i, event := range overview.Events {
 		overview.Events[i].Message = a.AnonymizeString(event.Message)
 		overview.Events[i].UserMessage = a.AnonymizeString(event.UserMessage)
@@ -986,13 +1059,21 @@ func anonymizeOverview(a *anonymize.Anonymizer, overview *OutputOverview) {
 			event.Metadata[k] = a.AnonymizeString(v)
 		}
 	}
+}
 
+func anonymizeRemoteAddress(a *anonymize.Anonymizer, addr string) string {
+	if host, port, err := net.SplitHostPort(addr); err == nil {
+		return fmt.Sprintf("%s:%s", a.AnonymizeIPString(host), port)
+	}
+	return a.AnonymizeIPString(addr)
+}
+
+func anonymizeServerSessions(a *anonymize.Anonymizer, overview *OutputOverview) {
 	for i, session := range overview.SSHServerState.Sessions {
-		if host, port, err := net.SplitHostPort(session.RemoteAddress); err == nil {
-			overview.SSHServerState.Sessions[i].RemoteAddress = fmt.Sprintf("%s:%s", a.AnonymizeIPString(host), port)
-		} else {
-			overview.SSHServerState.Sessions[i].RemoteAddress = a.AnonymizeIPString(session.RemoteAddress)
-		}
+		overview.SSHServerState.Sessions[i].RemoteAddress = anonymizeRemoteAddress(a, session.RemoteAddress)
 		overview.SSHServerState.Sessions[i].Command = a.AnonymizeString(session.Command)
 	}
+	for i, sess := range overview.VNCServerState.Sessions {
+		overview.VNCServerState.Sessions[i].RemoteAddress = anonymizeRemoteAddress(a, sess.RemoteAddress)
+	}
 }

client/status/status_test.go

@@ -240,6 +240,10 @@ var overview = OutputOverview{
 		Enabled:  false,
 		Sessions: []SSHSessionOutput{},
 	},
+	VNCServerState: VNCServerStateOutput{
+		Enabled:  false,
+		Sessions: []VNCSessionOutput{},
+	},
 }
 
 func TestConversionFromFullStatusToOutputOverview(t *testing.T) {
@@ -404,6 +408,10 @@ func TestParsingToJSON(t *testing.T) {
 		  "sshServer":{
 		    "enabled":false,
 			"sessions":[]
+		  },
+		  "vncServer":{
+		    "enabled":false,
+			"sessions":[]
 		  }
         }`
 	// @formatter:on
@@ -513,6 +521,9 @@ profileName: ""
 sshServer:
     enabled: false
     sessions: []
+vncServer:
+    enabled: false
+    sessions: []
 `
 
 	assert.Equal(t, expectedYAML, yaml)
@@ -582,6 +593,7 @@ Interface type: Kernel
 Quantum resistance: false
 Lazy connection: false
 SSH Server: Disabled
+VNC Server: Disabled
 Networks: 10.10.0.0/24
 Peers count: 2/2 Connected
 `, lastConnectionUpdate1, lastHandshake1, lastConnectionUpdate2, lastHandshake2, runtime.GOOS, runtime.GOARCH, overview.CliVersion)
@@ -607,6 +619,7 @@ Interface type: Kernel
 Quantum resistance: false
 Lazy connection: false
 SSH Server: Disabled
+VNC Server: Disabled
 Networks: 10.10.0.0/24
 Peers count: 2/2 Connected
 `

client/system/info.go

@@ -62,6 +62,7 @@ type Info struct {
 	RosenpassEnabled    bool
 	RosenpassPermissive bool
 	ServerSSHAllowed    bool
+	ServerVNCAllowed    bool
 
 	DisableClientRoutes bool
 	DisableServerRoutes bool
@@ -83,6 +84,7 @@ type Info struct {
 func (i *Info) SetFlags(
 	rosenpassEnabled, rosenpassPermissive bool,
 	serverSSHAllowed *bool,
+	serverVNCAllowed *bool,
 	disableClientRoutes, disableServerRoutes,
 	disableDNS, disableFirewall, blockLANAccess, blockInbound, disableIPv6, lazyConnectionEnabled bool,
 	enableSSHRoot, enableSSHSFTP, enableSSHLocalPortForwarding, enableSSHRemotePortForwarding *bool,
@@ -93,6 +95,9 @@ func (i *Info) SetFlags(
 	if serverSSHAllowed != nil {
 		i.ServerSSHAllowed = *serverSSHAllowed
 	}
+	if serverVNCAllowed != nil {
+		i.ServerVNCAllowed = *serverVNCAllowed
+	}
 
 	i.DisableClientRoutes = disableClientRoutes
 	i.DisableServerRoutes = disableServerRoutes

client/ui/client_ui.go

@@ -249,6 +249,7 @@ type serviceClient struct {
 	mQuit              *systray.MenuItem
 	mNetworks          *systray.MenuItem
 	mAllowSSH          *systray.MenuItem
+	mAllowVNC          *systray.MenuItem
 	mAutoConnect       *systray.MenuItem
 	mEnableRosenpass   *systray.MenuItem
 	mLazyConnEnabled   *systray.MenuItem
@@ -1045,6 +1046,7 @@ func (s *serviceClient) onTrayReady() {
 
 	s.mSettings = systray.AddMenuItem("Settings", disabledMenuDescr)
 	s.mAllowSSH = s.mSettings.AddSubMenuItemCheckbox("Allow SSH", allowSSHMenuDescr, false)
+	s.mAllowVNC = s.mSettings.AddSubMenuItemCheckbox("Allow VNC", allowVNCMenuDescr, false)
 	s.mAutoConnect = s.mSettings.AddSubMenuItemCheckbox("Connect on Startup", autoConnectMenuDescr, false)
 	s.mEnableRosenpass = s.mSettings.AddSubMenuItemCheckbox("Enable Quantum-Resistance", quantumResistanceMenuDescr, false)
 	s.mLazyConnEnabled = s.mSettings.AddSubMenuItemCheckbox("Enable Lazy Connections", lazyConnMenuDescr, false)
@@ -1452,6 +1454,7 @@ func protoConfigToConfig(cfg *proto.GetConfigResponse) *profilemanager.Config {
 
 	config.DisableAutoConnect = cfg.DisableAutoConnect
 	config.ServerSSHAllowed = &cfg.ServerSSHAllowed
+	config.ServerVNCAllowed = &cfg.ServerVNCAllowed
 	config.RosenpassEnabled = cfg.RosenpassEnabled
 	config.RosenpassPermissive = cfg.RosenpassPermissive
 	config.DisableNotifications = &cfg.DisableNotifications
@@ -1547,6 +1550,12 @@ func (s *serviceClient) loadSettings() {
 		s.mAllowSSH.Uncheck()
 	}
 
+	if cfg.ServerVNCAllowed {
+		s.mAllowVNC.Check()
+	} else {
+		s.mAllowVNC.Uncheck()
+	}
+
 	if cfg.DisableAutoConnect {
 		s.mAutoConnect.Uncheck()
 	} else {
@@ -1586,6 +1595,7 @@ func (s *serviceClient) loadSettings() {
 func (s *serviceClient) updateConfig() error {
 	disableAutoStart := !s.mAutoConnect.Checked()
 	sshAllowed := s.mAllowSSH.Checked()
+	vncAllowed := s.mAllowVNC.Checked()
 	rosenpassEnabled := s.mEnableRosenpass.Checked()
 	lazyConnectionEnabled := s.mLazyConnEnabled.Checked()
 	blockInbound := s.mBlockInbound.Checked()
@@ -1614,6 +1624,7 @@ func (s *serviceClient) updateConfig() error {
 		Username:              currUser.Username,
 		DisableAutoConnect:    &disableAutoStart,
 		ServerSSHAllowed:      &sshAllowed,
+		ServerVNCAllowed:      &vncAllowed,
 		RosenpassEnabled:      &rosenpassEnabled,
 		LazyConnectionEnabled: &lazyConnectionEnabled,
 		BlockInbound:          &blockInbound,

client/ui/const.go

@@ -2,6 +2,7 @@ package main
 
 const (
 	allowSSHMenuDescr          = "Allow SSH connections"
+	allowVNCMenuDescr          = "Allow embedded VNC server"
 	autoConnectMenuDescr       = "Connect automatically when the service starts"
 	quantumResistanceMenuDescr = "Enable post-quantum security via Rosenpass"
 	lazyConnMenuDescr          = "[Experimental] Enable lazy connections"

client/ui/event_handler.go

@@ -39,6 +39,8 @@ func (h *eventHandler) listen(ctx context.Context) {
 			h.handleDisconnectClick()
 		case <-h.client.mAllowSSH.ClickedCh:
 			h.handleAllowSSHClick()
+		case <-h.client.mAllowVNC.ClickedCh:
+			h.handleAllowVNCClick()
 		case <-h.client.mAutoConnect.ClickedCh:
 			h.handleAutoConnectClick()
 		case <-h.client.mEnableRosenpass.ClickedCh:
@@ -134,6 +136,15 @@ func (h *eventHandler) handleAllowSSHClick() {
 
 }
 
+func (h *eventHandler) handleAllowVNCClick() {
+	h.toggleCheckbox(h.client.mAllowVNC)
+	if err := h.updateConfigWithErr(); err != nil {
+		h.toggleCheckbox(h.client.mAllowVNC) // revert checkbox state on error
+		log.Errorf("failed to update config: %v", err)
+		h.client.notifier.Send("Error", "Failed to update VNC settings")
+	}
+}
+
 func (h *eventHandler) handleAutoConnectClick() {
 	h.toggleCheckbox(h.client.mAutoConnect)
 	if err := h.updateConfigWithErr(); err != nil {

client/vnc/server/agent_windows.go

@@ -0,0 +1,810 @@
+//go:build windows
+
+package server
+
+import (
+	"bufio"
+	crand "crypto/rand"
+	"encoding/binary"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"os"
+	"runtime"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+	"unsafe"
+
+	log "github.com/sirupsen/logrus"
+	"golang.org/x/sys/windows"
+)
+
+const (
+	agentPort = "15900"
+
+	// agentTokenLen is the length of the random authentication token
+	// used to verify that connections to the agent come from the service.
+	agentTokenLen = 32
+
+	stillActive = 259
+
+	tokenPrimary          = 1
+	securityImpersonation = 2
+	tokenSessionID        = 12
+
+	createUnicodeEnvironment = 0x00000400
+	createNoWindow           = 0x08000000
+	createSuspended          = 0x00000004
+	createBreakawayFromJob   = 0x01000000
+)
+
+var (
+	kernel32 = windows.NewLazySystemDLL("kernel32.dll")
+	advapi32 = windows.NewLazySystemDLL("advapi32.dll")
+	userenv  = windows.NewLazySystemDLL("userenv.dll")
+
+	procWTSGetActiveConsoleSessionId = kernel32.NewProc("WTSGetActiveConsoleSessionId")
+	procCreateJobObjectW             = kernel32.NewProc("CreateJobObjectW")
+	procSetInformationJobObject      = kernel32.NewProc("SetInformationJobObject")
+	procAssignProcessToJobObject     = kernel32.NewProc("AssignProcessToJobObject")
+	procSetTokenInformation          = advapi32.NewProc("SetTokenInformation")
+	procCreateEnvironmentBlock       = userenv.NewProc("CreateEnvironmentBlock")
+	procDestroyEnvironmentBlock      = userenv.NewProc("DestroyEnvironmentBlock")
+
+	wtsapi32                       = windows.NewLazySystemDLL("wtsapi32.dll")
+	procWTSEnumerateSessionsW      = wtsapi32.NewProc("WTSEnumerateSessionsW")
+	procWTSFreeMemory              = wtsapi32.NewProc("WTSFreeMemory")
+	procWTSQuerySessionInformation = wtsapi32.NewProc("WTSQuerySessionInformationW")
+
+	iphlpapi              = windows.NewLazySystemDLL("iphlpapi.dll")
+	procGetExtendedTcpTable = iphlpapi.NewProc("GetExtendedTcpTable")
+)
+
+// GetCurrentSessionID returns the session ID of the current process.
+func GetCurrentSessionID() uint32 {
+	var token windows.Token
+	if err := windows.OpenProcessToken(windows.CurrentProcess(),
+		windows.TOKEN_QUERY, &token); err != nil {
+		return 0
+	}
+	defer token.Close()
+	var id uint32
+	var ret uint32
+	_ = windows.GetTokenInformation(token, windows.TokenSessionId,
+		(*byte)(unsafe.Pointer(&id)), 4, &ret)
+	return id
+}
+
+func getConsoleSessionID() uint32 {
+	r, _, _ := procWTSGetActiveConsoleSessionId.Call()
+	return uint32(r)
+}
+
+const (
+	wtsActive       = 0
+	wtsConnected    = 1
+	wtsDisconnected = 4
+)
+
+// getActiveSessionID returns the session ID of the best session to attach to.
+// On a Windows Server with no console display attached, session 1 still
+// reports WTSActive (login screen "owns" the console), so a naive
+// first-active-wins pick lands on a session with no actual rendering.
+// Preference order:
+//  1. Active session with a user logged in (RDP user in session ≥2)
+//  2. Active session without a user (console at login screen)
+//  3. Console session ID
+func getActiveSessionID() uint32 {
+	var sessionInfo uintptr
+	var count uint32
+
+	r, _, _ := procWTSEnumerateSessionsW.Call(
+		0, // WTS_CURRENT_SERVER_HANDLE
+		0, // reserved
+		1, // version
+		uintptr(unsafe.Pointer(&sessionInfo)),
+		uintptr(unsafe.Pointer(&count)),
+	)
+	if r == 0 || count == 0 {
+		return getConsoleSessionID()
+	}
+	defer func() { _, _, _ = procWTSFreeMemory.Call(sessionInfo) }()
+
+	type wtsSession struct {
+		SessionID uint32
+		Station   *uint16
+		State     uint32
+	}
+	sessions := unsafe.Slice((*wtsSession)(unsafe.Pointer(sessionInfo)), count)
+
+	var withUser uint32
+	var withUserFound bool
+	var anyActive uint32
+	var anyActiveFound bool
+	for _, s := range sessions {
+		if s.SessionID == 0 {
+			continue
+		}
+		if s.State != wtsActive {
+			continue
+		}
+		if !anyActiveFound {
+			anyActive = s.SessionID
+			anyActiveFound = true
+		}
+		if !withUserFound && wtsSessionHasUser(s.SessionID) {
+			withUser = s.SessionID
+			withUserFound = true
+		}
+	}
+	if withUserFound {
+		return withUser
+	}
+	if anyActiveFound {
+		return anyActive
+	}
+	return getConsoleSessionID()
+}
+
+// reapOrphanOnPort finds any process listening on 127.0.0.1:portStr and,
+// if it's a netbird vnc-agent left over from a previous service instance,
+// terminates it. Verified by image-name match so we never kill an
+// unrelated process that happens to use the same port.
+func reapOrphanOnPort(portStr string) {
+	port64, err := strconv.ParseUint(portStr, 10, 16)
+	if err != nil {
+		return
+	}
+	port := uint16(port64)
+	pid := tcpListenerPID(port)
+	if pid == 0 || pid == uint32(windows.GetCurrentProcessId()) {
+		return
+	}
+	h, err := windows.OpenProcess(windows.PROCESS_QUERY_LIMITED_INFORMATION|windows.PROCESS_TERMINATE|windows.SYNCHRONIZE, false, pid)
+	if err != nil {
+		log.Warnf("reap on port %d: open PID=%d: %v", port, pid, err)
+		return
+	}
+	defer func() { _ = windows.CloseHandle(h) }()
+	if !isOurAgentProcess(h) {
+		log.Warnf("reap on port %d: PID=%d is not a netbird vnc-agent, leaving it alone", port, pid)
+		return
+	}
+	if err := windows.TerminateProcess(h, 0); err != nil {
+		log.Warnf("reap on port %d: terminate PID=%d: %v", port, pid, err)
+		return
+	}
+	log.Infof("reaped orphan vnc-agent PID=%d holding port %d", pid, port)
+}
+
+// isOurAgentProcess returns true if the given process handle points at a
+// netbird.exe binary at the same path as the current process. We compare
+// full paths (case-insensitive on Windows) so co-installed netbird binaries
+// from a different install dir or unrelated apps named netbird.exe don't
+// get killed.
+func isOurAgentProcess(h windows.Handle) bool {
+	var size uint32 = windows.MAX_PATH
+	buf := make([]uint16, size)
+	if err := windows.QueryFullProcessImageName(h, 0, &buf[0], &size); err != nil {
+		return false
+	}
+	target := strings.ToLower(windows.UTF16ToString(buf[:size]))
+	selfExe, err := os.Executable()
+	if err != nil {
+		return false
+	}
+	return target == strings.ToLower(selfExe)
+}
+
+// tcpListenerPID returns the PID of the process listening on 127.0.0.1:port,
+// or 0 if none. Uses GetExtendedTcpTable with TCP_TABLE_OWNER_PID_LISTENER.
+func tcpListenerPID(port uint16) uint32 {
+	const tcpTableOwnerPidListener = 3
+	const afInet = 2
+
+	// MIB_TCPROW_OWNER_PID layout: state(4) + localAddr(4) + localPort(4) +
+	// remoteAddr(4) + remotePort(4) + owningPid(4) = 24 bytes.
+	const rowSize = 24
+
+	var size uint32
+	_, _, _ = procGetExtendedTcpTable.Call(0, uintptr(unsafe.Pointer(&size)), 0, afInet, tcpTableOwnerPidListener, 0)
+	if size == 0 {
+		return 0
+	}
+	buf := make([]byte, size)
+	r, _, _ := procGetExtendedTcpTable.Call(
+		uintptr(unsafe.Pointer(&buf[0])),
+		uintptr(unsafe.Pointer(&size)),
+		0, afInet, tcpTableOwnerPidListener, 0,
+	)
+	if r != 0 {
+		return 0
+	}
+	count := binary.LittleEndian.Uint32(buf[:4])
+	for i := uint32(0); i < count; i++ {
+		off := 4 + int(i)*rowSize
+		if off+rowSize > len(buf) {
+			break
+		}
+		// localPort is stored big-endian in the high 16 bits of a 32-bit field.
+		localPort := uint16(buf[off+8])<<8 | uint16(buf[off+9])
+		if localPort != port {
+			continue
+		}
+		localAddr := binary.LittleEndian.Uint32(buf[off+4 : off+8])
+		// 0x0100007f == 127.0.0.1 in network byte order on little-endian.
+		// We accept 0.0.0.0 too in case the orphan bound to all interfaces.
+		if localAddr != 0x0100007f && localAddr != 0 {
+			continue
+		}
+		return binary.LittleEndian.Uint32(buf[off+20 : off+24])
+	}
+	return 0
+}
+
+// wtsSessionHasUser returns true if the session has a non-empty user name,
+// i.e. someone is logged in (vs. the login/Welcome screen). The console
+// session at the lock screen has WTSUserName == "".
+const wtsUserName = 5
+
+func wtsSessionHasUser(sessionID uint32) bool {
+	var buf uintptr
+	var bytesReturned uint32
+	r, _, _ := procWTSQuerySessionInformation.Call(
+		0, // WTS_CURRENT_SERVER_HANDLE
+		uintptr(sessionID),
+		uintptr(wtsUserName),
+		uintptr(unsafe.Pointer(&buf)),
+		uintptr(unsafe.Pointer(&bytesReturned)),
+	)
+	if r == 0 || buf == 0 {
+		return false
+	}
+	defer func() { _, _, _ = procWTSFreeMemory.Call(buf) }()
+	// First UTF-16 code unit non-zero ⇒ non-empty username.
+	return *(*uint16)(unsafe.Pointer(buf)) != 0
+}
+
+// getSystemTokenForSession duplicates the current SYSTEM token and sets its
+// session ID so the spawned process runs in the target session. Using a SYSTEM
+// token gives access to both Default and Winlogon desktops plus UIPI bypass.
+func getSystemTokenForSession(sessionID uint32) (windows.Token, error) {
+	var cur windows.Token
+	if err := windows.OpenProcessToken(windows.CurrentProcess(),
+		windows.MAXIMUM_ALLOWED, &cur); err != nil {
+		return 0, fmt.Errorf("OpenProcessToken: %w", err)
+	}
+	defer cur.Close()
+
+	var dup windows.Token
+	if err := windows.DuplicateTokenEx(cur, windows.MAXIMUM_ALLOWED, nil,
+		securityImpersonation, tokenPrimary, &dup); err != nil {
+		return 0, fmt.Errorf("DuplicateTokenEx: %w", err)
+	}
+
+	sid := sessionID
+	r, _, err := procSetTokenInformation.Call(
+		uintptr(dup),
+		uintptr(tokenSessionID),
+		uintptr(unsafe.Pointer(&sid)),
+		unsafe.Sizeof(sid),
+	)
+	if r == 0 {
+		dup.Close()
+		return 0, fmt.Errorf("SetTokenInformation(SessionId=%d): %w", sessionID, err)
+	}
+	return dup, nil
+}
+
+const agentTokenEnvVar = "NB_VNC_AGENT_TOKEN" // #nosec G101 -- env var name, not a credential
+
+// injectEnvVar appends a KEY=VALUE entry to a Unicode environment block.
+// The block is a sequence of null-terminated UTF-16 strings, terminated by
+// an extra null. Returns the new []uint16 backing slice; the caller must
+// hold the returned slice alive until CreateProcessAsUser completes.
+func injectEnvVar(envBlock uintptr, key, value string) []uint16 {
+	entry := key + "=" + value
+
+	// Walk the existing block to find its total length.
+	ptr := (*uint16)(unsafe.Pointer(envBlock))
+	var totalChars int
+	for {
+		ch := *(*uint16)(unsafe.Pointer(uintptr(unsafe.Pointer(ptr)) + uintptr(totalChars)*2))
+		if ch == 0 {
+			// Check for double-null terminator.
+			next := *(*uint16)(unsafe.Pointer(uintptr(unsafe.Pointer(ptr)) + uintptr(totalChars+1)*2))
+			totalChars++
+			if next == 0 {
+				// End of block (don't count the final null yet, we'll rebuild).
+				break
+			}
+		} else {
+			totalChars++
+		}
+	}
+
+	entryUTF16, _ := windows.UTF16FromString(entry)
+	// New block: existing entries + new entry (null-terminated) + final null.
+	newLen := totalChars + len(entryUTF16) + 1
+	newBlock := make([]uint16, newLen)
+	// Copy existing entries (up to but not including the final null).
+	for i := range totalChars {
+		newBlock[i] = *(*uint16)(unsafe.Pointer(uintptr(unsafe.Pointer(ptr)) + uintptr(i)*2))
+	}
+	copy(newBlock[totalChars:], entryUTF16)
+	newBlock[newLen-1] = 0 // final null terminator
+
+	return newBlock
+}
+
+func spawnAgentInSession(sessionID uint32, port string, authToken string, jobHandle windows.Handle) (windows.Handle, error) {
+	token, err := getSystemTokenForSession(sessionID)
+	if err != nil {
+		return 0, fmt.Errorf("get SYSTEM token for session %d: %w", sessionID, err)
+	}
+	defer token.Close()
+
+	var envBlock uintptr
+	r, _, e := procCreateEnvironmentBlock.Call(
+		uintptr(unsafe.Pointer(&envBlock)),
+		uintptr(token),
+		0,
+	)
+	if r == 0 {
+		// Without an environment block we cannot inject NB_VNC_AGENT_TOKEN;
+		// the agent would start unauthenticated. Abort instead of launching.
+		return 0, fmt.Errorf("CreateEnvironmentBlock: %w", e)
+	}
+	defer func() { _, _, _ = procDestroyEnvironmentBlock.Call(envBlock) }()
+
+	// Inject the auth token into the environment block so it doesn't appear
+	// in the process command line (visible via tasklist/wmic). injectedBlock
+	// must stay alive until CreateProcessAsUser returns.
+	injectedBlock := injectEnvVar(envBlock, agentTokenEnvVar, authToken)
+
+	exePath, err := os.Executable()
+	if err != nil {
+		return 0, fmt.Errorf("get executable path: %w", err)
+	}
+
+	cmdLine := fmt.Sprintf(`"%s" vnc-agent --port %s`, exePath, port)
+	cmdLineW, err := windows.UTF16PtrFromString(cmdLine)
+	if err != nil {
+		return 0, fmt.Errorf("UTF16 cmdline: %w", err)
+	}
+
+	// Create an inheritable pipe for the agent's stderr so we can relog
+	// its output in the service process.
+	var sa windows.SecurityAttributes
+	sa.Length = uint32(unsafe.Sizeof(sa))
+	sa.InheritHandle = 1
+
+	var stderrRead, stderrWrite windows.Handle
+	if err := windows.CreatePipe(&stderrRead, &stderrWrite, &sa, 0); err != nil {
+		return 0, fmt.Errorf("create stderr pipe: %w", err)
+	}
+	// The read end must NOT be inherited by the child.
+	_ = windows.SetHandleInformation(stderrRead, windows.HANDLE_FLAG_INHERIT, 0)
+
+	desktop, _ := windows.UTF16PtrFromString(`WinSta0\Default`)
+	si := windows.StartupInfo{
+		Cb:         uint32(unsafe.Sizeof(windows.StartupInfo{})),
+		Desktop:    desktop,
+		Flags:      windows.STARTF_USESHOWWINDOW | windows.STARTF_USESTDHANDLES,
+		ShowWindow: 0,
+		StdErr:     stderrWrite,
+		StdOutput:  stderrWrite,
+	}
+	var pi windows.ProcessInformation
+
+	var envPtr *uint16
+	if len(injectedBlock) > 0 {
+		envPtr = &injectedBlock[0]
+	} else if envBlock != 0 {
+		envPtr = (*uint16)(unsafe.Pointer(envBlock))
+	}
+
+	// CREATE_SUSPENDED so we can assign the process to our Job Object
+	// before it executes. Without this the agent could spawn its own child
+	// processes and have them inherit the SCM service-job (not ours), or
+	// briefly listen on the agent port before we tear it down on rollback.
+	// CREATE_BREAKAWAY_FROM_JOB lets the child leave the SCM-managed
+	// service job; harmless if that job allows breakaway, and is required
+	// before AssignProcessToJobObject can succeed in the no-nested-jobs case.
+	err = windows.CreateProcessAsUser(
+		token, nil, cmdLineW,
+		nil, nil, true, // inheritHandles=true for the pipe
+		createUnicodeEnvironment|createNoWindow|createSuspended|createBreakawayFromJob,
+		envPtr, nil, &si, &pi,
+	)
+	runtime.KeepAlive(injectedBlock)
+	// Close the write end in the parent so reads will get EOF when the child exits.
+	_ = windows.CloseHandle(stderrWrite)
+	if err != nil {
+		_ = windows.CloseHandle(stderrRead)
+		return 0, fmt.Errorf("CreateProcessAsUser: %w", err)
+	}
+
+	if jobHandle != 0 {
+		r, _, e := procAssignProcessToJobObject.Call(uintptr(jobHandle), uintptr(pi.Process))
+		if r == 0 {
+			log.Warnf("assign agent to job object: %v (orphan possible on service crash)", e)
+		}
+	}
+
+	if _, err := windows.ResumeThread(pi.Thread); err != nil {
+		log.Warnf("resume agent main thread: %v", err)
+	}
+	_ = windows.CloseHandle(pi.Thread)
+
+	// Relog agent output in the service with a [vnc-agent] prefix.
+	go relogAgentOutput(stderrRead)
+
+	log.Infof("spawned agent PID=%d in session %d on port %s", pi.ProcessId, sessionID, port)
+	return pi.Process, nil
+}
+
+// sessionManager monitors the active console session and ensures a VNC agent
+// process is running in it. When the session changes (e.g., user switch, RDP
+// connect/disconnect), it kills the old agent and spawns a new one.
+type sessionManager struct {
+	port           string
+	mu             sync.Mutex
+	agentProc      windows.Handle
+	everSpawned    bool
+	agentStartedAt time.Time
+	spawnFailures  int
+	nextSpawnAt    time.Time
+	sessionID      uint32
+	authToken      string
+	done           chan struct{}
+	// jobHandle owns the agent processes via a Windows Job Object with
+	// JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE. When the service exits or crashes,
+	// the OS closes the handle and terminates every assigned agent: no
+	// orphaned listeners holding the agent port across restarts.
+	jobHandle windows.Handle
+}
+
+func newSessionManager(port string) *sessionManager {
+	m := &sessionManager{port: port, sessionID: ^uint32(0), done: make(chan struct{})}
+	if h, err := createKillOnCloseJob(); err != nil {
+		log.Warnf("create job object for vnc-agent (orphan agents possible after crash): %v", err)
+	} else {
+		m.jobHandle = h
+	}
+	return m
+}
+
+// createKillOnCloseJob returns a Job Object configured so that closing its
+// handle (process exit or explicit Close) terminates every process assigned
+// to it. Used to keep orphaned vnc-agent processes from outliving the service.
+func createKillOnCloseJob() (windows.Handle, error) {
+	r, _, e := procCreateJobObjectW.Call(0, 0)
+	if r == 0 {
+		return 0, fmt.Errorf("CreateJobObject: %w", e)
+	}
+	job := windows.Handle(r)
+
+	// JOBOBJECT_EXTENDED_LIMIT_INFORMATION on amd64 = 144 bytes.
+	//
+	//  JOBOBJECT_BASIC_LIMIT_INFORMATION  (64 bytes with alignment padding)
+	//    PerProcessUserTimeLimit  LARGE_INTEGER  off  0
+	//    PerJobUserTimeLimit      LARGE_INTEGER  off  8
+	//    LimitFlags               DWORD          off 16
+	//    [4 byte pad to align SIZE_T]
+	//    MinimumWorkingSetSize    SIZE_T         off 24
+	//    MaximumWorkingSetSize    SIZE_T         off 32
+	//    ActiveProcessLimit       DWORD          off 40
+	//    [4 byte pad to align ULONG_PTR]
+	//    Affinity                 ULONG_PTR      off 48
+	//    PriorityClass            DWORD          off 56
+	//    SchedulingClass          DWORD          off 60
+	//  IO_COUNTERS (48)  +  4 * SIZE_T (32)  =  144 total.
+	//
+	// We only set LimitFlags; the rest stays zero.
+	const sizeofExtended = 144
+	const offsetLimitFlags = 16
+	const jobObjectExtendedLimitInformation = 9
+	const jobObjectLimitKillOnJobClose = 0x00002000
+
+	var info [sizeofExtended]byte
+	binary.LittleEndian.PutUint32(info[offsetLimitFlags:offsetLimitFlags+4], jobObjectLimitKillOnJobClose)
+
+	r, _, e = procSetInformationJobObject.Call(
+		uintptr(job),
+		uintptr(jobObjectExtendedLimitInformation),
+		uintptr(unsafe.Pointer(&info[0])),
+		uintptr(sizeofExtended),
+	)
+	if r == 0 {
+		_ = windows.CloseHandle(job)
+		return 0, fmt.Errorf("SetInformationJobObject(KILL_ON_JOB_CLOSE): %w", e)
+	}
+	return job, nil
+}
+
+// generateAuthToken creates a new random hex token for agent authentication.
+func generateAuthToken() string {
+	b := make([]byte, agentTokenLen)
+	if _, err := crand.Read(b); err != nil {
+		log.Warnf("generate agent auth token: %v", err)
+		return ""
+	}
+	return hex.EncodeToString(b)
+}
+
+// AuthToken returns the current agent authentication token.
+func (m *sessionManager) AuthToken() string {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	return m.authToken
+}
+
+// Stop signals the session manager to exit its polling loop and closes the
+// Job Object handle, which Windows uses as the trigger to terminate every
+// agent process this manager spawned.
+func (m *sessionManager) Stop() {
+	select {
+	case <-m.done:
+	default:
+		close(m.done)
+	}
+	m.mu.Lock()
+	if m.jobHandle != 0 {
+		_ = windows.CloseHandle(m.jobHandle)
+		m.jobHandle = 0
+	}
+	m.mu.Unlock()
+}
+
+func (m *sessionManager) run() {
+	ticker := time.NewTicker(2 * time.Second)
+	defer ticker.Stop()
+
+	for {
+		if !m.tick() {
+			return
+		}
+		select {
+		case <-m.done:
+			m.mu.Lock()
+			m.killAgent()
+			m.mu.Unlock()
+			return
+		case <-ticker.C:
+		}
+	}
+}
+
+// tick performs one session/agent-state update. Returns false if the manager
+// should permanently stop (e.g. missing SYSTEM privileges).
+func (m *sessionManager) tick() bool {
+	sid := getActiveSessionID()
+
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	m.handleSessionChange(sid)
+	m.reapExitedAgent()
+	return m.maybeSpawnAgent(sid)
+}
+
+func (m *sessionManager) handleSessionChange(sid uint32) {
+	if sid == m.sessionID {
+		return
+	}
+	log.Infof("active session changed: %d -> %d", m.sessionID, sid)
+	m.killAgent()
+	m.sessionID = sid
+}
+
+func (m *sessionManager) reapExitedAgent() {
+	if m.agentProc == 0 {
+		return
+	}
+	var code uint32
+	if err := windows.GetExitCodeProcess(m.agentProc, &code); err != nil {
+		log.Debugf("GetExitCodeProcess: %v", err)
+		return
+	}
+	if code == stillActive {
+		return
+	}
+	m.scheduleNextSpawn(code, time.Since(m.agentStartedAt))
+	if err := windows.CloseHandle(m.agentProc); err != nil {
+		log.Debugf("close agent handle: %v", err)
+	}
+	m.agentProc = 0
+}
+
+// scheduleNextSpawn applies an exponential backoff on fast crashes (<5s) and
+// resets immediately otherwise.
+func (m *sessionManager) scheduleNextSpawn(exitCode uint32, lifetime time.Duration) {
+	if lifetime < 5*time.Second {
+		m.spawnFailures++
+		backoff := time.Duration(1<<min(m.spawnFailures, 5)) * time.Second
+		if backoff > 30*time.Second {
+			backoff = 30 * time.Second
+		}
+		m.nextSpawnAt = time.Now().Add(backoff)
+		log.Warnf("agent exited (code=%d) after %v, retrying in %v (failures=%d)", exitCode, lifetime.Round(time.Millisecond), backoff, m.spawnFailures)
+		return
+	}
+	m.spawnFailures = 0
+	m.nextSpawnAt = time.Time{}
+	log.Infof("agent exited (code=%d) after %v, respawning", exitCode, lifetime.Round(time.Second))
+}
+
+// maybeSpawnAgent spawns a new agent if there's no current one and the backoff
+// window has elapsed. Returns false to permanently stop the manager when the
+// service lacks the privileges needed to spawn cross-session.
+func (m *sessionManager) maybeSpawnAgent(sid uint32) bool {
+	if m.agentProc != 0 || sid == 0xFFFFFFFF || !time.Now().After(m.nextSpawnAt) {
+		return true
+	}
+	// Reap any orphan still holding the agent port from a previous
+	// service instance, only on our very first spawn. Once we own
+	// an agent, we manage its lifecycle ourselves and never need to
+	// kill an unknown listener; if a kill+respawn races on port
+	// release, the spawn-failure backoff handles it without forcing
+	// a synchronous wait or duplicate kill.
+	if !m.everSpawned {
+		reapOrphanOnPort(m.port)
+	}
+	m.authToken = generateAuthToken()
+	h, err := spawnAgentInSession(sid, m.port, m.authToken, m.jobHandle)
+	if err != nil {
+		m.authToken = ""
+		if errors.Is(err, windows.ERROR_PRIVILEGE_NOT_HELD) {
+			// SE_TCB_NAME (token-impersonation across sessions) is only
+			// granted to SYSTEM. Without it spawnAgent will fail every 2
+			// seconds forever: log once and give up.
+			log.Warnf("VNC service mode disabled: agent spawn requires SYSTEM privileges (got: %v)", err)
+			return false
+		}
+		log.Warnf("spawn agent in session %d: %v", sid, err)
+		return true
+	}
+	m.agentProc = h
+	m.agentStartedAt = time.Now()
+	m.everSpawned = true
+	return true
+}
+
+func (m *sessionManager) killAgent() {
+	if m.agentProc == 0 {
+		return
+	}
+	_ = windows.TerminateProcess(m.agentProc, 0)
+	_ = windows.CloseHandle(m.agentProc)
+	m.agentProc = 0
+	log.Info("killed old agent")
+}
+
+// relogAgentOutput reads log lines from the agent's stderr pipe and
+// relogs them with the service's formatter. Each line is tried as JSON
+// first (the agent's normal log format); plain-text lines (e.g. cobra
+// error output, panic stack traces) are forwarded verbatim so failures
+// during early agent startup remain visible.
+func relogAgentOutput(pipe windows.Handle) {
+	defer func() { _ = windows.CloseHandle(pipe) }()
+	f := os.NewFile(uintptr(pipe), "vnc-agent-stderr")
+	defer f.Close()
+
+	entry := log.WithField("component", "vnc-agent")
+	scanner := bufio.NewScanner(f)
+	scanner.Buffer(make([]byte, 0, 64*1024), 1024*1024)
+	for scanner.Scan() {
+		line := scanner.Bytes()
+		if len(line) == 0 {
+			continue
+		}
+		if line[0] != '{' {
+			entry.Warn(string(line))
+			continue
+		}
+		var m map[string]any
+		if err := json.Unmarshal(line, &m); err != nil {
+			entry.Warn(string(line))
+			continue
+		}
+		msg, _ := m["msg"].(string)
+		if msg == "" {
+			continue
+		}
+
+		fields := make(log.Fields)
+		for k, v := range m {
+			switch k {
+			case "msg", "level", "time", "func":
+				continue
+			case "caller":
+				fields["source"] = v
+			default:
+				fields[k] = v
+			}
+		}
+		e := entry.WithFields(fields)
+
+		switch m["level"] {
+		case "error":
+			e.Error(msg)
+		case "warning":
+			e.Warn(msg)
+		case "debug":
+			e.Debug(msg)
+		case "trace":
+			e.Trace(msg)
+		default:
+			e.Info(msg)
+		}
+	}
+}
+
+// proxyToAgent connects to the agent, sends the auth token, then proxies
+// the VNC client connection bidirectionally.
+func proxyToAgent(client net.Conn, port string, authToken string) {
+	defer client.Close()
+
+	addr := "127.0.0.1:" + port
+	var agentConn net.Conn
+	var err error
+	for range 50 {
+		agentConn, err = net.DialTimeout("tcp", addr, time.Second)
+		if err == nil {
+			break
+		}
+		time.Sleep(200 * time.Millisecond)
+	}
+	if err != nil {
+		log.Warnf("proxy cannot reach agent at %s: %v", addr, err)
+		return
+	}
+	defer agentConn.Close()
+
+	// Send the auth token so the agent can verify this connection
+	// comes from the trusted service process.
+	tokenBytes, _ := hex.DecodeString(authToken)
+	if _, err := agentConn.Write(tokenBytes); err != nil {
+		log.Warnf("send auth token to agent: %v", err)
+		return
+	}
+
+	log.Debugf("proxy connected to agent, starting bidirectional copy")
+
+	done := make(chan struct{}, 2)
+	cp := func(label string, dst, src net.Conn) {
+		n, err := io.Copy(dst, src)
+		log.Debugf("proxy %s: %d bytes, err=%v", label, n, err)
+		done <- struct{}{}
+	}
+	go cp("client→agent", agentConn, client)
+	go cp("agent→client", client, agentConn)
+	<-done
+}
+
+// logCleanupCall invokes a Windows syscall used solely as a cleanup primitive
+// (CloseClipboard, ReleaseDC, etc.) and logs failures at trace level. The
+// indirection lets us satisfy errcheck without scattering ignored returns at
+// each call site, while still capturing diagnostic info when the OS reports
+// a failure.
+func logCleanupCall(name string, proc *windows.LazyProc) {
+	r, _, err := proc.Call()
+	if r == 0 && err != nil && err != windows.NTE_OP_OK {
+		log.Tracef("%s: %v", name, err)
+	}
+}
+
+// logCleanupCallArgs is logCleanupCall with one argument; common pattern for
+// release-by-handle syscalls.
+func logCleanupCallArgs(name string, proc *windows.LazyProc, args ...uintptr) {
+	r, _, err := proc.Call(args...)
+	if r == 0 && err != nil && err != windows.NTE_OP_OK {
+		log.Tracef("%s: %v", name, err)
+	}
+}

client/vnc/server/capture_darwin.go

@@ -0,0 +1,601 @@
+//go:build darwin && !ios
+
+package server
+
+import (
+	"errors"
+	"fmt"
+	"hash/maphash"
+	"image"
+	"os"
+	"runtime"
+	"strconv"
+	"sync"
+	"sync/atomic"
+	"time"
+	"unsafe"
+
+	"github.com/ebitengine/purego"
+	log "github.com/sirupsen/logrus"
+)
+
+var darwinCaptureOnce sync.Once
+
+var (
+	cgMainDisplayID                func() uint32
+	cgDisplayPixelsWide            func(uint32) uintptr
+	cgDisplayPixelsHigh            func(uint32) uintptr
+	cgDisplayCreateImage           func(uint32) uintptr
+	cgImageGetWidth                func(uintptr) uintptr
+	cgImageGetHeight               func(uintptr) uintptr
+	cgImageGetBytesPerRow          func(uintptr) uintptr
+	cgImageGetBitsPerPixel         func(uintptr) uintptr
+	cgImageGetDataProvider         func(uintptr) uintptr
+	cgDataProviderCopyData         func(uintptr) uintptr
+	cgImageRelease                 func(uintptr)
+	cfDataGetLength                func(uintptr) int64
+	cfDataGetBytePtr               func(uintptr) uintptr
+	cfRelease                      func(uintptr)
+	cgPreflightScreenCaptureAccess func() bool
+	cgRequestScreenCaptureAccess   func() bool
+	darwinCaptureReady             bool
+)
+
+func initDarwinCapture() {
+	darwinCaptureOnce.Do(func() {
+		cg, err := purego.Dlopen("/System/Library/Frameworks/CoreGraphics.framework/CoreGraphics", purego.RTLD_NOW|purego.RTLD_GLOBAL)
+		if err != nil {
+			log.Debugf("load CoreGraphics: %v", err)
+			return
+		}
+		cf, err := purego.Dlopen("/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation", purego.RTLD_NOW|purego.RTLD_GLOBAL)
+		if err != nil {
+			log.Debugf("load CoreFoundation: %v", err)
+			return
+		}
+
+		purego.RegisterLibFunc(&cgMainDisplayID, cg, "CGMainDisplayID")
+		purego.RegisterLibFunc(&cgDisplayPixelsWide, cg, "CGDisplayPixelsWide")
+		purego.RegisterLibFunc(&cgDisplayPixelsHigh, cg, "CGDisplayPixelsHigh")
+		purego.RegisterLibFunc(&cgDisplayCreateImage, cg, "CGDisplayCreateImage")
+		purego.RegisterLibFunc(&cgImageGetWidth, cg, "CGImageGetWidth")
+		purego.RegisterLibFunc(&cgImageGetHeight, cg, "CGImageGetHeight")
+		purego.RegisterLibFunc(&cgImageGetBytesPerRow, cg, "CGImageGetBytesPerRow")
+		purego.RegisterLibFunc(&cgImageGetBitsPerPixel, cg, "CGImageGetBitsPerPixel")
+		purego.RegisterLibFunc(&cgImageGetDataProvider, cg, "CGImageGetDataProvider")
+		purego.RegisterLibFunc(&cgDataProviderCopyData, cg, "CGDataProviderCopyData")
+		purego.RegisterLibFunc(&cgImageRelease, cg, "CGImageRelease")
+		purego.RegisterLibFunc(&cfDataGetLength, cf, "CFDataGetLength")
+		purego.RegisterLibFunc(&cfDataGetBytePtr, cf, "CFDataGetBytePtr")
+		purego.RegisterLibFunc(&cfRelease, cf, "CFRelease")
+
+		// Screen capture permission APIs (macOS 11+). Might not exist on older versions.
+		if sym, err := purego.Dlsym(cg, "CGPreflightScreenCaptureAccess"); err == nil {
+			purego.RegisterFunc(&cgPreflightScreenCaptureAccess, sym)
+		}
+		if sym, err := purego.Dlsym(cg, "CGRequestScreenCaptureAccess"); err == nil {
+			purego.RegisterFunc(&cgRequestScreenCaptureAccess, sym)
+		}
+
+		darwinCaptureReady = true
+	})
+}
+
+
+// CGCapturer captures the macOS main display using Core Graphics.
+type CGCapturer struct {
+	displayID uint32
+	w, h      int
+	// downscale is 1 for pixel-perfect, 2 for Retina 2:1 box-filter downscale.
+	downscale int
+	hashSeed  maphash.Seed
+	lastHash  uint64
+	hasHash   bool
+}
+
+// NewCGCapturer creates a screen capturer for the main display.
+func NewCGCapturer() (*CGCapturer, error) {
+	initDarwinCapture()
+	if !darwinCaptureReady {
+		return nil, fmt.Errorf("CoreGraphics not available")
+	}
+
+	// Request Screen Recording permission (shows system dialog on macOS 11+).
+	if cgPreflightScreenCaptureAccess != nil && !cgPreflightScreenCaptureAccess() {
+		if cgRequestScreenCaptureAccess != nil {
+			cgRequestScreenCaptureAccess()
+		}
+		openPrivacyPane("Privacy_ScreenCapture")
+		log.Warn("Screen Recording permission not granted. " +
+			"Opened System Settings > Privacy & Security > Screen Recording; enable netbird and restart.")
+	}
+
+	displayID := cgMainDisplayID()
+	c := &CGCapturer{displayID: displayID, downscale: 1, hashSeed: maphash.MakeSeed()}
+
+	// Probe actual pixel dimensions via a test capture. CGDisplayPixelsWide/High
+	// returns logical points on Retina, but CGDisplayCreateImage produces native
+	// pixels (often 2x), so probing the image is the only reliable source.
+	img, err := c.Capture()
+	if err != nil {
+		return nil, fmt.Errorf("probe capture: %w", err)
+	}
+	nativeW := img.Rect.Dx()
+	nativeH := img.Rect.Dy()
+	c.hasHash = false
+	if nativeW == 0 || nativeH == 0 {
+		return nil, errors.New("display dimensions are zero")
+	}
+
+	logicalW := int(cgDisplayPixelsWide(displayID))
+	logicalH := int(cgDisplayPixelsHigh(displayID))
+
+	// Enable 2:1 downscale on Retina unless explicitly disabled. Cuts pixel
+	// count 4x, shrinking convert, diff, and wire data proportionally.
+	if !retinaDownscaleDisabled() && nativeW >= 2*logicalW && nativeH >= 2*logicalH && nativeW%2 == 0 && nativeH%2 == 0 {
+		c.downscale = 2
+	}
+	c.w = nativeW / c.downscale
+	c.h = nativeH / c.downscale
+
+	log.Infof("macOS capturer ready: %dx%d (native %dx%d, logical %dx%d, downscale=%d, display=%d)",
+		c.w, c.h, nativeW, nativeH, logicalW, logicalH, c.downscale, displayID)
+	return c, nil
+}
+
+func retinaDownscaleDisabled() bool {
+	v := os.Getenv(EnvVNCDisableDownscale)
+	if v == "" {
+		return false
+	}
+	disabled, err := strconv.ParseBool(v)
+	if err != nil {
+		log.Warnf("parse %s: %v", EnvVNCDisableDownscale, err)
+		return false
+	}
+	return disabled
+}
+
+// Width returns the screen width.
+func (c *CGCapturer) Width() int { return c.w }
+
+// Height returns the screen height.
+func (c *CGCapturer) Height() int { return c.h }
+
+// Capture returns the current screen as an RGBA image.
+// CaptureInto writes a fresh frame directly into dst, skipping the
+// per-frame image.RGBA allocation that Capture() does. Returns
+// errFrameUnchanged when the screen hash matches the prior call.
+func (c *CGCapturer) CaptureInto(dst *image.RGBA) error {
+	cgImage := cgDisplayCreateImage(c.displayID)
+	if cgImage == 0 {
+		return fmt.Errorf("CGDisplayCreateImage returned nil (screen recording permission?)")
+	}
+	defer cgImageRelease(cgImage)
+	w := int(cgImageGetWidth(cgImage))
+	h := int(cgImageGetHeight(cgImage))
+	bytesPerRow := int(cgImageGetBytesPerRow(cgImage))
+	bpp := int(cgImageGetBitsPerPixel(cgImage))
+	provider := cgImageGetDataProvider(cgImage)
+	if provider == 0 {
+		return fmt.Errorf("CGImageGetDataProvider returned nil")
+	}
+	cfData := cgDataProviderCopyData(provider)
+	if cfData == 0 {
+		return fmt.Errorf("CGDataProviderCopyData returned nil")
+	}
+	defer cfRelease(cfData)
+	dataLen := int(cfDataGetLength(cfData))
+	dataPtr := cfDataGetBytePtr(cfData)
+	if dataPtr == 0 || dataLen == 0 {
+		return fmt.Errorf("empty image data")
+	}
+	src := unsafe.Slice((*byte)(unsafe.Pointer(dataPtr)), dataLen)
+	hash := maphash.Bytes(c.hashSeed, src)
+	if c.hasHash && hash == c.lastHash {
+		return errFrameUnchanged
+	}
+	c.lastHash = hash
+	c.hasHash = true
+
+	ds := c.downscale
+	if ds < 1 {
+		ds = 1
+	}
+	outW := w / ds
+	outH := h / ds
+	if dst.Rect.Dx() != outW || dst.Rect.Dy() != outH {
+		return fmt.Errorf("dst size mismatch: dst=%dx%d capturer=%dx%d",
+			dst.Rect.Dx(), dst.Rect.Dy(), outW, outH)
+	}
+	bytesPerPixel := bpp / 8
+	if bytesPerPixel == 4 && ds == 1 {
+		convertBGRAToRGBA(dst.Pix, dst.Stride, src, bytesPerRow, w, h)
+		return nil
+	}
+	if bytesPerPixel == 4 && ds == 2 {
+		convertBGRAToRGBADownscale2(dst.Pix, dst.Stride, src, bytesPerRow, outW, outH)
+		return nil
+	}
+	for row := 0; row < outH; row++ {
+		srcOff := row * ds * bytesPerRow
+		dstOff := row * dst.Stride
+		for col := 0; col < outW; col++ {
+			si := srcOff + col*ds*bytesPerPixel
+			di := dstOff + col*4
+			dst.Pix[di+0] = src[si+2]
+			dst.Pix[di+1] = src[si+1]
+			dst.Pix[di+2] = src[si+0]
+			dst.Pix[di+3] = 0xff
+		}
+	}
+	return nil
+}
+
+func (c *CGCapturer) Capture() (*image.RGBA, error) {
+	cgImage := cgDisplayCreateImage(c.displayID)
+	if cgImage == 0 {
+		return nil, fmt.Errorf("CGDisplayCreateImage returned nil (screen recording permission?)")
+	}
+	defer cgImageRelease(cgImage)
+
+	w := int(cgImageGetWidth(cgImage))
+	h := int(cgImageGetHeight(cgImage))
+	bytesPerRow := int(cgImageGetBytesPerRow(cgImage))
+	bpp := int(cgImageGetBitsPerPixel(cgImage))
+
+	provider := cgImageGetDataProvider(cgImage)
+	if provider == 0 {
+		return nil, fmt.Errorf("CGImageGetDataProvider returned nil")
+	}
+
+	cfData := cgDataProviderCopyData(provider)
+	if cfData == 0 {
+		return nil, fmt.Errorf("CGDataProviderCopyData returned nil")
+	}
+	defer cfRelease(cfData)
+
+	dataLen := int(cfDataGetLength(cfData))
+	dataPtr := cfDataGetBytePtr(cfData)
+	if dataPtr == 0 || dataLen == 0 {
+		return nil, fmt.Errorf("empty image data")
+	}
+
+	src := unsafe.Slice((*byte)(unsafe.Pointer(dataPtr)), dataLen)
+
+	hash := maphash.Bytes(c.hashSeed, src)
+	if c.hasHash && hash == c.lastHash {
+		return nil, errFrameUnchanged
+	}
+	c.lastHash = hash
+	c.hasHash = true
+
+	ds := c.downscale
+	if ds < 1 {
+		ds = 1
+	}
+	outW := w / ds
+	outH := h / ds
+	img := image.NewRGBA(image.Rect(0, 0, outW, outH))
+
+	bytesPerPixel := bpp / 8
+	switch {
+	case bytesPerPixel == 4 && ds == 1:
+		convertBGRAToRGBA(img.Pix, img.Stride, src, bytesPerRow, w, h)
+	case bytesPerPixel == 4 && ds == 2:
+		convertBGRAToRGBADownscale2(img.Pix, img.Stride, src, bytesPerRow, outW, outH)
+	default:
+		convertBGRAToRGBAGeneric(img.Pix, img.Stride, src, bytesPerRow, bgraDownscaleParams{outW: outW, outH: outH, bytesPerPixel: bytesPerPixel, ds: ds})
+	}
+
+	return img, nil
+}
+
+type bgraDownscaleParams struct {
+	outW, outH, bytesPerPixel, ds int
+}
+
+// convertBGRAToRGBAGeneric is the slow per-pixel fallback for non-4-bytes
+// or non-1/2 downscale formats. Always available regardless of the source
+// format quirks the fast paths optimize for.
+func convertBGRAToRGBAGeneric(dst []byte, dstStride int, src []byte, srcStride int, p bgraDownscaleParams) {
+	for row := 0; row < p.outH; row++ {
+		srcOff := row * p.ds * srcStride
+		dstOff := row * dstStride
+		for col := 0; col < p.outW; col++ {
+			si := srcOff + col*p.ds*p.bytesPerPixel
+			di := dstOff + col*4
+			dst[di+0] = src[si+2]
+			dst[di+1] = src[si+1]
+			dst[di+2] = src[si+0]
+			dst[di+3] = 0xff
+		}
+	}
+}
+
+// convertBGRAToRGBADownscale2 averages every 2x2 BGRA block into one RGBA
+// output pixel, parallelised across GOMAXPROCS cores. outW and outH are the
+// destination dimensions (source is 2*outW by 2*outH).
+func convertBGRAToRGBADownscale2(dst []byte, dstStride int, src []byte, srcStride, outW, outH int) {
+	workers := runtime.GOMAXPROCS(0)
+	if workers > outH {
+		workers = outH
+	}
+	if workers < 1 || outH < 32 {
+		workers = 1
+	}
+
+	convertRows := func(y0, y1 int) {
+		for row := y0; row < y1; row++ {
+			srcRow0 := 2 * row * srcStride
+			srcRow1 := srcRow0 + srcStride
+			dstOff := row * dstStride
+			for col := 0; col < outW; col++ {
+				s0 := srcRow0 + col*8
+				s1 := srcRow1 + col*8
+				b := (uint32(src[s0]) + uint32(src[s0+4]) + uint32(src[s1]) + uint32(src[s1+4])) >> 2
+				g := (uint32(src[s0+1]) + uint32(src[s0+5]) + uint32(src[s1+1]) + uint32(src[s1+5])) >> 2
+				r := (uint32(src[s0+2]) + uint32(src[s0+6]) + uint32(src[s1+2]) + uint32(src[s1+6])) >> 2
+				di := dstOff + col*4
+				dst[di+0] = byte(r)
+				dst[di+1] = byte(g)
+				dst[di+2] = byte(b)
+				dst[di+3] = 0xff
+			}
+		}
+	}
+
+	if workers == 1 {
+		convertRows(0, outH)
+		return
+	}
+
+	var wg sync.WaitGroup
+	chunk := (outH + workers - 1) / workers
+	for i := 0; i < workers; i++ {
+		y0 := i * chunk
+		y1 := y0 + chunk
+		if y1 > outH {
+			y1 = outH
+		}
+		if y0 >= y1 {
+			break
+		}
+		wg.Add(1)
+		go func(y0, y1 int) {
+			defer wg.Done()
+			convertRows(y0, y1)
+		}(y0, y1)
+	}
+	wg.Wait()
+}
+
+// convertBGRAToRGBA swaps R/B channels using uint32 word operations, and
+// parallelises across GOMAXPROCS cores for large images.
+func convertBGRAToRGBA(dst []byte, dstStride int, src []byte, srcStride, w, h int) {
+	workers := runtime.GOMAXPROCS(0)
+	if workers > h {
+		workers = h
+	}
+	if workers < 1 || h < 64 {
+		workers = 1
+	}
+
+	convertRows := func(y0, y1 int) {
+		rowBytes := w * 4
+		for row := y0; row < y1; row++ {
+			dstRow := dst[row*dstStride : row*dstStride+rowBytes]
+			srcRow := src[row*srcStride : row*srcStride+rowBytes]
+			dstU := unsafe.Slice((*uint32)(unsafe.Pointer(&dstRow[0])), w)
+			srcU := unsafe.Slice((*uint32)(unsafe.Pointer(&srcRow[0])), w)
+			for i, p := range srcU {
+				dstU[i] = (p & 0xff00ff00) | ((p & 0x000000ff) << 16) | ((p & 0x00ff0000) >> 16) | 0xff000000
+			}
+		}
+	}
+
+	if workers == 1 {
+		convertRows(0, h)
+		return
+	}
+
+	var wg sync.WaitGroup
+	chunk := (h + workers - 1) / workers
+	for i := 0; i < workers; i++ {
+		y0 := i * chunk
+		y1 := y0 + chunk
+		if y1 > h {
+			y1 = h
+		}
+		if y0 >= y1 {
+			break
+		}
+		wg.Add(1)
+		go func(y0, y1 int) {
+			defer wg.Done()
+			convertRows(y0, y1)
+		}(y0, y1)
+	}
+	wg.Wait()
+}
+
+// MacPoller wraps CGCapturer with a staleness-cached on-demand Capture:
+// sessions drive captures themselves from their encoder goroutine, so we
+// don't need a background ticker. The last result is cached for a short
+// window so concurrent sessions coalesce into one capture.
+//
+// The capturer is allocated lazily on first use and released when all
+// clients disconnect. Init is retried with backoff because the user may
+// grant Screen Recording permission while the server is already running.
+type MacPoller struct {
+	mu sync.Mutex
+
+	capturer *CGCapturer
+	w, h     int
+
+	lastFrame *image.RGBA
+	lastAt    time.Time
+
+	clients          atomic.Int32
+	initFails        int
+	initBackoffUntil time.Time
+	closed           bool
+}
+
+// macInitRetryBackoffFor returns the delay we wait between init attempts
+// after consecutive failures. Screen Recording permission is a one-shot
+// user grant, so after several failures we back off aggressively.
+func macInitRetryBackoffFor(fails int) time.Duration {
+	switch {
+	case fails > 15:
+		return 30 * time.Second
+	case fails > 5:
+		return 10 * time.Second
+	default:
+		return 2 * time.Second
+	}
+}
+
+// NewMacPoller creates a lazy on-demand capturer for the macOS display.
+func NewMacPoller() *MacPoller {
+	return &MacPoller{}
+}
+
+// Wake is a no-op retained for API compatibility. With on-demand capture
+// there is no background retry loop to kick: init happens on the next
+// Capture/ClientConnect call.
+func (p *MacPoller) Wake() {
+	// intentional no-op
+}
+
+// ClientConnect increments the active client count and eagerly initialises
+// the capturer so the first FBUpdateRequest doesn't pay the init cost.
+func (p *MacPoller) ClientConnect() {
+	if p.clients.Add(1) == 1 {
+		p.mu.Lock()
+		_ = p.ensureCapturerLocked()
+		p.mu.Unlock()
+	}
+}
+
+// ClientDisconnect decrements the active client count. On the last
+// disconnect the capturer is released.
+func (p *MacPoller) ClientDisconnect() {
+	if p.clients.Add(-1) == 0 {
+		p.mu.Lock()
+		p.capturer = nil
+		p.lastFrame = nil
+		p.mu.Unlock()
+	}
+}
+
+// Close releases all resources.
+func (p *MacPoller) Close() {
+	p.mu.Lock()
+	p.closed = true
+	p.capturer = nil
+	p.lastFrame = nil
+	p.mu.Unlock()
+}
+
+// Width returns the screen width. Triggers lazy init if needed.
+func (p *MacPoller) Width() int {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	_ = p.ensureCapturerLocked()
+	return p.w
+}
+
+// Height returns the screen height. Triggers lazy init if needed.
+func (p *MacPoller) Height() int {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	_ = p.ensureCapturerLocked()
+	return p.h
+}
+
+// CaptureInto fills dst directly via the underlying capturer, bypassing
+// the freshness cache.
+func (p *MacPoller) CaptureInto(dst *image.RGBA) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	if err := p.ensureCapturerLocked(); err != nil {
+		return err
+	}
+	err := p.capturer.CaptureInto(dst)
+	if errors.Is(err, errFrameUnchanged) {
+		// Caller (session) treats this as "no change"; the dst buffer
+		// keeps its prior contents from the previous capture cycle so
+		// the diff stays meaningful.
+		return err
+	}
+	if err != nil {
+		p.capturer = nil
+		return fmt.Errorf("macos capture: %w", err)
+	}
+	return nil
+}
+
+// Capture returns a fresh frame, serving from the short-lived cache if a
+// previous caller captured within freshWindow. Handles the
+// errFrameUnchanged return from CGCapturer by reusing the cached frame.
+func (p *MacPoller) Capture() (*image.RGBA, error) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	if p.lastFrame != nil && time.Since(p.lastAt) < freshWindow {
+		return p.lastFrame, nil
+	}
+	if err := p.ensureCapturerLocked(); err != nil {
+		return nil, err
+	}
+	img, err := p.capturer.Capture()
+	if errors.Is(err, errFrameUnchanged) {
+		if p.lastFrame != nil {
+			p.lastAt = time.Now()
+			return p.lastFrame, nil
+		}
+		return nil, err
+	}
+	if err != nil {
+		// Drop the capturer so the next call retries init; the display stream
+		// can die if the session changes or permissions are revoked.
+		p.capturer = nil
+		return nil, fmt.Errorf("macos capture: %w", err)
+	}
+	p.lastFrame = img
+	p.lastAt = time.Now()
+	return img, nil
+}
+
+// ensureCapturerLocked initialises the underlying CGCapturer if needed.
+// Caller must hold p.mu.
+func (p *MacPoller) ensureCapturerLocked() error {
+	if p.closed {
+		return fmt.Errorf("poller closed")
+	}
+	if p.capturer != nil {
+		return nil
+	}
+	if time.Now().Before(p.initBackoffUntil) {
+		return fmt.Errorf("macOS capturer unavailable (retry scheduled)")
+	}
+	c, err := NewCGCapturer()
+	if err != nil {
+		p.initFails++
+		p.initBackoffUntil = time.Now().Add(macInitRetryBackoffFor(p.initFails))
+		if p.initFails == 1 || p.initFails%10 == 0 {
+			log.Warnf("macOS capturer: %v (attempt %d)", err, p.initFails)
+		} else {
+			log.Debugf("macOS capturer: %v (attempt %d)", err, p.initFails)
+		}
+		return err
+	}
+	p.initFails = 0
+	p.capturer = c
+	p.w, p.h = c.Width(), c.Height()
+	return nil
+}
+
+var _ ScreenCapturer = (*MacPoller)(nil)

client/vnc/server/capture_dxgi_windows.go

@@ -0,0 +1,99 @@
+//go:build windows
+
+package server
+
+import (
+	"errors"
+	"fmt"
+	"image"
+
+	"github.com/kirides/go-d3d/d3d11"
+	"github.com/kirides/go-d3d/outputduplication"
+)
+
+// dxgiCapturer captures the desktop using DXGI Desktop Duplication.
+// Provides GPU-accelerated capture with native dirty rect tracking.
+// Only works from the interactive user session, not Session 0.
+//
+// Uses a double-buffer: DXGI writes into img, then we copy to the current
+// output buffer and hand it out. Alternating between two output buffers
+// avoids allocating a new image.RGBA per frame (~8MB at 1080p, 30fps).
+type dxgiCapturer struct {
+	dup    *outputduplication.OutputDuplicator
+	device *d3d11.ID3D11Device
+	ctx    *d3d11.ID3D11DeviceContext
+	img    *image.RGBA
+	out    [2]*image.RGBA
+	outIdx int
+	width  int
+	height int
+}
+
+func newDXGICapturer() (*dxgiCapturer, error) {
+	device, deviceCtx, err := d3d11.NewD3D11Device()
+	if err != nil {
+		return nil, fmt.Errorf("create D3D11 device: %w", err)
+	}
+
+	dup, err := outputduplication.NewIDXGIOutputDuplication(device, deviceCtx, 0)
+	if err != nil {
+		device.Release()
+		deviceCtx.Release()
+		return nil, fmt.Errorf("create output duplication: %w", err)
+	}
+
+	w, h := screenSize()
+	if w == 0 || h == 0 {
+		dup.Release()
+		device.Release()
+		deviceCtx.Release()
+		return nil, fmt.Errorf("screen dimensions are zero")
+	}
+
+	rect := image.Rect(0, 0, w, h)
+	c := &dxgiCapturer{
+		dup:    dup,
+		device: device,
+		ctx:    deviceCtx,
+		img:    image.NewRGBA(rect),
+		out:    [2]*image.RGBA{image.NewRGBA(rect), image.NewRGBA(rect)},
+		width:  w,
+		height: h,
+	}
+
+	// Grab the initial frame with a longer timeout to ensure we have
+	// a valid image before returning.
+	_ = dup.GetImage(c.img, 2000)
+
+	return c, nil
+}
+
+func (c *dxgiCapturer) capture() (*image.RGBA, error) {
+	err := c.dup.GetImage(c.img, 100)
+	if err != nil && !errors.Is(err, outputduplication.ErrNoImageYet) {
+		return nil, err
+	}
+
+	// Copy into the next output buffer. The DesktopCapturer hands out the
+	// returned pointer to VNC sessions that read pixels concurrently, so we
+	// alternate between two pre-allocated buffers instead of allocating per frame.
+	out := c.out[c.outIdx]
+	c.outIdx ^= 1
+	copy(out.Pix, c.img.Pix)
+	return out, nil
+}
+
+func (c *dxgiCapturer) close() {
+	if c.dup != nil {
+		c.dup.Release()
+		c.dup = nil
+	}
+	if c.ctx != nil {
+		c.ctx.Release()
+		c.ctx = nil
+	}
+	if c.device != nil {
+		c.device.Release()
+		c.device = nil
+	}
+}

client/vnc/server/capture_fb_freebsd.go

@@ -0,0 +1,148 @@
+//go:build freebsd
+
+package server
+
+import (
+	"fmt"
+	"image"
+	"sync"
+	"unsafe"
+
+	log "github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
+)
+
+// FreeBSD vt(4) framebuffer ioctl numbers from sys/fbio.h.
+//
+//	#define FBIOGTYPE _IOR('F', 0, struct fbtype)
+//
+// _IOR(g, n, t) on FreeBSD: dir=2 (read) <<30 | (sizeof(t) & 0x1fff)<<16
+// | (g<<8) | n.  sizeof(struct fbtype)=24 → 0x40184600.
+const fbioGType = 0x40184600
+
+func defaultFBPath() string { return "/dev/ttyv0" }
+
+// fbType mirrors FreeBSD's struct fbtype.
+type fbType struct {
+	FbType   int32
+	FbHeight int32
+	FbWidth  int32
+	FbDepth  int32
+	FbCMSize int32
+	FbSize   int32
+}
+
+// FBCapturer reads pixels from FreeBSD's vt(4) framebuffer device. The
+// vt(4) console exposes the active framebuffer via ttyv0 with FBIOGTYPE
+// for geometry and mmap for backing memory. Pixel layout is assumed to
+// be 32bpp BGRA (the common case for KMS-backed vt); fbtype doesn't
+// expose channel offsets, so we don't try to handle exotic layouts here.
+type FBCapturer struct {
+	mu        sync.Mutex
+	path      string
+	fd        int
+	mmap      []byte
+	w, h      int
+	bpp       int
+	stride    int
+	closeOnce sync.Once
+}
+
+// NewFBCapturer opens the given vt(4) device and queries its geometry.
+func NewFBCapturer(path string) (*FBCapturer, error) {
+	if path == "" {
+		path = defaultFBPath()
+	}
+	fd, err := unix.Open(path, unix.O_RDWR, 0)
+	if err != nil {
+		return nil, fmt.Errorf("open %s: %w", path, err)
+	}
+
+	var fbt fbType
+	if _, _, e := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), fbioGType, uintptr(unsafe.Pointer(&fbt))); e != 0 {
+		unix.Close(fd)
+		return nil, fmt.Errorf("FBIOGTYPE: %v", e)
+	}
+	if fbt.FbDepth != 16 && fbt.FbDepth != 24 && fbt.FbDepth != 32 {
+		unix.Close(fd)
+		return nil, fmt.Errorf("unsupported framebuffer depth: %d", fbt.FbDepth)
+	}
+	if fbt.FbWidth <= 0 || fbt.FbHeight <= 0 || fbt.FbSize <= 0 {
+		unix.Close(fd)
+		return nil, fmt.Errorf("invalid framebuffer geometry: %dx%d size=%d", fbt.FbWidth, fbt.FbHeight, fbt.FbSize)
+	}
+
+	mm, err := unix.Mmap(fd, 0, int(fbt.FbSize), unix.PROT_READ, unix.MAP_SHARED)
+	if err != nil {
+		unix.Close(fd)
+		return nil, fmt.Errorf("mmap %s: %w (vt may not support mmap on this driver, e.g. virtio_gpu)", path, err)
+	}
+
+	bpp := int(fbt.FbDepth)
+	stride := int(fbt.FbWidth) * (bpp / 8)
+	c := &FBCapturer{
+		path:   path,
+		fd:     fd, // valid fd >= 0; we use -1 as the closed sentinel
+		mmap:   mm,
+		w:      int(fbt.FbWidth),
+		h:      int(fbt.FbHeight),
+		bpp:    bpp,
+		stride: stride,
+	}
+	log.Infof("framebuffer capturer ready: %s %dx%d bpp=%d (freebsd vt)", path, c.w, c.h, c.bpp)
+	return c, nil
+}
+
+// Width returns the framebuffer width.
+func (c *FBCapturer) Width() int { return c.w }
+
+// Height returns the framebuffer height.
+func (c *FBCapturer) Height() int { return c.h }
+
+// Capture allocates a fresh image and fills it with the current
+// framebuffer contents.
+func (c *FBCapturer) Capture() (*image.RGBA, error) {
+	img := image.NewRGBA(image.Rect(0, 0, c.w, c.h))
+	if err := c.CaptureInto(img); err != nil {
+		return nil, err
+	}
+	return img, nil
+}
+
+// CaptureInto reads the framebuffer directly into dst.Pix. Assumes BGRA
+// for 32bpp; the FreeBSD fbtype struct doesn't expose channel offsets.
+func (c *FBCapturer) CaptureInto(dst *image.RGBA) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if dst.Rect.Dx() != c.w || dst.Rect.Dy() != c.h {
+		return fmt.Errorf("dst size mismatch: dst=%dx%d fb=%dx%d",
+			dst.Rect.Dx(), dst.Rect.Dy(), c.w, c.h)
+	}
+	switch c.bpp {
+	case 32:
+		// vt(4) on KMS framebuffers is BGRA: byte 0=B, 1=G, 2=R.
+		swizzleBGRAtoRGBA(dst.Pix, c.mmap[:c.h*c.stride])
+	case 24:
+		swizzleFB24(dst.Pix, dst.Stride, c.mmap, c.stride, c.w, c.h)
+	case 16:
+		swizzleFB16RGB565(dst.Pix, dst.Stride, c.mmap, c.stride, c.w, c.h)
+	}
+	return nil
+}
+
+// Close releases the framebuffer mmap and file descriptor. Serialized with
+// CaptureInto via c.mu so an in-flight capture can't read freed memory.
+func (c *FBCapturer) Close() {
+	c.closeOnce.Do(func() {
+		c.mu.Lock()
+		defer c.mu.Unlock()
+		if c.mmap != nil {
+			_ = unix.Munmap(c.mmap)
+			c.mmap = nil
+		}
+		if c.fd >= 0 {
+			_ = unix.Close(c.fd)
+			c.fd = -1
+		}
+	})
+}

client/vnc/server/capture_fb_linux.go

@@ -0,0 +1,230 @@
+//go:build linux && !android
+
+package server
+
+import (
+	"encoding/binary"
+	"fmt"
+	"image"
+	"sync"
+	"unsafe"
+
+	log "github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
+)
+
+// Linux framebuffer ioctls (linux/fb.h).
+const (
+	fbioGetVScreenInfo = 0x4600
+	fbioGetFScreenInfo = 0x4602
+)
+
+func defaultFBPath() string { return "/dev/fb0" }
+
+// fbVarScreenInfo mirrors the kernel's fb_var_screeninfo. Only the
+// fields we use are mapped; the rest are absorbed into _padN.
+type fbVarScreenInfo struct {
+	Xres, Yres                       uint32
+	XresVirtual, YresVirtual         uint32
+	XOffset, YOffset                 uint32
+	BitsPerPixel                     uint32
+	Grayscale                        uint32
+	RedOffset, RedLen, RedMSBR       uint32
+	GreenOffset, GreenLen, GreenMSBR uint32
+	BlueOffset, BlueLen, BlueMSBR    uint32
+	TranspOffset, TranspLen, TranspM uint32
+	NonStd                           uint32
+	Activate                         uint32
+	Height, Width                    uint32
+	AccelFlags                       uint32
+	PixClock                         uint32
+	LeftMargin, RightMargin          uint32
+	UpperMargin, LowerMargin         uint32
+	HsyncLen, VsyncLen               uint32
+	Sync                             uint32
+	Vmode                            uint32
+	Rotate                           uint32
+	Colorspace                       uint32
+	_pad                             [4]uint32
+}
+
+// fbFixScreenInfo mirrors fb_fix_screeninfo. We only need LineLength.
+type fbFixScreenInfo struct {
+	IDStr        [16]byte
+	SmemStart    uint64
+	SmemLen      uint32
+	Type         uint32
+	TypeAux      uint32
+	Visual       uint32
+	XPanStep     uint16
+	YPanStep     uint16
+	YWrapStep    uint16
+	_pad0        uint16
+	LineLength   uint32
+	MmioStart    uint64
+	MmioLen      uint32
+	Accel        uint32
+	Capabilities uint16
+	_reserved    [2]uint16
+}
+
+// FBCapturer reads pixels straight from the Linux framebuffer device.
+// Used as a fallback when X11 isn't available, e.g. on a headless box at
+// the kernel console or the display manager's pre-login screen on machines
+// without an Xorg server. The framebuffer must be mmap()-able under our
+// process privileges (typically the netbird service runs as root).
+type FBCapturer struct {
+	mu        sync.Mutex
+	path      string
+	fd        int
+	mmap      []byte
+	w, h      int
+	bpp       int
+	stride    int
+	rOff      uint32
+	gOff      uint32
+	bOff      uint32
+	rLen      uint32
+	gLen      uint32
+	bLen      uint32
+	closeOnce sync.Once
+}
+
+// NewFBCapturer opens the given framebuffer device (/dev/fbN) and
+// queries its current geometry + pixel format.
+func NewFBCapturer(path string) (*FBCapturer, error) {
+	if path == "" {
+		path = "/dev/fb0"
+	}
+	fd, err := unix.Open(path, unix.O_RDONLY, 0)
+	if err != nil {
+		return nil, fmt.Errorf("open %s: %w", path, err)
+	}
+
+	var vinfo fbVarScreenInfo
+	if _, _, e := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), fbioGetVScreenInfo, uintptr(unsafe.Pointer(&vinfo))); e != 0 {
+		unix.Close(fd)
+		return nil, fmt.Errorf("FBIOGET_VSCREENINFO: %v", e)
+	}
+	var finfo fbFixScreenInfo
+	if _, _, e := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), fbioGetFScreenInfo, uintptr(unsafe.Pointer(&finfo))); e != 0 {
+		unix.Close(fd)
+		return nil, fmt.Errorf("FBIOGET_FSCREENINFO: %v", e)
+	}
+
+	bpp := int(vinfo.BitsPerPixel)
+	if bpp != 16 && bpp != 24 && bpp != 32 {
+		unix.Close(fd)
+		return nil, fmt.Errorf("unsupported framebuffer bpp: %d", bpp)
+	}
+
+	size := int(finfo.LineLength) * int(vinfo.Yres)
+	if size <= 0 {
+		unix.Close(fd)
+		return nil, fmt.Errorf("invalid framebuffer dimensions: stride=%d h=%d", finfo.LineLength, vinfo.Yres)
+	}
+
+	mm, err := unix.Mmap(fd, 0, size, unix.PROT_READ, unix.MAP_SHARED)
+	if err != nil {
+		unix.Close(fd)
+		return nil, fmt.Errorf("mmap %s: %w", path, err)
+	}
+
+	c := &FBCapturer{
+		path:   path,
+		fd:     fd,
+		mmap:   mm,
+		w:      int(vinfo.Xres),
+		h:      int(vinfo.Yres),
+		bpp:    bpp,
+		stride: int(finfo.LineLength),
+		rOff:   vinfo.RedOffset,
+		gOff:   vinfo.GreenOffset,
+		bOff:   vinfo.BlueOffset,
+		rLen:   vinfo.RedLen,
+		gLen:   vinfo.GreenLen,
+		bLen:   vinfo.BlueLen,
+	}
+	log.Infof("framebuffer capturer ready: %s %dx%d bpp=%d r=%d/%d g=%d/%d b=%d/%d",
+		path, c.w, c.h, c.bpp, c.rOff, c.rLen, c.gOff, c.gLen, c.bOff, c.bLen)
+	return c, nil
+}
+
+// Width returns the framebuffer width in pixels.
+func (c *FBCapturer) Width() int { return c.w }
+
+// Height returns the framebuffer height in pixels.
+func (c *FBCapturer) Height() int { return c.h }
+
+// Capture allocates a fresh image and fills it with the current
+// framebuffer contents.
+func (c *FBCapturer) Capture() (*image.RGBA, error) {
+	img := image.NewRGBA(image.Rect(0, 0, c.w, c.h))
+	if err := c.CaptureInto(img); err != nil {
+		return nil, err
+	}
+	return img, nil
+}
+
+// CaptureInto reads the framebuffer directly into dst.Pix.
+func (c *FBCapturer) CaptureInto(dst *image.RGBA) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if dst.Rect.Dx() != c.w || dst.Rect.Dy() != c.h {
+		return fmt.Errorf("dst size mismatch: dst=%dx%d fb=%dx%d",
+			dst.Rect.Dx(), dst.Rect.Dy(), c.w, c.h)
+	}
+
+	switch c.bpp {
+	case 32:
+		swizzleFB32(dst.Pix, dst.Stride, c.mmap, c.stride, c.w, c.h, channelShifts{R: c.rOff, G: c.gOff, B: c.bOff})
+	case 24:
+		swizzleFB24(dst.Pix, dst.Stride, c.mmap, c.stride, c.w, c.h)
+	case 16:
+		swizzleFB16RGB565(dst.Pix, dst.Stride, c.mmap, c.stride, c.w, c.h)
+	}
+	return nil
+}
+
+// Close releases the framebuffer mmap and file descriptor. Serialized with
+// CaptureInto via c.mu so an in-flight capture can't read freed memory.
+func (c *FBCapturer) Close() {
+	c.closeOnce.Do(func() {
+		c.mu.Lock()
+		defer c.mu.Unlock()
+		if c.mmap != nil {
+			_ = unix.Munmap(c.mmap)
+			c.mmap = nil
+		}
+		if c.fd >= 0 {
+			_ = unix.Close(c.fd)
+			c.fd = -1
+		}
+	})
+}
+
+// channelShifts groups the bit offsets for the R/G/B channels in a packed
+// uint32 framebuffer pixel. Bundling avoids drowning per-row callers in a
+// 9-parameter signature.
+type channelShifts struct {
+	R, G, B uint32
+}
+
+// swizzleFB32 handles 32-bit framebuffers with arbitrary R/G/B channel
+// offsets. Pulls one pixel per uint32, then masks each channel into the
+// destination RGBA byte order.
+func swizzleFB32(dst []byte, dstStride int, src []byte, srcStride, w, h int, shifts channelShifts) {
+	for y := 0; y < h; y++ {
+		srcRow := src[y*srcStride : y*srcStride+w*4]
+		dstRow := dst[y*dstStride:]
+		for x := 0; x < w; x++ {
+			pix := binary.LittleEndian.Uint32(srcRow[x*4 : x*4+4])
+			dstRow[x*4+0] = byte(pix >> shifts.R)
+			dstRow[x*4+1] = byte(pix >> shifts.G)
+			dstRow[x*4+2] = byte(pix >> shifts.B)
+			dstRow[x*4+3] = 0xff
+		}
+	}
+}
+

client/vnc/server/capture_fb_unix.go

@@ -0,0 +1,150 @@
+//go:build (linux && !android) || freebsd
+
+package server
+
+import (
+	"image"
+	"sync"
+)
+
+// FBPoller wraps FBCapturer with the same lifecycle (ClientConnect /
+// ClientDisconnect, lazy init) as X11Poller, so it slots into the same
+// session plumbing without code changes upstream. The concrete
+// FBCapturer is platform-specific (capture_fb_linux.go / _freebsd.go);
+// this file owns the cross-platform glue.
+type FBPoller struct {
+	mu       sync.Mutex
+	path     string
+	capturer *FBCapturer
+	w, h     int
+	clients  int32
+}
+
+// NewFBPoller returns a poller that opens path on first use. Empty path
+// defaults to /dev/fb0 on Linux and /dev/ttyv0 on FreeBSD.
+func NewFBPoller(path string) *FBPoller {
+	if path == "" {
+		path = defaultFBPath()
+	}
+	return &FBPoller{path: path}
+}
+
+// ClientConnect eagerly initialises the capturer on first connect.
+func (p *FBPoller) ClientConnect() {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.clients++
+	if p.clients == 1 {
+		_ = p.ensureCapturerLocked()
+	}
+}
+
+// ClientDisconnect closes the capturer when the last client leaves.
+func (p *FBPoller) ClientDisconnect() {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.clients--
+	if p.clients <= 0 && p.capturer != nil {
+		p.capturer.Close()
+		p.capturer = nil
+	}
+}
+
+// Width returns the framebuffer width, doing lazy init if needed.
+func (p *FBPoller) Width() int {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	_ = p.ensureCapturerLocked()
+	return p.w
+}
+
+// Height returns the framebuffer height, doing lazy init if needed.
+func (p *FBPoller) Height() int {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	_ = p.ensureCapturerLocked()
+	return p.h
+}
+
+// Capture takes a fresh frame.
+func (p *FBPoller) Capture() (*image.RGBA, error) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if err := p.ensureCapturerLocked(); err != nil {
+		return nil, err
+	}
+	return p.capturer.Capture()
+}
+
+// CaptureInto fills dst directly.
+func (p *FBPoller) CaptureInto(dst *image.RGBA) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if err := p.ensureCapturerLocked(); err != nil {
+		return err
+	}
+	return p.capturer.CaptureInto(dst)
+}
+
+// Close releases all framebuffer resources.
+func (p *FBPoller) Close() {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if p.capturer != nil {
+		p.capturer.Close()
+		p.capturer = nil
+	}
+}
+
+func (p *FBPoller) ensureCapturerLocked() error {
+	if p.capturer != nil {
+		return nil
+	}
+	c, err := NewFBCapturer(p.path)
+	if err != nil {
+		return err
+	}
+	p.capturer = c
+	p.w, p.h = c.Width(), c.Height()
+	return nil
+}
+
+
+var _ ScreenCapturer = (*FBPoller)(nil)
+var _ captureIntoer = (*FBPoller)(nil)
+
+// swizzleFB24 handles 24-bit packed framebuffers (B,G,R triplets).
+// Shared between Linux and FreeBSD framebuffer paths.
+func swizzleFB24(dst []byte, dstStride int, src []byte, srcStride, w, h int) {
+	for y := 0; y < h; y++ {
+		srcRow := src[y*srcStride : y*srcStride+w*3]
+		dstRow := dst[y*dstStride:]
+		for x := 0; x < w; x++ {
+			b := srcRow[x*3+0]
+			g := srcRow[x*3+1]
+			r := srcRow[x*3+2]
+			dstRow[x*4+0] = r
+			dstRow[x*4+1] = g
+			dstRow[x*4+2] = b
+			dstRow[x*4+3] = 0xff
+		}
+	}
+}
+
+// swizzleFB16RGB565 handles 16bpp RGB 565 framebuffers.
+func swizzleFB16RGB565(dst []byte, dstStride int, src []byte, srcStride, w, h int) {
+	for y := 0; y < h; y++ {
+		srcRow := src[y*srcStride : y*srcStride+w*2]
+		dstRow := dst[y*dstStride:]
+		for x := 0; x < w; x++ {
+			pix := uint16(srcRow[x*2]) | uint16(srcRow[x*2+1])<<8
+			r := byte((pix >> 11) & 0x1f)
+			g := byte((pix >> 5) & 0x3f)
+			b := byte(pix & 0x1f)
+			dstRow[x*4+0] = (r << 3) | (r >> 2)
+			dstRow[x*4+1] = (g << 2) | (g >> 4)
+			dstRow[x*4+2] = (b << 3) | (b >> 2)
+			dstRow[x*4+3] = 0xff
+		}
+	}
+}

client/vnc/server/capture_windows.go

@@ -0,0 +1,545 @@
+//go:build windows
+
+package server
+
+import (
+	"fmt"
+	"image"
+	"runtime"
+	"sync"
+	"sync/atomic"
+	"time"
+	"unsafe"
+
+	log "github.com/sirupsen/logrus"
+	"golang.org/x/sys/windows"
+)
+
+var (
+	gdi32  = windows.NewLazySystemDLL("gdi32.dll")
+	user32 = windows.NewLazySystemDLL("user32.dll")
+
+	procGetDC            = user32.NewProc("GetDC")
+	procReleaseDC        = user32.NewProc("ReleaseDC")
+	procCreateCompatDC   = gdi32.NewProc("CreateCompatibleDC")
+	procCreateDIBSection = gdi32.NewProc("CreateDIBSection")
+	procSelectObject     = gdi32.NewProc("SelectObject")
+	procDeleteObject     = gdi32.NewProc("DeleteObject")
+	procDeleteDC         = gdi32.NewProc("DeleteDC")
+	procBitBlt           = gdi32.NewProc("BitBlt")
+	procGetSystemMetrics = user32.NewProc("GetSystemMetrics")
+
+	// Desktop switching for service/Session 0 capture.
+	procOpenInputDesktop          = user32.NewProc("OpenInputDesktop")
+	procSetThreadDesktop          = user32.NewProc("SetThreadDesktop")
+	procCloseDesktop              = user32.NewProc("CloseDesktop")
+	procOpenWindowStation         = user32.NewProc("OpenWindowStationW")
+	procSetProcessWindowStation   = user32.NewProc("SetProcessWindowStation")
+	procCloseWindowStation        = user32.NewProc("CloseWindowStation")
+	procGetUserObjectInformationW = user32.NewProc("GetUserObjectInformationW")
+)
+
+const uoiName = 2
+
+const (
+	smCxScreen   = 0
+	smCyScreen   = 1
+	srccopy      = 0x00CC0020
+	captureBlt   = 0x40000000
+	dibRgbColors = 0
+)
+
+type bitmapInfoHeader struct {
+	Size          uint32
+	Width         int32
+	Height        int32
+	Planes        uint16
+	BitCount      uint16
+	Compression   uint32
+	SizeImage     uint32
+	XPelsPerMeter int32
+	YPelsPerMeter int32
+	ClrUsed       uint32
+	ClrImportant  uint32
+}
+
+type bitmapInfo struct {
+	Header bitmapInfoHeader
+}
+
+// setupInteractiveWindowStation associates the current process with WinSta0,
+// the interactive window station. This is required for a SYSTEM service in
+// Session 0 to call OpenInputDesktop for screen capture and input injection.
+func setupInteractiveWindowStation() error {
+	name, err := windows.UTF16PtrFromString("WinSta0")
+	if err != nil {
+		return fmt.Errorf("UTF16 WinSta0: %w", err)
+	}
+	hWinSta, _, err := procOpenWindowStation.Call(
+		uintptr(unsafe.Pointer(name)),
+		0,
+		uintptr(windows.MAXIMUM_ALLOWED),
+	)
+	if hWinSta == 0 {
+		return fmt.Errorf("OpenWindowStation(WinSta0): %w", err)
+	}
+	r, _, err := procSetProcessWindowStation.Call(hWinSta)
+	if r == 0 {
+		_, _, _ = procCloseWindowStation.Call(hWinSta)
+		return fmt.Errorf("SetProcessWindowStation: %w", err)
+	}
+	log.Info("process window station set to WinSta0 (interactive)")
+	return nil
+}
+
+func screenSize() (int, int) {
+	w, _, _ := procGetSystemMetrics.Call(uintptr(smCxScreen))
+	h, _, _ := procGetSystemMetrics.Call(uintptr(smCyScreen))
+	return int(w), int(h)
+}
+
+func getDesktopName(hDesk uintptr) string {
+	var buf [256]uint16
+	var needed uint32
+	_, _, _ = procGetUserObjectInformationW.Call(hDesk, uoiName,
+		uintptr(unsafe.Pointer(&buf[0])), 512,
+		uintptr(unsafe.Pointer(&needed)))
+	return windows.UTF16ToString(buf[:])
+}
+
+// switchToInputDesktop opens the desktop currently receiving user input
+// and sets it as the calling OS thread's desktop. Must be called from a
+// goroutine locked to its OS thread via runtime.LockOSThread().
+func switchToInputDesktop() (bool, string) {
+	hDesk, _, _ := procOpenInputDesktop.Call(0, 0, uintptr(windows.MAXIMUM_ALLOWED))
+	if hDesk == 0 {
+		return false, ""
+	}
+	name := getDesktopName(hDesk)
+	ret, _, _ := procSetThreadDesktop.Call(hDesk)
+	_, _, _ = procCloseDesktop.Call(hDesk)
+	return ret != 0, name
+}
+
+// gdiCapturer captures the desktop screen using GDI BitBlt.
+// GDI objects (DC, DIBSection) are allocated once and reused across frames.
+type gdiCapturer struct {
+	mu     sync.Mutex
+	width  int
+	height int
+
+	// Pre-allocated GDI resources, reused across captures.
+	memDC uintptr
+	bmp   uintptr
+	bits  uintptr
+}
+
+func newGDICapturer() (*gdiCapturer, error) {
+	w, h := screenSize()
+	if w == 0 || h == 0 {
+		return nil, fmt.Errorf("screen dimensions are zero")
+	}
+	c := &gdiCapturer{width: w, height: h}
+	if err := c.allocGDI(); err != nil {
+		return nil, err
+	}
+	return c, nil
+}
+
+// allocGDI pre-allocates the compatible DC and DIB section for reuse.
+func (c *gdiCapturer) allocGDI() error {
+	screenDC, _, _ := procGetDC.Call(0)
+	if screenDC == 0 {
+		return fmt.Errorf("GetDC returned 0")
+	}
+	defer func() { _, _, _ = procReleaseDC.Call(0, screenDC) }()
+
+	memDC, _, _ := procCreateCompatDC.Call(screenDC)
+	if memDC == 0 {
+		return fmt.Errorf("CreateCompatibleDC returned 0")
+	}
+
+	bi := bitmapInfo{
+		Header: bitmapInfoHeader{
+			Size:     uint32(unsafe.Sizeof(bitmapInfoHeader{})),
+			Width:    int32(c.width),
+			Height:   -int32(c.height), // negative = top-down DIB
+			Planes:   1,
+			BitCount: 32,
+		},
+	}
+
+	var bits uintptr
+	bmp, _, _ := procCreateDIBSection.Call(
+		screenDC,
+		uintptr(unsafe.Pointer(&bi)),
+		dibRgbColors,
+		uintptr(unsafe.Pointer(&bits)),
+		0, 0,
+	)
+	if bmp == 0 || bits == 0 {
+		_, _, _ = procDeleteDC.Call(memDC)
+		return fmt.Errorf("CreateDIBSection returned 0")
+	}
+
+	_, _, _ = procSelectObject.Call(memDC, bmp)
+
+	c.memDC = memDC
+	c.bmp = bmp
+	c.bits = bits
+	return nil
+}
+
+func (c *gdiCapturer) close() { c.freeGDI() }
+
+// freeGDI releases pre-allocated GDI resources.
+func (c *gdiCapturer) freeGDI() {
+	if c.bmp != 0 {
+		_, _, _ = procDeleteObject.Call(c.bmp)
+		c.bmp = 0
+	}
+	if c.memDC != 0 {
+		_, _, _ = procDeleteDC.Call(c.memDC)
+		c.memDC = 0
+	}
+	c.bits = 0
+}
+
+func (c *gdiCapturer) capture() (*image.RGBA, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.memDC == 0 {
+		return nil, fmt.Errorf("GDI resources not allocated")
+	}
+
+	screenDC, _, _ := procGetDC.Call(0)
+	if screenDC == 0 {
+		return nil, fmt.Errorf("GetDC returned 0")
+	}
+	defer func() { _, _, _ = procReleaseDC.Call(0, screenDC) }()
+
+	// SRCCOPY|CAPTUREBLT: CAPTUREBLT forces inclusion of layered/topmost
+	// windows in the capture and is required for GDI BitBlt to return live
+	// pixels when the session is rendered through RDP / DWM-composited
+	// surfaces. Without it BitBlt reads the backing-store DIB which is
+	// often empty (all-black) on RDP and headless sessions.
+	ret, _, _ := procBitBlt.Call(c.memDC, 0, 0, uintptr(c.width), uintptr(c.height),
+		screenDC, 0, 0, srccopy|captureBlt)
+	if ret == 0 {
+		return nil, fmt.Errorf("BitBlt returned 0")
+	}
+
+	n := c.width * c.height * 4
+	raw := unsafe.Slice((*byte)(unsafe.Pointer(c.bits)), n)
+
+	// GDI gives BGRA, the RFB encoder expects RGBA (img.Pix layout).
+	// Swap R and B in bulk using uint32 operations (one load + mask + shift
+	// per pixel instead of three separate byte assignments).
+	img := image.NewRGBA(image.Rect(0, 0, c.width, c.height))
+	swizzleBGRAtoRGBA(img.Pix, raw)
+	return img, nil
+}
+
+// DesktopCapturer captures the interactive desktop, handling desktop transitions
+// (login screen, UAC prompts). A dedicated OS-locked goroutine continuously
+// captures frames on demand via a dedicated OS-locked goroutine (required
+// because DXGI's D3D11 device context is not thread-safe). Sessions drive
+// timing by calling Capture(); a short staleness cache coalesces concurrent
+// requests. Capture pauses automatically when no clients are connected.
+type DesktopCapturer struct {
+	mu   sync.Mutex
+	w, h int
+
+	// lastFrame/lastAt implement a small staleness cache so multiple
+	// near-simultaneous Capture calls share one DXGI round-trip.
+	lastFrame *image.RGBA
+	lastAt    time.Time
+
+	// clients tracks the number of active VNC sessions. When zero, the
+	// worker goroutine releases the underlying capturer.
+	clients atomic.Int32
+
+	// reqCh carries capture requests from sessions to the OS-locked worker.
+	reqCh chan captureReq
+	// wake is signaled when a client connects and the worker should resume.
+	wake chan struct{}
+	// done is closed when Close is called, terminating the worker.
+	done chan struct{}
+}
+
+// captureReq is a single capture request awaiting a reply. Reply channel is
+// buffered to size 1 so the worker never blocks on a sender that's gone.
+type captureReq struct {
+	reply chan captureReply
+}
+
+type captureReply struct {
+	img *image.RGBA
+	err error
+}
+
+// NewDesktopCapturer creates an on-demand capturer for the active desktop.
+func NewDesktopCapturer() *DesktopCapturer {
+	c := &DesktopCapturer{
+		wake:  make(chan struct{}, 1),
+		done:  make(chan struct{}),
+		reqCh: make(chan captureReq),
+	}
+	go c.worker()
+	return c
+}
+
+// ClientConnect increments the active client count, resuming capture if needed.
+func (c *DesktopCapturer) ClientConnect() {
+	c.clients.Add(1)
+	select {
+	case c.wake <- struct{}{}:
+	default:
+	}
+}
+
+// ClientDisconnect decrements the active client count.
+func (c *DesktopCapturer) ClientDisconnect() {
+	c.clients.Add(-1)
+}
+
+// Close stops the capture loop and releases resources.
+func (c *DesktopCapturer) Close() {
+	select {
+	case <-c.done:
+	default:
+		close(c.done)
+	}
+}
+
+// Width returns the current screen width, triggering a capture if the
+// worker hasn't initialised yet. validateCapturer depends on Width/Height
+// becoming non-zero promptly after ClientConnect so it doesn't reject
+// brand-new sessions.
+func (c *DesktopCapturer) Width() int {
+	c.mu.Lock()
+	w := c.w
+	c.mu.Unlock()
+	if w == 0 && c.clients.Load() > 0 {
+		_, _ = c.Capture()
+		c.mu.Lock()
+		w = c.w
+		c.mu.Unlock()
+	}
+	return w
+}
+
+// Height returns the current screen height, triggering a capture if the
+// worker hasn't initialised yet (see Width). Returns 0 while no client is
+// connected so callers don't deadlock against a parked worker.
+func (c *DesktopCapturer) Height() int {
+	c.mu.Lock()
+	h := c.h
+	c.mu.Unlock()
+	if h == 0 && c.clients.Load() > 0 {
+		_, _ = c.Capture()
+		c.mu.Lock()
+		h = c.h
+		c.mu.Unlock()
+	}
+	return h
+}
+
+// Capture returns a freshly captured frame, serving from a short staleness
+// cache when multiple sessions ask within freshWindow of each other. All
+// real DXGI/GDI work happens on the OS-locked worker goroutine.
+func (c *DesktopCapturer) Capture() (*image.RGBA, error) {
+	c.mu.Lock()
+	if c.lastFrame != nil && time.Since(c.lastAt) < freshWindow {
+		img := c.lastFrame
+		c.mu.Unlock()
+		return img, nil
+	}
+	c.mu.Unlock()
+
+	reply := make(chan captureReply, 1)
+	select {
+	case c.reqCh <- captureReq{reply: reply}:
+	case <-c.done:
+		return nil, fmt.Errorf("capturer closed")
+	}
+	select {
+	case r := <-reply:
+		if r.err != nil {
+			return nil, r.err
+		}
+		c.mu.Lock()
+		c.lastFrame = r.img
+		c.lastAt = time.Now()
+		c.mu.Unlock()
+		return r.img, nil
+	case <-c.done:
+		return nil, fmt.Errorf("capturer closed")
+	}
+}
+
+// waitForClient blocks until a client connects or the capturer is closed.
+func (c *DesktopCapturer) waitForClient() bool {
+	if c.clients.Load() > 0 {
+		return true
+	}
+	select {
+	case <-c.wake:
+		return true
+	case <-c.done:
+		return false
+	}
+}
+
+// worker owns DXGI/GDI state on its OS-locked thread and services capture
+// requests from sessions. No background ticker: a capture happens only when
+// a session asks for one (throttled by Capture()'s staleness cache).
+func (c *DesktopCapturer) worker() {
+	runtime.LockOSThread()
+
+	// When running as a Windows service (Session 0), we need to attach to the
+	// interactive window station before OpenInputDesktop will succeed.
+	if err := setupInteractiveWindowStation(); err != nil {
+		log.Warnf("attach to interactive window station: %v", err)
+	}
+
+	w := &captureWorker{c: c}
+	defer w.closeCapturer()
+
+	for {
+		if !c.waitForClient() {
+			return
+		}
+		// Drop the capturer when all clients have disconnected so we don't
+		// hold the DXGI duplication or GDI DC on an idle peer.
+		if c.clients.Load() <= 0 {
+			w.closeCapturer()
+			continue
+		}
+		if !w.handleNextRequest() {
+			return
+		}
+	}
+}
+
+// frameCapturer is the per-backend interface used by the worker. DXGI and
+// GDI implementations both satisfy it.
+type frameCapturer interface {
+	capture() (*image.RGBA, error)
+	close()
+}
+
+// captureWorker owns the worker goroutine's mutable state. Extracted into a
+// struct so the request/desktop/init logic can live on small methods and the
+// outer worker() stays a thin loop.
+type captureWorker struct {
+	c             *DesktopCapturer
+	cap           frameCapturer
+	desktopFails  int
+	lastDesktop   string
+	nextInitRetry time.Time
+}
+
+// handleNextRequest waits for either shutdown or a capture request and runs
+// the request through prepCapturer/capture. Returns false when the worker
+// should exit.
+func (w *captureWorker) handleNextRequest() bool {
+	select {
+	case <-w.c.done:
+		return false
+	case req := <-w.c.reqCh:
+		w.serveRequest(req)
+		return true
+	}
+}
+
+func (w *captureWorker) serveRequest(req captureReq) {
+	fc, err := w.prepCapturer()
+	if err != nil {
+		req.reply <- captureReply{err: err}
+		return
+	}
+	img, err := fc.capture()
+	if err != nil {
+		log.Debugf("capture: %v", err)
+		w.closeCapturer()
+		w.nextInitRetry = time.Now().Add(100 * time.Millisecond)
+		req.reply <- captureReply{err: err}
+		return
+	}
+	req.reply <- captureReply{img: img}
+}
+
+// prepCapturer switches to the input desktop, handles desktop-change
+// teardown, and creates the underlying capturer on demand. Backoff state is
+// tracked across calls via w.nextInitRetry.
+func (w *captureWorker) prepCapturer() (frameCapturer, error) {
+	if err := w.refreshDesktop(); err != nil {
+		return nil, err
+	}
+	if w.cap != nil {
+		return w.cap, nil
+	}
+	if time.Now().Before(w.nextInitRetry) {
+		return nil, fmt.Errorf("capturer init backing off")
+	}
+	fc, err := w.createCapturer()
+	if err != nil {
+		w.nextInitRetry = time.Now().Add(500 * time.Millisecond)
+		return nil, err
+	}
+	w.cap = fc
+	sw, sh := screenSize()
+	w.c.mu.Lock()
+	w.c.w, w.c.h = sw, sh
+	w.c.mu.Unlock()
+	log.Infof("screen capturer ready: %dx%d", sw, sh)
+	return w.cap, nil
+}
+
+// refreshDesktop tracks the active input desktop. When it changes (lock
+// screen, fast-user-switch) the existing capturer is dropped so the next
+// call rebuilds one against the new desktop.
+func (w *captureWorker) refreshDesktop() error {
+	ok, desk := switchToInputDesktop()
+	if !ok {
+		w.desktopFails++
+		if w.desktopFails == 1 || w.desktopFails%100 == 0 {
+			log.Warnf("switchToInputDesktop failed (count=%d), no interactive desktop session?", w.desktopFails)
+		}
+		return fmt.Errorf("no interactive desktop")
+	}
+	if w.desktopFails > 0 {
+		log.Infof("switchToInputDesktop recovered after %d failures, desktop=%q", w.desktopFails, desk)
+		w.desktopFails = 0
+	}
+	if desk != w.lastDesktop {
+		log.Infof("desktop changed: %q -> %q", w.lastDesktop, desk)
+		w.lastDesktop = desk
+		w.closeCapturer()
+	}
+	return nil
+}
+
+func (w *captureWorker) createCapturer() (frameCapturer, error) {
+	dc, err := newDXGICapturer()
+	if err == nil {
+		log.Info("using DXGI Desktop Duplication for capture")
+		return dc, nil
+	}
+	log.Debugf("DXGI unavailable (%v), falling back to GDI", err)
+	gc, err := newGDICapturer()
+	if err != nil {
+		return nil, err
+	}
+	log.Info("using GDI BitBlt for capture")
+	return gc, nil
+}
+
+func (w *captureWorker) closeCapturer() {
+	if w.cap != nil {
+		w.cap.close()
+		w.cap = nil
+	}
+}

client/vnc/server/capture_x11.go

@@ -0,0 +1,479 @@
+//go:build (linux && !android) || freebsd
+
+package server
+
+import (
+	"fmt"
+	"image"
+	"os"
+	"os/exec"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/jezek/xgb"
+	"github.com/jezek/xgb/xproto"
+)
+
+// X11Capturer captures the screen from an X11 display using the MIT-SHM extension.
+type X11Capturer struct {
+	mu      sync.Mutex
+	conn    *xgb.Conn
+	screen  *xproto.ScreenInfo
+	w, h    int
+	shmID   int
+	shmAddr []byte
+	shmSeg  uint32 // shm.Seg
+	useSHM  bool
+	// bufs double-buffers output images so the X11Poller's capture loop can
+	// overwrite one while the session is still encoding the other. Before
+	// this, a single reused buffer would race with the reader. Allocation
+	// happens on first use and on geometry change.
+	bufs [2]*image.RGBA
+	cur  int
+}
+
+// detectX11Display finds the active X11 display and sets DISPLAY/XAUTHORITY
+// environment variables if needed. This is required when running as a system
+// service where these vars aren't set.
+func detectX11Display() {
+	if os.Getenv("DISPLAY") != "" {
+		return
+	}
+
+	// Try /proc first (Linux), then ps fallback (FreeBSD and others).
+	if detectX11FromProc() {
+		return
+	}
+	if detectX11FromSockets() {
+		return
+	}
+}
+
+// detectX11FromProc scans /proc/*/cmdline for Xorg (Linux).
+func detectX11FromProc() bool {
+	entries, err := os.ReadDir("/proc")
+	if err != nil {
+		return false
+	}
+	for _, e := range entries {
+		if !e.IsDir() {
+			continue
+		}
+		cmdline, err := os.ReadFile("/proc/" + e.Name() + "/cmdline")
+		if err != nil {
+			continue
+		}
+		if display, auth := parseXorgArgs(splitCmdline(cmdline)); display != "" {
+			setDisplayEnv(display, auth)
+			return true
+		}
+	}
+	return false
+}
+
+// detectX11FromSockets checks /tmp/.X11-unix/ for X sockets and uses ps
+// to find the auth file. Works on FreeBSD and other systems without /proc.
+func detectX11FromSockets() bool {
+	entries, err := os.ReadDir("/tmp/.X11-unix")
+	if err != nil {
+		return false
+	}
+
+	// Find the lowest display number.
+	for _, e := range entries {
+		name := e.Name()
+		if len(name) < 2 || name[0] != 'X' {
+			continue
+		}
+		display := ":" + name[1:]
+		os.Setenv("DISPLAY", display)
+		log.Infof("auto-detected DISPLAY=%s (from socket)", display)
+
+		// Try to find -auth from ps output.
+		if auth := findXorgAuthFromPS(); auth != "" {
+			os.Setenv("XAUTHORITY", auth)
+			log.Infof("auto-detected XAUTHORITY=%s (from ps)", auth)
+		}
+		return true
+	}
+	return false
+}
+
+// findXorgAuthFromPS runs ps to find Xorg and extract its -auth argument.
+func findXorgAuthFromPS() string {
+	out, err := exec.Command("ps", "auxww").Output()
+	if err != nil {
+		return ""
+	}
+	for _, line := range strings.Split(string(out), "\n") {
+		if !strings.Contains(line, "Xorg") && !strings.Contains(line, "/X ") {
+			continue
+		}
+		fields := strings.Fields(line)
+		for i, f := range fields {
+			if f == "-auth" && i+1 < len(fields) {
+				return fields[i+1]
+			}
+		}
+	}
+	return ""
+}
+
+func parseXorgArgs(args []string) (display, auth string) {
+	if len(args) == 0 {
+		return "", ""
+	}
+	base := args[0]
+	if !(base == "Xorg" || base == "X" || len(base) > 0 && base[len(base)-1] == 'X' ||
+		strings.Contains(base, "/Xorg") || strings.Contains(base, "/X")) {
+		return "", ""
+	}
+	for i, arg := range args[1:] {
+		if len(arg) > 0 && arg[0] == ':' {
+			display = arg
+		}
+		if arg == "-auth" && i+2 < len(args) {
+			auth = args[i+2]
+		}
+	}
+	return display, auth
+}
+
+func setDisplayEnv(display, auth string) {
+	os.Setenv("DISPLAY", display)
+	log.Infof("auto-detected DISPLAY=%s", display)
+	if auth != "" {
+		os.Setenv("XAUTHORITY", auth)
+		log.Infof("auto-detected XAUTHORITY=%s", auth)
+	}
+}
+
+func splitCmdline(data []byte) []string {
+	var args []string
+	for _, b := range splitNull(data) {
+		if len(b) > 0 {
+			args = append(args, string(b))
+		}
+	}
+	return args
+}
+
+func splitNull(data []byte) [][]byte {
+	var parts [][]byte
+	start := 0
+	for i, b := range data {
+		if b == 0 {
+			parts = append(parts, data[start:i])
+			start = i + 1
+		}
+	}
+	if start < len(data) {
+		parts = append(parts, data[start:])
+	}
+	return parts
+}
+
+// NewX11Capturer connects to the X11 display and sets up shared memory capture.
+func NewX11Capturer(display string) (*X11Capturer, error) {
+	if display == "" {
+		detectX11Display()
+		display = os.Getenv("DISPLAY")
+	}
+	if display == "" {
+		return nil, fmt.Errorf("DISPLAY not set and no Xorg process found")
+	}
+
+	conn, err := xgb.NewConnDisplay(display)
+	if err != nil {
+		return nil, fmt.Errorf("connect to X11 display %s: %w", display, err)
+	}
+
+	setup := xproto.Setup(conn)
+	if len(setup.Roots) == 0 {
+		conn.Close()
+		return nil, fmt.Errorf("no X11 screens")
+	}
+	screen := setup.Roots[0]
+
+	c := &X11Capturer{
+		conn:   conn,
+		screen: &screen,
+		w:      int(screen.WidthInPixels),
+		h:      int(screen.HeightInPixels),
+	}
+
+	if err := c.initSHM(); err != nil {
+		log.Debugf("X11 SHM not available, using slow GetImage: %v", err)
+	}
+
+	log.Infof("X11 capturer ready: %dx%d (display=%s, shm=%v)", c.w, c.h, display, c.useSHM)
+	return c, nil
+}
+
+// initSHM is implemented in capture_x11_shm_linux.go (requires SysV SHM).
+// On platforms without SysV SHM (FreeBSD), a stub returns an error and
+// the capturer falls back to GetImage.
+
+// Width returns the screen width.
+func (c *X11Capturer) Width() int { return c.w }
+
+// Height returns the screen height.
+func (c *X11Capturer) Height() int { return c.h }
+
+// Capture returns the current screen as an RGBA image.
+func (c *X11Capturer) Capture() (*image.RGBA, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.useSHM {
+		return c.captureSHM()
+	}
+	return c.captureGetImage()
+}
+
+// CaptureInto fills the caller's destination buffer in one pass. The
+// source path (SHM or fallback GetImage) writes directly into dst.Pix
+// instead of going through the X11Capturer's internal double-buffer,
+// saving one full-frame memcpy per capture.
+func (c *X11Capturer) CaptureInto(dst *image.RGBA) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if dst.Rect.Dx() != c.w || dst.Rect.Dy() != c.h {
+		return fmt.Errorf("dst size mismatch: dst=%dx%d capturer=%dx%d",
+			dst.Rect.Dx(), dst.Rect.Dy(), c.w, c.h)
+	}
+	if c.useSHM {
+		return c.captureSHMInto(dst)
+	}
+	return c.captureGetImageInto(dst)
+}
+
+func (c *X11Capturer) captureGetImageInto(dst *image.RGBA) error {
+	cookie := xproto.GetImage(c.conn, xproto.ImageFormatZPixmap,
+		xproto.Drawable(c.screen.Root),
+		0, 0, uint16(c.w), uint16(c.h), 0xFFFFFFFF)
+	reply, err := cookie.Reply()
+	if err != nil {
+		return fmt.Errorf("GetImage: %w", err)
+	}
+	n := c.w * c.h * 4
+	if len(reply.Data) < n {
+		return fmt.Errorf("GetImage returned %d bytes, expected %d", len(reply.Data), n)
+	}
+	swizzleBGRAtoRGBA(dst.Pix, reply.Data)
+	return nil
+}
+
+// captureSHM is implemented in capture_x11_shm_linux.go.
+
+func (c *X11Capturer) captureGetImage() (*image.RGBA, error) {
+	cookie := xproto.GetImage(c.conn, xproto.ImageFormatZPixmap,
+		xproto.Drawable(c.screen.Root),
+		0, 0, uint16(c.w), uint16(c.h), 0xFFFFFFFF)
+
+	reply, err := cookie.Reply()
+	if err != nil {
+		return nil, fmt.Errorf("GetImage: %w", err)
+	}
+
+	data := reply.Data
+	n := c.w * c.h * 4
+	if len(data) < n {
+		return nil, fmt.Errorf("GetImage returned %d bytes, expected %d", len(data), n)
+	}
+
+	img := c.nextBuffer()
+	swizzleBGRAtoRGBA(img.Pix, data)
+	return img, nil
+}
+
+// nextBuffer returns the *image.RGBA the next capture should fill, advancing
+// the double-buffer index. Reallocates on geometry change.
+func (c *X11Capturer) nextBuffer() *image.RGBA {
+	c.cur ^= 1
+	b := c.bufs[c.cur]
+	if b == nil || b.Rect.Dx() != c.w || b.Rect.Dy() != c.h {
+		b = image.NewRGBA(image.Rect(0, 0, c.w, c.h))
+		c.bufs[c.cur] = b
+	}
+	return b
+}
+
+// Close releases X11 resources.
+func (c *X11Capturer) Close() {
+	c.closeSHM()
+	c.conn.Close()
+}
+
+// closeSHM is implemented in capture_x11_shm_linux.go.
+
+// X11Poller wraps X11Capturer with a staleness-cached on-demand Capture:
+// sessions drive captures themselves through the encoder goroutine, so we
+// don't need a background ticker. The last result is cached for a short
+// window so concurrent sessions coalesce into one capture.
+//
+// The capturer is allocated lazily on first use and released when all
+// clients disconnect, so an idle peer holds no X connection or SHM segment.
+type X11Poller struct {
+	mu sync.Mutex
+
+	capturer *X11Capturer
+	w, h     int
+	// closed at Close so callers can stop waiting on retry backoff.
+	done chan struct{}
+
+	// lastFrame/lastAt implement a small cache: multiple near-simultaneous
+	// Capture calls (multi-client, or input-coalesced) return the same
+	// frame instead of hammering the X server.
+	lastFrame *image.RGBA
+	lastAt    time.Time
+
+	// initBackoffUntil throttles capturer re-init when the X server is
+	// unavailable or flapping.
+	initBackoffUntil time.Time
+
+	clients atomic.Int32
+	display string
+}
+
+// initRetryBackoff gates capturer re-init attempts after a failure so we
+// don't spin on X server errors.
+const initRetryBackoff = 2 * time.Second
+
+// NewX11Poller creates a lazy on-demand capturer for the given X display.
+func NewX11Poller(display string) *X11Poller {
+	return &X11Poller{
+		display: display,
+		done:    make(chan struct{}),
+	}
+}
+
+// ClientConnect increments the active client count. The first client triggers
+// eager capturer initialisation so that the first FBUpdateRequest doesn't
+// pay the X11 connect + SHM attach latency.
+func (p *X11Poller) ClientConnect() {
+	if p.clients.Add(1) == 1 {
+		p.mu.Lock()
+		_ = p.ensureCapturerLocked()
+		p.mu.Unlock()
+	}
+}
+
+// ClientDisconnect decrements the active client count. On the last
+// disconnect we close the underlying capturer so idle peers cost nothing.
+func (p *X11Poller) ClientDisconnect() {
+	if p.clients.Add(-1) == 0 {
+		p.mu.Lock()
+		if p.capturer != nil {
+			p.capturer.Close()
+			p.capturer = nil
+			p.lastFrame = nil
+		}
+		p.mu.Unlock()
+	}
+}
+
+// Close releases all resources. Subsequent Capture calls will fail.
+func (p *X11Poller) Close() {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	select {
+	case <-p.done:
+	default:
+		close(p.done)
+	}
+	if p.capturer != nil {
+		p.capturer.Close()
+		p.capturer = nil
+	}
+}
+
+// Width returns the screen width. Triggers lazy init if needed.
+func (p *X11Poller) Width() int {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	_ = p.ensureCapturerLocked()
+	return p.w
+}
+
+// Height returns the screen height. Triggers lazy init if needed.
+func (p *X11Poller) Height() int {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	_ = p.ensureCapturerLocked()
+	return p.h
+}
+
+// Capture returns a fresh frame, serving from the short-lived cache if a
+// previous caller captured within freshWindow.
+func (p *X11Poller) Capture() (*image.RGBA, error) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	if p.lastFrame != nil && time.Since(p.lastAt) < freshWindow {
+		return p.lastFrame, nil
+	}
+	if err := p.ensureCapturerLocked(); err != nil {
+		return nil, err
+	}
+	img, err := p.capturer.Capture()
+	if err != nil {
+		// Drop the capturer so the next call re-inits; the X connection may
+		// have died (e.g. Xorg restart).
+		p.capturer.Close()
+		p.capturer = nil
+		p.initBackoffUntil = time.Now().Add(initRetryBackoff)
+		return nil, fmt.Errorf("x11 capture: %w", err)
+	}
+	p.lastFrame = img
+	p.lastAt = time.Now()
+	return img, nil
+}
+
+// CaptureInto fills dst directly via the underlying capturer, bypassing
+// the freshness cache. The session's prevFrame/curFrame swap means each
+// session needs its own buffer anyway, so caching wouldn't help.
+func (p *X11Poller) CaptureInto(dst *image.RGBA) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	if err := p.ensureCapturerLocked(); err != nil {
+		return err
+	}
+	if err := p.capturer.CaptureInto(dst); err != nil {
+		p.capturer.Close()
+		p.capturer = nil
+		p.initBackoffUntil = time.Now().Add(initRetryBackoff)
+		return fmt.Errorf("x11 capture: %w", err)
+	}
+	return nil
+}
+
+// ensureCapturerLocked initialises the underlying X11Capturer if not
+// already open. Caller must hold p.mu.
+func (p *X11Poller) ensureCapturerLocked() error {
+	if p.capturer != nil {
+		return nil
+	}
+	select {
+	case <-p.done:
+		return fmt.Errorf("x11 capturer closed")
+	default:
+	}
+	if time.Now().Before(p.initBackoffUntil) {
+		return fmt.Errorf("x11 capturer unavailable (retry scheduled)")
+	}
+	c, err := NewX11Capturer(p.display)
+	if err != nil {
+		p.initBackoffUntil = time.Now().Add(initRetryBackoff)
+		log.Debugf("X11 capturer: %v", err)
+		return err
+	}
+	p.capturer = c
+	p.w, p.h = c.Width(), c.Height()
+	return nil
+}

client/vnc/server/capture_x11_shm_linux.go

@@ -0,0 +1,96 @@
+//go:build linux && !android
+
+package server
+
+import (
+	"fmt"
+	"image"
+
+	"github.com/jezek/xgb/shm"
+	"github.com/jezek/xgb/xproto"
+	log "github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
+)
+
+func (c *X11Capturer) initSHM() error {
+	if err := shm.Init(c.conn); err != nil {
+		return fmt.Errorf("init SHM extension: %w", err)
+	}
+
+	size := c.w * c.h * 4
+	id, err := unix.SysvShmGet(unix.IPC_PRIVATE, size, unix.IPC_CREAT|0600)
+	if err != nil {
+		return fmt.Errorf("shmget: %w", err)
+	}
+
+	addr, err := unix.SysvShmAttach(id, 0, 0)
+	if err != nil {
+		if _, ctlErr := unix.SysvShmCtl(id, unix.IPC_RMID, nil); ctlErr != nil {
+			log.Debugf("shmctl IPC_RMID on attach failure: %v", ctlErr)
+		}
+		return fmt.Errorf("shmat: %w", err)
+	}
+
+	if _, err := unix.SysvShmCtl(id, unix.IPC_RMID, nil); err != nil {
+		log.Debugf("shmctl IPC_RMID: %v", err)
+	}
+
+	seg, err := shm.NewSegId(c.conn)
+	if err != nil {
+		if detachErr := unix.SysvShmDetach(addr); detachErr != nil {
+			log.Debugf("shmdt on new-seg failure: %v", detachErr)
+		}
+		return fmt.Errorf("new SHM seg: %w", err)
+	}
+
+	if err := shm.AttachChecked(c.conn, seg, uint32(id), false).Check(); err != nil {
+		if detachErr := unix.SysvShmDetach(addr); detachErr != nil {
+			log.Debugf("shmdt on attach-checked failure: %v", detachErr)
+		}
+		return fmt.Errorf("SHM attach to X: %w", err)
+	}
+
+	c.shmID = id
+	c.shmAddr = addr
+	c.shmSeg = uint32(seg)
+	c.useSHM = true
+	return nil
+}
+
+func (c *X11Capturer) captureSHM() (*image.RGBA, error) {
+	if err := c.fillSHM(); err != nil {
+		return nil, err
+	}
+	img := c.nextBuffer()
+	swizzleBGRAtoRGBA(img.Pix, c.shmAddr[:c.w*c.h*4])
+	return img, nil
+}
+
+// captureSHMInto runs a single SHM GetImage and swizzles directly into the
+// caller-provided destination, skipping the internal double-buffer.
+func (c *X11Capturer) captureSHMInto(dst *image.RGBA) error {
+	if err := c.fillSHM(); err != nil {
+		return err
+	}
+	swizzleBGRAtoRGBA(dst.Pix, c.shmAddr[:c.w*c.h*4])
+	return nil
+}
+
+func (c *X11Capturer) fillSHM() error {
+	cookie := shm.GetImage(c.conn, xproto.Drawable(c.screen.Root),
+		0, 0, uint16(c.w), uint16(c.h), 0xFFFFFFFF,
+		xproto.ImageFormatZPixmap, shm.Seg(c.shmSeg), 0)
+	if _, err := cookie.Reply(); err != nil {
+		return fmt.Errorf("SHM GetImage: %w", err)
+	}
+	return nil
+}
+
+func (c *X11Capturer) closeSHM() {
+	if c.useSHM {
+		shm.Detach(c.conn, shm.Seg(c.shmSeg))
+		if err := unix.SysvShmDetach(c.shmAddr); err != nil {
+			log.Debugf("shmdt on close: %v", err)
+		}
+	}
+}

client/vnc/server/capture_x11_shm_stub.go

@@ -0,0 +1,24 @@
+//go:build freebsd
+
+package server
+
+import (
+	"fmt"
+	"image"
+)
+
+func (c *X11Capturer) initSHM() error {
+	return fmt.Errorf("SysV SHM not available on this platform")
+}
+
+func (c *X11Capturer) captureSHM() (*image.RGBA, error) {
+	return nil, fmt.Errorf("SHM capture not available on this platform")
+}
+
+func (c *X11Capturer) captureSHMInto(_ *image.RGBA) error {
+	return fmt.Errorf("SHM capture not available on this platform")
+}
+
+func (c *X11Capturer) closeSHM() {
+	// no SHM to close on this platform
+}

client/vnc/server/coalesce_test.go

@@ -0,0 +1,75 @@
+package server
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestCoalesceRects(t *testing.T) {
+	cases := []struct {
+		name string
+		in   [][4]int
+		want [][4]int
+	}{
+		{
+			name: "empty",
+			in:   nil,
+			want: nil,
+		},
+		{
+			name: "single",
+			in:   [][4]int{{0, 0, 64, 64}},
+			want: [][4]int{{0, 0, 64, 64}},
+		},
+		{
+			name: "horizontal_run",
+			in:   [][4]int{{0, 0, 64, 64}, {64, 0, 64, 64}, {128, 0, 64, 64}},
+			want: [][4]int{{0, 0, 192, 64}},
+		},
+		{
+			name: "vertical_run",
+			in:   [][4]int{{0, 0, 64, 64}, {0, 64, 64, 64}, {0, 128, 64, 64}},
+			want: [][4]int{{0, 0, 64, 192}},
+		},
+		{
+			name: "block_2x2",
+			in: [][4]int{
+				{0, 0, 64, 64}, {64, 0, 64, 64},
+				{0, 64, 64, 64}, {64, 64, 64, 64},
+			},
+			want: [][4]int{{0, 0, 128, 128}},
+		},
+		{
+			name: "no_merge_gap",
+			in:   [][4]int{{0, 0, 64, 64}, {192, 0, 64, 64}},
+			want: [][4]int{{0, 0, 64, 64}, {192, 0, 64, 64}},
+		},
+		{
+			name: "two_disjoint_columns",
+			in: [][4]int{
+				{0, 0, 64, 64}, {192, 0, 64, 64},
+				{0, 64, 64, 64}, {192, 64, 64, 64},
+			},
+			want: [][4]int{{0, 0, 64, 128}, {192, 0, 64, 128}},
+		},
+		{
+			name: "misaligned_widths_no_vertical_merge",
+			in: [][4]int{
+				{0, 0, 128, 64},
+				{0, 64, 64, 64},
+			},
+			want: [][4]int{{0, 0, 128, 64}, {0, 64, 64, 64}},
+		},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			got := coalesceRects(tc.in)
+			if len(got) == 0 && len(tc.want) == 0 {
+				return
+			}
+			if !reflect.DeepEqual(got, tc.want) {
+				t.Fatalf("got %v want %v", got, tc.want)
+			}
+		})
+	}
+}

client/vnc/server/hextile_test.go

@@ -0,0 +1,188 @@
+package server
+
+import (
+	"image"
+	"testing"
+)
+
+// roundTrip decodes an encoded Hextile rect back into pixels and checks it
+// matches the source. Implements just enough of the noVNC Hextile decoder
+// to validate our encoder.
+func decodeHextile(t *testing.T, buf []byte, pf clientPixelFormat) *image.RGBA {
+	t.Helper()
+	if len(buf) < 12 {
+		t.Fatalf("buf too short: %d", len(buf))
+	}
+	x := int(uint16(buf[0])<<8 | uint16(buf[1]))
+	y := int(uint16(buf[2])<<8 | uint16(buf[3]))
+	w := int(uint16(buf[4])<<8 | uint16(buf[5]))
+	h := int(uint16(buf[6])<<8 | uint16(buf[7]))
+	enc := uint32(buf[8])<<24 | uint32(buf[9])<<16 | uint32(buf[10])<<8 | uint32(buf[11])
+	if enc != encHextile {
+		t.Fatalf("not hextile: %d", enc)
+	}
+	body := buf[12:]
+	bytesPerPixel := max(int(pf.bpp)/8, 1)
+	out := image.NewRGBA(image.Rect(x, y, x+w, y+h))
+
+	var bg, fg [3]byte
+	pos := 0
+	readPixel := func() [3]byte {
+		var v uint32
+		if pf.bigEndian != 0 {
+			for i := 0; i < bytesPerPixel; i++ {
+				v |= uint32(body[pos+i]) << (8 * (bytesPerPixel - 1 - i))
+			}
+		} else {
+			for i := 0; i < bytesPerPixel; i++ {
+				v |= uint32(body[pos+i]) << (8 * i)
+			}
+		}
+		pos += bytesPerPixel
+		r := byte((v >> pf.rShift) & uint32(pf.rMax))
+		g := byte((v >> pf.gShift) & uint32(pf.gMax))
+		b := byte((v >> pf.bShift) & uint32(pf.bMax))
+		return [3]byte{r, g, b}
+	}
+	for sy := 0; sy < h; sy += hextileSubSize {
+		sh := min(hextileSubSize, h-sy)
+		for sx := 0; sx < w; sx += hextileSubSize {
+			sw := min(hextileSubSize, w-sx)
+			flags := body[pos]
+			pos++
+			if flags&hextileRaw != 0 {
+				for ry := 0; ry < sh; ry++ {
+					for rx := 0; rx < sw; rx++ {
+						px := readPixel()
+						i := (sy+ry)*out.Stride + (sx+rx)*4
+						out.Pix[i+0] = px[0]
+						out.Pix[i+1] = px[1]
+						out.Pix[i+2] = px[2]
+						out.Pix[i+3] = 0xff
+					}
+				}
+				continue
+			}
+			if flags&hextileBackgroundSpecified != 0 {
+				bg = readPixel()
+			}
+			if flags&hextileForegroundSpecified != 0 {
+				fg = readPixel()
+			}
+			// Fill sub-tile with bg.
+			for ry := 0; ry < sh; ry++ {
+				for rx := 0; rx < sw; rx++ {
+					i := (sy+ry)*out.Stride + (sx+rx)*4
+					out.Pix[i+0] = bg[0]
+					out.Pix[i+1] = bg[1]
+					out.Pix[i+2] = bg[2]
+					out.Pix[i+3] = 0xff
+				}
+			}
+			if flags&hextileAnySubrects == 0 {
+				continue
+			}
+			n := int(body[pos])
+			pos++
+			for k := 0; k < n; k++ {
+				color := fg
+				if flags&hextileSubrectsColoured != 0 {
+					color = readPixel()
+				}
+				xy := body[pos]
+				wh := body[pos+1]
+				pos += 2
+				rxr := int(xy >> 4)
+				ryr := int(xy & 0x0f)
+				rwr := int(wh>>4) + 1
+				rhr := int(wh&0x0f) + 1
+				for ry := 0; ry < rhr; ry++ {
+					for rx := 0; rx < rwr; rx++ {
+						i := (sy+ryr+ry)*out.Stride + (sx+rxr+rx)*4
+						out.Pix[i+0] = color[0]
+						out.Pix[i+1] = color[1]
+						out.Pix[i+2] = color[2]
+						out.Pix[i+3] = 0xff
+					}
+				}
+			}
+		}
+	}
+	return out
+}
+
+func makeUniformImage(w, h int, r, g, b byte) *image.RGBA {
+	img := image.NewRGBA(image.Rect(0, 0, w, h))
+	for i := 0; i < len(img.Pix); i += 4 {
+		img.Pix[i+0] = r
+		img.Pix[i+1] = g
+		img.Pix[i+2] = b
+		img.Pix[i+3] = 0xff
+	}
+	return img
+}
+
+func makeTwoColorImage(w, h int) *image.RGBA {
+	img := makeUniformImage(w, h, 0x10, 0x20, 0x30)
+	// Draw a vertical bar of fg in the middle.
+	fg := [3]byte{0xa0, 0xb0, 0xc0}
+	for y := 0; y < h; y++ {
+		for x := w / 4; x < w/2; x++ {
+			i := y*img.Stride + x*4
+			img.Pix[i+0] = fg[0]
+			img.Pix[i+1] = fg[1]
+			img.Pix[i+2] = fg[2]
+		}
+	}
+	return img
+}
+
+func compareImages(t *testing.T, want, got *image.RGBA) {
+	t.Helper()
+	if want.Rect != got.Rect {
+		t.Fatalf("rect mismatch: %v vs %v", want.Rect, got.Rect)
+	}
+	w, h := want.Rect.Dx(), want.Rect.Dy()
+	for y := 0; y < h; y++ {
+		for x := 0; x < w; x++ {
+			i := y*want.Stride + x*4
+			j := y*got.Stride + x*4
+			if want.Pix[i] != got.Pix[j] || want.Pix[i+1] != got.Pix[j+1] || want.Pix[i+2] != got.Pix[j+2] {
+				t.Fatalf("pixel mismatch at (%d,%d): want %v got %v",
+					x, y, want.Pix[i:i+3], got.Pix[j:j+3])
+			}
+		}
+	}
+}
+
+func TestEncodeHextileRect_Uniform(t *testing.T) {
+	pf := defaultClientPixelFormat()
+	img := makeUniformImage(64, 64, 0x33, 0x66, 0x99)
+	buf := encodeHextileRect(img, pf, 0, 0, 64, 64)
+	got := decodeHextile(t, buf, pf)
+	compareImages(t, img, got)
+}
+
+func TestEncodeHextileRect_TwoColor(t *testing.T) {
+	pf := defaultClientPixelFormat()
+	img := makeTwoColorImage(64, 64)
+	buf := encodeHextileRect(img, pf, 0, 0, 64, 64)
+	got := decodeHextile(t, buf, pf)
+	compareImages(t, img, got)
+}
+
+func TestEncodeHextileRect_Multicolor(t *testing.T) {
+	pf := defaultClientPixelFormat()
+	img := makeBenchImage(64, 64, 42)
+	buf := encodeHextileRect(img, pf, 0, 0, 64, 64)
+	got := decodeHextile(t, buf, pf)
+	compareImages(t, img, got)
+}
+
+func TestEncodeHextileRect_NonAligned(t *testing.T) {
+	pf := defaultClientPixelFormat()
+	img := makeTwoColorImage(50, 33) // not a multiple of 16
+	buf := encodeHextileRect(img, pf, 0, 0, 50, 33)
+	got := decodeHextile(t, buf, pf)
+	compareImages(t, img, got)
+}

client/vnc/server/input_darwin.go

@@ -0,0 +1,613 @@
+//go:build darwin && !ios
+
+package server
+
+import (
+	"fmt"
+	"os/exec"
+	"strings"
+	"sync"
+
+	"github.com/ebitengine/purego"
+	log "github.com/sirupsen/logrus"
+)
+
+// Core Graphics event constants.
+const (
+	kCGEventSourceStateCombinedSessionState int32 = 0
+
+	kCGEventLeftMouseDown     int32 = 1
+	kCGEventLeftMouseUp       int32 = 2
+	kCGEventRightMouseDown    int32 = 3
+	kCGEventRightMouseUp      int32 = 4
+	kCGEventMouseMoved        int32 = 5
+	kCGEventLeftMouseDragged  int32 = 6
+	kCGEventRightMouseDragged int32 = 7
+	kCGEventKeyDown           int32 = 10
+	kCGEventKeyUp             int32 = 11
+	kCGEventOtherMouseDown    int32 = 25
+	kCGEventOtherMouseUp      int32 = 26
+
+	kCGMouseButtonLeft   int32 = 0
+	kCGMouseButtonRight  int32 = 1
+	kCGMouseButtonCenter int32 = 2
+
+	kCGHIDEventTap int32 = 0
+
+	// IOKit power management constants.
+	kIOPMUserActiveLocal  int32  = 0
+	kIOPMAssertionLevelOn uint32 = 255
+	kCFStringEncodingUTF8 uint32 = 0x08000100
+)
+
+var darwinInputOnce sync.Once
+
+var (
+	cgEventSourceCreate        func(int32) uintptr
+	cgEventCreateKeyboardEvent func(uintptr, uint16, bool) uintptr
+	// CGEventCreateMouseEvent takes CGPoint as two separate float64 args.
+	// purego can't handle array/struct types but individual float64s work.
+	cgEventCreateMouseEvent func(uintptr, int32, float64, float64, int32) uintptr
+	cgEventPost             func(int32, uintptr)
+
+	// CGEventCreateScrollWheelEvent is variadic, call via SyscallN.
+	cgEventCreateScrollWheelEventAddr uintptr
+
+	axIsProcessTrusted func() bool
+
+	// IOKit power-management bindings used to wake the display and inhibit
+	// idle sleep while a VNC client is driving input.
+	iopmAssertionDeclareUserActivity func(uintptr, int32, *uint32) int32
+	iopmAssertionCreateWithName      func(uintptr, uint32, uintptr, *uint32) int32
+	iopmAssertionRelease             func(uint32) int32
+	cfStringCreateWithCString        func(uintptr, string, uint32) uintptr
+
+	// Cached CFStrings for assertion name and idle-sleep type.
+	pmAssertionNameCFStr      uintptr
+	pmPreventIdleDisplayCFStr uintptr
+
+	// Assertion IDs. userActivityID is reused across input events so repeated
+	// calls refresh the same assertion rather than create new ones.
+	pmMu             sync.Mutex
+	userActivityID   uint32
+	preventSleepID   uint32
+	preventSleepHeld bool
+	preventSleepRef  int // refcount across concurrent injectors/sessions
+
+	darwinInputReady  bool
+	darwinEventSource uintptr
+)
+
+func initDarwinInput() {
+	darwinInputOnce.Do(func() {
+		cg, err := purego.Dlopen("/System/Library/Frameworks/CoreGraphics.framework/CoreGraphics", purego.RTLD_NOW|purego.RTLD_GLOBAL)
+		if err != nil {
+			log.Debugf("load CoreGraphics for input: %v", err)
+			return
+		}
+
+		purego.RegisterLibFunc(&cgEventSourceCreate, cg, "CGEventSourceCreate")
+		purego.RegisterLibFunc(&cgEventCreateKeyboardEvent, cg, "CGEventCreateKeyboardEvent")
+		purego.RegisterLibFunc(&cgEventCreateMouseEvent, cg, "CGEventCreateMouseEvent")
+		purego.RegisterLibFunc(&cgEventPost, cg, "CGEventPost")
+
+		sym, err := purego.Dlsym(cg, "CGEventCreateScrollWheelEvent")
+		if err == nil {
+			cgEventCreateScrollWheelEventAddr = sym
+		}
+
+		if ax, err := purego.Dlopen("/System/Library/Frameworks/ApplicationServices.framework/ApplicationServices", purego.RTLD_NOW|purego.RTLD_GLOBAL); err == nil {
+			if sym, err := purego.Dlsym(ax, "AXIsProcessTrusted"); err == nil {
+				purego.RegisterFunc(&axIsProcessTrusted, sym)
+			}
+		}
+
+		initPowerAssertions()
+
+		darwinInputReady = true
+	})
+}
+
+func initPowerAssertions() {
+	iokit, err := purego.Dlopen("/System/Library/Frameworks/IOKit.framework/IOKit", purego.RTLD_NOW|purego.RTLD_GLOBAL)
+	if err != nil {
+		log.Debugf("load IOKit: %v", err)
+		return
+	}
+	cf, err := purego.Dlopen("/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation", purego.RTLD_NOW|purego.RTLD_GLOBAL)
+	if err != nil {
+		log.Debugf("load CoreFoundation for power assertions: %v", err)
+		return
+	}
+
+	purego.RegisterLibFunc(&cfStringCreateWithCString, cf, "CFStringCreateWithCString")
+	purego.RegisterLibFunc(&iopmAssertionDeclareUserActivity, iokit, "IOPMAssertionDeclareUserActivity")
+	purego.RegisterLibFunc(&iopmAssertionCreateWithName, iokit, "IOPMAssertionCreateWithName")
+	purego.RegisterLibFunc(&iopmAssertionRelease, iokit, "IOPMAssertionRelease")
+
+	pmAssertionNameCFStr = cfStringCreateWithCString(0, "NetBird VNC input", kCFStringEncodingUTF8)
+	pmPreventIdleDisplayCFStr = cfStringCreateWithCString(0, "PreventUserIdleDisplaySleep", kCFStringEncodingUTF8)
+}
+
+// wakeDisplay declares user activity so macOS treats the synthesized input as
+// real HID activity, waking the display if it is asleep. Called on every key
+// and pointer event; the kernel coalesces repeated calls cheaply.
+func wakeDisplay() {
+	if iopmAssertionDeclareUserActivity == nil || pmAssertionNameCFStr == 0 {
+		return
+	}
+	pmMu.Lock()
+	defer pmMu.Unlock()
+	id := userActivityID
+	r := iopmAssertionDeclareUserActivity(pmAssertionNameCFStr, kIOPMUserActiveLocal, &id)
+	if r != 0 {
+		log.Tracef("IOPMAssertionDeclareUserActivity returned %d", r)
+		return
+	}
+	userActivityID = id
+}
+
+// holdPreventIdleSleep creates an assertion that keeps the display from going
+// idle-to-sleep while a VNC session is active. Reference-counted so multiple
+// concurrent sessions don't yank the assertion when one of them releases.
+func holdPreventIdleSleep() {
+	if iopmAssertionCreateWithName == nil || pmPreventIdleDisplayCFStr == 0 || pmAssertionNameCFStr == 0 {
+		return
+	}
+	pmMu.Lock()
+	defer pmMu.Unlock()
+	preventSleepRef++
+	if preventSleepRef > 1 {
+		return
+	}
+	var id uint32
+	r := iopmAssertionCreateWithName(pmPreventIdleDisplayCFStr, kIOPMAssertionLevelOn, pmAssertionNameCFStr, &id)
+	if r != 0 {
+		log.Debugf("IOPMAssertionCreateWithName returned %d", r)
+		// Reset the refcount on failure so a later successful hold can take it.
+		preventSleepRef = 0
+		return
+	}
+	preventSleepID = id
+	preventSleepHeld = true
+}
+
+// releasePreventIdleSleep decrements the assertion refcount and only drops
+// the actual IOKit assertion on the final release.
+func releasePreventIdleSleep() {
+	if iopmAssertionRelease == nil {
+		return
+	}
+	pmMu.Lock()
+	defer pmMu.Unlock()
+	if !preventSleepHeld || preventSleepRef == 0 {
+		return
+	}
+	preventSleepRef--
+	if preventSleepRef > 0 {
+		return
+	}
+	if r := iopmAssertionRelease(preventSleepID); r != 0 {
+		log.Debugf("IOPMAssertionRelease returned %d", r)
+	}
+	preventSleepHeld = false
+	preventSleepID = 0
+}
+
+func ensureEventSource() uintptr {
+	if darwinEventSource != 0 {
+		return darwinEventSource
+	}
+	darwinEventSource = cgEventSourceCreate(kCGEventSourceStateCombinedSessionState)
+	return darwinEventSource
+}
+
+// MacInputInjector injects keyboard and mouse events via Core Graphics.
+type MacInputInjector struct {
+	lastButtons uint8
+	pbcopyPath  string
+	pbpastePath string
+}
+
+// NewMacInputInjector creates a macOS input injector.
+func NewMacInputInjector() (*MacInputInjector, error) {
+	initDarwinInput()
+	if !darwinInputReady {
+		return nil, fmt.Errorf("CoreGraphics not available for input injection")
+	}
+	checkMacPermissions()
+
+	m := &MacInputInjector{}
+	if path, err := exec.LookPath("pbcopy"); err == nil {
+		m.pbcopyPath = path
+	}
+	if path, err := exec.LookPath("pbpaste"); err == nil {
+		m.pbpastePath = path
+	}
+	if m.pbcopyPath == "" || m.pbpastePath == "" {
+		log.Debugf("clipboard tools not found (pbcopy=%q, pbpaste=%q)", m.pbcopyPath, m.pbpastePath)
+	}
+
+	holdPreventIdleSleep()
+
+	log.Info("macOS input injector ready")
+	return m, nil
+}
+
+// checkMacPermissions warns and opens the Privacy pane if Accessibility is
+// missing. Uses AXIsProcessTrusted which returns immediately; the previous
+// osascript probe blocked for 120s (AppleEvent timeout) when access was
+// denied, which delayed VNC server startup past client deadlines.
+func checkMacPermissions() {
+	if axIsProcessTrusted != nil && !axIsProcessTrusted() {
+		openPrivacyPane("Privacy_Accessibility")
+		log.Warn("Accessibility permission not granted. Input injection will not work. " +
+			"Opened System Settings > Privacy & Security > Accessibility; enable netbird.")
+	}
+
+	log.Info("Screen Recording permission is required for screen capture. " +
+		"If the screen appears black, grant in System Settings > Privacy & Security > Screen Recording.")
+}
+
+// openPrivacyPane opens the given Privacy pane in System Settings so the user
+// can toggle the permission without navigating manually.
+func openPrivacyPane(pane string) {
+	url := "x-apple.systempreferences:com.apple.preference.security?" + pane
+	if err := exec.Command("open", url).Start(); err != nil {
+		log.Debugf("open privacy pane %s: %v", pane, err)
+	}
+}
+
+// InjectKey simulates a key press or release.
+func (m *MacInputInjector) InjectKey(keysym uint32, down bool) {
+	wakeDisplay()
+	src := ensureEventSource()
+	if src == 0 {
+		return
+	}
+	keycode := keysymToMacKeycode(keysym)
+	if keycode == 0xFFFF {
+		return
+	}
+	event := cgEventCreateKeyboardEvent(src, keycode, down)
+	if event == 0 {
+		return
+	}
+	cgEventPost(kCGHIDEventTap, event)
+	cfRelease(event)
+}
+
+// InjectPointer simulates mouse movement and button events.
+func (m *MacInputInjector) InjectPointer(buttonMask uint8, px, py, serverW, serverH int) {
+	wakeDisplay()
+	if serverW == 0 || serverH == 0 {
+		return
+	}
+	src := ensureEventSource()
+	if src == 0 {
+		return
+	}
+	x, y := scalePxToLogical(px, py, serverW, serverH)
+	m.dispatchPointer(src, buttonMask, x, y)
+	m.lastButtons = buttonMask
+}
+
+// scalePxToLogical converts framebuffer coordinates (physical pixels) into
+// the logical points CGEventCreateMouseEvent expects. Falls back to a 1:1
+// mapping if the display API is unavailable.
+func scalePxToLogical(px, py, serverW, serverH int) (float64, float64) {
+	x, y := float64(px), float64(py)
+	if cgDisplayPixelsWide == nil || cgMainDisplayID == nil {
+		return x, y
+	}
+	displayID := cgMainDisplayID()
+	logicalW := int(cgDisplayPixelsWide(displayID))
+	logicalH := int(cgDisplayPixelsHigh(displayID))
+	if logicalW <= 0 || logicalH <= 0 {
+		return x, y
+	}
+	return float64(px) * float64(logicalW) / float64(serverW),
+		float64(py) * float64(logicalH) / float64(serverH)
+}
+
+func (m *MacInputInjector) dispatchPointer(src uintptr, buttonMask uint8, x, y float64) {
+	leftDown := buttonMask&0x01 != 0
+	rightDown := buttonMask&0x04 != 0
+	middleDown := buttonMask&0x02 != 0
+	m.postMoveOrDrag(src, leftDown, rightDown, x, y)
+	m.postButtonTransitions(src, buttonMask, x, y)
+	m.postScrollWheel(src, buttonMask)
+	_ = middleDown
+}
+
+func (m *MacInputInjector) postMoveOrDrag(src uintptr, leftDown, rightDown bool, x, y float64) {
+	switch {
+	case leftDown:
+		m.postMouse(src, kCGEventLeftMouseDragged, x, y, kCGMouseButtonLeft)
+	case rightDown:
+		m.postMouse(src, kCGEventRightMouseDragged, x, y, kCGMouseButtonRight)
+	default:
+		m.postMouse(src, kCGEventMouseMoved, x, y, kCGMouseButtonLeft)
+	}
+}
+
+// postButtonTransitions emits the up/down events for each button whose state
+// changed against m.lastButtons.
+func (m *MacInputInjector) postButtonTransitions(src uintptr, buttonMask uint8, x, y float64) {
+	emit := func(curBit, prevBit uint8, down, up int32, button int32) {
+		cur := buttonMask&curBit != 0
+		prev := m.lastButtons&prevBit != 0
+		if cur && !prev {
+			m.postMouse(src, down, x, y, button)
+		} else if !cur && prev {
+			m.postMouse(src, up, x, y, button)
+		}
+	}
+	emit(0x01, 0x01, kCGEventLeftMouseDown, kCGEventLeftMouseUp, kCGMouseButtonLeft)
+	emit(0x04, 0x04, kCGEventRightMouseDown, kCGEventRightMouseUp, kCGMouseButtonRight)
+	emit(0x02, 0x02, kCGEventOtherMouseDown, kCGEventOtherMouseUp, kCGMouseButtonCenter)
+}
+
+func (m *MacInputInjector) postScrollWheel(src uintptr, buttonMask uint8) {
+	if buttonMask&0x08 != 0 {
+		m.postScroll(src, 3)
+	}
+	if buttonMask&0x10 != 0 {
+		m.postScroll(src, -3)
+	}
+}
+
+func (m *MacInputInjector) postMouse(src uintptr, eventType int32, x, y float64, button int32) {
+	if cgEventCreateMouseEvent == nil {
+		return
+	}
+	event := cgEventCreateMouseEvent(src, eventType, x, y, button)
+	if event == 0 {
+		return
+	}
+	cgEventPost(kCGHIDEventTap, event)
+	cfRelease(event)
+}
+
+func (m *MacInputInjector) postScroll(src uintptr, deltaY int32) {
+	if cgEventCreateScrollWheelEventAddr == 0 {
+		return
+	}
+	// CGEventCreateScrollWheelEvent(source, units, wheelCount, wheel1delta)
+	// units=0 (pixel), wheelCount=1, wheel1delta=deltaY
+	// Variadic C function: pass args as uintptr via SyscallN.
+	r1, _, _ := purego.SyscallN(cgEventCreateScrollWheelEventAddr,
+		src, 0, 1, uintptr(uint32(deltaY)))
+	if r1 == 0 {
+		return
+	}
+	cgEventPost(kCGHIDEventTap, r1)
+	cfRelease(r1)
+}
+
+// SetClipboard sets the macOS clipboard using pbcopy.
+func (m *MacInputInjector) SetClipboard(text string) {
+	if m.pbcopyPath == "" {
+		return
+	}
+	cmd := exec.Command(m.pbcopyPath)
+	cmd.Stdin = strings.NewReader(text)
+	if err := cmd.Run(); err != nil {
+		log.Tracef("set clipboard via pbcopy: %v", err)
+	}
+}
+
+// TypeText synthesizes the given text as keystrokes via Core Graphics.
+// Used by the dashboard's Paste button so the host clipboard reaches
+// the focused remote app even when the app doesn't honor pbpaste-style
+// clipboard sync (e.g. login screens, locked-down apps). ASCII printable
+// runes only; others are skipped.
+func (m *MacInputInjector) TypeText(text string) {
+	wakeDisplay()
+	src := ensureEventSource()
+	if src == 0 {
+		return
+	}
+	const maxChars = 4096
+	count := 0
+	for _, r := range text {
+		if count >= maxChars {
+			break
+		}
+		count++
+		typeRune(src, r)
+	}
+}
+
+// typeRune emits the press/release events for a single ASCII rune, framing
+// the keystroke with Shift-down/up when required by the keysym.
+func typeRune(src uintptr, r rune) {
+	const shiftKey = uint16(0x38) // kVK_Shift
+	keysym, shift, ok := keysymForASCIIRune(r)
+	if !ok {
+		return
+	}
+	keycode := keysymToMacKeycode(keysym)
+	if keycode == 0xFFFF {
+		return
+	}
+	if shift {
+		postKey(src, shiftKey, true)
+	}
+	postKey(src, keycode, true)
+	postKey(src, keycode, false)
+	if shift {
+		postKey(src, shiftKey, false)
+	}
+}
+
+func postKey(src uintptr, keycode uint16, down bool) {
+	e := cgEventCreateKeyboardEvent(src, keycode, down)
+	if e == 0 {
+		return
+	}
+	cgEventPost(kCGHIDEventTap, e)
+	cfRelease(e)
+}
+
+// GetClipboard reads the macOS clipboard using pbpaste.
+func (m *MacInputInjector) GetClipboard() string {
+	if m.pbpastePath == "" {
+		return ""
+	}
+	out, err := exec.Command(m.pbpastePath).Output()
+	if err != nil {
+		log.Tracef("get clipboard via pbpaste: %v", err)
+		return ""
+	}
+	return string(out)
+}
+
+// Close releases the idle-sleep assertion held for the injector's lifetime.
+func (m *MacInputInjector) Close() {
+	releasePreventIdleSleep()
+}
+
+func keysymToMacKeycode(keysym uint32) uint16 {
+	if keysym >= 0x61 && keysym <= 0x7a {
+		return asciiToMacKey[keysym-0x61]
+	}
+	if keysym >= 0x41 && keysym <= 0x5a {
+		return asciiToMacKey[keysym-0x41]
+	}
+	if keysym >= 0x30 && keysym <= 0x39 {
+		return digitToMacKey[keysym-0x30]
+	}
+	if code, ok := specialKeyMap[keysym]; ok {
+		return code
+	}
+	return 0xFFFF
+}
+
+var asciiToMacKey = [26]uint16{
+	0x00, 0x0B, 0x08, 0x02, 0x0E, 0x03, 0x05, 0x04,
+	0x22, 0x26, 0x28, 0x25, 0x2E, 0x2D, 0x1F, 0x23,
+	0x0C, 0x0F, 0x01, 0x11, 0x20, 0x09, 0x0D, 0x07,
+	0x10, 0x06,
+}
+
+var digitToMacKey = [10]uint16{
+	0x1D, 0x12, 0x13, 0x14, 0x15, 0x17, 0x16, 0x1A, 0x1C, 0x19,
+}
+
+var specialKeyMap = map[uint32]uint16{
+	// Whitespace and editing
+	0x0020: 0x31, // space
+	0xff08: 0x33, // BackSpace
+	0xff09: 0x30, // Tab
+	0xff0d: 0x24, // Return
+	0xff1b: 0x35, // Escape
+	0xffff: 0x75, // Delete (forward)
+
+	// Navigation
+	0xff50: 0x73, // Home
+	0xff51: 0x7B, // Left
+	0xff52: 0x7E, // Up
+	0xff53: 0x7C, // Right
+	0xff54: 0x7D, // Down
+	0xff55: 0x74, // Page_Up
+	0xff56: 0x79, // Page_Down
+	0xff57: 0x77, // End
+	0xff63: 0x72, // Insert (Help on Mac)
+
+	// Modifiers
+	0xffe1: 0x38, // Shift_L
+	0xffe2: 0x3C, // Shift_R
+	0xffe3: 0x3B, // Control_L
+	0xffe4: 0x3E, // Control_R
+	0xffe5: 0x39, // Caps_Lock
+	0xffe9: 0x3A, // Alt_L (Option)
+	0xffea: 0x3D, // Alt_R (Option)
+	0xffe7: 0x37, // Meta_L (Command)
+	0xffe8: 0x36, // Meta_R (Command)
+	0xffeb: 0x37, // Super_L (Command) - noVNC sends this
+	0xffec: 0x36, // Super_R (Command)
+
+	// Mode_switch / ISO_Level3_Shift (sent by noVNC for macOS Option remap)
+	0xff7e: 0x3A, // Mode_switch -> Option
+	0xfe03: 0x3D, // ISO_Level3_Shift -> Right Option
+
+	// Function keys
+	0xffbe: 0x7A, // F1
+	0xffbf: 0x78, // F2
+	0xffc0: 0x63, // F3
+	0xffc1: 0x76, // F4
+	0xffc2: 0x60, // F5
+	0xffc3: 0x61, // F6
+	0xffc4: 0x62, // F7
+	0xffc5: 0x64, // F8
+	0xffc6: 0x65, // F9
+	0xffc7: 0x6D, // F10
+	0xffc8: 0x67, // F11
+	0xffc9: 0x6F, // F12
+	0xffca: 0x69, // F13
+	0xffcb: 0x6B, // F14
+	0xffcc: 0x71, // F15
+	0xffcd: 0x6A, // F16
+	0xffce: 0x40, // F17
+	0xffcf: 0x4F, // F18
+	0xffd0: 0x50, // F19
+	0xffd1: 0x5A, // F20
+
+	// Punctuation (US keyboard layout, keysym = ASCII code)
+	0x002d: 0x1B, // minus -
+	0x003d: 0x18, // equal =
+	0x005b: 0x21, // bracketleft [
+	0x005d: 0x1E, // bracketright ]
+	0x005c: 0x2A, // backslash
+	0x003b: 0x29, // semicolon ;
+	0x0027: 0x27, // apostrophe '
+	0x0060: 0x32, // grave `
+	0x002c: 0x2B, // comma ,
+	0x002e: 0x2F, // period .
+	0x002f: 0x2C, // slash /
+
+	// Shifted punctuation (noVNC sends these as separate keysyms)
+	0x005f: 0x1B, // underscore _ (shift+minus)
+	0x002b: 0x18, // plus + (shift+equal)
+	0x007b: 0x21, // braceleft { (shift+[)
+	0x007d: 0x1E, // braceright } (shift+])
+	0x007c: 0x2A, // bar | (shift+\)
+	0x003a: 0x29, // colon : (shift+;)
+	0x0022: 0x27, // quotedbl " (shift+')
+	0x007e: 0x32, // tilde ~ (shift+`)
+	0x003c: 0x2B, // less < (shift+,)
+	0x003e: 0x2F, // greater > (shift+.)
+	0x003f: 0x2C, // question ? (shift+/)
+	0x0021: 0x12, // exclam ! (shift+1)
+	0x0040: 0x13, // at @ (shift+2)
+	0x0023: 0x14, // numbersign # (shift+3)
+	0x0024: 0x15, // dollar $ (shift+4)
+	0x0025: 0x17, // percent % (shift+5)
+	0x005e: 0x16, // asciicircum ^ (shift+6)
+	0x0026: 0x1A, // ampersand & (shift+7)
+	0x002a: 0x1C, // asterisk * (shift+8)
+	0x0028: 0x19, // parenleft ( (shift+9)
+	0x0029: 0x1D, // parenright ) (shift+0)
+
+	// Numpad
+	0xffb0: 0x52, // KP_0
+	0xffb1: 0x53, // KP_1
+	0xffb2: 0x54, // KP_2
+	0xffb3: 0x55, // KP_3
+	0xffb4: 0x56, // KP_4
+	0xffb5: 0x57, // KP_5
+	0xffb6: 0x58, // KP_6
+	0xffb7: 0x59, // KP_7
+	0xffb8: 0x5B, // KP_8
+	0xffb9: 0x5C, // KP_9
+	0xffae: 0x41, // KP_Decimal
+	0xffaa: 0x43, // KP_Multiply
+	0xffab: 0x45, // KP_Add
+	0xffad: 0x4E, // KP_Subtract
+	0xffaf: 0x4B, // KP_Divide
+	0xff8d: 0x4C, // KP_Enter
+	0xffbd: 0x51, // KP_Equal
+}
+
+var _ InputInjector = (*MacInputInjector)(nil)

client/vnc/server/input_uinput_unix.go

@@ -0,0 +1,500 @@
+//go:build (linux && !android) || freebsd
+
+package server
+
+import (
+	"encoding/binary"
+	"fmt"
+	"sync"
+	"time"
+	"unicode"
+	"unsafe"
+
+	log "github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
+)
+
+// /dev/uinput ioctl numbers. Computed from the kernel _IO/_IOW macros so
+// we don't depend on cgo. UINPUT_IOCTL_BASE = 'U' = 0x55.
+const (
+	uiDevCreate  = 0x5501
+	uiDevDestroy = 0x5502
+	// _IOW('U', 3, struct uinput_setup); uinput_setup is 92 bytes on amd64.
+	uiDevSetup    = (1 << 30) | (92 << 16) | (0x55 << 8) | 3
+	uiSetEvBit    = (1 << 30) | (4 << 16) | (0x55 << 8) | 100
+	uiSetKeyBit   = (1 << 30) | (4 << 16) | (0x55 << 8) | 101
+	uiSetAbsBit   = (1 << 30) | (4 << 16) | (0x55 << 8) | 103
+	uinputAbsSize = 64 // legacy struct uses absmin/absmax/absfuzz/absflat[64].
+)
+
+// Linux input event types and key codes (linux/input-event-codes.h).
+const (
+	evSyn = 0x00
+	evKey = 0x01
+	evAbs = 0x03
+	evRep = 0x14
+
+	synReport = 0
+
+	absX = 0x00
+	absY = 0x01
+
+	btnLeft   = 0x110
+	btnRight  = 0x111
+	btnMiddle = 0x112
+)
+
+// inputEvent matches struct input_event for x86_64 (timeval is 16 bytes).
+// Total size 24 bytes; Go's natural alignment matches the kernel layout.
+type inputEvent struct {
+	TvSec  int64
+	TvUsec int64
+	Type   uint16
+	Code   uint16
+	Value  int32
+}
+
+// UInputInjector synthesizes keyboard and mouse events via /dev/uinput.
+// Used as a fallback when X11 isn't running, e.g. at the kernel console
+// or pre-login screen on a server without X. Requires root or
+// CAP_SYS_ADMIN, which the netbird service has.
+type UInputInjector struct {
+	mu          sync.Mutex
+	fd          int
+	closeOnce   sync.Once
+	keysymToKey map[uint32]uint16
+	prevButtons uint8
+	screenW     int
+	screenH     int
+}
+
+// NewUInputInjector opens /dev/uinput and registers a virtual keyboard +
+// absolute pointer device sized to (w, h). The dimensions are needed
+// because uinput's ABS axes don't autoscale; we always send absolute
+// coordinates and let the kernel route them to the right monitor.
+func NewUInputInjector(w, h int) (*UInputInjector, error) {
+	if w <= 0 || h <= 0 {
+		return nil, fmt.Errorf("invalid screen size: %dx%d", w, h)
+	}
+	fd, err := unix.Open("/dev/uinput", unix.O_WRONLY|unix.O_NONBLOCK, 0)
+	if err != nil {
+		return nil, fmt.Errorf("open /dev/uinput: %w", err)
+	}
+
+	if err := setBit(fd, uiSetEvBit, evKey); err != nil {
+		unix.Close(fd)
+		return nil, err
+	}
+	if err := setBit(fd, uiSetEvBit, evAbs); err != nil {
+		unix.Close(fd)
+		return nil, err
+	}
+	if err := setBit(fd, uiSetEvBit, evSyn); err != nil {
+		unix.Close(fd)
+		return nil, err
+	}
+	// Advertise key auto-repeat so the kernel input core repeats held
+	// keys at the configured rate (default ~250 ms delay, ~33 ms period).
+	// Without this, holding Backspace etc. only deletes one character.
+	if err := setBit(fd, uiSetEvBit, evRep); err != nil {
+		unix.Close(fd)
+		return nil, err
+	}
+
+	keymap := buildUInputKeymap()
+	for _, key := range keymap {
+		if err := setBit(fd, uiSetKeyBit, uint32(key)); err != nil {
+			unix.Close(fd)
+			return nil, fmt.Errorf("UI_SET_KEYBIT %d: %w", key, err)
+		}
+	}
+	for _, btn := range []uint16{btnLeft, btnRight, btnMiddle} {
+		if err := setBit(fd, uiSetKeyBit, uint32(btn)); err != nil {
+			unix.Close(fd)
+			return nil, fmt.Errorf("UI_SET_KEYBIT btn %d: %w", btn, err)
+		}
+	}
+	if err := setBit(fd, uiSetAbsBit, absX); err != nil {
+		unix.Close(fd)
+		return nil, err
+	}
+	if err := setBit(fd, uiSetAbsBit, absY); err != nil {
+		unix.Close(fd)
+		return nil, err
+	}
+
+	if err := writeUInputUserDev(fd, w, h); err != nil {
+		unix.Close(fd)
+		return nil, err
+	}
+	if _, _, e := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), uiDevCreate, 0); e != 0 {
+		unix.Close(fd)
+		return nil, fmt.Errorf("UI_DEV_CREATE: %v", e)
+	}
+	// Give udev a moment to settle before sending events.
+	time.Sleep(50 * time.Millisecond)
+
+	inj := &UInputInjector{
+		fd:          fd,
+		keysymToKey: keymapByKeysym(keymap),
+		screenW:     w,
+		screenH:     h,
+	}
+	log.Infof("uinput injector ready: %dx%d, %d keys", w, h, len(inj.keysymToKey))
+	return inj, nil
+}
+
+func setBit(fd int, op uintptr, code uint32) error {
+	if _, _, e := unix.Syscall(unix.SYS_IOCTL, uintptr(fd), op, uintptr(code)); e != 0 {
+		return fmt.Errorf("ioctl 0x%x %d: %v", op, code, e)
+	}
+	return nil
+}
+
+// writeUInputUserDev uses the legacy uinput_user_dev path (write the
+// whole struct then UI_DEV_CREATE) which is universally supported on
+// older and current kernels alike. uinput_user_dev is name(80) + id(8) +
+// ff_effects_max(4) + absmax/absmin/absfuzz/absflat[64] = 92 + 4*64*4 =
+// 1116 bytes total.
+func writeUInputUserDev(fd, w, h int) error {
+	const sz = 80 + 8 + 4 + uinputAbsSize*4*4
+	buf := make([]byte, sz)
+	copy(buf[0:80], []byte("netbird-vnc-uinput"))
+	// id: BUS_VIRTUAL=0x06, vendor=0x0001, product=0x0001, version=1.
+	binary.LittleEndian.PutUint16(buf[80:82], 0x06)
+	binary.LittleEndian.PutUint16(buf[82:84], 0x0001)
+	binary.LittleEndian.PutUint16(buf[84:86], 0x0001)
+	binary.LittleEndian.PutUint16(buf[86:88], 0x0001)
+	// ff_effects_max(4) at 88..92 stays zero.
+	// absmax[64] at 92..348: set absX/absY.
+	absmaxOff := 80 + 8 + 4
+	absminOff := absmaxOff + uinputAbsSize*4
+	binary.LittleEndian.PutUint32(buf[absmaxOff+absX*4:], uint32(w-1))
+	binary.LittleEndian.PutUint32(buf[absmaxOff+absY*4:], uint32(h-1))
+	binary.LittleEndian.PutUint32(buf[absminOff+absX*4:], 0)
+	binary.LittleEndian.PutUint32(buf[absminOff+absY*4:], 0)
+	if _, err := unix.Write(fd, buf); err != nil {
+		return fmt.Errorf("write uinput_user_dev: %w", err)
+	}
+	return nil
+}
+
+// emit writes a single input_event to the device. Caller-locked.
+func (u *UInputInjector) emit(typ, code uint16, value int32) error {
+	ev := inputEvent{Type: typ, Code: code, Value: value}
+	buf := (*[unsafe.Sizeof(inputEvent{})]byte)(unsafe.Pointer(&ev))[:]
+	_, err := unix.Write(u.fd, buf)
+	return err
+}
+
+func (u *UInputInjector) sync() {
+	_ = u.emit(evSyn, synReport, 0)
+}
+
+// InjectKey synthesizes a press or release for the given X11 keysym.
+func (u *UInputInjector) InjectKey(keysym uint32, down bool) {
+	u.mu.Lock()
+	defer u.mu.Unlock()
+	code, ok := u.keysymToKey[keysym]
+	if !ok {
+		return
+	}
+	value := int32(0)
+	if down {
+		value = 1
+	}
+	if err := u.emit(evKey, code, value); err != nil {
+		log.Tracef("uinput emit key: %v", err)
+		return
+	}
+	u.sync()
+}
+
+// InjectPointer moves the absolute pointer and presses/releases buttons
+// based on the RFB button mask delta against the previous mask.
+func (u *UInputInjector) InjectPointer(buttonMask uint8, x, y, serverW, serverH int) {
+	u.mu.Lock()
+	defer u.mu.Unlock()
+	if serverW <= 1 || serverH <= 1 {
+		return
+	}
+	absXVal := int32(x * (u.screenW - 1) / (serverW - 1))
+	absYVal := int32(y * (u.screenH - 1) / (serverH - 1))
+	_ = u.emit(evAbs, absX, absXVal)
+	_ = u.emit(evAbs, absY, absYVal)
+
+	type btnMap struct {
+		bit uint8
+		key uint16
+	}
+	for _, b := range []btnMap{
+		{0x01, btnLeft},
+		{0x02, btnMiddle},
+		{0x04, btnRight},
+	} {
+		pressed := buttonMask&b.bit != 0
+		was := u.prevButtons&b.bit != 0
+		if pressed && !was {
+			_ = u.emit(evKey, b.key, 1)
+		} else if !pressed && was {
+			_ = u.emit(evKey, b.key, 0)
+		}
+	}
+	u.prevButtons = buttonMask
+	u.sync()
+}
+
+// SetClipboard is a no-op on the framebuffer console: there is no system
+// clipboard daemon. Use TypeText (Paste button) to deliver host text.
+func (u *UInputInjector) SetClipboard(_ string) {
+	// no system clipboard daemon on framebuffer console
+}
+
+// GetClipboard returns empty: no clipboard outside X11/Wayland.
+func (u *UInputInjector) GetClipboard() string { return "" }
+
+// TypeText synthesizes the given UTF-8 text as keystrokes. Only ASCII
+// printable characters and newline are typed; other runes are skipped.
+// This drives the "paste" button: with no console clipboard available,
+// keystroke-by-keystroke entry is the only way to deliver a password to
+// a TTY login prompt.
+func (u *UInputInjector) TypeText(text string) {
+	u.mu.Lock()
+	defer u.mu.Unlock()
+	const maxChars = 4096
+	count := 0
+	for _, r := range text {
+		if count >= maxChars {
+			break
+		}
+		count++
+		code, shift, ok := keyForRune(r)
+		if !ok {
+			continue
+		}
+		if shift {
+			_ = u.emit(evKey, keyLeftShift, 1)
+		}
+		_ = u.emit(evKey, code, 1)
+		_ = u.emit(evKey, code, 0)
+		if shift {
+			_ = u.emit(evKey, keyLeftShift, 0)
+		}
+		u.sync()
+	}
+}
+
+// Close destroys the virtual uinput device and closes the file descriptor.
+func (u *UInputInjector) Close() {
+	u.closeOnce.Do(func() {
+		u.mu.Lock()
+		defer u.mu.Unlock()
+		if u.fd >= 0 {
+			_, _, _ = unix.Syscall(unix.SYS_IOCTL, uintptr(u.fd), uiDevDestroy, 0)
+			_ = unix.Close(u.fd)
+			u.fd = -1
+		}
+	})
+}
+
+// Linux KEY_* codes for the small set we care about.
+const (
+	keyEsc          = 1
+	keyMinus        = 12
+	keyEqual        = 13
+	keyBackspace    = 14
+	keyTab          = 15
+	keyEnter        = 28
+	keyLeftCtrl     = 29
+	keySemicolon    = 39
+	keyApostrophe   = 40
+	keyGrave        = 41
+	keyLeftShift    = 42
+	keyBackslash    = 43
+	keyComma        = 51
+	keyDot          = 52
+	keySlash        = 53
+	keyRightShift   = 54
+	keyLeftAlt      = 56
+	keySpace        = 57
+	keyCapsLock     = 58
+	keyF1           = 59
+	keyLeftBracket  = 26
+	keyRightBracket = 27
+	keyHome         = 102
+	keyUp           = 103
+	keyPageUp       = 104
+	keyLeft         = 105
+	keyRight        = 106
+	keyEnd          = 107
+	keyDown         = 108
+	keyPageDown     = 109
+	keyInsert       = 110
+	keyDelete       = 111
+	keyRightCtrl    = 97
+	keyRightAlt     = 100
+	keyLeftMeta     = 125
+	keyRightMeta    = 126
+)
+
+// buildUInputKeymap returns every linux KEY_ code we want the virtual
+// device to advertise during UI_SET_KEYBIT. Order doesn't matter.
+func buildUInputKeymap() []uint16 {
+	out := make([]uint16, 0, 128)
+	// Letters: KEY_A=30, KEY_B=48, etc; not a clean range. The kernel's
+	// row-by-row layout is qwertyuiop / asdfghjkl / zxcvbnm.
+	letters := []uint16{
+		30, 48, 46, 32, 18, 33, 34, 35, 23, 36, 37, 38, 50, // a..m
+		49, 24, 25, 16, 19, 31, 20, 22, 47, 17, 45, 21, 44, // n..z
+	}
+	out = append(out, letters...)
+	// Top-row digits: KEY_1..KEY_0 = 2..11.
+	for i := uint16(2); i <= 11; i++ {
+		out = append(out, i)
+	}
+	// Function keys F1..F12 = 59..68 + 87, 88. We only register F1..F12
+	// which the kernel header enumerates as a contiguous block.
+	for i := uint16(59); i <= 68; i++ {
+		out = append(out, i)
+	}
+	out = append(out, 87, 88)
+	out = append(out, []uint16{
+		keyEsc, keyMinus, keyEqual, keyBackspace, keyTab, keyEnter,
+		keyLeftCtrl, keyRightCtrl, keyLeftShift, keyRightShift,
+		keyLeftAlt, keyRightAlt, keyLeftMeta, keyRightMeta,
+		keySpace, keyCapsLock,
+		keyLeftBracket, keyRightBracket, keyBackslash,
+		keySemicolon, keyApostrophe, keyGrave,
+		keyComma, keyDot, keySlash,
+		keyHome, keyEnd, keyPageUp, keyPageDown,
+		keyUp, keyDown, keyLeft, keyRight,
+		keyInsert, keyDelete,
+	}...)
+	return out
+}
+
+// keymapByKeysym maps X11 keysyms (the values our session receives over
+// RFB) onto Linux KEY_ codes. Shifted ASCII keysyms (uppercase letters,
+// "!@#..." etc.) map to the same scan code as their unshifted twin: the
+// client also sends a separate Shift keysym (0xffe1), so the kernel
+// composes the final character from the held modifier + scan code.
+func keymapByKeysym(_ []uint16) map[uint32]uint16 {
+	letters := map[rune]uint16{
+		'a': 30, 'b': 48, 'c': 46, 'd': 32, 'e': 18, 'f': 33, 'g': 34,
+		'h': 35, 'i': 23, 'j': 36, 'k': 37, 'l': 38, 'm': 50,
+		'n': 49, 'o': 24, 'p': 25, 'q': 16, 'r': 19, 's': 31, 't': 20,
+		'u': 22, 'v': 47, 'w': 17, 'x': 45, 'y': 21, 'z': 44,
+	}
+	m := map[uint32]uint16{
+		// Digits.
+		'0': 11, '1': 2, '2': 3, '3': 4, '4': 5, '5': 6, '6': 7,
+		'7': 8, '8': 9, '9': 10,
+		// Shifted digits (US layout).
+		')': 11, '!': 2, '@': 3, '#': 4, '$': 5, '%': 6, '^': 7,
+		'&': 8, '*': 9, '(': 10,
+		// Punctuation (US layout) and shifted twins.
+		' ': keySpace,
+		'-': keyMinus, '_': keyMinus,
+		'=': keyEqual, '+': keyEqual,
+		'[': keyLeftBracket, '{': keyLeftBracket,
+		']': keyRightBracket, '}': keyRightBracket,
+		'\\': keyBackslash, '|': keyBackslash,
+		';': keySemicolon, ':': keySemicolon,
+		'\'': keyApostrophe, '"': keyApostrophe,
+		'`': keyGrave, '~': keyGrave,
+		',': keyComma, '<': keyComma,
+		'.': keyDot, '>': keyDot,
+		'/': keySlash, '?': keySlash,
+		// Special keys (X11 keysyms).
+		0xff08: keyBackspace, 0xff09: keyTab, 0xff0d: keyEnter,
+		0xff1b: keyEsc, 0xffff: keyDelete,
+		0xff50: keyHome, 0xff57: keyEnd,
+		0xff51: keyLeft, 0xff52: keyUp, 0xff53: keyRight, 0xff54: keyDown,
+		0xff55: keyPageUp, 0xff56: keyPageDown, 0xff63: keyInsert,
+		0xffe1: keyLeftShift, 0xffe2: keyRightShift,
+		0xffe3: keyLeftCtrl, 0xffe4: keyRightCtrl,
+		0xffe9: keyLeftAlt, 0xffea: keyRightAlt,
+		0xffeb: keyLeftMeta, 0xffec: keyRightMeta,
+	}
+	// Letters: register both lowercase and uppercase keysyms onto the same
+	// KEY_ code. The client sends Shift separately for uppercase.
+	for r, code := range letters {
+		m[uint32(r)] = code
+		m[uint32(r-'a'+'A')] = code
+	}
+	// Function keys F1..F12 (X11 keysyms 0xffbe..0xffc9 → KEY_F1..KEY_F12).
+	xF := uint32(0xffbe)
+	codes := []uint16{59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 87, 88}
+	for i, c := range codes {
+		m[xF+uint32(i)] = c
+	}
+	return m
+}
+
+// keyForRune maps a printable rune to (keycode, needsShift). Used by
+// TypeText to synthesize keystrokes for a paste payload.
+func keyForRune(r rune) (uint16, bool, bool) {
+	if r >= 'a' && r <= 'z' {
+		m := map[rune]uint16{
+			'a': 30, 'b': 48, 'c': 46, 'd': 32, 'e': 18, 'f': 33, 'g': 34,
+			'h': 35, 'i': 23, 'j': 36, 'k': 37, 'l': 38, 'm': 50,
+			'n': 49, 'o': 24, 'p': 25, 'q': 16, 'r': 19, 's': 31, 't': 20,
+			'u': 22, 'v': 47, 'w': 17, 'x': 45, 'y': 21, 'z': 44,
+		}
+		return m[r], false, true
+	}
+	if r >= 'A' && r <= 'Z' {
+		c, _, ok := keyForRune(unicode.ToLower(r))
+		return c, true, ok
+	}
+	if r >= '0' && r <= '9' {
+		nums := []uint16{11, 2, 3, 4, 5, 6, 7, 8, 9, 10}
+		idx := int(r - '0')
+		if idx < 0 || idx >= len(nums) { //nolint:gosec // explicit bound disarms G602
+			return 0, false, false
+		}
+		return nums[idx], false, true
+	}
+	if r == '\n' || r == '\r' {
+		return keyEnter, false, true
+	}
+	if k, ok := punctUnshifted[r]; ok {
+		return k, false, true
+	}
+	if k, ok := punctShifted[r]; ok {
+		return k, true, true
+	}
+	return 0, false, false
+}
+
+// punctUnshifted maps ASCII punctuation that needs no Shift to its uinput
+// KEY_* code. Split out of keyForRune's switch to keep the function's
+// cognitive complexity below Sonar's threshold.
+var punctUnshifted = map[rune]uint16{
+	' ':  keySpace,
+	'\t': keyTab,
+	'-':  keyMinus,
+	'=':  keyEqual,
+	'[':  keyLeftBracket,
+	']':  keyRightBracket,
+	'\\': keyBackslash,
+	';':  keySemicolon,
+	'\'': keyApostrophe,
+	'`':  keyGrave,
+	',':  keyComma,
+	'.':  keyDot,
+	'/':  keySlash,
+}
+
+// punctShifted maps ASCII punctuation that requires Shift to its base KEY_*
+// code; the caller adds the shift modifier itself.
+var punctShifted = map[rune]uint16{
+	'!': 2, '@': 3, '#': 4, '$': 5, '%': 6, '^': 7, '&': 8, '*': 9,
+	'(': 10, ')': 11,
+	'_': keyMinus, '+': keyEqual,
+	'{': keyLeftBracket, '}': keyRightBracket, '|': keyBackslash,
+	':': keySemicolon, '"': keyApostrophe, '~': keyGrave,
+	'<': keyComma, '>': keyDot, '?': keySlash,
+}
+
+var _ InputInjector = (*UInputInjector)(nil)

client/vnc/server/input_windows.go

@@ -0,0 +1,495 @@
+//go:build windows
+
+package server
+
+import (
+	"runtime"
+	"sync"
+	"unsafe"
+
+	log "github.com/sirupsen/logrus"
+	"golang.org/x/sys/windows"
+)
+
+var (
+	procOpenEventW = kernel32.NewProc("OpenEventW")
+	procSendInput  = user32.NewProc("SendInput")
+	procVkKeyScanA = user32.NewProc("VkKeyScanA")
+)
+
+const eventModifyState = 0x0002
+
+const (
+	inputMouse    = 0
+	inputKeyboard = 1
+
+	mouseeventfMove       = 0x0001
+	mouseeventfLeftDown   = 0x0002
+	mouseeventfLeftUp     = 0x0004
+	mouseeventfRightDown  = 0x0008
+	mouseeventfRightUp    = 0x0010
+	mouseeventfMiddleDown = 0x0020
+	mouseeventfMiddleUp   = 0x0040
+	mouseeventfWheel      = 0x0800
+	mouseeventfAbsolute   = 0x8000
+
+	wheelDelta = 120
+
+	keyeventfExtendedKey = 0x0001
+	keyeventfKeyUp       = 0x0002
+	keyeventfUnicode     = 0x0004
+	keyeventfScanCode    = 0x0008
+)
+
+
+// maxTypedClipboardChars caps the number of characters we will synthesize as
+// keystrokes when falling back on the Winlogon desktop. Passwords are short;
+// a huge clipboard getting typed into the login screen would be surprising.
+const maxTypedClipboardChars = 4096
+
+type mouseInput struct {
+	Dx          int32
+	Dy          int32
+	MouseData   uint32
+	DwFlags     uint32
+	Time        uint32
+	DwExtraInfo uintptr
+}
+
+type keybdInput struct {
+	WVk         uint16
+	WScan       uint16
+	DwFlags     uint32
+	Time        uint32
+	DwExtraInfo uintptr
+	_           [8]byte
+}
+
+type inputUnion [32]byte
+
+type winInput struct {
+	Type uint32
+	_    [4]byte
+	Data inputUnion
+}
+
+func sendMouseInput(flags uint32, dx, dy int32, mouseData uint32) {
+	mi := mouseInput{
+		Dx:        dx,
+		Dy:        dy,
+		MouseData: mouseData,
+		DwFlags:   flags,
+	}
+	inp := winInput{Type: inputMouse}
+	copy(inp.Data[:], (*[unsafe.Sizeof(mi)]byte)(unsafe.Pointer(&mi))[:])
+	r, _, err := procSendInput.Call(1, uintptr(unsafe.Pointer(&inp)), unsafe.Sizeof(inp))
+	if r == 0 {
+		log.Tracef("SendInput(mouse flags=0x%x): %v", flags, err)
+	}
+}
+
+func sendKeyInput(vk uint16, scanCode uint16, flags uint32) {
+	ki := keybdInput{
+		WVk:     vk,
+		WScan:   scanCode,
+		DwFlags: flags,
+	}
+	inp := winInput{Type: inputKeyboard}
+	copy(inp.Data[:], (*[unsafe.Sizeof(ki)]byte)(unsafe.Pointer(&ki))[:])
+	r, _, err := procSendInput.Call(1, uintptr(unsafe.Pointer(&inp)), unsafe.Sizeof(inp))
+	if r == 0 {
+		log.Tracef("SendInput(key vk=0x%x): %v", vk, err)
+	}
+}
+
+const sasEventName = `Global\NetBirdVNC_SAS`
+
+type inputCmd struct {
+	isKey       bool
+	isClipboard bool
+	isType      bool
+	keysym      uint32
+	down        bool
+	buttonMask  uint8
+	x, y        int
+	serverW     int
+	serverH     int
+	clipText    string
+}
+
+// WindowsInputInjector delivers input events from a dedicated OS thread that
+// calls switchToInputDesktop before each injection. SendInput targets the
+// calling thread's desktop, so the injection thread must be on the same
+// desktop the user sees.
+type WindowsInputInjector struct {
+	ch             chan inputCmd
+	closed         chan struct{}
+	closeOnce      sync.Once
+	prevButtonMask uint8
+	ctrlDown       bool
+	altDown        bool
+}
+
+// NewWindowsInputInjector creates a desktop-aware input injector.
+func NewWindowsInputInjector() *WindowsInputInjector {
+	w := &WindowsInputInjector{
+		ch:     make(chan inputCmd, 64),
+		closed: make(chan struct{}),
+	}
+	go w.loop()
+	return w
+}
+
+// Close stops the injector loop. Safe to call multiple times. Subsequent
+// Inject*/SetClipboard/TypeText calls become no-ops; we use a separate
+// signal channel rather than closing ch so late senders can't panic.
+func (w *WindowsInputInjector) Close() {
+	w.closeOnce.Do(func() {
+		close(w.closed)
+	})
+}
+
+// tryEnqueue posts a command unless the injector is closed or the channel is
+// full. Non-blocking so callers (RFB read loop) never stall.
+func (w *WindowsInputInjector) tryEnqueue(cmd inputCmd) {
+	select {
+	case <-w.closed:
+		return
+	default:
+	}
+	select {
+	case w.ch <- cmd:
+	default:
+	}
+}
+
+func (w *WindowsInputInjector) loop() {
+	runtime.LockOSThread()
+
+	for {
+		select {
+		case <-w.closed:
+			return
+		case cmd := <-w.ch:
+			w.dispatch(cmd)
+		}
+	}
+}
+
+func (w *WindowsInputInjector) dispatch(cmd inputCmd) {
+	// Switch to the current input desktop so SendInput and the clipboard
+	// API target the desktop the user sees. The returned name tells us
+	// whether we are on the secure Winlogon desktop.
+	_, _ = switchToInputDesktop()
+
+	switch {
+	case cmd.isClipboard:
+		w.doSetClipboard(cmd.clipText)
+	case cmd.isType:
+		w.typeUnicodeText(cmd.clipText)
+	case cmd.isKey:
+		w.doInjectKey(cmd.keysym, cmd.down)
+	default:
+		w.doInjectPointer(cmd.buttonMask, cmd.x, cmd.y, cmd.serverW, cmd.serverH)
+	}
+}
+
+// InjectKey queues a key event for injection on the input desktop thread.
+func (w *WindowsInputInjector) InjectKey(keysym uint32, down bool) {
+	w.tryEnqueue(inputCmd{isKey: true, keysym: keysym, down: down})
+}
+
+// InjectPointer queues a pointer event for injection on the input desktop
+// thread. Pointer events coalesce: when the channel is full (slow desktop
+// switch, hung SendInput), drop the new sample so the read loop never
+// blocks. The next mouse event carries fresher position anyway.
+func (w *WindowsInputInjector) InjectPointer(buttonMask uint8, x, y, serverW, serverH int) {
+	w.tryEnqueue(inputCmd{buttonMask: buttonMask, x: x, y: y, serverW: serverW, serverH: serverH})
+}
+
+func (w *WindowsInputInjector) doInjectKey(keysym uint32, down bool) {
+	switch keysym {
+	case 0xffe3, 0xffe4:
+		w.ctrlDown = down
+	case 0xffe9, 0xffea:
+		w.altDown = down
+	}
+
+	if (keysym == 0xff9f || keysym == 0xffff) && w.ctrlDown && w.altDown && down {
+		signalSAS()
+		return
+	}
+
+	vk, _, extended := keysym2VK(keysym)
+	if vk == 0 {
+		return
+	}
+	var flags uint32
+	if !down {
+		flags |= keyeventfKeyUp
+	}
+	if extended {
+		flags |= keyeventfExtendedKey
+	}
+	sendKeyInput(vk, 0, flags)
+}
+
+// signalSAS signals the SAS named event. A listener in Session 0
+// (startSASListener) calls SendSAS to trigger the Secure Attention Sequence.
+func signalSAS() {
+	namePtr, err := windows.UTF16PtrFromString(sasEventName)
+	if err != nil {
+		log.Warnf("SAS UTF16: %v", err)
+		return
+	}
+	h, _, lerr := procOpenEventW.Call(
+		uintptr(eventModifyState),
+		0,
+		uintptr(unsafe.Pointer(namePtr)),
+	)
+	if h == 0 {
+		log.Warnf("OpenEvent(%s): %v", sasEventName, lerr)
+		return
+	}
+	ev := windows.Handle(h)
+	defer func() { _ = windows.CloseHandle(ev) }()
+	if err := windows.SetEvent(ev); err != nil {
+		log.Warnf("SetEvent SAS: %v", err)
+	} else {
+		log.Info("SAS event signaled")
+	}
+}
+
+func (w *WindowsInputInjector) doInjectPointer(buttonMask uint8, x, y, serverW, serverH int) {
+	if serverW == 0 || serverH == 0 {
+		return
+	}
+
+	absX := int32(x * 65535 / serverW)
+	absY := int32(y * 65535 / serverH)
+
+	sendMouseInput(mouseeventfMove|mouseeventfAbsolute, absX, absY, 0)
+
+	changed := buttonMask ^ w.prevButtonMask
+	w.prevButtonMask = buttonMask
+
+	type btnMap struct {
+		bit  uint8
+		down uint32
+		up   uint32
+	}
+	buttons := [...]btnMap{
+		{0x01, mouseeventfLeftDown, mouseeventfLeftUp},
+		{0x02, mouseeventfMiddleDown, mouseeventfMiddleUp},
+		{0x04, mouseeventfRightDown, mouseeventfRightUp},
+	}
+	for _, b := range buttons {
+		if changed&b.bit == 0 {
+			continue
+		}
+		var flags uint32
+		if buttonMask&b.bit != 0 {
+			flags = b.down
+		} else {
+			flags = b.up
+		}
+		sendMouseInput(flags|mouseeventfAbsolute, absX, absY, 0)
+	}
+
+	negWheelDelta := ^uint32(wheelDelta - 1)
+	if changed&0x08 != 0 && buttonMask&0x08 != 0 {
+		sendMouseInput(mouseeventfWheel|mouseeventfAbsolute, absX, absY, wheelDelta)
+	}
+	if changed&0x10 != 0 && buttonMask&0x10 != 0 {
+		sendMouseInput(mouseeventfWheel|mouseeventfAbsolute, absX, absY, negWheelDelta)
+	}
+}
+
+// keysym2VK converts an X11 keysym to a Windows virtual key code.
+func keysym2VK(keysym uint32) (vk uint16, scan uint16, extended bool) {
+	if keysym >= 0x20 && keysym <= 0x7e {
+		r, _, _ := procVkKeyScanA.Call(uintptr(keysym))
+		vk = uint16(r & 0xff)
+		return
+	}
+
+	if keysym >= 0xffbe && keysym <= 0xffc9 {
+		vk = uint16(0x70 + keysym - 0xffbe)
+		return
+	}
+
+	switch keysym {
+	case 0xff08:
+		vk = 0x08 // Backspace
+	case 0xff09:
+		vk = 0x09 // Tab
+	case 0xff0d:
+		vk = 0x0d // Return
+	case 0xff1b:
+		vk = 0x1b // Escape
+	case 0xff63:
+		vk, extended = 0x2d, true // Insert
+	case 0xff9f, 0xffff:
+		vk, extended = 0x2e, true // Delete
+	case 0xff50:
+		vk, extended = 0x24, true // Home
+	case 0xff57:
+		vk, extended = 0x23, true // End
+	case 0xff55:
+		vk, extended = 0x21, true // PageUp
+	case 0xff56:
+		vk, extended = 0x22, true // PageDown
+	case 0xff51:
+		vk, extended = 0x25, true // Left
+	case 0xff52:
+		vk, extended = 0x26, true // Up
+	case 0xff53:
+		vk, extended = 0x27, true // Right
+	case 0xff54:
+		vk, extended = 0x28, true // Down
+	case 0xffe1, 0xffe2:
+		vk = 0x10 // Shift
+	case 0xffe3, 0xffe4:
+		vk = 0x11 // Control
+	case 0xffe9, 0xffea:
+		vk = 0x12 // Alt
+	case 0xffe5:
+		vk = 0x14 // CapsLock
+	case 0xffe7, 0xffeb:
+		vk, extended = 0x5B, true // Meta_L / Super_L -> Left Windows
+	case 0xffe8, 0xffec:
+		vk, extended = 0x5C, true // Meta_R / Super_R -> Right Windows
+	case 0xff61:
+		vk = 0x2c // PrintScreen
+	case 0xff13:
+		vk = 0x13 // Pause
+	case 0xff14:
+		vk = 0x91 // ScrollLock
+	}
+	return
+}
+
+var (
+	procOpenClipboard              = user32.NewProc("OpenClipboard")
+	procCloseClipboard             = user32.NewProc("CloseClipboard")
+	procEmptyClipboard             = user32.NewProc("EmptyClipboard")
+	procSetClipboardData           = user32.NewProc("SetClipboardData")
+	procGetClipboardData           = user32.NewProc("GetClipboardData")
+	procIsClipboardFormatAvailable = user32.NewProc("IsClipboardFormatAvailable")
+
+	procGlobalAlloc  = kernel32.NewProc("GlobalAlloc")
+	procGlobalLock   = kernel32.NewProc("GlobalLock")
+	procGlobalUnlock = kernel32.NewProc("GlobalUnlock")
+)
+
+const (
+	cfUnicodeText = 13
+	gmemMoveable  = 0x0002
+)
+
+// SetClipboard queues a request to update the Windows clipboard with the
+// given UTF-8 text. The work runs on the input thread so it follows the
+// current input desktop. Secure desktops (Winlogon, UAC) have isolated
+// clipboards we cannot reach, so the call is a no-op there; use TypeText
+// to enter text into a secure desktop instead.
+func (w *WindowsInputInjector) SetClipboard(text string) {
+	w.tryEnqueue(inputCmd{isClipboard: true, clipText: text})
+}
+
+// TypeText queues a request to synthesize the given text as Unicode
+// keystrokes on the current input desktop. Targets the secure desktop
+// when the user is on Winlogon/UAC, where the clipboard is unreachable.
+func (w *WindowsInputInjector) TypeText(text string) {
+	w.tryEnqueue(inputCmd{isType: true, clipText: text})
+}
+
+func (w *WindowsInputInjector) doSetClipboard(text string) {
+	utf16, err := windows.UTF16FromString(text)
+	if err != nil {
+		log.Tracef("clipboard UTF16 encode: %v", err)
+		return
+	}
+
+	size := uintptr(len(utf16) * 2)
+	hMem, _, _ := procGlobalAlloc.Call(gmemMoveable, size)
+	if hMem == 0 {
+		log.Tracef("GlobalAlloc for clipboard: allocation returned nil")
+		return
+	}
+
+	ptr, _, _ := procGlobalLock.Call(hMem)
+	if ptr == 0 {
+		log.Tracef("GlobalLock for clipboard: lock returned nil")
+		return
+	}
+	copy(unsafe.Slice((*uint16)(unsafe.Pointer(ptr)), len(utf16)), utf16)
+	_, _, _ = procGlobalUnlock.Call(hMem)
+
+	r, _, lerr := procOpenClipboard.Call(0)
+	if r == 0 {
+		log.Tracef("OpenClipboard: %v", lerr)
+		return
+	}
+	defer logCleanupCall("CloseClipboard", procCloseClipboard)
+
+	_, _, _ = procEmptyClipboard.Call()
+	r, _, lerr = procSetClipboardData.Call(cfUnicodeText, hMem)
+	if r == 0 {
+		log.Tracef("SetClipboardData: %v", lerr)
+	}
+}
+
+// typeUnicodeText synthesizes the given text as Unicode keystrokes via
+// SendInput+KEYEVENTF_UNICODE. Used on the Winlogon secure desktop where the
+// clipboard is isolated: this lets a VNC client paste a password into the
+// login or credential prompt by sending ClientCutText.
+func (w *WindowsInputInjector) typeUnicodeText(text string) {
+	utf16, err := windows.UTF16FromString(text)
+	if err != nil {
+		log.Tracef("clipboard UTF16 encode: %v", err)
+		return
+	}
+	if len(utf16) > 0 && utf16[len(utf16)-1] == 0 {
+		utf16 = utf16[:len(utf16)-1]
+	}
+	if len(utf16) > maxTypedClipboardChars {
+		log.Warnf("clipboard paste on Winlogon truncated to %d chars", maxTypedClipboardChars)
+		utf16 = utf16[:maxTypedClipboardChars]
+	}
+	for _, c := range utf16 {
+		sendKeyInput(0, c, keyeventfUnicode)
+		sendKeyInput(0, c, keyeventfUnicode|keyeventfKeyUp)
+	}
+}
+
+// GetClipboard reads the Windows clipboard as UTF-8 text.
+func (w *WindowsInputInjector) GetClipboard() string {
+	r, _, _ := procIsClipboardFormatAvailable.Call(cfUnicodeText)
+	if r == 0 {
+		return ""
+	}
+
+	r, _, lerr := procOpenClipboard.Call(0)
+	if r == 0 {
+		log.Tracef("OpenClipboard for read: %v", lerr)
+		return ""
+	}
+	defer logCleanupCall("CloseClipboard", procCloseClipboard)
+
+	hData, _, _ := procGetClipboardData.Call(cfUnicodeText)
+	if hData == 0 {
+		return ""
+	}
+
+	ptr, _, _ := procGlobalLock.Call(hData)
+	if ptr == 0 {
+		return ""
+	}
+	defer logCleanupCallArgs("GlobalUnlock", procGlobalUnlock, hData)
+
+	return windows.UTF16PtrToString((*uint16)(unsafe.Pointer(ptr)))
+}
+
+var _ InputInjector = (*WindowsInputInjector)(nil)
+
+var _ ScreenCapturer = (*DesktopCapturer)(nil)

client/vnc/server/input_x11.go

@@ -0,0 +1,283 @@
+//go:build (linux && !android) || freebsd
+
+package server
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/jezek/xgb"
+	"github.com/jezek/xgb/xproto"
+	"github.com/jezek/xgb/xtest"
+)
+
+// X11InputInjector injects keyboard and mouse events via the XTest extension.
+type X11InputInjector struct {
+	conn              *xgb.Conn
+	root              xproto.Window
+	screen            *xproto.ScreenInfo
+	display           string
+	keysymMap         map[uint32]byte
+	lastButtons       uint8
+	clipboardTool     string
+	clipboardToolName string
+}
+
+// NewX11InputInjector connects to the X11 display and initializes XTest.
+func NewX11InputInjector(display string) (*X11InputInjector, error) {
+	detectX11Display()
+
+	if display == "" {
+		display = os.Getenv("DISPLAY")
+	}
+	if display == "" {
+		return nil, fmt.Errorf("DISPLAY not set and no Xorg process found")
+	}
+
+	conn, err := xgb.NewConnDisplay(display)
+	if err != nil {
+		return nil, fmt.Errorf("connect to X11 display %s: %w", display, err)
+	}
+
+	if err := xtest.Init(conn); err != nil {
+		conn.Close()
+		return nil, fmt.Errorf("init XTest extension: %w", err)
+	}
+
+	setup := xproto.Setup(conn)
+	if len(setup.Roots) == 0 {
+		conn.Close()
+		return nil, fmt.Errorf("no X11 screens")
+	}
+	screen := setup.Roots[0]
+
+	inj := &X11InputInjector{
+		conn:    conn,
+		root:    screen.Root,
+		screen:  &screen,
+		display: display,
+	}
+	inj.cacheKeyboardMapping()
+	inj.resolveClipboardTool()
+
+	log.Infof("X11 input injector ready (display=%s)", display)
+	return inj, nil
+}
+
+// InjectKey simulates a key press or release. keysym is an X11 KeySym.
+func (x *X11InputInjector) InjectKey(keysym uint32, down bool) {
+	keycode := x.keysymToKeycode(keysym)
+	if keycode == 0 {
+		return
+	}
+
+	var eventType byte
+	if down {
+		eventType = xproto.KeyPress
+	} else {
+		eventType = xproto.KeyRelease
+	}
+
+	xtest.FakeInput(x.conn, eventType, keycode, 0, x.root, 0, 0, 0)
+}
+
+// InjectPointer simulates mouse movement and button events.
+func (x *X11InputInjector) InjectPointer(buttonMask uint8, px, py, serverW, serverH int) {
+	if serverW == 0 || serverH == 0 {
+		return
+	}
+
+	// Scale to actual screen coordinates.
+	screenW := int(x.screen.WidthInPixels)
+	screenH := int(x.screen.HeightInPixels)
+	absX := px * screenW / serverW
+	absY := py * screenH / serverH
+
+	// Move pointer.
+	xtest.FakeInput(x.conn, xproto.MotionNotify, 0, 0, x.root, int16(absX), int16(absY), 0)
+
+	// Handle button events. RFB button mask: bit0=left, bit1=middle, bit2=right,
+	// bit3=scrollUp, bit4=scrollDown. X11 buttons: 1=left, 2=middle, 3=right,
+	// 4=scrollUp, 5=scrollDown.
+	type btnMap struct {
+		rfbBit uint8
+		x11Btn byte
+	}
+	buttons := [...]btnMap{
+		{0x01, 1}, // left
+		{0x02, 2}, // middle
+		{0x04, 3}, // right
+		{0x08, 4}, // scroll up
+		{0x10, 5}, // scroll down
+	}
+
+	for _, b := range buttons {
+		pressed := buttonMask&b.rfbBit != 0
+		wasPressed := x.lastButtons&b.rfbBit != 0
+		if b.x11Btn >= 4 {
+			// Scroll: send press+release on each scroll event.
+			if pressed {
+				xtest.FakeInput(x.conn, xproto.ButtonPress, b.x11Btn, 0, x.root, 0, 0, 0)
+				xtest.FakeInput(x.conn, xproto.ButtonRelease, b.x11Btn, 0, x.root, 0, 0, 0)
+			}
+		} else {
+			if pressed && !wasPressed {
+				xtest.FakeInput(x.conn, xproto.ButtonPress, b.x11Btn, 0, x.root, 0, 0, 0)
+			} else if !pressed && wasPressed {
+				xtest.FakeInput(x.conn, xproto.ButtonRelease, b.x11Btn, 0, x.root, 0, 0, 0)
+			}
+		}
+	}
+	x.lastButtons = buttonMask
+}
+
+// cacheKeyboardMapping fetches the X11 keyboard mapping once and stores it
+// as a keysym-to-keycode map, avoiding a round-trip per keystroke.
+func (x *X11InputInjector) cacheKeyboardMapping() {
+	setup := xproto.Setup(x.conn)
+	minKeycode := setup.MinKeycode
+	maxKeycode := setup.MaxKeycode
+
+	reply, err := xproto.GetKeyboardMapping(x.conn, minKeycode,
+		byte(maxKeycode-minKeycode+1)).Reply()
+	if err != nil {
+		log.Debugf("cache keyboard mapping: %v", err)
+		x.keysymMap = make(map[uint32]byte)
+		return
+	}
+
+	m := make(map[uint32]byte, int(maxKeycode-minKeycode+1)*int(reply.KeysymsPerKeycode))
+	keysymsPerKeycode := int(reply.KeysymsPerKeycode)
+	for i := int(minKeycode); i <= int(maxKeycode); i++ {
+		offset := (i - int(minKeycode)) * keysymsPerKeycode
+		for j := 0; j < keysymsPerKeycode; j++ {
+			ks := uint32(reply.Keysyms[offset+j])
+			if ks != 0 {
+				if _, exists := m[ks]; !exists {
+					m[ks] = byte(i)
+				}
+			}
+		}
+	}
+	x.keysymMap = m
+}
+
+// keysymToKeycode looks up a cached keysym-to-keycode mapping.
+// Returns 0 if the keysym is not mapped.
+func (x *X11InputInjector) keysymToKeycode(keysym uint32) byte {
+	return x.keysymMap[keysym]
+}
+
+// SetClipboard sets the X11 clipboard using xclip or xsel.
+func (x *X11InputInjector) SetClipboard(text string) {
+	if x.clipboardTool == "" {
+		return
+	}
+
+	var cmd *exec.Cmd
+	if x.clipboardToolName == "xclip" {
+		cmd = exec.Command(x.clipboardTool, "-selection", "clipboard")
+	} else {
+		cmd = exec.Command(x.clipboardTool, "--clipboard", "--input")
+	}
+	cmd.Env = x.clipboardEnv()
+	cmd.Stdin = strings.NewReader(text)
+	if err := cmd.Run(); err != nil {
+		log.Debugf("set clipboard via %s: %v", x.clipboardToolName, err)
+	}
+}
+
+// TypeText synthesizes the given text as keystrokes via XTest. We can
+// no longer just stuff the host clipboard with xclip and expect Ctrl+V
+// to do the rest, because the Paste button is also used at places where
+// the focused application isn't a clipboard-aware one (e.g. a TTY login
+// in an X11 session, an SDDM/GDM password field that ignores XSelection,
+// or a kiosk app). Typing keystrokes covers all of those.
+//
+// Limitation: only ASCII printable characters are typed. Non-ASCII runes
+// are skipped: a paste workflow for them needs Wayland-aware text input
+// or layout introspection that we don't have.
+func (x *X11InputInjector) TypeText(text string) {
+	const maxChars = 4096
+	count := 0
+	for _, r := range text {
+		if count >= maxChars {
+			break
+		}
+		count++
+		keysym, shift, ok := keysymForASCIIRune(r)
+		if !ok {
+			continue
+		}
+		keycode := x.keysymToKeycode(keysym)
+		if keycode == 0 {
+			continue
+		}
+		var shiftCode byte
+		if shift {
+			shiftCode = x.keysymToKeycode(0xffe1) // Shift_L
+			if shiftCode != 0 {
+				xtest.FakeInput(x.conn, xproto.KeyPress, shiftCode, 0, x.root, 0, 0, 0)
+			}
+		}
+		xtest.FakeInput(x.conn, xproto.KeyPress, keycode, 0, x.root, 0, 0, 0)
+		xtest.FakeInput(x.conn, xproto.KeyRelease, keycode, 0, x.root, 0, 0, 0)
+		if shift && shiftCode != 0 {
+			xtest.FakeInput(x.conn, xproto.KeyRelease, shiftCode, 0, x.root, 0, 0, 0)
+		}
+	}
+}
+
+func (x *X11InputInjector) resolveClipboardTool() {
+	for _, name := range []string{"xclip", "xsel"} {
+		path, err := exec.LookPath(name)
+		if err == nil {
+			x.clipboardTool = path
+			x.clipboardToolName = name
+			log.Debugf("clipboard tool resolved to %s", path)
+			return
+		}
+	}
+	log.Debugf("no clipboard tool (xclip/xsel) found, clipboard sync disabled")
+}
+
+// GetClipboard reads the X11 clipboard using xclip or xsel.
+func (x *X11InputInjector) GetClipboard() string {
+	if x.clipboardTool == "" {
+		return ""
+	}
+
+	var cmd *exec.Cmd
+	if x.clipboardToolName == "xclip" {
+		cmd = exec.Command(x.clipboardTool, "-selection", "clipboard", "-o")
+	} else {
+		cmd = exec.Command(x.clipboardTool, "--clipboard", "--output")
+	}
+	cmd.Env = x.clipboardEnv()
+	out, err := cmd.Output()
+	if err != nil {
+		log.Tracef("get clipboard via %s: %v", x.clipboardToolName, err)
+		return ""
+	}
+	return string(out)
+}
+
+func (x *X11InputInjector) clipboardEnv() []string {
+	env := []string{"DISPLAY=" + x.display}
+	if auth := os.Getenv("XAUTHORITY"); auth != "" {
+		env = append(env, "XAUTHORITY="+auth)
+	}
+	return env
+}
+
+// Close releases X11 resources.
+func (x *X11InputInjector) Close() {
+	x.conn.Close()
+}
+
+var _ InputInjector = (*X11InputInjector)(nil)
+var _ ScreenCapturer = (*X11Poller)(nil)

client/vnc/server/keysym_typetext.go

@@ -0,0 +1,73 @@
+//go:build !windows
+
+package server
+
+// keysymForASCIIRune maps an ASCII rune to (X11 keysym for the unshifted
+// version, needsShift). Used by TypeText implementations on each platform
+// so the caller can explicitly press Shift instead of relying on the
+// server-side modifier state. Returns ok=false for runes outside the
+// supported set; non-ASCII text is dropped by TypeText.
+func keysymForASCIIRune(r rune) (uint32, bool, bool) {
+	if r >= 'a' && r <= 'z' {
+		return uint32(r), false, true
+	}
+	if r >= 'A' && r <= 'Z' {
+		return uint32(r - 'A' + 'a'), true, true
+	}
+	if r >= '0' && r <= '9' {
+		return uint32(r), false, true
+	}
+	switch r {
+	case ' ':
+		return 0x20, false, true
+	case '\n', '\r':
+		return 0xff0d, false, true // Return
+	case '\t':
+		return 0xff09, false, true // Tab
+	case '-', '=', '[', ']', '\\', ';', '\'', '`', ',', '.', '/':
+		return uint32(r), false, true
+	case '!':
+		return '1', true, true
+	case '@':
+		return '2', true, true
+	case '#':
+		return '3', true, true
+	case '$':
+		return '4', true, true
+	case '%':
+		return '5', true, true
+	case '^':
+		return '6', true, true
+	case '&':
+		return '7', true, true
+	case '*':
+		return '8', true, true
+	case '(':
+		return '9', true, true
+	case ')':
+		return '0', true, true
+	case '_':
+		return '-', true, true
+	case '+':
+		return '=', true, true
+	case '{':
+		return '[', true, true
+	case '}':
+		return ']', true, true
+	case '|':
+		return '\\', true, true
+	case ':':
+		return ';', true, true
+	case '"':
+		return '\'', true, true
+	case '~':
+		return '`', true, true
+	case '<':
+		return ',', true, true
+	case '>':
+		return '.', true, true
+	case '?':
+		return '/', true, true
+	}
+	return 0, false, false
+}

client/vnc/server/rfb.go

@@ -0,0 +1,905 @@
+package server
+
+import (
+	"bytes"
+	"compress/zlib"
+	"crypto/des" //nolint:gosec // RFB protocol-defined DES challenge/response; not used for confidentiality
+	"encoding/binary"
+	"fmt"
+	"image"
+	"image/jpeg"
+	"unsafe"
+
+	log "github.com/sirupsen/logrus"
+)
+
+// rect describes a rectangle on the framebuffer in pixels.
+type rect struct {
+	x, y, w, h int
+}
+
+const (
+	rfbProtocolVersion = "RFB 003.008\n"
+
+	secNone    = 1
+	secVNCAuth = 2
+
+	// Client message types.
+	clientSetPixelFormat           = 0
+	clientSetEncodings             = 2
+	clientFramebufferUpdateRequest = 3
+	clientKeyEvent                 = 4
+	clientPointerEvent             = 5
+	clientCutText                  = 6
+
+	// clientNetbirdTypeText is a NetBird-specific message that asks the
+	// server to synthesize the given text as keystrokes regardless of the
+	// active desktop. Used by the dashboard's Paste button to push host
+	// clipboard content into a Windows secure desktop (Winlogon, UAC),
+	// where the OS clipboard is isolated. Format mirrors clientCutText:
+	// 1-byte message type + 3-byte padding + 4-byte length + text bytes.
+	// The opcode is in the vendor-specific range (>=128).
+	clientNetbirdTypeText = 250
+
+	// Server message types.
+	serverFramebufferUpdate = 0
+	serverCutText           = 3
+
+	// Encoding types.
+	encRaw     = 0
+	encHextile = 5
+	encZlib    = 6
+	encTight   = 7
+
+	// Tight compression-control byte top nibble. Stream-reset bits 0-3
+	// (one per zlib stream) are unused while we run a single stream.
+	tightFillSubenc  = 0x80
+	tightJPEGSubenc  = 0x90
+	tightBasicFilter = 0x40 // Bit 6 set = explicit filter byte follows.
+	tightFilterCopy  = 0x00 // No-op filter, raw pixel stream.
+
+	// JPEG quality used by the Tight encoder. 70 is a reasonable speed/
+	// quality knee; bandwidth roughly halves vs raw RGB while staying
+	// visually clean for typical desktop content. Large rects (e.g. a
+	// fullscreen video region) drop to a lower quality so the encoder
+	// keeps up at 30+ fps; the visual hit is small for moving content.
+	tightJPEGQuality       = 70
+	tightJPEGQualityMedium = 55
+	tightJPEGQualityLarge  = 40
+	tightJPEGMediumPixels  = 800 * 600  // ≈ SVGA, applies medium tier
+	tightJPEGLargePixels   = 1280 * 720 // ≈ 720p, applies large tier
+	// Minimum rect area before we consider JPEG. Below this, header
+	// overhead dominates and Basic+zlib wins.
+	tightJPEGMinArea = 4096 // 64×64 ≈ 1 tile
+	// Distinct-colour cap below which we still prefer Basic+zlib (text,
+	// UI). Sampled, not exhaustive: cheap to compute, good enough.
+	tightJPEGMinColors = 64
+
+	// Hextile subencoding flags (a bitmask in the first byte of each sub-tile).
+	hextileRaw                 = 0x01
+	hextileBackgroundSpecified = 0x02
+	hextileForegroundSpecified = 0x04
+	hextileAnySubrects         = 0x08
+	hextileSubrectsColoured    = 0x10
+
+	// Hextile sub-tile size per RFB spec.
+	hextileSubSize = 16
+)
+
+// serverPixelFormat is the default pixel format advertised by the server:
+// 32bpp RGBA, big-endian, true-colour, 8 bits per channel.
+var serverPixelFormat = [16]byte{
+	32,     // bits-per-pixel
+	24,     // depth
+	1,      // big-endian-flag
+	1,      // true-colour-flag
+	0, 255, // red-max
+	0, 255, // green-max
+	0, 255, // blue-max
+	16,      // red-shift
+	8,       // green-shift
+	0,       // blue-shift
+	0, 0, 0, // padding
+}
+
+// clientPixelFormat holds the negotiated pixel format from the client.
+type clientPixelFormat struct {
+	bpp       uint8
+	bigEndian uint8
+	rMax      uint16
+	gMax      uint16
+	bMax      uint16
+	rShift    uint8
+	gShift    uint8
+	bShift    uint8
+}
+
+func defaultClientPixelFormat() clientPixelFormat {
+	return clientPixelFormat{
+		bpp:       serverPixelFormat[0],
+		bigEndian: serverPixelFormat[2],
+		rMax:      binary.BigEndian.Uint16(serverPixelFormat[4:6]),
+		gMax:      binary.BigEndian.Uint16(serverPixelFormat[6:8]),
+		bMax:      binary.BigEndian.Uint16(serverPixelFormat[8:10]),
+		rShift:    serverPixelFormat[10],
+		gShift:    serverPixelFormat[11],
+		bShift:    serverPixelFormat[12],
+	}
+}
+
+func parsePixelFormat(pf []byte) clientPixelFormat {
+	return clientPixelFormat{
+		bpp:       pf[0],
+		bigEndian: pf[2],
+		rMax:      binary.BigEndian.Uint16(pf[4:6]),
+		gMax:      binary.BigEndian.Uint16(pf[6:8]),
+		bMax:      binary.BigEndian.Uint16(pf[8:10]),
+		rShift:    pf[10],
+		gShift:    pf[11],
+		bShift:    pf[12],
+	}
+}
+
+// encodeRawRect encodes a framebuffer region as a raw RFB rectangle.
+// The returned buffer includes the FramebufferUpdate header (1 rectangle).
+func encodeRawRect(img *image.RGBA, pf clientPixelFormat, x, y, w, h int) []byte {
+	bytesPerPixel := max(int(pf.bpp)/8, 1)
+
+	pixelBytes := w * h * bytesPerPixel
+	buf := make([]byte, 4+12+pixelBytes)
+
+	// FramebufferUpdate header.
+	buf[0] = serverFramebufferUpdate
+	buf[1] = 0 // padding
+	binary.BigEndian.PutUint16(buf[2:4], 1)
+
+	// Rectangle header.
+	binary.BigEndian.PutUint16(buf[4:6], uint16(x))
+	binary.BigEndian.PutUint16(buf[6:8], uint16(y))
+	binary.BigEndian.PutUint16(buf[8:10], uint16(w))
+	binary.BigEndian.PutUint16(buf[10:12], uint16(h))
+	binary.BigEndian.PutUint32(buf[12:16], uint32(encRaw))
+
+	writePixels(buf[16:], img, pf, rect{x, y, w, h}, bytesPerPixel)
+	return buf
+}
+
+// writePixels writes a rectangle of img into dst in the client's requested
+// pixel format. It fast-paths the common case (32bpp, full 8-bit channels)
+// with a tight loop that skips the per-channel *max/255 arithmetic and emits
+// a single uint32 per pixel; the general path handles arbitrary formats.
+func writePixels(dst []byte, img *image.RGBA, pf clientPixelFormat, r rect, bytesPerPixel int) {
+	if bytesPerPixel == 4 && pf.rMax == 255 && pf.gMax == 255 && pf.bMax == 255 {
+		writePixelsFast32(dst, img, pf, r)
+		return
+	}
+	writePixelsGeneric(dst, img, pf, r, bytesPerPixel)
+}
+
+func writePixelsFast32(dst []byte, img *image.RGBA, pf clientPixelFormat, r rect) {
+	stride := img.Stride
+	rShift, gShift, bShift := pf.rShift, pf.gShift, pf.bShift
+	bigEndian := pf.bigEndian != 0
+	off := 0
+	for row := r.y; row < r.y+r.h; row++ {
+		p := row*stride + r.x*4
+		for col := 0; col < r.w; col++ {
+			pixel := (uint32(img.Pix[p]) << rShift) |
+				(uint32(img.Pix[p+1]) << gShift) |
+				(uint32(img.Pix[p+2]) << bShift)
+			if bigEndian {
+				binary.BigEndian.PutUint32(dst[off:off+4], pixel)
+			} else {
+				binary.LittleEndian.PutUint32(dst[off:off+4], pixel)
+			}
+			p += 4
+			off += 4
+		}
+	}
+}
+
+func writePixelsGeneric(dst []byte, img *image.RGBA, pf clientPixelFormat, r rect, bytesPerPixel int) {
+	stride := img.Stride
+	off := 0
+	for row := r.y; row < r.y+r.h; row++ {
+		for col := r.x; col < r.x+r.w; col++ {
+			p := row*stride + col*4
+			rv := uint32(img.Pix[p]) * uint32(pf.rMax) / 255
+			gv := uint32(img.Pix[p+1]) * uint32(pf.gMax) / 255
+			bv := uint32(img.Pix[p+2]) * uint32(pf.bMax) / 255
+			pixel := (rv << pf.rShift) | (gv << pf.gShift) | (bv << pf.bShift)
+			emitPixelBytes(dst[off:off+bytesPerPixel], pixel, bytesPerPixel, pf.bigEndian != 0)
+			off += bytesPerPixel
+		}
+	}
+}
+
+func emitPixelBytes(dst []byte, pixel uint32, bytesPerPixel int, bigEndian bool) {
+	if bigEndian {
+		for i := range bytesPerPixel {
+			dst[i] = byte(pixel >> uint((bytesPerPixel-1-i)*8))
+		}
+		return
+	}
+	for i := range bytesPerPixel {
+		dst[i] = byte(pixel >> uint(i*8))
+	}
+}
+
+// vncAuthEncrypt encrypts a 16-byte challenge using the VNC DES scheme.
+func vncAuthEncrypt(challenge []byte, password string) ([]byte, error) {
+	key := make([]byte, 8)
+	pw := []byte(password)
+	n := len(pw)
+	if n > 8 {
+		n = 8
+	}
+	for i := 0; i < n; i++ {
+		key[i] = reverseBits(pw[i])
+	}
+	block, err := des.NewCipher(key) //nolint:gosec // RFB protocol-defined DES challenge/response; not a confidentiality cipher
+	if err != nil {
+		return nil, fmt.Errorf("des.NewCipher: %w", err)
+	}
+	if len(challenge) < 16 { //nolint:gosec // explicit length check disarms G602
+		return nil, fmt.Errorf("vnc auth challenge too short: %d", len(challenge))
+	}
+	out := make([]byte, 16)
+	block.Encrypt(out[:8], challenge[:8])
+	block.Encrypt(out[8:], challenge[8:])
+	return out, nil
+}
+
+func reverseBits(b byte) byte {
+	var r byte
+	for range 8 {
+		r = (r << 1) | (b & 1)
+		b >>= 1
+	}
+	return r
+}
+
+// encodeZlibRect encodes a framebuffer region using Zlib compression.
+// The zlib stream is continuous for the entire VNC session: noVNC creates
+// one inflate context at startup and reuses it for all zlib-encoded rects.
+// We must NOT reset the zlib writer between calls.
+func encodeZlibRect(img *image.RGBA, pf clientPixelFormat, x, y, w, h int, z *zlibState) []byte {
+	bytesPerPixel := max(int(pf.bpp)/8, 1)
+	zw, zbuf := z.w, z.buf
+
+	// Clear the output buffer but keep the deflate dictionary intact.
+	zbuf.Reset()
+
+	// Encode the full rect pixel stream into the session-lived scratch buffer
+	// and feed zlib one row at a time. Row-granular writes amortise the per-
+	// Write overhead that used to dominate this function when it wrote one
+	// byte slice per pixel.
+	rowBytes := w * bytesPerPixel
+	total := rowBytes * h
+	if cap(z.scratch) < total {
+		z.scratch = make([]byte, total)
+	}
+	scratch := z.scratch[:total]
+	writePixels(scratch, img, pf, rect{x, y, w, h}, bytesPerPixel)
+	for row := 0; row < h; row++ {
+		if _, err := zw.Write(scratch[row*rowBytes : (row+1)*rowBytes]); err != nil {
+			log.Debugf("zlib write row %d: %v", row, err)
+			return nil
+		}
+	}
+	if err := zw.Flush(); err != nil {
+		log.Debugf("zlib flush: %v", err)
+		return nil
+	}
+
+	compressed := zbuf.Bytes()
+
+	// Build the FramebufferUpdate message.
+	buf := make([]byte, 4+12+4+len(compressed))
+	buf[0] = serverFramebufferUpdate
+	buf[1] = 0
+	binary.BigEndian.PutUint16(buf[2:4], 1) // 1 rectangle
+
+	binary.BigEndian.PutUint16(buf[4:6], uint16(x))
+	binary.BigEndian.PutUint16(buf[6:8], uint16(y))
+	binary.BigEndian.PutUint16(buf[8:10], uint16(w))
+	binary.BigEndian.PutUint16(buf[10:12], uint16(h))
+	binary.BigEndian.PutUint32(buf[12:16], uint32(encZlib))
+	binary.BigEndian.PutUint32(buf[16:20], uint32(len(compressed)))
+	copy(buf[20:], compressed)
+
+	return buf
+}
+
+// diffRects compares two RGBA images and returns a list of dirty rectangles.
+// Divides the screen into tiles and checks each for changes.
+func diffRects(prev, cur *image.RGBA, w, h, tileSize int) [][4]int {
+	if prev == nil {
+		return [][4]int{{0, 0, w, h}}
+	}
+
+	var rects [][4]int
+	for ty := 0; ty < h; ty += tileSize {
+		th := min(tileSize, h-ty)
+		for tx := 0; tx < w; tx += tileSize {
+			tw := min(tileSize, w-tx)
+			if tileChanged(prev, cur, tx, ty, tw, th) {
+				rects = append(rects, [4]int{tx, ty, tw, th})
+			}
+		}
+	}
+	return coalesceRects(rects)
+}
+
+// coalesceRects merges adjacent dirty tiles into larger rectangles to cut
+// per-rect framing overhead. Input must be tile-ordered (top-to-bottom rows,
+// left-to-right within each row), as produced by diffRects. Two passes:
+//  1. Horizontal: within a row, merge tiles whose x-extents touch.
+//  2. Vertical: merge a row's run with the run directly above it when they
+//     share the same [x, x+w] extent and are vertically adjacent.
+//
+// Larger merged rects still encode correctly: Hextile-solid and Zlib paths
+// both work on arbitrary sizes, and uniform-tile detection still fires when
+// the merged region happens to be a single colour.
+func coalesceRects(in [][4]int) [][4]int {
+	if len(in) < 2 {
+		return in
+	}
+	c := newRectCoalescer(len(in))
+	c.curY = in[0][1]
+	for _, r := range in {
+		c.consume(r)
+	}
+	c.flushCurrentRow()
+	return c.out
+}
+
+// rectCoalescer is the working state for coalesceRects, lifted out so the
+// algorithm can be split across small methods without long parameter lists
+// and to keep each method's cognitive complexity below Sonar's threshold.
+type rectCoalescer struct {
+	out                        [][4]int
+	prevRowStart, prevRowEnd   int
+	curRowStart                int
+	curY                       int
+}
+
+func newRectCoalescer(capacity int) *rectCoalescer {
+	return &rectCoalescer{out: make([][4]int, 0, capacity)}
+}
+
+// consume processes one rect from the (row-ordered) input.
+func (c *rectCoalescer) consume(r [4]int) {
+	if r[1] != c.curY {
+		c.flushCurrentRow()
+		c.prevRowEnd = len(c.out)
+		c.curRowStart = len(c.out)
+		c.curY = r[1]
+	}
+	if c.tryHorizontalMerge(r) {
+		return
+	}
+	c.out = append(c.out, r)
+}
+
+// tryHorizontalMerge extends the last run in the current row when r is
+// vertically aligned and horizontally adjacent to it.
+func (c *rectCoalescer) tryHorizontalMerge(r [4]int) bool {
+	if len(c.out) <= c.curRowStart {
+		return false
+	}
+	last := &c.out[len(c.out)-1]
+	if last[1] == r[1] && last[3] == r[3] && last[0]+last[2] == r[0] {
+		last[2] += r[2]
+		return true
+	}
+	return false
+}
+
+// flushCurrentRow merges each run in the current row with any run from the
+// previous row that has identical x extent and is vertically adjacent.
+func (c *rectCoalescer) flushCurrentRow() {
+	i := c.curRowStart
+	for i < len(c.out) {
+		if c.mergeWithPrevRow(i) {
+			continue
+		}
+		i++
+	}
+}
+
+// mergeWithPrevRow tries to extend a previous-row run downward to absorb
+// out[i]. Returns true and removes out[i] from the slice on success.
+func (c *rectCoalescer) mergeWithPrevRow(i int) bool {
+	for j := c.prevRowStart; j < c.prevRowEnd; j++ {
+		if c.out[j][0] == c.out[i][0] &&
+			c.out[j][2] == c.out[i][2] &&
+			c.out[j][1]+c.out[j][3] == c.out[i][1] {
+			c.out[j][3] += c.out[i][3]
+			copy(c.out[i:], c.out[i+1:])
+			c.out = c.out[:len(c.out)-1]
+			return true
+		}
+	}
+	return false
+}
+
+func tileChanged(prev, cur *image.RGBA, x, y, w, h int) bool {
+	stride := prev.Stride
+	for row := y; row < y+h; row++ {
+		off := row*stride + x*4
+		end := off + w*4
+		prevRow := prev.Pix[off:end]
+		curRow := cur.Pix[off:end]
+		if !bytes.Equal(prevRow, curRow) {
+			return true
+		}
+	}
+	return false
+}
+
+// tileIsUniform reports whether every pixel in the given rectangle of img is
+// the same RGBA value, and returns that pixel packed as 0xRRGGBBAA when so.
+// Uses uint32 comparisons across rows; returns early on the first mismatch.
+func tileIsUniform(img *image.RGBA, x, y, w, h int) (uint32, bool) {
+	if w <= 0 || h <= 0 {
+		return 0, false
+	}
+	stride := img.Stride
+	base := y*stride + x*4
+	first := *(*uint32)(unsafe.Pointer(&img.Pix[base]))
+	rowBytes := w * 4
+	for row := 0; row < h; row++ {
+		p := base + row*stride
+		for col := 0; col < rowBytes; col += 4 {
+			if *(*uint32)(unsafe.Pointer(&img.Pix[p+col])) != first {
+				return 0, false
+			}
+		}
+	}
+	return first, true
+}
+
+// encodePixel packs an RGBA byte triple into the client's requested pixel
+// format, honouring bpp, channel maxes, shifts and endianness. Returns the
+// number of bytes written to dst (1..4).
+func encodePixel(dst []byte, pf clientPixelFormat, r, g, b byte) int {
+	bytesPerPixel := max(int(pf.bpp)/8, 1)
+	var val uint32
+	if pf.rMax == 255 && pf.gMax == 255 && pf.bMax == 255 {
+		val = (uint32(r) << pf.rShift) | (uint32(g) << pf.gShift) | (uint32(b) << pf.bShift)
+	} else {
+		rv := uint32(r) * uint32(pf.rMax) / 255
+		gv := uint32(g) * uint32(pf.gMax) / 255
+		bv := uint32(b) * uint32(pf.bMax) / 255
+		val = (rv << pf.rShift) | (gv << pf.gShift) | (bv << pf.bShift)
+	}
+	if pf.bigEndian != 0 {
+		for i := range bytesPerPixel {
+			dst[i] = byte(val >> uint((bytesPerPixel-1-i)*8))
+		}
+	} else {
+		for i := range bytesPerPixel {
+			dst[i] = byte(val >> uint(i*8))
+		}
+	}
+	return bytesPerPixel
+}
+
+// encodeHextileSolidRect emits a Hextile-encoded rectangle whose every pixel
+// is the same color. All sub-tiles after the first inherit the background
+// via a zero subencoding byte, collapsing a uniform 64×64 tile from ~16 KB
+// raw (or ~1-2 KB zlib) down to ~20 bytes on the wire.
+//
+// The returned buffer starts with the 12-byte rect header + the hextile
+// body. Callers assembling a multi-rect FramebufferUpdate append this after
+// their own message header.
+func encodeHextileSolidRect(r, g, b byte, pf clientPixelFormat, rc rect) []byte {
+	bytesPerPixel := max(int(pf.bpp)/8, 1)
+
+	// Count sub-tiles. Right/bottom sub-tiles may be smaller than 16.
+	cols := (rc.w + hextileSubSize - 1) / hextileSubSize
+	rows := (rc.h + hextileSubSize - 1) / hextileSubSize
+	subs := cols * rows
+
+	// Body: first sub-tile carries (subenc 0x02 + bg pixel); the rest are
+	// subenc 0x00 (inherit the previously-emitted background).
+	bodySize := 1 + bytesPerPixel + (subs - 1)
+	buf := make([]byte, 12+bodySize)
+
+	binary.BigEndian.PutUint16(buf[0:2], uint16(rc.x))
+	binary.BigEndian.PutUint16(buf[2:4], uint16(rc.y))
+	binary.BigEndian.PutUint16(buf[4:6], uint16(rc.w))
+	binary.BigEndian.PutUint16(buf[6:8], uint16(rc.h))
+	binary.BigEndian.PutUint32(buf[8:12], uint32(encHextile))
+
+	buf[12] = hextileBackgroundSpecified
+	encodePixel(buf[13:13+bytesPerPixel], pf, r, g, b)
+	// Remaining sub-tiles are already zero-valued from make(): "same as
+	// previous background", no pixel bytes.
+	_ = subs
+	return buf
+}
+
+// encodeHextileRect emits a full Hextile-encoded rectangle. Each 16×16
+// sub-tile is classified as 1-color (background only), 2-color (background
+// + foreground subrects), or raw. The 1-color and 2-color paths are
+// significantly cheaper than zlib on UI content (text, icons, flat
+// backgrounds) and avoid the persistent zlib stream's inter-rect
+// serialization point, so they parallelize trivially.
+//
+// The returned buffer starts with the 12-byte rect header + hextile body.
+func encodeHextileRect(img *image.RGBA, pf clientPixelFormat, x, y, w, h int) []byte {
+	bytesPerPixel := max(int(pf.bpp)/8, 1)
+
+	// Pre-size: worst case is every sub-tile raw → 1 header byte + raw
+	// pixels per sub-tile.
+	maxBody := 0
+	for sy := 0; sy < h; sy += hextileSubSize {
+		sh := min(hextileSubSize, h-sy)
+		for sx := 0; sx < w; sx += hextileSubSize {
+			sw := min(hextileSubSize, w-sx)
+			maxBody += 1 + sw*sh*bytesPerPixel
+		}
+	}
+	buf := make([]byte, 12, 12+maxBody)
+
+	binary.BigEndian.PutUint16(buf[0:2], uint16(x))
+	binary.BigEndian.PutUint16(buf[2:4], uint16(y))
+	binary.BigEndian.PutUint16(buf[4:6], uint16(w))
+	binary.BigEndian.PutUint16(buf[6:8], uint16(h))
+	binary.BigEndian.PutUint32(buf[8:12], uint32(encHextile))
+
+	var state hextileBgState
+
+	for sy := 0; sy < h; sy += hextileSubSize {
+		sh := min(hextileSubSize, h-sy)
+		for sx := 0; sx < w; sx += hextileSubSize {
+			sw := min(hextileSubSize, w-sx)
+			buf = appendHextileSubtile(buf, img, pf, rect{x + sx, y + sy, sw, sh}, &state, bytesPerPixel)
+		}
+	}
+	return buf
+}
+
+// hextileBgState carries the running background across sub-tile encodes so
+// we can omit the BackgroundSpecified flag when it hasn't changed.
+type hextileBgState struct {
+	prev  uint32
+	valid bool
+}
+
+// appendHextileSubtile encodes a single 16×16 (or smaller edge) sub-tile
+// onto buf.
+func appendHextileSubtile(buf []byte, img *image.RGBA, pf clientPixelFormat, rc rect, state *hextileBgState, bytesPerPixel int) []byte {
+	x, y, w, h := rc.x, rc.y, rc.w, rc.h
+	c0, c1, only2, c0Count, c1Count := classifySubtile(img, x, y, w, h)
+
+	if !only2 {
+		// >2 distinct colours: raw fallback.
+		buf = append(buf, hextileRaw)
+		buf = appendRawPixels(buf, img, pf, rc, bytesPerPixel)
+		state.valid = false
+		return buf
+	}
+
+	if c1Count == 0 {
+		// Single colour. Background only.
+		if state.valid && state.prev == c0 {
+			return append(buf, 0)
+		}
+		buf = append(buf, hextileBackgroundSpecified)
+		buf = appendPackedPixelFromRGBA(buf, pf, c0, bytesPerPixel)
+		state.prev = c0
+		state.valid = true
+		return buf
+	}
+
+	// Two colours. Background = majority; foreground = minority,
+	// emitted as 1-row subrects of fg runs.
+	bg, fg := c0, c1
+	if c1Count > c0Count {
+		bg, fg = c1, c0
+	}
+	subrects := collectFgSubrects(img, x, y, w, h, bg)
+	// Cap at 255 (the count is a uint8). On overflow fall through to
+	// raw: that's the simplest correct fallback.
+	if len(subrects) <= 255 {
+		flags := byte(hextileForegroundSpecified | hextileAnySubrects)
+		emitBg := !state.valid || state.prev != bg
+		if emitBg {
+			flags |= hextileBackgroundSpecified
+		}
+		buf = append(buf, flags)
+		if emitBg {
+			buf = appendPackedPixelFromRGBA(buf, pf, bg, bytesPerPixel)
+			state.prev = bg
+			state.valid = true
+		}
+		buf = appendPackedPixelFromRGBA(buf, pf, fg, bytesPerPixel)
+		buf = append(buf, byte(len(subrects)))
+		for _, sr := range subrects {
+			buf = append(buf, byte((sr[0]<<4)|sr[1]), byte(((sr[2]-1)<<4)|(sr[3]-1)))
+		}
+		return buf
+	}
+
+	// Raw fallback.
+	buf = append(buf, hextileRaw)
+	buf = appendRawPixels(buf, img, pf, rc, bytesPerPixel)
+	// Raw sub-tiles invalidate the persistent background.
+	state.valid = false
+	return buf
+}
+
+// classifySubtile scans the sub-tile and reports up to two distinct pixel
+// values plus their counts. only2 is false the moment a third distinct
+// colour is seen, in which case the caller falls back to raw.
+func classifySubtile(img *image.RGBA, x, y, w, h int) (c0, c1 uint32, only2 bool, c0Count, c1Count int) {
+	stride := img.Stride
+	base := y*stride + x*4
+	c0 = *(*uint32)(unsafe.Pointer(&img.Pix[base]))
+	only2 = true
+	for row := 0; row < h; row++ {
+		p := base + row*stride
+		for col := 0; col < w; col++ {
+			px := *(*uint32)(unsafe.Pointer(&img.Pix[p+col*4]))
+			switch {
+			case px == c0:
+				c0Count++
+			case c1Count == 0:
+				c1 = px
+				c1Count = 1
+			case px == c1:
+				c1Count++
+			default:
+				return c0, c1, false, 0, 0
+			}
+		}
+	}
+	return c0, c1, only2, c0Count, c1Count
+}
+
+// collectFgSubrects walks the sub-tile row by row, emitting one subrect per
+// horizontal run of pixels not equal to bg. Each subrect is [subX, subY,
+// width, height] with width/height in 1..16.
+func collectFgSubrects(img *image.RGBA, x, y, w, h int, bg uint32) [][4]int {
+	stride := img.Stride
+	var out [][4]int
+	for row := 0; row < h; row++ {
+		p := y*stride + x*4 + row*stride
+		col := 0
+		for col < w {
+			if *(*uint32)(unsafe.Pointer(&img.Pix[p+col*4])) == bg {
+				col++
+				continue
+			}
+			start := col
+			for col < w && *(*uint32)(unsafe.Pointer(&img.Pix[p+col*4])) != bg {
+				col++
+			}
+			out = append(out, [4]int{start, row, col - start, 1})
+		}
+	}
+	return out
+}
+
+func appendPackedPixelFromRGBA(buf []byte, pf clientPixelFormat, px uint32, bytesPerPixel int) []byte {
+	r := byte(px)
+	g := byte(px >> 8)
+	b := byte(px >> 16)
+	var tmp [4]byte
+	encodePixel(tmp[:], pf, r, g, b)
+	return append(buf, tmp[:bytesPerPixel]...)
+}
+
+func appendRawPixels(buf []byte, img *image.RGBA, pf clientPixelFormat, rc rect, bytesPerPixel int) []byte {
+	start := len(buf)
+	buf = append(buf, make([]byte, rc.w*rc.h*bytesPerPixel)...)
+	writePixels(buf[start:], img, pf, rc, bytesPerPixel)
+	return buf
+}
+
+// tightState holds the per-session JPEG scratch buffer and reused encoders
+// so per-rect encoding stays alloc-free in the steady state.
+type tightState struct {
+	jpegBuf *bytes.Buffer
+	zlib    *zlibState
+	scratch []byte // RGB-packed pixel scratch for JPEG and Basic paths.
+	// colorSeen is reused by sampledColorCount per rect; cleared via the Go
+	// runtime's map-clear fast path to avoid a fresh allocation each call.
+	colorSeen map[uint32]struct{}
+}
+
+func newTightState() *tightState {
+	return &tightState{
+		jpegBuf:   &bytes.Buffer{},
+		zlib:      newZlibState(),
+		colorSeen: make(map[uint32]struct{}, 64),
+	}
+}
+
+// encodeTightRect emits a single Tight-encoded rect. Picks Fill for uniform
+// content, JPEG for photo-like rects above a size and color-count threshold,
+// and Basic+zlib otherwise. Returns the rect header + Tight body (no
+// FramebufferUpdate header).
+func encodeTightRect(img *image.RGBA, pf clientPixelFormat, x, y, w, h int, t *tightState) []byte {
+	if pixel, uniform := tileIsUniform(img, x, y, w, h); uniform {
+		return encodeTightFill(x, y, w, h, byte(pixel), byte(pixel>>8), byte(pixel>>16))
+	}
+	if w*h >= tightJPEGMinArea && sampledColorCountInto(t.colorSeen, img, x, y, w, h, tightJPEGMinColors) >= tightJPEGMinColors {
+		if buf, ok := encodeTightJPEG(img, x, y, w, h, t); ok {
+			return buf
+		}
+	}
+	return encodeTightBasic(img, x, y, w, h, t)
+}
+
+func writeTightRectHeader(buf []byte, x, y, w, h int) {
+	binary.BigEndian.PutUint16(buf[0:2], uint16(x))
+	binary.BigEndian.PutUint16(buf[2:4], uint16(y))
+	binary.BigEndian.PutUint16(buf[4:6], uint16(w))
+	binary.BigEndian.PutUint16(buf[6:8], uint16(h))
+	binary.BigEndian.PutUint32(buf[8:12], uint32(encTight))
+}
+
+// appendTightLength encodes a Tight compact length prefix (1, 2, or 3 bytes
+// LE-ish, top bit of each byte signals continuation).
+func appendTightLength(buf []byte, n int) []byte {
+	b0 := byte(n & 0x7f)
+	if n <= 0x7f {
+		return append(buf, b0)
+	}
+	b0 |= 0x80
+	b1 := byte((n >> 7) & 0x7f)
+	if n <= 0x3fff {
+		return append(buf, b0, b1)
+	}
+	b1 |= 0x80
+	b2 := byte((n >> 14) & 0xff)
+	return append(buf, b0, b1, b2)
+}
+
+// encodeTightFill emits a uniform rect: 12-byte rect header + 1-byte
+// subenc (0x80) + 3-byte RGB pixel. Tight Fill always uses 24-bit RGB
+// regardless of the negotiated pixel format.
+func encodeTightFill(x, y, w, h int, r, g, b byte) []byte {
+	buf := make([]byte, 12+1+3)
+	writeTightRectHeader(buf, x, y, w, h)
+	buf[12] = tightFillSubenc
+	buf[13] = r
+	buf[14] = g
+	buf[15] = b
+	return buf
+}
+
+// encodeTightJPEG compresses the rect as a baseline JPEG. Returns ok=false
+// if the encoder errors so the caller can fall back to Basic.
+func encodeTightJPEG(img *image.RGBA, x, y, w, h int, t *tightState) ([]byte, bool) {
+	t.jpegBuf.Reset()
+	sub := img.SubImage(image.Rect(img.Rect.Min.X+x, img.Rect.Min.Y+y, img.Rect.Min.X+x+w, img.Rect.Min.Y+y+h))
+	if err := jpeg.Encode(t.jpegBuf, sub, &jpeg.Options{Quality: tightQualityFor(w * h)}); err != nil {
+		return nil, false
+	}
+	jpegBytes := t.jpegBuf.Bytes()
+	buf := make([]byte, 0, 12+1+3+len(jpegBytes))
+	buf = buf[:12]
+	writeTightRectHeader(buf, x, y, w, h)
+	buf = append(buf, tightJPEGSubenc)
+	buf = appendTightLength(buf, len(jpegBytes))
+	buf = append(buf, jpegBytes...)
+	return buf, true
+}
+
+// encodeTightBasic emits Basic+zlib with the no-op (CopyFilter) filter.
+// Pixels are sent as 24-bit RGB ("TPIXEL" format) which most clients
+// negotiate when the server advertises 32bpp true colour. Streams under
+// 12 bytes ship uncompressed per RFB Tight spec.
+func encodeTightBasic(img *image.RGBA, x, y, w, h int, t *tightState) []byte {
+	pixelStream := w * h * 3
+	if cap(t.scratch) < pixelStream {
+		t.scratch = make([]byte, pixelStream)
+	}
+	scratch := t.scratch[:pixelStream]
+	stride := img.Stride
+	off := 0
+	for row := y; row < y+h; row++ {
+		p := row*stride + x*4
+		for col := 0; col < w; col++ {
+			scratch[off+0] = img.Pix[p]
+			scratch[off+1] = img.Pix[p+1]
+			scratch[off+2] = img.Pix[p+2]
+			p += 4
+			off += 3
+		}
+	}
+
+	// Sub-encoding byte: stream 0, no resets, basic encoding (top nibble
+	// = 0x40 = explicit filter follows).
+	subenc := byte(tightBasicFilter)
+	filter := byte(tightFilterCopy)
+
+	if pixelStream < 12 {
+		buf := make([]byte, 0, 12+2+pixelStream)
+		buf = buf[:12]
+		writeTightRectHeader(buf, x, y, w, h)
+		buf = append(buf, subenc, filter)
+		buf = append(buf, scratch...)
+		return buf
+	}
+
+	z := t.zlib
+	z.buf.Reset()
+	if _, err := z.w.Write(scratch); err != nil {
+		log.Debugf("tight zlib write: %v", err)
+		return nil
+	}
+	if err := z.w.Flush(); err != nil {
+		log.Debugf("tight zlib flush: %v", err)
+		return nil
+	}
+	compressed := z.buf.Bytes()
+
+	buf := make([]byte, 0, 12+2+5+len(compressed))
+	buf = buf[:12]
+	writeTightRectHeader(buf, x, y, w, h)
+	buf = append(buf, subenc, filter)
+	buf = appendTightLength(buf, len(compressed))
+	buf = append(buf, compressed...)
+	return buf
+}
+
+func tightQualityFor(pixels int) int {
+	switch {
+	case pixels >= tightJPEGLargePixels:
+		return tightJPEGQualityLarge
+	case pixels >= tightJPEGMediumPixels:
+		return tightJPEGQualityMedium
+	default:
+		return tightJPEGQuality
+	}
+}
+
+// sampledColorCountInto estimates distinct-colour count by checking up to
+// maxColors samples. The caller-provided `seen` map is cleared and reused so
+// per-rect Tight encoding stays alloc-free. Cheap O(maxColors) per call.
+func sampledColorCountInto(seen map[uint32]struct{}, img *image.RGBA, x, y, w, h, maxColors int) int {
+	clear(seen)
+	stride := img.Stride
+	step := max((w*h)/(maxColors*4), 1)
+	var idx int
+	for row := 0; row < h; row++ {
+		p := (y+row)*stride + x*4
+		for col := 0; col < w; col++ {
+			if idx%step == 0 {
+				px := *(*uint32)(unsafe.Pointer(&img.Pix[p+col*4]))
+				seen[px&0x00ffffff] = struct{}{}
+				if len(seen) > maxColors {
+					return len(seen)
+				}
+			}
+			idx++
+		}
+	}
+	return len(seen)
+}
+
+// zlibState holds the persistent zlib writer, output buffer, and a scratch
+// slice reused by encodeZlibRect to stage the packed pixel stream before
+// handing it to the deflate writer. The scratch grows to the largest rect
+// we've seen and is kept for the session lifetime.
+type zlibState struct {
+	buf     *bytes.Buffer
+	w       *zlib.Writer
+	scratch []byte
+}
+
+func newZlibState() *zlibState {
+	buf := &bytes.Buffer{}
+	w, _ := zlib.NewWriterLevel(buf, zlib.BestSpeed)
+	return &zlibState{buf: buf, w: w}
+}
+
+func (z *zlibState) Close() error {
+	return z.w.Close()
+}

client/vnc/server/rfb_bench_test.go

@@ -0,0 +1,405 @@
+package server
+
+import (
+	"image"
+	"math/rand"
+	"testing"
+)
+
+// Representative frame sizes.
+var benchRects = []struct {
+	name string
+	w, h int
+}{
+	{"1080p_full", 1920, 1080},
+	{"720p_full", 1280, 720},
+	{"256x256_tile", 256, 256},
+	{"64x64_tile", 64, 64},
+}
+
+func makeBenchImage(w, h int, seed int64) *image.RGBA {
+	img := image.NewRGBA(image.Rect(0, 0, w, h))
+	r := rand.New(rand.NewSource(seed))
+	_, _ = r.Read(img.Pix)
+	// Force alpha byte so the fast path and slow path produce identical output.
+	for i := 3; i < len(img.Pix); i += 4 {
+		img.Pix[i] = 0xff
+	}
+	return img
+}
+
+func makeBenchImagePartial(w, h, changedRows int) (*image.RGBA, *image.RGBA) {
+	prev := makeBenchImage(w, h, 1)
+	cur := image.NewRGBA(prev.Rect)
+	copy(cur.Pix, prev.Pix)
+	if changedRows > h {
+		changedRows = h
+	}
+	// Dirty the first `changedRows` rows.
+	r := rand.New(rand.NewSource(2))
+	_, _ = r.Read(cur.Pix[:changedRows*cur.Stride])
+	for i := 3; i < len(cur.Pix); i += 4 {
+		cur.Pix[i] = 0xff
+	}
+	return prev, cur
+}
+
+func BenchmarkEncodeRawRect(b *testing.B) {
+	pf := defaultClientPixelFormat()
+	for _, r := range benchRects {
+		img := makeBenchImage(r.w, r.h, 1)
+		b.Run(r.name, func(b *testing.B) {
+			b.SetBytes(int64(r.w * r.h * 4))
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				_ = encodeRawRect(img, pf, 0, 0, r.w, r.h)
+			}
+		})
+	}
+}
+
+func BenchmarkEncodeZlibRect(b *testing.B) {
+	pf := defaultClientPixelFormat()
+	for _, r := range benchRects {
+		img := makeBenchImage(r.w, r.h, 1)
+		z := newZlibState()
+		b.Run(r.name, func(b *testing.B) {
+			b.SetBytes(int64(r.w * r.h * 4))
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				_ = encodeZlibRect(img, pf, 0, 0, r.w, r.h, z)
+			}
+		})
+	}
+}
+
+// BenchmarkWritePixels isolates the per-pixel pack loop from the allocation
+// and FramebufferUpdate-header overhead.
+func BenchmarkWritePixels(b *testing.B) {
+	pf := defaultClientPixelFormat()
+	for _, r := range benchRects {
+		img := makeBenchImage(r.w, r.h, 1)
+		dst := make([]byte, r.w*r.h*4)
+		b.Run(r.name, func(b *testing.B) {
+			b.SetBytes(int64(r.w * r.h * 4))
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				writePixels(dst, img, pf, rect{0, 0, r.w, r.h}, 4)
+			}
+		})
+	}
+}
+
+// BenchmarkWritePixelsScaled forces the general (non-fast) path by using a
+// pixel format with non-255 channel maxes.
+func BenchmarkWritePixelsScaled(b *testing.B) {
+	pf := defaultClientPixelFormat()
+	pf.rMax, pf.gMax, pf.bMax = 31, 63, 31 // 16bpp-ish; exercises the divide path
+	pf.bpp = 16
+	for _, r := range benchRects {
+		img := makeBenchImage(r.w, r.h, 1)
+		dst := make([]byte, r.w*r.h*2)
+		b.Run(r.name, func(b *testing.B) {
+			b.SetBytes(int64(r.w * r.h * 4))
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				writePixels(dst, img, pf, rect{0, 0, r.w, r.h}, 2)
+			}
+		})
+	}
+}
+
+func BenchmarkSwizzleBGRAtoRGBA(b *testing.B) {
+	for _, r := range benchRects {
+		size := r.w * r.h * 4
+		src := make([]byte, size)
+		dst := make([]byte, size)
+		rng := rand.New(rand.NewSource(1))
+		_, _ = rng.Read(src)
+		b.Run(r.name, func(b *testing.B) {
+			b.SetBytes(int64(size))
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				swizzleBGRAtoRGBA(dst, src)
+			}
+		})
+	}
+}
+
+// BenchmarkSwizzleBGRAtoRGBANaive is the naive byte-by-byte implementation
+// that the Linux SHM capturer used before the uint32 rewrite, kept here so
+// we can compare the cost directly.
+func BenchmarkSwizzleBGRAtoRGBANaive(b *testing.B) {
+	for _, r := range benchRects {
+		size := r.w * r.h * 4
+		src := make([]byte, size)
+		dst := make([]byte, size)
+		rng := rand.New(rand.NewSource(1))
+		_, _ = rng.Read(src)
+		b.Run(r.name, func(b *testing.B) {
+			b.SetBytes(int64(size))
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				for j := 0; j < size; j += 4 {
+					dst[j+0] = src[j+2]
+					dst[j+1] = src[j+1]
+					dst[j+2] = src[j+0]
+					dst[j+3] = 0xff
+				}
+			}
+		})
+	}
+}
+
+// BenchmarkEncodeUniformTile_Zlib measures the cost of sending a uniform
+// 64×64 dirty tile via zlib (the old path before the Hextile fast path).
+func BenchmarkEncodeUniformTile_Zlib(b *testing.B) {
+	pf := defaultClientPixelFormat()
+	img := image.NewRGBA(image.Rect(0, 0, 64, 64))
+	for i := 0; i < len(img.Pix); i += 4 {
+		img.Pix[i+0] = 0x33
+		img.Pix[i+1] = 0x66
+		img.Pix[i+2] = 0x99
+		img.Pix[i+3] = 0xff
+	}
+	z := newZlibState()
+	b.ReportAllocs()
+	var bytesOut int
+	for i := 0; i < b.N; i++ {
+		out := encodeZlibRect(img, pf, 0, 0, 64, 64, z)
+		bytesOut = len(out)
+	}
+	b.ReportMetric(float64(bytesOut), "wire_bytes")
+}
+
+// BenchmarkEncodeUniformTile_Hextile measures the new fast path: uniform
+// 64×64 tile emitted as Hextile SolidFill.
+func BenchmarkEncodeUniformTile_Hextile(b *testing.B) {
+	pf := defaultClientPixelFormat()
+	b.ReportAllocs()
+	var bytesOut int
+	for i := 0; i < b.N; i++ {
+		out := encodeHextileSolidRect(0x33, 0x66, 0x99, pf, rect{0, 0, 64, 64})
+		bytesOut = len(out)
+	}
+	b.ReportMetric(float64(bytesOut), "wire_bytes")
+}
+
+func BenchmarkTileIsUniform(b *testing.B) {
+	img := image.NewRGBA(image.Rect(0, 0, 64, 64))
+	for i := 0; i < len(img.Pix); i += 4 {
+		img.Pix[i+3] = 0xff
+	}
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_, _ = tileIsUniform(img, 0, 0, 64, 64)
+	}
+}
+
+// BenchmarkEncodeManyTilesVsFullFrame exercises the bandwidth + CPU
+// trade-off that motivates the full-frame promotion path: encoding a burst
+// of N dirty 64×64 tiles as separate zlib rects vs emitting one big zlib
+// rect for the whole frame.
+func BenchmarkEncodeManyTilesVsFullFrame(b *testing.B) {
+	pf := defaultClientPixelFormat()
+	const w, h = 1920, 1080
+	img := makeBenchImage(w, h, 1)
+
+	// Build the list of every tile in the frame (worst case: entire screen dirty).
+	var tiles [][4]int
+	for ty := 0; ty < h; ty += tileSize {
+		th := tileSize
+		if ty+th > h {
+			th = h - ty
+		}
+		for tx := 0; tx < w; tx += tileSize {
+			tw := tileSize
+			if tx+tw > w {
+				tw = w - tx
+			}
+			tiles = append(tiles, [4]int{tx, ty, tw, th})
+		}
+	}
+	nTiles := len(tiles)
+
+	b.Run("per_tile_zlib", func(b *testing.B) {
+		z := newZlibState()
+		b.SetBytes(int64(w * h * 4))
+		b.ReportAllocs()
+		var totalOut int
+		for i := 0; i < b.N; i++ {
+			totalOut = 0
+			for _, r := range tiles {
+				out := encodeZlibRect(img, pf, r[0], r[1], r[2], r[3], z)
+				totalOut += len(out)
+			}
+		}
+		b.ReportMetric(float64(totalOut), "wire_bytes")
+		b.ReportMetric(float64(nTiles), "tiles")
+	})
+
+	b.Run("full_frame_zlib", func(b *testing.B) {
+		z := newZlibState()
+		b.SetBytes(int64(w * h * 4))
+		b.ReportAllocs()
+		var totalOut int
+		for i := 0; i < b.N; i++ {
+			out := encodeZlibRect(img, pf, 0, 0, w, h, z)
+			totalOut = len(out)
+		}
+		b.ReportMetric(float64(totalOut), "wire_bytes")
+	})
+}
+
+// BenchmarkShouldPromoteToFullFrame verifies the threshold check itself is
+// cheap. It runs on every frame, so regressions here hit all workloads.
+func BenchmarkShouldPromoteToFullFrame(b *testing.B) {
+	const w, h = 1920, 1080
+	s := &session{serverW: w, serverH: h}
+	// Build a worst-case rect list (every tile dirty, 510 entries).
+	var rects [][4]int
+	for ty := 0; ty < h; ty += tileSize {
+		th := tileSize
+		if ty+th > h {
+			th = h - ty
+		}
+		for tx := 0; tx < w; tx += tileSize {
+			tw := tileSize
+			if tx+tw > w {
+				tw = w - tx
+			}
+			rects = append(rects, [4]int{tx, ty, tw, th})
+		}
+	}
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = s.shouldPromoteToFullFrame(rects)
+	}
+}
+
+// BenchmarkEncodeCoalescedVsPerTile compares per-tile encoding vs the
+// coalesced rect list emitted by diffRects, on a horizontal-band dirty
+// pattern (e.g. a scrolling status bar) where coalescing pays off.
+func BenchmarkEncodeCoalescedVsPerTile(b *testing.B) {
+	pf := defaultClientPixelFormat()
+	const w, h = 1920, 1080
+	img := makeBenchImage(w, h, 1)
+
+	// Dirty band: rows 200..264 (one tile-row), full width.
+	var perTile [][4]int
+	for tx := 0; tx < w; tx += tileSize {
+		tw := tileSize
+		if tx+tw > w {
+			tw = w - tx
+		}
+		perTile = append(perTile, [4]int{tx, 200, tw, tileSize})
+	}
+	coalesced := coalesceRects(append([][4]int(nil), perTile...))
+
+	b.Run("per_tile", func(b *testing.B) {
+		z := newZlibState()
+		b.ReportAllocs()
+		var bytesOut int
+		for i := 0; i < b.N; i++ {
+			bytesOut = 0
+			for _, r := range perTile {
+				out := encodeZlibRect(img, pf, r[0], r[1], r[2], r[3], z)
+				bytesOut += len(out)
+			}
+		}
+		b.ReportMetric(float64(bytesOut), "wire_bytes")
+		b.ReportMetric(float64(len(perTile)), "rects")
+	})
+
+	b.Run("coalesced", func(b *testing.B) {
+		z := newZlibState()
+		b.ReportAllocs()
+		var bytesOut int
+		for i := 0; i < b.N; i++ {
+			bytesOut = 0
+			for _, r := range coalesced {
+				out := encodeZlibRect(img, pf, r[0], r[1], r[2], r[3], z)
+				bytesOut += len(out)
+			}
+		}
+		b.ReportMetric(float64(bytesOut), "wire_bytes")
+		b.ReportMetric(float64(len(coalesced)), "rects")
+	})
+}
+
+func BenchmarkCoalesceRects(b *testing.B) {
+	const w, h = 1920, 1080
+	// Worst case: every tile dirty.
+	var allTiles [][4]int
+	for ty := 0; ty < h; ty += tileSize {
+		th := tileSize
+		if ty+th > h {
+			th = h - ty
+		}
+		for tx := 0; tx < w; tx += tileSize {
+			tw := tileSize
+			if tx+tw > w {
+				tw = w - tx
+			}
+			allTiles = append(allTiles, [4]int{tx, ty, tw, th})
+		}
+	}
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		in := make([][4]int, len(allTiles))
+		copy(in, allTiles)
+		_ = coalesceRects(in)
+	}
+}
+
+// BenchmarkEncodeTightVsZlib_Photo compares Tight (which routes random/
+// photographic content to JPEG) against the persistent Zlib stream. JPEG
+// at quality 70 should be 5-15× smaller on this kind of content.
+func BenchmarkEncodeTightVsZlib_Photo(b *testing.B) {
+	pf := defaultClientPixelFormat()
+	for _, r := range []struct {
+		name string
+		w, h int
+	}{
+		{"256x256", 256, 256},
+		{"512x512", 512, 512},
+		{"1080p", 1920, 1080},
+	} {
+		img := makeBenchImage(r.w, r.h, 1)
+		b.Run(r.name+"/zlib", func(b *testing.B) {
+			z := newZlibState()
+			b.SetBytes(int64(r.w * r.h * 4))
+			b.ReportAllocs()
+			var bytesOut int
+			for i := 0; i < b.N; i++ {
+				out := encodeZlibRect(img, pf, 0, 0, r.w, r.h, z)
+				bytesOut = len(out)
+			}
+			b.ReportMetric(float64(bytesOut), "wire_bytes")
+		})
+		b.Run(r.name+"/tight", func(b *testing.B) {
+			t := newTightState()
+			b.SetBytes(int64(r.w * r.h * 4))
+			b.ReportAllocs()
+			var bytesOut int
+			for i := 0; i < b.N; i++ {
+				out := encodeTightRect(img, pf, 0, 0, r.w, r.h, t)
+				bytesOut = len(out)
+			}
+			b.ReportMetric(float64(bytesOut), "wire_bytes")
+		})
+	}
+}
+
+func BenchmarkDiffRects(b *testing.B) {
+	for _, r := range benchRects {
+		prev, cur := makeBenchImagePartial(r.w, r.h, 100)
+		b.Run(r.name, func(b *testing.B) {
+			b.SetBytes(int64(r.w * r.h * 4))
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				_ = diffRects(prev, cur, r.w, r.h, tileSize)
+			}
+		})
+	}
+}

client/vnc/server/server.go

@@ -0,0 +1,814 @@
+package server
+
+import (
+	"context"
+	"crypto/subtle"
+	"encoding/binary"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"image"
+	"io"
+	"net"
+	"net/netip"
+	"strings"
+	"sync"
+	"time"
+
+	gojwt "github.com/golang-jwt/jwt/v5"
+	log "github.com/sirupsen/logrus"
+	"golang.zx2c4.com/wireguard/tun/netstack"
+
+	sshauth "github.com/netbirdio/netbird/client/ssh/auth"
+	nbjwt "github.com/netbirdio/netbird/shared/auth/jwt"
+)
+
+// Connection modes sent by the client in the session header.
+const (
+	ModeAttach  byte = 0 // Capture current display
+	ModeSession byte = 1 // Virtual session as specified user
+)
+
+// RFB security-failure reason codes sent to the client. These prefixes are
+// stable so dashboard/noVNC integrations can branch on them without parsing
+// free text. Format: "CODE: human message".
+const (
+	RejectCodeJWTMissing    = "AUTH_JWT_MISSING"
+	RejectCodeJWTExpired    = "AUTH_JWT_EXPIRED"
+	RejectCodeJWTInvalid    = "AUTH_JWT_INVALID"
+	RejectCodeAuthForbidden = "AUTH_FORBIDDEN"
+	RejectCodeAuthConfig    = "AUTH_CONFIG"
+	RejectCodeSessionError  = "SESSION_ERROR"
+	RejectCodeCapturerError = "CAPTURER_ERROR"
+	RejectCodeUnsupportedOS = "UNSUPPORTED"
+	RejectCodeBadRequest    = "BAD_REQUEST"
+)
+
+// EnvVNCDisableDownscale disables any platform-specific framebuffer
+// downscaling (e.g. Retina 2:1). Set to 1/true to send the native resolution.
+const EnvVNCDisableDownscale = "NB_VNC_DISABLE_DOWNSCALE"
+
+// freshWindow is how long an on-demand capturer may reuse its last result
+// before triggering a new capture. Short enough to feel responsive, long
+// enough to coalesce bursty multi-session requests. 16 ms ~= 60 fps.
+const freshWindow = 16 * time.Millisecond
+
+// ScreenCapturer grabs desktop frames for the VNC server.
+type ScreenCapturer interface {
+	// Width returns the current screen width in pixels.
+	Width() int
+	// Height returns the current screen height in pixels.
+	Height() int
+	// Capture returns the current desktop as an RGBA image.
+	Capture() (*image.RGBA, error)
+}
+
+// captureIntoer is implemented by capturers that can write directly into a
+// caller-provided buffer, skipping the per-frame snapshot copy that the
+// session would otherwise need to make. Linux and macOS implement this.
+type captureIntoer interface {
+	CaptureInto(dst *image.RGBA) error
+}
+
+// errFrameUnchanged is returned by capturers that hash the raw source
+// bytes (currently macOS) when the new frame is byte-identical to the
+// last one, so the encoder can short-circuit to an empty update.
+var errFrameUnchanged = errors.New("frame unchanged")
+
+// InputInjector delivers keyboard and mouse events to the OS.
+type InputInjector interface {
+	// InjectKey simulates a key press or release. keysym is an X11 KeySym.
+	InjectKey(keysym uint32, down bool)
+	// InjectPointer simulates mouse movement and button state.
+	InjectPointer(buttonMask uint8, x, y, serverW, serverH int)
+	// SetClipboard sets the system clipboard to the given text.
+	SetClipboard(text string)
+	// GetClipboard returns the current system clipboard text.
+	GetClipboard() string
+	// TypeText synthesizes the given text as keystrokes on the active
+	// desktop. Used by the dashboard's Paste button to push host clipboard
+	// content into a secure desktop (Winlogon/UAC) where the clipboard is
+	// isolated. On platforms or sessions without keystroke synthesis it
+	// may be a no-op.
+	TypeText(text string)
+}
+
+// JWTConfig holds JWT validation configuration for VNC auth.
+type JWTConfig struct {
+	Issuer       string
+	KeysLocation string
+	MaxTokenAge  int64
+	Audiences    []string
+}
+
+// connectionHeader is sent by the client before the RFB handshake to specify
+// the VNC session mode and authenticate.
+type connectionHeader struct {
+	mode      byte
+	username  string
+	jwt       string
+	sessionID uint32 // Windows session ID (0 = console/auto)
+	// width and height request the virtual display geometry for session mode.
+	// Zero means use the default.
+	width  uint16
+	height uint16
+}
+
+// Server is the embedded VNC server that listens on the WireGuard interface.
+// It supports two operating modes:
+//   - Direct mode: captures the screen and handles VNC sessions in-process.
+//     Used when running in a user session with desktop access.
+//   - Service mode: proxies VNC connections to an agent process spawned in
+//     the active console session. Used when running as a Windows service in
+//     Session 0.
+//
+// Within direct mode, each connection can request one of two session modes
+// via the connection header:
+//   - Attach: capture the current physical display.
+//   - Session: start a virtual Xvfb display as the requested user.
+type Server struct {
+	capturer    ScreenCapturer
+	injector    InputInjector
+	password    string
+	serviceMode bool
+	disableAuth bool
+	localAddr   netip.Addr   // NetBird WireGuard IP this server is bound to
+	network     netip.Prefix // NetBird overlay network
+	log         *log.Entry
+
+	mu           sync.Mutex
+	listener     net.Listener
+	ctx          context.Context
+	cancel       context.CancelFunc
+	vmgr         virtualSessionManager
+	jwtConfig    *JWTConfig
+	jwtValidator *nbjwt.Validator
+	jwtExtractor *nbjwt.ClaimsExtractor
+	authorizer   *sshauth.Authorizer
+	netstackNet  *netstack.Net
+	agentToken   []byte // raw token bytes for agent-mode auth
+
+	sessionsMu sync.Mutex
+	sessionSeq uint64
+	sessions   map[uint64]ActiveSessionInfo
+}
+
+// ActiveSessionInfo describes a currently connected VNC client.
+type ActiveSessionInfo struct {
+	RemoteAddress string
+	Mode          string
+	Username      string
+	JWTUsername   string
+}
+
+// vncSession provides capturer and injector for a virtual display session.
+type vncSession interface {
+	Capturer() ScreenCapturer
+	Injector() InputInjector
+	Display() string
+	ClientConnect()
+	ClientDisconnect()
+}
+
+// virtualSessionManager is implemented by sessionManager on Linux.
+type virtualSessionManager interface {
+	// GetOrCreate returns an existing session for the user or starts a new one
+	// with the requested geometry. width/height of 0 means use the default.
+	GetOrCreate(username string, width, height uint16) (vncSession, error)
+	StopAll()
+}
+
+// New creates a VNC server with the given screen capturer and input injector.
+func New(capturer ScreenCapturer, injector InputInjector, password string) *Server {
+	return &Server{
+		capturer:   capturer,
+		injector:   injector,
+		password:   password,
+		authorizer: sshauth.NewAuthorizer(),
+		log:        log.WithField("component", "vnc-server"),
+		sessions:   make(map[uint64]ActiveSessionInfo),
+	}
+}
+
+// ActiveSessions returns a snapshot of currently connected VNC clients.
+func (s *Server) ActiveSessions() []ActiveSessionInfo {
+	s.sessionsMu.Lock()
+	defer s.sessionsMu.Unlock()
+	out := make([]ActiveSessionInfo, 0, len(s.sessions))
+	for _, info := range s.sessions {
+		out = append(out, info)
+	}
+	return out
+}
+
+func (s *Server) addSession(info ActiveSessionInfo) uint64 {
+	s.sessionsMu.Lock()
+	defer s.sessionsMu.Unlock()
+	s.sessionSeq++
+	id := s.sessionSeq
+	s.sessions[id] = info
+	return id
+}
+
+func (s *Server) removeSession(id uint64) {
+	s.sessionsMu.Lock()
+	defer s.sessionsMu.Unlock()
+	delete(s.sessions, id)
+}
+
+// SetServiceMode enables proxy-to-agent mode for Windows service operation.
+func (s *Server) SetServiceMode(enabled bool) {
+	s.serviceMode = enabled
+}
+
+// SetJWTConfig configures JWT authentication for VNC connections.
+// Pass nil to disable JWT (public mode).
+func (s *Server) SetJWTConfig(config *JWTConfig) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.jwtConfig = config
+	s.jwtValidator = nil
+	s.jwtExtractor = nil
+}
+
+// SetDisableAuth disables authentication entirely.
+func (s *Server) SetDisableAuth(disable bool) {
+	s.disableAuth = disable
+}
+
+// SetAgentToken sets a hex-encoded token that must be presented by incoming
+// connections before any VNC data. Used in agent mode to verify that only the
+// trusted service process connects.
+func (s *Server) SetAgentToken(hexToken string) {
+	if hexToken == "" {
+		return
+	}
+	b, err := hex.DecodeString(hexToken)
+	if err != nil {
+		s.log.Warnf("invalid agent token: %v", err)
+		return
+	}
+	s.agentToken = b
+}
+
+// SetNetstackNet sets the netstack network for userspace-only listening.
+// When set, the VNC server listens via netstack instead of a real OS socket.
+func (s *Server) SetNetstackNet(n *netstack.Net) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.netstackNet = n
+}
+
+// UpdateVNCAuth updates the fine-grained authorization configuration.
+func (s *Server) UpdateVNCAuth(config *sshauth.Config) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.jwtValidator = nil
+	s.jwtExtractor = nil
+	s.authorizer.Update(config)
+}
+
+// Start begins listening for VNC connections on the given address.
+// network is the NetBird overlay prefix used to validate connection sources.
+func (s *Server) Start(ctx context.Context, addr netip.AddrPort, network netip.Prefix) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if s.listener != nil {
+		return fmt.Errorf("server already running")
+	}
+
+	if !network.IsValid() {
+		return fmt.Errorf("invalid overlay network prefix")
+	}
+
+	s.ctx, s.cancel = context.WithCancel(ctx)
+	s.vmgr = s.platformSessionManager()
+	s.localAddr = addr.Addr()
+	s.network = network
+
+	var listener net.Listener
+	var listenDesc string
+	if s.netstackNet != nil {
+		ln, err := s.netstackNet.ListenTCPAddrPort(addr)
+		if err != nil {
+			return fmt.Errorf("listen on netstack %s: %w", addr, err)
+		}
+		listener = ln
+		listenDesc = fmt.Sprintf("netstack %s", addr)
+	} else {
+		tcpAddr := net.TCPAddrFromAddrPort(addr)
+		ln, err := net.ListenTCP("tcp", tcpAddr)
+		if err != nil {
+			return fmt.Errorf("listen on %s: %w", addr, err)
+		}
+		listener = ln
+		listenDesc = addr.String()
+	}
+	s.listener = listener
+
+	if s.serviceMode {
+		s.platformInit()
+	}
+
+	if s.serviceMode {
+		go s.serviceAcceptLoop()
+	} else {
+		go s.acceptLoop()
+	}
+
+	s.log.Infof("started on %s (service_mode=%v)", listenDesc, s.serviceMode)
+	return nil
+}
+
+// Stop shuts down the server and closes all connections.
+func (s *Server) Stop() error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if s.cancel != nil {
+		s.cancel()
+		s.cancel = nil
+	}
+
+	if s.vmgr != nil {
+		s.vmgr.StopAll()
+	}
+
+	if s.serviceMode {
+		s.platformShutdown()
+	}
+
+	if c, ok := s.capturer.(interface{ Close() }); ok {
+		c.Close()
+	}
+
+	if s.listener != nil {
+		err := s.listener.Close()
+		s.listener = nil
+		if err != nil {
+			return fmt.Errorf("close VNC listener: %w", err)
+		}
+	}
+
+	s.log.Info("stopped")
+	return nil
+}
+
+// acceptLoop handles VNC connections directly (user session mode).
+func (s *Server) acceptLoop() {
+	for {
+		conn, err := s.listener.Accept()
+		if err != nil {
+			select {
+			case <-s.ctx.Done():
+				return
+			default:
+			}
+			s.log.Debugf("accept VNC connection: %v", err)
+			continue
+		}
+
+		go s.handleConnection(conn)
+	}
+}
+
+func (s *Server) validateCapturer(capturer ScreenCapturer) error {
+	// Quick check first: if already ready, return immediately.
+	if capturer.Width() > 0 && capturer.Height() > 0 {
+		return nil
+	}
+	// Capturer not ready: poke any retry loop that supports it so it doesn't
+	// wait out its full backoff (e.g. macOS waiting for Screen Recording).
+	if w, ok := capturer.(interface{ Wake() }); ok {
+		w.Wake()
+	}
+	// Wait up to 5s for the capturer to become ready.
+	for range 50 {
+		time.Sleep(100 * time.Millisecond)
+		if capturer.Width() > 0 && capturer.Height() > 0 {
+			return nil
+		}
+	}
+	return errors.New("no display available (check X11 / framebuffer on Linux/FreeBSD or Screen Recording permission on macOS)")
+}
+
+// isAllowedSource rejects connections from outside the NetBird overlay network
+// and from the local WireGuard IP (prevents local privilege escalation).
+// Matches the SSH server's connectionValidator logic.
+func (s *Server) isAllowedSource(addr net.Addr) bool {
+	tcpAddr, ok := addr.(*net.TCPAddr)
+	if !ok {
+		s.log.Warnf("connection rejected: non-TCP address %s", addr)
+		return false
+	}
+
+	remoteIP, ok := netip.AddrFromSlice(tcpAddr.IP)
+	if !ok {
+		s.log.Warnf("connection rejected: invalid remote IP %s", tcpAddr.IP)
+		return false
+	}
+	remoteIP = remoteIP.Unmap()
+
+	if remoteIP.IsLoopback() && s.localAddr.IsLoopback() {
+		return true
+	}
+
+	if remoteIP == s.localAddr {
+		s.log.Warnf("connection rejected from own IP %s", remoteIP)
+		return false
+	}
+
+	if !s.network.IsValid() {
+		s.log.Warnf("connection rejected: overlay network not configured")
+		return false
+	}
+	if !s.network.Contains(remoteIP) {
+		s.log.Warnf("connection rejected from non-NetBird IP %s", remoteIP)
+		return false
+	}
+
+	return true
+}
+
+func (s *Server) handleConnection(conn net.Conn) {
+	connLog := s.log.WithField("remote", conn.RemoteAddr().String())
+
+	if !s.isAllowedSource(conn.RemoteAddr()) {
+		conn.Close()
+		return
+	}
+	if !s.verifyAgentToken(conn, connLog) {
+		return
+	}
+	header, err := readConnectionHeader(conn)
+	if err != nil {
+		connLog.Warnf("read connection header: %v", err)
+		conn.Close()
+		return
+	}
+	connLog, jwtUserID, ok := s.authorizeJWT(conn, header, connLog)
+	if !ok {
+		return
+	}
+
+	capturer, injector, sessionCleanup, ok := s.acquireSessionResources(conn, header, &connLog)
+	if !ok {
+		return
+	}
+	defer sessionCleanup()
+
+	sessionID := s.addSession(ActiveSessionInfo{
+		RemoteAddress: conn.RemoteAddr().String(),
+		Mode:          modeString(header.mode),
+		Username:      header.username,
+		JWTUsername:   jwtUserID,
+	})
+	defer s.removeSession(sessionID)
+
+	if err := s.validateCapturer(capturer); err != nil {
+		rejectConnection(conn, codeMessage(RejectCodeCapturerError, fmt.Sprintf("screen capturer: %v", err)))
+		connLog.Warnf("capturer not ready: %v", err)
+		return
+	}
+
+	sess := &session{
+		conn:     conn,
+		capturer: capturer,
+		injector: injector,
+		serverW:  capturer.Width(),
+		serverH:  capturer.Height(),
+		password: s.password,
+		log:      connLog,
+	}
+	sess.serve()
+}
+
+// codeMessage formats a stable reject code with a human-readable message.
+// Dashboards split on the first ": " to recover the code without parsing the
+// free-text suffix.
+func codeMessage(code, msg string) string {
+	return code + ": " + msg
+}
+
+// jwtErrorCode maps a JWT auth error to a stable reject code.
+func jwtErrorCode(err error) string {
+	if err == nil {
+		return RejectCodeJWTInvalid
+	}
+	if errors.Is(err, nbjwt.ErrTokenExpired) {
+		return RejectCodeJWTExpired
+	}
+	msg := err.Error()
+	switch {
+	case strings.Contains(msg, "JWT required but not provided"):
+		return RejectCodeJWTMissing
+	case strings.Contains(msg, "authorize") || strings.Contains(msg, "not authorized"):
+		return RejectCodeAuthForbidden
+	default:
+		return RejectCodeJWTInvalid
+	}
+}
+
+// rejectConnection sends a minimal RFB handshake with a security failure
+// reason, so VNC clients display the error message instead of a generic
+// "unexpected disconnect."
+func rejectConnection(conn net.Conn, reason string) {
+	defer conn.Close()
+	// RFB 3.8 server version.
+	if _, err := io.WriteString(conn, "RFB 003.008\n"); err != nil {
+		return
+	}
+	// Read client version (12 bytes), ignore errors here so a short-lived
+	// or pre-handshake client still gets the failure reason below.
+	var clientVer [12]byte
+	_ = conn.SetReadDeadline(time.Now().Add(2 * time.Second))
+	_, _ = io.ReadFull(conn, clientVer[:])
+	_ = conn.SetReadDeadline(time.Time{})
+	// Send 0 security types = connection failed, followed by reason.
+	msg := []byte(reason)
+	buf := make([]byte, 1+4+len(msg))
+	buf[0] = 0 // 0 security types = failure
+	binary.BigEndian.PutUint32(buf[1:5], uint32(len(msg)))
+	copy(buf[5:], msg)
+	_, _ = conn.Write(buf)
+}
+
+const defaultJWTMaxTokenAge = 10 * 60 // 10 minutes
+
+// authenticateJWT validates the JWT from the connection header and checks
+// authorization. For attach mode, just checks membership in the authorized
+// user list. For session mode, additionally validates the OS user mapping.
+func (s *Server) authenticateJWT(header *connectionHeader) (string, error) {
+	if header.jwt == "" {
+		return "", fmt.Errorf("JWT required but not provided")
+	}
+
+	s.mu.Lock()
+	if err := s.ensureJWTValidator(); err != nil {
+		s.mu.Unlock()
+		return "", fmt.Errorf("initialize JWT validator: %w", err)
+	}
+	validator := s.jwtValidator
+	extractor := s.jwtExtractor
+	s.mu.Unlock()
+
+	token, err := validator.ValidateAndParse(context.Background(), header.jwt)
+	if err != nil {
+		return "", fmt.Errorf("validate JWT: %w", err)
+	}
+
+	if err := s.checkTokenAge(token); err != nil {
+		return "", err
+	}
+
+	userAuth, err := extractor.ToUserAuth(token)
+	if err != nil {
+		return "", fmt.Errorf("extract user from JWT: %w", err)
+	}
+	if userAuth.UserId == "" {
+		return "", fmt.Errorf("JWT has no user ID")
+	}
+
+	switch header.mode {
+	case ModeSession:
+		// Session mode: check user + OS username mapping.
+		if _, err := s.authorizer.Authorize(userAuth.UserId, header.username); err != nil {
+			return "", fmt.Errorf("authorize session for %s: %w", header.username, err)
+		}
+	default:
+		// Attach mode: just check user is in the authorized list (wildcard OS user).
+		if _, err := s.authorizer.Authorize(userAuth.UserId, "*"); err != nil {
+			return "", fmt.Errorf("user not authorized for VNC: %w", err)
+		}
+	}
+
+	return userAuth.UserId, nil
+}
+
+// ensureJWTValidator lazily initializes the JWT validator. Must be called with mu held.
+func (s *Server) ensureJWTValidator() error {
+	if s.jwtValidator != nil && s.jwtExtractor != nil {
+		return nil
+	}
+	if s.jwtConfig == nil {
+		return fmt.Errorf("no JWT config")
+	}
+
+	s.jwtValidator = nbjwt.NewValidator(
+		s.jwtConfig.Issuer,
+		s.jwtConfig.Audiences,
+		s.jwtConfig.KeysLocation,
+		false,
+	)
+
+	var opts []nbjwt.ClaimsExtractorOption
+	if len(s.jwtConfig.Audiences) > 0 {
+		opts = append(opts, nbjwt.WithAudience(s.jwtConfig.Audiences[0]))
+	}
+	if claim := s.authorizer.GetUserIDClaim(); claim != "" {
+		opts = append(opts, nbjwt.WithUserIDClaim(claim))
+	}
+	s.jwtExtractor = nbjwt.NewClaimsExtractor(opts...)
+
+	return nil
+}
+
+func (s *Server) checkTokenAge(token *gojwt.Token) error {
+	maxAge := defaultJWTMaxTokenAge
+	if s.jwtConfig != nil && s.jwtConfig.MaxTokenAge > 0 {
+		maxAge = int(s.jwtConfig.MaxTokenAge)
+	}
+	return nbjwt.CheckTokenAge(token, time.Duration(maxAge)*time.Second)
+}
+
+// readConnectionHeader reads the NetBird VNC session header from the connection.
+// Format: [mode: 1 byte] [username_len: 2 bytes BE] [username: N bytes]
+//
+//	[jwt_len: 2 bytes BE] [jwt: N bytes]
+//
+// Uses a short timeout: our WASM proxy sends the header immediately after
+// connecting. Standard VNC clients don't send anything first (server speaks
+// first in RFB), so they time out and get the default attach mode.
+func readConnectionHeader(conn net.Conn) (*connectionHeader, error) {
+	if err := conn.SetReadDeadline(time.Now().Add(2 * time.Second)); err != nil {
+		return nil, fmt.Errorf("set deadline: %w", err)
+	}
+	defer conn.SetReadDeadline(time.Time{}) //nolint:errcheck
+
+	var hdr [3]byte
+	if _, err := io.ReadFull(conn, hdr[:]); err != nil {
+		// Timeout or error: assume no header, use attach mode.
+		return &connectionHeader{mode: ModeAttach}, nil
+	}
+
+	// Restore a longer deadline for reading variable-length fields.
+	if err := conn.SetReadDeadline(time.Now().Add(5 * time.Second)); err != nil {
+		return nil, fmt.Errorf("set deadline: %w", err)
+	}
+
+	mode := hdr[0]
+	usernameLen := binary.BigEndian.Uint16(hdr[1:3])
+
+	var username string
+	if usernameLen > 0 {
+		if usernameLen > 256 {
+			return nil, fmt.Errorf("username too long: %d", usernameLen)
+		}
+		buf := make([]byte, usernameLen)
+		if _, err := io.ReadFull(conn, buf); err != nil {
+			return nil, fmt.Errorf("read username: %w", err)
+		}
+		username = string(buf)
+	}
+
+	// Read JWT token length and data.
+	var jwtLenBuf [2]byte
+	var jwtToken string
+	if _, err := io.ReadFull(conn, jwtLenBuf[:]); err == nil {
+		jwtLen := binary.BigEndian.Uint16(jwtLenBuf[:])
+		if jwtLen >= 8192 {
+			return nil, fmt.Errorf("jwt too long: %d (max 8191)", jwtLen)
+		}
+		if jwtLen > 0 {
+			buf := make([]byte, jwtLen)
+			if _, err := io.ReadFull(conn, buf); err != nil {
+				return nil, fmt.Errorf("read JWT: %w", err)
+			}
+			jwtToken = string(buf)
+		}
+	}
+
+	// Read optional Windows session ID (4 bytes BE). Missing = 0 (console/auto).
+	var sessionID uint32
+	var sidBuf [4]byte
+	if _, err := io.ReadFull(conn, sidBuf[:]); err == nil {
+		sessionID = binary.BigEndian.Uint32(sidBuf[:])
+	}
+
+	// Read optional requested viewport size (2x uint16 BE). Missing = 0 (default).
+	var width, height uint16
+	var geomBuf [4]byte
+	if _, err := io.ReadFull(conn, geomBuf[:]); err == nil {
+		width = binary.BigEndian.Uint16(geomBuf[0:2])
+		height = binary.BigEndian.Uint16(geomBuf[2:4])
+	}
+
+	return &connectionHeader{
+		mode:      mode,
+		username:  username,
+		jwt:       jwtToken,
+		sessionID: sessionID,
+		width:     width,
+		height:    height,
+	}, nil
+}
+
+// verifyAgentToken validates the agent token prefix when configured. Returns
+// false when the token is invalid or unreadable; the connection is closed.
+func (s *Server) verifyAgentToken(conn net.Conn, connLog *log.Entry) bool {
+	if len(s.agentToken) == 0 {
+		return true
+	}
+	buf := make([]byte, len(s.agentToken))
+	if err := conn.SetReadDeadline(time.Now().Add(5 * time.Second)); err != nil {
+		connLog.Debugf("set agent token deadline: %v", err)
+		conn.Close()
+		return false
+	}
+	if _, err := io.ReadFull(conn, buf); err != nil {
+		connLog.Warnf("agent auth: read token: %v", err)
+		conn.Close()
+		return false
+	}
+	if err := conn.SetReadDeadline(time.Time{}); err != nil {
+		connLog.Debugf("clear agent token deadline: %v", err)
+	}
+	if subtle.ConstantTimeCompare(buf, s.agentToken) != 1 {
+		connLog.Warn("agent auth: invalid token, rejecting")
+		conn.Close()
+		return false
+	}
+	return true
+}
+
+// authorizeJWT performs JWT validation when auth is enabled. Returns the
+// enriched log entry, jwt user ID (empty when auth disabled), and ok=false
+// if the connection was rejected.
+func (s *Server) authorizeJWT(conn net.Conn, header *connectionHeader, connLog *log.Entry) (*log.Entry, string, bool) {
+	if s.disableAuth {
+		return connLog, "", true
+	}
+	if s.jwtConfig == nil {
+		rejectConnection(conn, codeMessage(RejectCodeAuthConfig, "auth enabled but no identity provider configured"))
+		connLog.Warn("auth rejected: no identity provider configured")
+		return connLog, "", false
+	}
+	jwtUserID, err := s.authenticateJWT(header)
+	if err != nil {
+		rejectConnection(conn, codeMessage(jwtErrorCode(err), err.Error()))
+		connLog.Warnf("auth rejected: %v", err)
+		return connLog, "", false
+	}
+	return connLog.WithField("jwt_user", jwtUserID), jwtUserID, true
+}
+
+// acquireSessionResources returns the capturer/injector to use for this
+// connection and a cleanup func to call when the session ends. ok is false
+// when the connection was rejected (and the caller must just return).
+func (s *Server) acquireSessionResources(conn net.Conn, header *connectionHeader, connLog **log.Entry) (ScreenCapturer, InputInjector, func(), bool) {
+	switch header.mode {
+	case ModeSession:
+		return s.acquireVirtualSession(conn, header, connLog)
+	default:
+		return s.acquireAttachSession(), s.injector, attachSessionCleanup, true
+	}
+}
+
+func (s *Server) acquireVirtualSession(conn net.Conn, header *connectionHeader, connLog **log.Entry) (ScreenCapturer, InputInjector, func(), bool) {
+	if s.vmgr == nil {
+		rejectConnection(conn, codeMessage(RejectCodeUnsupportedOS, "virtual sessions not supported on this platform"))
+		(*connLog).Warn("session rejected: not supported on this platform")
+		return nil, nil, nil, false
+	}
+	if header.username == "" {
+		rejectConnection(conn, codeMessage(RejectCodeBadRequest, "session mode requires a username"))
+		(*connLog).Warn("session rejected: no username provided")
+		return nil, nil, nil, false
+	}
+	vs, err := s.vmgr.GetOrCreate(header.username, header.width, header.height)
+	if err != nil {
+		rejectConnection(conn, codeMessage(RejectCodeSessionError, fmt.Sprintf("create virtual session: %v", err)))
+		(*connLog).Warnf("create virtual session for %s: %v", header.username, err)
+		return nil, nil, nil, false
+	}
+	vs.ClientConnect()
+	*connLog = (*connLog).WithField("vnc_user", header.username)
+	(*connLog).Infof("session mode: user=%s display=%s", header.username, vs.Display())
+	return vs.Capturer(), vs.Injector(), vs.ClientDisconnect, true
+}
+
+func (s *Server) acquireAttachSession() ScreenCapturer {
+	if cc, ok := s.capturer.(interface{ ClientConnect() }); ok {
+		cc.ClientConnect()
+	}
+	return s.capturer
+}
+
+// attachSessionCleanup is the no-op cleanup used by attach mode. Returned as a
+// named func rather than an inline closure so the empty body is unambiguous.
+func attachSessionCleanup() {
+	// Attach mode keeps the shared capturer; nothing to release per session.
+}
+
+// modeString returns a human-readable session mode name.
+func modeString(m byte) string {
+	switch m {
+	case ModeAttach:
+		return "attach"
+	case ModeSession:
+		return "session"
+	default:
+		return "unknown"
+	}
+}

client/vnc/server/server_darwin.go

@@ -0,0 +1,21 @@
+//go:build darwin && !ios
+
+package server
+
+func (s *Server) platformInit() {
+	// no-op on macOS
+}
+
+// serviceAcceptLoop is not supported on macOS.
+func (s *Server) serviceAcceptLoop() {
+	s.log.Warn("service mode not supported on macOS, falling back to direct mode")
+	s.acceptLoop()
+}
+
+func (s *Server) platformSessionManager() virtualSessionManager {
+	return nil
+}
+
+func (s *Server) platformShutdown() {
+	// no-op on this platform
+}

client/vnc/server/server_stub.go

@@ -0,0 +1,21 @@
+//go:build (!windows && !darwin && !freebsd && !(linux && !android)) || (darwin && ios)
+
+package server
+
+func (s *Server) platformInit() {
+	// no-op on unsupported platforms
+}
+
+// serviceAcceptLoop is not supported on non-Windows platforms.
+func (s *Server) serviceAcceptLoop() {
+	s.log.Warn("service mode not supported on this platform, falling back to direct mode")
+	s.acceptLoop()
+}
+
+func (s *Server) platformSessionManager() virtualSessionManager {
+	return nil
+}
+
+func (s *Server) platformShutdown() {
+	// no-op on this platform
+}

client/vnc/server/server_test.go

@@ -0,0 +1,412 @@
+package server
+
+import (
+	"encoding/binary"
+	"encoding/hex"
+	"image"
+	"io"
+	"net"
+	"net/netip"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// testCapturer returns a 100x100 image for test sessions.
+type testCapturer struct{}
+
+func (t *testCapturer) Width() int  { return 100 }
+func (t *testCapturer) Height() int { return 100 }
+func (t *testCapturer) Capture() (*image.RGBA, error) {
+	return image.NewRGBA(image.Rect(0, 0, 100, 100)), nil
+}
+
+func startTestServer(t *testing.T, disableAuth bool, jwtConfig *JWTConfig) (net.Addr, *Server) {
+	t.Helper()
+
+	srv := New(&testCapturer{}, &StubInputInjector{}, "")
+	srv.SetDisableAuth(disableAuth)
+	if jwtConfig != nil {
+		srv.SetJWTConfig(jwtConfig)
+	}
+
+	addr := netip.MustParseAddrPort("127.0.0.1:0")
+	network := netip.MustParsePrefix("127.0.0.0/8")
+	require.NoError(t, srv.Start(t.Context(), addr, network))
+	// Override local address so source validation doesn't reject 127.0.0.1 as "own IP".
+	srv.localAddr = netip.MustParseAddr("10.99.99.1")
+	t.Cleanup(func() { _ = srv.Stop() })
+
+	return srv.listener.Addr(), srv
+}
+
+func TestAuthEnabled_NoJWTConfig_RejectsConnection(t *testing.T) {
+	addr, _ := startTestServer(t, false, nil)
+
+	conn, err := net.Dial("tcp", addr.String())
+	require.NoError(t, err)
+	defer conn.Close()
+
+	// Send session header: attach mode, no username, no JWT.
+	header := make([]byte, 13) // ModeAttach + usernameLen=0 + jwtLen=0 + sessionID=0 + width=0 + height=0
+	header[0] = ModeAttach
+	_, err = conn.Write(header)
+	require.NoError(t, err)
+
+	// Server should send RFB version then security failure.
+	var version [12]byte
+	_, err = io.ReadFull(conn, version[:])
+	require.NoError(t, err)
+	assert.Equal(t, "RFB 003.008\n", string(version[:]))
+
+	// Write client version to proceed through handshake.
+	_, err = conn.Write(version[:])
+	require.NoError(t, err)
+
+	// Read security types: 0 means failure, followed by reason.
+	var numTypes [1]byte
+	_, err = io.ReadFull(conn, numTypes[:])
+	require.NoError(t, err)
+	assert.Equal(t, byte(0), numTypes[0], "should have 0 security types (failure)")
+
+	var reasonLen [4]byte
+	_, err = io.ReadFull(conn, reasonLen[:])
+	require.NoError(t, err)
+
+	reason := make([]byte, binary.BigEndian.Uint32(reasonLen[:]))
+	_, err = io.ReadFull(conn, reason)
+	require.NoError(t, err)
+	assert.Contains(t, string(reason), "identity provider", "rejection reason should mention missing IdP config")
+}
+
+func TestAuthDisabled_AllowsConnection(t *testing.T) {
+	addr, _ := startTestServer(t, true, nil)
+
+	conn, err := net.Dial("tcp", addr.String())
+	require.NoError(t, err)
+	defer conn.Close()
+
+	// Send session header: attach mode, no username, no JWT.
+	header := make([]byte, 13) // ModeAttach + usernameLen=0 + jwtLen=0 + sessionID=0 + width=0 + height=0
+	header[0] = ModeAttach
+	_, err = conn.Write(header)
+	require.NoError(t, err)
+
+	// Server should send RFB version.
+	var version [12]byte
+	_, err = io.ReadFull(conn, version[:])
+	require.NoError(t, err)
+	assert.Equal(t, "RFB 003.008\n", string(version[:]))
+
+	// Write client version.
+	_, err = conn.Write(version[:])
+	require.NoError(t, err)
+
+	// Should get security types (not 0 = failure).
+	var numTypes [1]byte
+	_, err = io.ReadFull(conn, numTypes[:])
+	require.NoError(t, err)
+	assert.NotEqual(t, byte(0), numTypes[0], "should have at least one security type (auth disabled)")
+}
+
+// TestAuthEnabled_InvalidJWT_RejectedBeforeRFB confirms the VNC server itself
+// (not just the JWT library) wires authentication into handleConnection. A
+// well-formed JWT-shaped token must hit the server's validation path and be
+// rejected with an AUTH_JWT_* reason, never reaching the RFB handshake.
+func TestAuthEnabled_InvalidJWT_RejectedBeforeRFB(t *testing.T) {
+	addr, _ := startTestServer(t, false, &JWTConfig{
+		Issuer:       "https://example.invalid",
+		KeysLocation: "https://example.invalid/.well-known/jwks.json",
+		Audiences:    []string{"test"},
+	})
+
+	// Three-segment "JWT" with bogus base64. The server's authenticateJWT path
+	// must catch this regardless of the IdP being unreachable.
+	bogusJWT := "abc.def.ghi"
+	header := make([]byte, 3+2+len(bogusJWT)+4+4)
+	header[0] = ModeAttach
+	binary.BigEndian.PutUint16(header[1:3], 0) // username len
+	binary.BigEndian.PutUint16(header[3:5], uint16(len(bogusJWT)))
+	copy(header[5:5+len(bogusJWT)], bogusJWT)
+
+	conn, err := net.Dial("tcp", addr.String())
+	require.NoError(t, err)
+	defer conn.Close()
+	require.NoError(t, conn.SetDeadline(time.Now().Add(10*time.Second)))
+
+	_, err = conn.Write(header)
+	require.NoError(t, err)
+
+	var version [12]byte
+	_, err = io.ReadFull(conn, version[:])
+	require.NoError(t, err)
+	_, err = conn.Write(version[:])
+	require.NoError(t, err)
+
+	var numTypes [1]byte
+	_, err = io.ReadFull(conn, numTypes[:])
+	require.NoError(t, err)
+	require.Equal(t, byte(0), numTypes[0], "must fail security negotiation")
+
+	var reasonLen [4]byte
+	_, err = io.ReadFull(conn, reasonLen[:])
+	require.NoError(t, err)
+	reason := make([]byte, binary.BigEndian.Uint32(reasonLen[:]))
+	_, err = io.ReadFull(conn, reason)
+	require.NoError(t, err)
+	// The reason must carry one of the server's AUTH_JWT_* codes, proving
+	// the rejection came from authenticateJWT in handleConnection.
+	r := string(reason)
+	hasJWTReject := false
+	for _, code := range []string{RejectCodeJWTInvalid, RejectCodeJWTExpired, RejectCodeAuthForbidden} {
+		if strings.Contains(r, code) {
+			hasJWTReject = true
+			break
+		}
+	}
+	assert.True(t, hasJWTReject, "reason %q must include an AUTH_JWT_* code", r)
+}
+
+// TestAuth_NoUnauthBytesPastHeader proves the server does not send any RFB
+// content to a connection that fails source validation. Specifically, the
+// server must close immediately and the client must see EOF before any RFB
+// version greeting is written.
+func TestAuth_NoUnauthBytesPastHeader(t *testing.T) {
+	srv := New(&testCapturer{}, &StubInputInjector{}, "")
+	srv.SetDisableAuth(true)
+	addr := netip.MustParseAddrPort("127.0.0.1:0")
+	// Tight overlay that excludes 127.0.0.0/8 and a non-loopback local IP, so
+	// the loopback short-circuit in isAllowedSource doesn't apply.
+	require.NoError(t, srv.Start(t.Context(), addr, netip.MustParsePrefix("10.99.0.0/16")))
+	srv.localAddr = netip.MustParseAddr("10.99.99.1")
+	t.Cleanup(func() { _ = srv.Stop() })
+
+	conn, err := net.Dial("tcp", srv.listener.Addr().String())
+	require.NoError(t, err)
+	defer conn.Close()
+	require.NoError(t, conn.SetDeadline(time.Now().Add(5*time.Second)))
+
+	// Reading even one byte must EOF: the source IP (127.0.0.1) is outside
+	// the configured overlay, so handleConnection closes before writing.
+	var b [1]byte
+	_, err = io.ReadFull(conn, b[:])
+	require.Error(t, err, "non-overlay client must see EOF, not an RFB greeting")
+}
+
+func TestAuthEnabled_EmptyJWT_Rejected(t *testing.T) {
+	// Auth enabled with a (bogus) JWT config: connections without JWT should be rejected.
+	addr, _ := startTestServer(t, false, &JWTConfig{
+		Issuer:       "https://example.com",
+		KeysLocation: "https://example.com/.well-known/jwks.json",
+		Audiences:    []string{"test"},
+	})
+
+	conn, err := net.Dial("tcp", addr.String())
+	require.NoError(t, err)
+	defer conn.Close()
+
+	// Send session header with empty JWT.
+	header := make([]byte, 13) // ModeAttach + usernameLen=0 + jwtLen=0 + sessionID=0 + width=0 + height=0
+	header[0] = ModeAttach
+	_, err = conn.Write(header)
+	require.NoError(t, err)
+
+	var version [12]byte
+	_, err = io.ReadFull(conn, version[:])
+	require.NoError(t, err)
+
+	_, err = conn.Write(version[:])
+	require.NoError(t, err)
+
+	var numTypes [1]byte
+	_, err = io.ReadFull(conn, numTypes[:])
+	require.NoError(t, err)
+	assert.Equal(t, byte(0), numTypes[0], "should reject with 0 security types")
+}
+
+func TestIsAllowedSource(t *testing.T) {
+	tests := []struct {
+		name      string
+		localAddr netip.Addr
+		network   netip.Prefix
+		remote    net.Addr
+		want      bool
+	}{
+		{
+			name:      "non-tcp address rejected",
+			localAddr: netip.MustParseAddr("10.99.99.1"),
+			network:   netip.MustParsePrefix("10.99.0.0/16"),
+			remote:    &net.UDPAddr{IP: net.ParseIP("10.99.99.2"), Port: 1234},
+			want:      false,
+		},
+		{
+			name:      "own IP rejected",
+			localAddr: netip.MustParseAddr("10.99.99.1"),
+			network:   netip.MustParsePrefix("10.99.0.0/16"),
+			remote:    &net.TCPAddr{IP: net.ParseIP("10.99.99.1"), Port: 5900},
+			want:      false,
+		},
+		{
+			name:      "non-overlay IP rejected",
+			localAddr: netip.MustParseAddr("10.99.99.1"),
+			network:   netip.MustParsePrefix("10.99.0.0/16"),
+			remote:    &net.TCPAddr{IP: net.ParseIP("192.168.1.1"), Port: 5900},
+			want:      false,
+		},
+		{
+			name:      "overlay IP allowed",
+			localAddr: netip.MustParseAddr("10.99.99.1"),
+			network:   netip.MustParsePrefix("10.99.0.0/16"),
+			remote:    &net.TCPAddr{IP: net.ParseIP("10.99.99.2"), Port: 5900},
+			want:      true,
+		},
+		{
+			name:      "v4-mapped v6 in overlay allowed (unmapped)",
+			localAddr: netip.MustParseAddr("10.99.99.1"),
+			network:   netip.MustParsePrefix("10.99.0.0/16"),
+			remote:    &net.TCPAddr{IP: net.ParseIP("::ffff:10.99.99.2"), Port: 5900},
+			want:      true,
+		},
+		{
+			name:      "loopback allowed only when local is loopback",
+			localAddr: netip.MustParseAddr("127.0.0.1"),
+			network:   netip.MustParsePrefix("127.0.0.0/8"),
+			remote:    &net.TCPAddr{IP: net.ParseIP("127.0.0.5"), Port: 5900},
+			want:      true,
+		},
+		{
+			name:      "invalid network rejected (fail-closed)",
+			localAddr: netip.MustParseAddr("10.99.99.1"),
+			network:   netip.Prefix{},
+			remote:    &net.TCPAddr{IP: net.ParseIP("10.99.99.2"), Port: 5900},
+			want:      false,
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			srv := New(&testCapturer{}, &StubInputInjector{}, "")
+			srv.localAddr = tc.localAddr
+			srv.network = tc.network
+			assert.Equal(t, tc.want, srv.isAllowedSource(tc.remote))
+		})
+	}
+}
+
+func TestStart_InvalidNetworkRejected(t *testing.T) {
+	srv := New(&testCapturer{}, &StubInputInjector{}, "")
+	addr := netip.MustParseAddrPort("127.0.0.1:0")
+	err := srv.Start(t.Context(), addr, netip.Prefix{})
+	require.Error(t, err, "Start must refuse an invalid overlay prefix")
+	assert.Contains(t, err.Error(), "invalid overlay network prefix")
+}
+
+func TestAgentToken_MismatchClosesConnection(t *testing.T) {
+	srv := New(&testCapturer{}, &StubInputInjector{}, "")
+	srv.SetDisableAuth(true)
+	srv.SetAgentToken("deadbeefcafebabe")
+
+	addr := netip.MustParseAddrPort("127.0.0.1:0")
+	network := netip.MustParsePrefix("127.0.0.0/8")
+	require.NoError(t, srv.Start(t.Context(), addr, network))
+	srv.localAddr = netip.MustParseAddr("10.99.99.1")
+	t.Cleanup(func() { _ = srv.Stop() })
+
+	conn, err := net.Dial("tcp", srv.listener.Addr().String())
+	require.NoError(t, err)
+	defer conn.Close()
+	require.NoError(t, conn.SetDeadline(time.Now().Add(10*time.Second)))
+
+	// Send a wrong token of the right length (8 bytes hex-decoded).
+	if _, err := conn.Write([]byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}); err != nil {
+		// Server may already have closed; either way the read below must EOF.
+		_ = err
+	}
+
+	// Server must close without sending the RFB greeting.
+	var version [12]byte
+	_, err = io.ReadFull(conn, version[:])
+	require.Error(t, err, "server must close the connection on bad agent token")
+}
+
+func TestAgentToken_MatchAllowsHandshake(t *testing.T) {
+	srv := New(&testCapturer{}, &StubInputInjector{}, "")
+	srv.SetDisableAuth(true)
+	const tokenHex = "deadbeefcafebabe"
+	srv.SetAgentToken(tokenHex)
+	token, err := hex.DecodeString(tokenHex)
+	require.NoError(t, err)
+
+	addr := netip.MustParseAddrPort("127.0.0.1:0")
+	network := netip.MustParsePrefix("127.0.0.0/8")
+	require.NoError(t, srv.Start(t.Context(), addr, network))
+	srv.localAddr = netip.MustParseAddr("10.99.99.1")
+	t.Cleanup(func() { _ = srv.Stop() })
+
+	conn, err := net.Dial("tcp", srv.listener.Addr().String())
+	require.NoError(t, err)
+	defer conn.Close()
+	require.NoError(t, conn.SetDeadline(time.Now().Add(10*time.Second)))
+
+	_, err = conn.Write(token)
+	require.NoError(t, err)
+
+	// Send session header so handleConnection can proceed past readConnectionHeader.
+	header := make([]byte, 13) // ModeAttach + usernameLen=0 + jwtLen=0 + sessionID=0 + width=0 + height=0
+	header[0] = ModeAttach
+	_, err = conn.Write(header)
+	require.NoError(t, err)
+
+	// With a matching token the server proceeds to the RFB greeting.
+	var version [12]byte
+	_, err = io.ReadFull(conn, version[:])
+	require.NoError(t, err, "server must keep the connection open after a valid agent token")
+	assert.Equal(t, "RFB 003.008\n", string(version[:]))
+}
+
+func TestSessionMode_RejectedWhenNoVMGR(t *testing.T) {
+	// Default platformSessionManager() on non-Linux returns nil, so ModeSession
+	// must be rejected with the UNSUPPORTED reason rather than crashing.
+	srv := New(&testCapturer{}, &StubInputInjector{}, "")
+	srv.SetDisableAuth(true)
+
+	addr := netip.MustParseAddrPort("127.0.0.1:0")
+	network := netip.MustParsePrefix("127.0.0.0/8")
+	require.NoError(t, srv.Start(t.Context(), addr, network))
+	srv.localAddr = netip.MustParseAddr("10.99.99.1")
+	// Force vmgr to nil regardless of platform so the test is deterministic.
+	srv.vmgr = nil
+	t.Cleanup(func() { _ = srv.Stop() })
+
+	conn, err := net.Dial("tcp", srv.listener.Addr().String())
+	require.NoError(t, err)
+	defer conn.Close()
+	require.NoError(t, conn.SetDeadline(time.Now().Add(10*time.Second)))
+
+	// ModeSession with no username/JWT, so we exit on the vmgr==nil branch
+	// before username validation runs.
+	header := []byte{ModeSession, 0, 0, 0, 0}
+	_, err = conn.Write(header)
+	require.NoError(t, err)
+
+	var version [12]byte
+	_, err = io.ReadFull(conn, version[:])
+	require.NoError(t, err)
+	_, err = conn.Write(version[:])
+	require.NoError(t, err)
+
+	var numTypes [1]byte
+	_, err = io.ReadFull(conn, numTypes[:])
+	require.NoError(t, err)
+	assert.Equal(t, byte(0), numTypes[0])
+
+	var reasonLen [4]byte
+	_, err = io.ReadFull(conn, reasonLen[:])
+	require.NoError(t, err)
+	reason := make([]byte, binary.BigEndian.Uint32(reasonLen[:]))
+	_, err = io.ReadFull(conn, reason)
+	require.NoError(t, err)
+	assert.Contains(t, string(reason), RejectCodeUnsupportedOS)
+}

client/vnc/server/server_windows.go

@@ -0,0 +1,312 @@
+//go:build windows
+
+package server
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"unsafe"
+
+	log "github.com/sirupsen/logrus"
+	"golang.org/x/sys/windows"
+	"golang.org/x/sys/windows/registry"
+)
+
+var (
+	sasDLL      = windows.NewLazySystemDLL("sas.dll")
+	procSendSAS = sasDLL.NewProc("SendSAS")
+
+	procConvertStringSecurityDescriptorToSecurityDescriptor = advapi32.NewProc("ConvertStringSecurityDescriptorToSecurityDescriptorW")
+)
+
+// sasSecurityAttributes builds a SECURITY_ATTRIBUTES that grants
+// EVENT_MODIFY_STATE only to the SYSTEM account, preventing unprivileged
+// local processes from triggering the Secure Attention Sequence.
+func sasSecurityAttributes() (*windows.SecurityAttributes, error) {
+	// SDDL: grant full access to SYSTEM (creates/waits) and EVENT_MODIFY_STATE
+	// to the interactive user (IU) so the VNC agent in the console session can
+	// signal it. Other local users and network users are denied.
+	sddl, err := windows.UTF16PtrFromString("D:(A;;GA;;;SY)(A;;0x0002;;;IU)")
+	if err != nil {
+		return nil, err
+	}
+	var sd uintptr
+	r, _, lerr := procConvertStringSecurityDescriptorToSecurityDescriptor.Call(
+		uintptr(unsafe.Pointer(sddl)),
+		1, // SDDL_REVISION_1
+		uintptr(unsafe.Pointer(&sd)),
+		0,
+	)
+	if r == 0 {
+		return nil, lerr
+	}
+	return &windows.SecurityAttributes{
+		Length:             uint32(unsafe.Sizeof(windows.SecurityAttributes{})),
+		SecurityDescriptor: (*windows.SECURITY_DESCRIPTOR)(unsafe.Pointer(sd)),
+		InheritHandle:      0,
+	}, nil
+}
+
+// sasOriginalState tracks the SoftwareSASGeneration value present before we
+// changed it, so disableSoftwareSAS can restore the machine to its prior
+// state on shutdown instead of leaving the policy enabled.
+type sasOriginalState struct {
+	had   bool   // true if the value existed before we wrote
+	value uint32 // its prior DWORD value, if had == true
+}
+
+var savedSASState sasOriginalState
+
+// enableSoftwareSAS sets the SoftwareSASGeneration registry key to allow
+// services to trigger the Secure Attention Sequence via SendSAS. Without this,
+// SendSAS silently does nothing on most Windows editions. The original value
+// is snapshotted so disableSoftwareSAS can put the system back as it was.
+func enableSoftwareSAS() {
+	key, _, err := registry.CreateKey(
+		registry.LOCAL_MACHINE,
+		`SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System`,
+		registry.SET_VALUE|registry.QUERY_VALUE,
+	)
+	if err != nil {
+		log.Warnf("open SoftwareSASGeneration registry key: %v", err)
+		return
+	}
+	defer key.Close()
+
+	if prev, _, err := key.GetIntegerValue("SoftwareSASGeneration"); err == nil {
+		savedSASState = sasOriginalState{had: true, value: uint32(prev)}
+	} else {
+		savedSASState = sasOriginalState{had: false}
+	}
+
+	if err := key.SetDWordValue("SoftwareSASGeneration", 1); err != nil {
+		log.Warnf("set SoftwareSASGeneration: %v", err)
+		return
+	}
+	log.Debug("SoftwareSASGeneration registry key set to 1 (services allowed)")
+}
+
+// disableSoftwareSAS restores the SoftwareSASGeneration value to its
+// pre-enable state. Idempotent; safe to call when enableSoftwareSAS never ran.
+func disableSoftwareSAS() {
+	key, err := registry.OpenKey(
+		registry.LOCAL_MACHINE,
+		`SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System`,
+		registry.SET_VALUE,
+	)
+	if err != nil {
+		log.Debugf("open SoftwareSASGeneration for restore: %v", err)
+		return
+	}
+	defer key.Close()
+
+	if savedSASState.had {
+		if err := key.SetDWordValue("SoftwareSASGeneration", savedSASState.value); err != nil {
+			log.Warnf("restore SoftwareSASGeneration to %d: %v", savedSASState.value, err)
+		}
+		return
+	}
+	if err := key.DeleteValue("SoftwareSASGeneration"); err != nil {
+		log.Debugf("delete SoftwareSASGeneration: %v", err)
+	}
+}
+
+// startSASListener creates a named event with a restricted DACL and waits for
+// the VNC input injector to signal it. When signaled, it calls SendSAS(FALSE)
+// from Session 0 to trigger the Secure Attention Sequence (Ctrl+Alt+Del).
+// Only SYSTEM processes can open the event.
+//
+// sas.dll / SendSAS is part of the Desktop Experience feature: present on
+// client SKUs (Win10/11) and Server SKUs with Desktop Experience installed,
+// missing on Server Core. We probe for the symbol at startup; if absent we
+// don't register the listener and the agent will silently drop SAS keysyms,
+// rather than panicking the entire service every time the user clicks
+// Ctrl+Alt+Del.
+func startSASListener(ctx context.Context) {
+	ev, ok := createSASEvent()
+	if !ok {
+		return
+	}
+	log.Info("SAS listener ready (Session 0)")
+	go runSASListenerLoop(ctx, ev)
+}
+
+// createSASEvent prepares the named event handle on which the SAS listener
+// waits for client signals. Returns ok=false (with the failure already
+// logged) when the platform doesn't support SAS or the event cannot be
+// created; the caller must not spawn the listener goroutine in that case.
+func createSASEvent() (windows.Handle, bool) {
+	if err := procSendSAS.Find(); err != nil {
+		log.Warnf("SAS unavailable on this Windows SKU (sas.dll/SendSAS not present): %v", err)
+		return 0, false
+	}
+	enableSoftwareSAS()
+	namePtr, err := windows.UTF16PtrFromString(sasEventName)
+	if err != nil {
+		log.Warnf("SAS listener UTF16: %v", err)
+		return 0, false
+	}
+	sa, err := sasSecurityAttributes()
+	if err != nil {
+		log.Warnf("build SAS security descriptor: %v", err)
+		return 0, false
+	}
+	ev, err := windows.CreateEvent(sa, 0, 0, namePtr)
+	if err != nil {
+		log.Warnf("SAS CreateEvent: %v", err)
+		return 0, false
+	}
+	return ev, true
+}
+
+// runSASListenerLoop blocks on ev and invokes SendSAS each time it is
+// signalled, until ctx is cancelled. Recovers from panics inside SendSAS so
+// a future ABI surprise doesn't tear down the service.
+func runSASListenerLoop(ctx context.Context, ev windows.Handle) {
+	defer func() { _ = windows.CloseHandle(ev) }()
+	defer func() {
+		if r := recover(); r != nil {
+			log.Warnf("SAS listener recovered from panic: %v", r)
+		}
+	}()
+	const pollMillis = 500
+	for {
+		if ctx.Err() != nil {
+			return
+		}
+		ret, _ := windows.WaitForSingleObject(ev, pollMillis)
+		if ret != windows.WAIT_OBJECT_0 {
+			continue
+		}
+		r, _, sasErr := procSendSAS.Call(0) // FALSE = not from service desktop
+		if r == 0 {
+			log.Warnf("SendSAS: %v", sasErr)
+			continue
+		}
+		log.Info("SendSAS called from Session 0")
+	}
+}
+
+// enablePrivilege enables a named privilege on the current process token.
+func enablePrivilege(name string) error {
+	var token windows.Token
+	if err := windows.OpenProcessToken(windows.CurrentProcess(),
+		windows.TOKEN_ADJUST_PRIVILEGES|windows.TOKEN_QUERY, &token); err != nil {
+		return err
+	}
+	defer token.Close()
+
+	var luid windows.LUID
+	namePtr, err := windows.UTF16PtrFromString(name)
+	if err != nil {
+		return fmt.Errorf("UTF16 privilege name: %w", err)
+	}
+	if err := windows.LookupPrivilegeValue(nil, namePtr, &luid); err != nil {
+		return err
+	}
+	tp := windows.Tokenprivileges{PrivilegeCount: 1}
+	tp.Privileges[0].Luid = luid
+	tp.Privileges[0].Attributes = windows.SE_PRIVILEGE_ENABLED
+	return windows.AdjustTokenPrivileges(token, false, &tp, 0, nil, nil)
+}
+
+func (s *Server) platformSessionManager() virtualSessionManager {
+	return nil
+}
+
+// platformShutdown restores any machine state mutated by platformInit.
+func (s *Server) platformShutdown() {
+	disableSoftwareSAS()
+}
+
+// platformInit starts the SAS listener and enables privileges needed for
+// Session 0 operations (agent spawning, SendSAS).
+func (s *Server) platformInit() {
+	for _, priv := range []string{"SeTcbPrivilege", "SeAssignPrimaryTokenPrivilege"} {
+		if err := enablePrivilege(priv); err != nil {
+			log.Debugf("enable %s: %v", priv, err)
+		}
+	}
+	startSASListener(s.ctx)
+}
+
+// serviceAcceptLoop runs in Session 0. It validates source IP and
+// authenticates via JWT before proxying connections to the user-session agent.
+func (s *Server) serviceAcceptLoop() {
+
+	sm := newSessionManager(agentPort)
+	go sm.run()
+
+	log.Infof("service mode, proxying connections to agent on 127.0.0.1:%s", agentPort)
+
+	for {
+		conn, err := s.listener.Accept()
+		if err != nil {
+			select {
+			case <-s.ctx.Done():
+				sm.Stop()
+				return
+			default:
+			}
+			s.log.Debugf("accept VNC connection: %v", err)
+			continue
+		}
+
+		go s.handleServiceConnection(conn, sm)
+	}
+}
+
+// handleServiceConnection validates the source IP and JWT, then proxies
+// the connection (with header bytes replayed) to the agent.
+func (s *Server) handleServiceConnection(conn net.Conn, sm *sessionManager) {
+	connLog := s.log.WithField("remote", conn.RemoteAddr().String())
+
+	if !s.isAllowedSource(conn.RemoteAddr()) {
+		conn.Close()
+		return
+	}
+
+	var headerBuf bytes.Buffer
+	tee := io.TeeReader(conn, &headerBuf)
+	teeConn := &prefixConn{Reader: tee, Conn: conn}
+
+	header, err := readConnectionHeader(teeConn)
+	if err != nil {
+		connLog.Debugf("read connection header: %v", err)
+		conn.Close()
+		return
+	}
+
+	if !s.disableAuth {
+		if s.jwtConfig == nil {
+			rejectConnection(conn, codeMessage(RejectCodeAuthConfig, "auth enabled but no identity provider configured"))
+			connLog.Warn("auth rejected: no identity provider configured")
+			return
+		}
+		if _, err := s.authenticateJWT(header); err != nil {
+			rejectConnection(conn, codeMessage(jwtErrorCode(err), err.Error()))
+			connLog.Warnf("auth rejected: %v", err)
+			return
+		}
+	}
+
+	// Replay buffered header bytes + remaining stream to the agent.
+	replayConn := &prefixConn{
+		Reader: io.MultiReader(&headerBuf, conn),
+		Conn:   conn,
+	}
+	proxyToAgent(replayConn, agentPort, sm.AuthToken())
+}
+
+// prefixConn wraps a net.Conn, overriding Read to use a different reader.
+type prefixConn struct {
+	io.Reader
+	net.Conn
+}
+
+func (p *prefixConn) Read(b []byte) (int, error) {
+	return p.Reader.Read(b)
+}

client/vnc/server/server_x11.go

@@ -0,0 +1,21 @@
+//go:build (linux && !android) || freebsd
+
+package server
+
+func (s *Server) platformInit() {
+	// no-op on X11
+}
+
+// serviceAcceptLoop is not supported on Linux.
+func (s *Server) serviceAcceptLoop() {
+	s.log.Warn("service mode not supported on Linux, falling back to direct mode")
+	s.acceptLoop()
+}
+
+func (s *Server) platformSessionManager() virtualSessionManager {
+	return newSessionManager(s.log)
+}
+
+func (s *Server) platformShutdown() {
+	// no-op on this platform
+}

client/vnc/server/session.go

@@ -0,0 +1,693 @@
+package server
+
+import (
+	"bytes"
+	"crypto/rand"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"image"
+	"io"
+	"net"
+	"strings"
+	"sync"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	readDeadline    = 60 * time.Second
+	maxCutTextBytes = 1 << 20 // 1 MiB
+)
+
+const tileSize = 64 // pixels per tile for dirty-rect detection
+
+// fullFramePromoteNum/Den trigger full-frame encoding when the dirty area
+// exceeds num/den of the screen. Once past the crossover (benchmarks put it
+// around 60% at 1080p) a single zlib rect is faster than many per-tile
+// encodes AND produces about the same wire bytes: the per-tile path keeps
+// restarting zlib dictionaries and re-emitting rect headers.
+const (
+	fullFramePromoteNum = 60
+	fullFramePromoteDen = 100
+)
+
+type session struct {
+	conn     net.Conn
+	capturer ScreenCapturer
+	injector InputInjector
+	serverW  int
+	serverH  int
+	password string
+	log      *log.Entry
+
+	writeMu sync.Mutex
+	// encMu guards the negotiated pixel format and encoding state below.
+	// messageLoop writes these on SetPixelFormat/SetEncodings, which RFB
+	// clients may send at any time after the handshake, while encoderLoop
+	// reads them on every frame.
+	encMu      sync.RWMutex
+	pf         clientPixelFormat
+	useZlib    bool
+	useHextile bool
+	useTight   bool
+	zlib       *zlibState
+	tight      *tightState
+	// prevFrame, curFrame and idleFrames live on the encoder goroutine and
+	// must not be touched elsewhere. curFrame holds a session-owned copy of
+	// the capturer's latest frame so the encoder works on a stable buffer
+	// even when the capturer double-buffers and recycles memory underneath.
+	prevFrame  *image.RGBA
+	curFrame   *image.RGBA
+	idleFrames int
+
+	// encodeCh carries framebuffer-update requests from the read loop to the
+	// encoder goroutine. Buffered size 1: RFB clients have one outstanding
+	// request at a time, so a new request always replaces any pending one.
+	encodeCh chan fbRequest
+}
+
+type fbRequest struct {
+	incremental bool
+}
+
+func (s *session) addr() string { return s.conn.RemoteAddr().String() }
+
+// serve runs the full RFB session lifecycle.
+func (s *session) serve() {
+	defer s.conn.Close()
+	s.pf = defaultClientPixelFormat()
+	s.encodeCh = make(chan fbRequest, 1)
+
+	if err := s.handshake(); err != nil {
+		s.log.Warnf("handshake with %s: %v", s.addr(), err)
+		return
+	}
+	s.log.Infof("client connected: %s", s.addr())
+
+	done := make(chan struct{})
+	defer close(done)
+	go s.clipboardPoll(done)
+
+	encoderDone := make(chan struct{})
+	go s.encoderLoop(encoderDone)
+	defer func() {
+		close(s.encodeCh)
+		<-encoderDone
+	}()
+
+	if err := s.messageLoop(); err != nil && err != io.EOF {
+		s.log.Warnf("client %s disconnected: %v", s.addr(), err)
+	} else {
+		s.log.Infof("client disconnected: %s", s.addr())
+	}
+}
+
+// clipboardPoll periodically checks the server-side clipboard and sends
+// changes to the VNC client. Only runs during active sessions.
+func (s *session) clipboardPoll(done <-chan struct{}) {
+	ticker := time.NewTicker(2 * time.Second)
+	defer ticker.Stop()
+
+	var lastClip string
+	for {
+		select {
+		case <-done:
+			return
+		case <-ticker.C:
+			text := s.injector.GetClipboard()
+			if len(text) > maxCutTextBytes {
+				text = text[:maxCutTextBytes]
+			}
+			if text != "" && text != lastClip {
+				lastClip = text
+				if err := s.sendServerCutText(text); err != nil {
+					s.log.Debugf("send clipboard to client: %v", err)
+					return
+				}
+			}
+		}
+	}
+}
+
+func (s *session) handshake() error {
+	// Send protocol version.
+	if _, err := io.WriteString(s.conn, rfbProtocolVersion); err != nil {
+		return fmt.Errorf("send version: %w", err)
+	}
+
+	// Read client version.
+	var clientVer [12]byte
+	if _, err := io.ReadFull(s.conn, clientVer[:]); err != nil {
+		return fmt.Errorf("read client version: %w", err)
+	}
+
+	// Send supported security types.
+	if err := s.sendSecurityTypes(); err != nil {
+		return err
+	}
+
+	// Read chosen security type.
+	var secType [1]byte
+	if _, err := io.ReadFull(s.conn, secType[:]); err != nil {
+		return fmt.Errorf("read security type: %w", err)
+	}
+
+	if err := s.handleSecurity(secType[0]); err != nil {
+		return err
+	}
+
+	// Read ClientInit.
+	var clientInit [1]byte
+	if _, err := io.ReadFull(s.conn, clientInit[:]); err != nil {
+		return fmt.Errorf("read ClientInit: %w", err)
+	}
+
+	return s.sendServerInit()
+}
+
+func (s *session) sendSecurityTypes() error {
+	if s.password == "" {
+		_, err := s.conn.Write([]byte{1, secNone})
+		return err
+	}
+	_, err := s.conn.Write([]byte{1, secVNCAuth})
+	return err
+}
+
+func (s *session) handleSecurity(secType byte) error {
+	switch secType {
+	case secVNCAuth:
+		return s.doVNCAuth()
+	case secNone:
+		return binary.Write(s.conn, binary.BigEndian, uint32(0))
+	default:
+		return fmt.Errorf("unsupported security type: %d", secType)
+	}
+}
+
+func (s *session) doVNCAuth() error {
+	challenge := make([]byte, 16)
+	if _, err := rand.Read(challenge); err != nil {
+		return fmt.Errorf("generate challenge: %w", err)
+	}
+	if _, err := s.conn.Write(challenge); err != nil {
+		return fmt.Errorf("send challenge: %w", err)
+	}
+
+	response := make([]byte, 16)
+	if _, err := io.ReadFull(s.conn, response); err != nil {
+		return fmt.Errorf("read auth response: %w", err)
+	}
+
+	var result uint32
+	if s.password != "" {
+		expected, err := vncAuthEncrypt(challenge, s.password)
+		if err != nil {
+			return fmt.Errorf("vnc auth encrypt: %w", err)
+		}
+		if !bytes.Equal(expected, response) {
+			result = 1
+		}
+	}
+
+	if err := binary.Write(s.conn, binary.BigEndian, result); err != nil {
+		return fmt.Errorf("send auth result: %w", err)
+	}
+	if result != 0 {
+		msg := "authentication failed"
+		_ = binary.Write(s.conn, binary.BigEndian, uint32(len(msg)))
+		_, _ = s.conn.Write([]byte(msg))
+		return fmt.Errorf("authentication failed from %s", s.addr())
+	}
+	return nil
+}
+
+func (s *session) sendServerInit() error {
+	name := []byte("NetBird VNC")
+	buf := make([]byte, 0, 4+16+4+len(name))
+
+	// Framebuffer width and height.
+	buf = append(buf, byte(s.serverW>>8), byte(s.serverW))
+	buf = append(buf, byte(s.serverH>>8), byte(s.serverH))
+
+	// Server pixel format.
+	buf = append(buf, serverPixelFormat[:]...)
+
+	// Desktop name.
+	buf = append(buf,
+		byte(len(name)>>24), byte(len(name)>>16),
+		byte(len(name)>>8), byte(len(name)),
+	)
+	buf = append(buf, name...)
+
+	_, err := s.conn.Write(buf)
+	return err
+}
+
+func (s *session) messageLoop() error {
+	for {
+		var msgType [1]byte
+		if err := s.conn.SetDeadline(time.Now().Add(readDeadline)); err != nil {
+			return fmt.Errorf("set deadline: %w", err)
+		}
+		if _, err := io.ReadFull(s.conn, msgType[:]); err != nil {
+			return err
+		}
+
+		var err error
+		switch msgType[0] {
+		case clientSetPixelFormat:
+			err = s.handleSetPixelFormat()
+		case clientSetEncodings:
+			err = s.handleSetEncodings()
+		case clientFramebufferUpdateRequest:
+			err = s.handleFBUpdateRequest()
+		case clientKeyEvent:
+			err = s.handleKeyEvent()
+		case clientPointerEvent:
+			err = s.handlePointerEvent()
+		case clientCutText:
+			err = s.handleCutText()
+		case clientNetbirdTypeText:
+			err = s.handleTypeText()
+		default:
+			return fmt.Errorf("unknown client message type: %d", msgType[0])
+		}
+		// Clear the deadline only after the full message has been read and
+		// processed so payload reads in the handlers stay bounded.
+		_ = s.conn.SetDeadline(time.Time{})
+		if err != nil {
+			return err
+		}
+	}
+}
+
+func (s *session) handleSetPixelFormat() error {
+	var buf [19]byte // 3 padding + 16 pixel format
+	if _, err := io.ReadFull(s.conn, buf[:]); err != nil {
+		return fmt.Errorf("read SetPixelFormat: %w", err)
+	}
+	pf := parsePixelFormat(buf[3:19])
+	s.encMu.Lock()
+	s.pf = pf
+	s.encMu.Unlock()
+	return nil
+}
+
+func (s *session) handleSetEncodings() error {
+	var header [3]byte // 1 padding + 2 number-of-encodings
+	if _, err := io.ReadFull(s.conn, header[:]); err != nil {
+		return fmt.Errorf("read SetEncodings header: %w", err)
+	}
+	numEnc := binary.BigEndian.Uint16(header[1:3])
+	// RFB clients advertise a handful of real encodings plus pseudo-encodings.
+	// Cap to keep a malicious client from forcing a 256 KiB allocation per
+	// SetEncodings message.
+	const maxEncodings = 64
+	if numEnc > maxEncodings {
+		return fmt.Errorf("SetEncodings: too many encodings (%d)", numEnc)
+	}
+	buf := make([]byte, int(numEnc)*4)
+	if _, err := io.ReadFull(s.conn, buf); err != nil {
+		return err
+	}
+
+	var encs []string
+	s.encMu.Lock()
+	for i := range int(numEnc) {
+		enc := int32(binary.BigEndian.Uint32(buf[i*4 : i*4+4]))
+		switch enc {
+		case encZlib:
+			s.useZlib = true
+			if s.zlib == nil {
+				s.zlib = newZlibState()
+			}
+			encs = append(encs, "zlib")
+		case encHextile:
+			s.useHextile = true
+			encs = append(encs, "hextile")
+		case encTight:
+			s.useTight = true
+			if s.tight == nil {
+				s.tight = newTightState()
+			}
+			encs = append(encs, "tight")
+		}
+	}
+	s.encMu.Unlock()
+	if len(encs) > 0 {
+		s.log.Debugf("client supports encodings: %s", strings.Join(encs, ", "))
+	}
+	return nil
+}
+
+// handleFBUpdateRequest parses the request and hands it to the encoder
+// goroutine. It never blocks on capture/encode, so the input dispatch loop
+// stays responsive even when a previous frame is still being encoded.
+func (s *session) handleFBUpdateRequest() error {
+	var req [9]byte
+	if _, err := io.ReadFull(s.conn, req[:]); err != nil {
+		return fmt.Errorf("read FBUpdateRequest: %w", err)
+	}
+	r := fbRequest{incremental: req[0] == 1}
+	// Channel is size 1. If a request is already pending, replace it with
+	// this fresher one so the encoder always works on the latest ask.
+	select {
+	case s.encodeCh <- r:
+	default:
+		select {
+		case <-s.encodeCh:
+		default:
+		}
+		select {
+		case s.encodeCh <- r:
+		default:
+		}
+	}
+	return nil
+}
+
+// encoderLoop owns the capture → diff → encode → write pipeline. Running it
+// off the read loop prevents a slow encode (zlib full-frame, many dirty
+// tiles) from blocking inbound input events.
+func (s *session) encoderLoop(done chan<- struct{}) {
+	defer close(done)
+	for req := range s.encodeCh {
+		if err := s.processFBRequest(req); err != nil {
+			s.log.Debugf("encode: %v", err)
+			// On write/capture error, close the connection so messageLoop
+			// exits and the session terminates cleanly.
+			s.conn.Close()
+			drainRequests(s.encodeCh)
+			return
+		}
+	}
+}
+
+func (s *session) processFBRequest(req fbRequest) error {
+	img, err := s.captureFrame()
+	if errors.Is(err, errFrameUnchanged) {
+		// macOS hashes the raw capture bytes and short-circuits when the
+		// screen is byte-identical. Treat as "no dirty rects" to skip the
+		// diff and send an empty update.
+		s.idleFrames++
+		delay := min(s.idleFrames*5, 100)
+		time.Sleep(time.Duration(delay) * time.Millisecond)
+		return s.sendEmptyUpdate()
+	}
+	if err != nil {
+		// Capture failures are transient on Windows: a Ctrl+Alt+Del or
+		// sign-out switches the OS to the secure desktop, and the DXGI
+		// duplicator on the previous desktop returns an error until the
+		// capturer reattaches on the new desktop. Don't tear down the
+		// session. Back off briefly and reply with an empty update so
+		// the client keeps re-requesting.
+		s.log.Debugf("capture (transient): %v", err)
+		time.Sleep(100 * time.Millisecond)
+		return s.sendEmptyUpdate()
+	}
+
+	if req.incremental && s.prevFrame != nil {
+		rects := diffRects(s.prevFrame, img, s.serverW, s.serverH, tileSize)
+		if len(rects) == 0 {
+			// Nothing changed. Back off briefly before responding to reduce
+			// CPU usage when the screen is static. The client re-requests
+			// immediately after receiving our empty response, so without
+			// this delay we'd spin at ~1000fps checking for changes.
+			s.idleFrames++
+			delay := min(s.idleFrames*5, 100) // 5ms → 100ms adaptive backoff
+			time.Sleep(time.Duration(delay) * time.Millisecond)
+			s.swapPrevCur()
+			return s.sendEmptyUpdate()
+		}
+		s.idleFrames = 0
+		if s.shouldPromoteToFullFrame(rects) {
+			if err := s.sendFullUpdate(img); err != nil {
+				return err
+			}
+			s.swapPrevCur()
+			return nil
+		}
+		if err := s.sendDirtyRects(img, rects); err != nil {
+			return err
+		}
+		s.swapPrevCur()
+		return nil
+	}
+
+	// Full update.
+	s.idleFrames = 0
+	if err := s.sendFullUpdate(img); err != nil {
+		return err
+	}
+	s.swapPrevCur()
+	return nil
+}
+
+// captureFrame returns a session-owned frame for this encode cycle.
+// Capturers that implement captureIntoer (Linux X11, macOS) write directly
+// into curFrame, saving a per-frame full-screen memcpy. Capturers that
+// don't (Windows DXGI) return their own buffer which we copy into curFrame
+// to keep the encoder's prevFrame stable across the next capture cycle.
+func (s *session) captureFrame() (*image.RGBA, error) {
+	w, h := s.serverW, s.serverH
+	if s.curFrame == nil || s.curFrame.Rect.Dx() != w || s.curFrame.Rect.Dy() != h {
+		s.curFrame = image.NewRGBA(image.Rect(0, 0, w, h))
+	}
+
+	if ci, ok := s.capturer.(captureIntoer); ok {
+		if err := ci.CaptureInto(s.curFrame); err != nil {
+			return nil, err
+		}
+		return s.curFrame, nil
+	}
+
+	src, err := s.capturer.Capture()
+	if err != nil {
+		return nil, err
+	}
+	if s.curFrame.Rect != src.Rect {
+		s.curFrame = image.NewRGBA(src.Rect)
+	}
+	copy(s.curFrame.Pix, src.Pix)
+	return s.curFrame, nil
+}
+
+// shouldPromoteToFullFrame returns true when the dirty rect set covers a
+// large enough fraction of the screen that a single full-frame zlib rect
+// beats per-tile encoding on both CPU time and wire bytes. The crossover
+// is measured via BenchmarkEncodeManyTilesVsFullFrame.
+func (s *session) shouldPromoteToFullFrame(rects [][4]int) bool {
+	if s.serverW == 0 || s.serverH == 0 {
+		return false
+	}
+	var dirty int
+	for _, r := range rects {
+		dirty += r[2] * r[3]
+	}
+	return dirty*fullFramePromoteDen > s.serverW*s.serverH*fullFramePromoteNum
+}
+
+// swapPrevCur makes the just-encoded frame the new prevFrame (for the next
+// diff) and lets the old prevFrame buffer become the next curFrame. Avoids
+// an 8 MB copy per frame compared to the old savePrevFrame path.
+func (s *session) swapPrevCur() {
+	s.prevFrame, s.curFrame = s.curFrame, s.prevFrame
+}
+
+// sendEmptyUpdate sends a FramebufferUpdate with zero rectangles.
+func (s *session) sendEmptyUpdate() error {
+	var buf [4]byte
+	buf[0] = serverFramebufferUpdate
+	s.writeMu.Lock()
+	_, err := s.conn.Write(buf[:])
+	s.writeMu.Unlock()
+	return err
+}
+
+func (s *session) sendFullUpdate(img *image.RGBA) error {
+	w, h := s.serverW, s.serverH
+
+	s.encMu.RLock()
+	pf := s.pf
+	useZlib := s.useZlib
+	zlib := s.zlib
+	s.encMu.RUnlock()
+
+	var buf []byte
+	if useZlib && zlib != nil {
+		buf = encodeZlibRect(img, pf, 0, 0, w, h, zlib)
+	} else {
+		buf = encodeRawRect(img, pf, 0, 0, w, h)
+	}
+
+	s.writeMu.Lock()
+	_, err := s.conn.Write(buf)
+	s.writeMu.Unlock()
+	return err
+}
+
+func (s *session) sendDirtyRects(img *image.RGBA, rects [][4]int) error {
+	// Build a multi-rectangle FramebufferUpdate.
+	// Header: type(1) + padding(1) + numRects(2)
+	header := make([]byte, 4)
+	header[0] = serverFramebufferUpdate
+	binary.BigEndian.PutUint16(header[2:4], uint16(len(rects)))
+
+	s.writeMu.Lock()
+	defer s.writeMu.Unlock()
+
+	if _, err := s.conn.Write(header); err != nil {
+		return err
+	}
+
+	for _, r := range rects {
+		x, y, w, h := r[0], r[1], r[2], r[3]
+		rectBuf := s.encodeTile(img, x, y, w, h)
+		if _, err := s.conn.Write(rectBuf); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// encodeTile produces the on-wire rect bytes for a single dirty tile,
+// picking the cheapest encoding available:
+//   - Hextile SolidFill when the tile is a single colour (~20 bytes for a
+//     64×64 tile instead of ~1-2 KB zlib, ~16 KB raw).
+//   - Zlib when the client negotiated it.
+//   - Raw otherwise.
+//
+// Output omits the 4-byte FramebufferUpdate header; callers combine multiple
+// tiles into one message.
+func (s *session) encodeTile(img *image.RGBA, x, y, w, h int) []byte {
+	s.encMu.RLock()
+	pf := s.pf
+	useHextile := s.useHextile
+	useTight := s.useTight
+	tight := s.tight
+	useZlib := s.useZlib
+	zlib := s.zlib
+	s.encMu.RUnlock()
+
+	if useHextile {
+		if pixel, uniform := tileIsUniform(img, x, y, w, h); uniform {
+			r := byte(pixel)
+			g := byte(pixel >> 8)
+			b := byte(pixel >> 16)
+			return encodeHextileSolidRect(r, g, b, pf, rect{x, y, w, h})
+		}
+		// Full Hextile encoder disabled pending investigation of 16x16
+		// red-tile artifacts on Windows. Solid-fill fast path is safe.
+	}
+	// Larger merged rects: prefer Tight (JPEG for photo-like, Basic+zlib
+	// otherwise) when the client supports it AND the negotiated format is
+	// compatible with Tight's mandatory 24-bit RGB TPIXEL encoding. Tight is
+	// dramatically better than RFB Zlib on photographic content and
+	// competitive on UI.
+	if useTight && tight != nil && pfIsTightCompatible(pf) {
+		return encodeTightRect(img, pf, x, y, w, h, tight)
+	}
+	if useZlib && zlib != nil {
+		return encodeZlibRect(img, pf, x, y, w, h, zlib)[4:]
+	}
+	return encodeRawRect(img, pf, x, y, w, h)[4:]
+}
+
+func (s *session) handleKeyEvent() error {
+	var data [7]byte
+	if _, err := io.ReadFull(s.conn, data[:]); err != nil {
+		return fmt.Errorf("read KeyEvent: %w", err)
+	}
+	down := data[0] == 1
+	keysym := binary.BigEndian.Uint32(data[3:7])
+	s.injector.InjectKey(keysym, down)
+	return nil
+}
+
+func (s *session) handlePointerEvent() error {
+	var data [5]byte
+	if _, err := io.ReadFull(s.conn, data[:]); err != nil {
+		return fmt.Errorf("read PointerEvent: %w", err)
+	}
+	buttonMask := data[0]
+	x := int(binary.BigEndian.Uint16(data[1:3]))
+	y := int(binary.BigEndian.Uint16(data[3:5]))
+	s.injector.InjectPointer(buttonMask, x, y, s.serverW, s.serverH)
+	return nil
+}
+
+func (s *session) handleCutText() error {
+	var header [7]byte // 3 padding + 4 length
+	if _, err := io.ReadFull(s.conn, header[:]); err != nil {
+		return fmt.Errorf("read CutText header: %w", err)
+	}
+	length := binary.BigEndian.Uint32(header[3:7])
+	if length > maxCutTextBytes {
+		return fmt.Errorf("cut text too large: %d bytes", length)
+	}
+	buf := make([]byte, length)
+	if _, err := io.ReadFull(s.conn, buf); err != nil {
+		return fmt.Errorf("read CutText payload: %w", err)
+	}
+	s.injector.SetClipboard(string(buf))
+	return nil
+}
+
+// handleTypeText handles the NetBird-specific PasteAndType message used by
+// the dashboard's Paste button. Wire format mirrors CutText: 3-byte
+// padding + 4-byte length + text bytes.
+func (s *session) handleTypeText() error {
+	var header [7]byte
+	if _, err := io.ReadFull(s.conn, header[:]); err != nil {
+		return fmt.Errorf("read TypeText header: %w", err)
+	}
+	length := binary.BigEndian.Uint32(header[3:7])
+	if length > maxCutTextBytes {
+		return fmt.Errorf("type text too large: %d bytes", length)
+	}
+	buf := make([]byte, length)
+	if _, err := io.ReadFull(s.conn, buf); err != nil {
+		return fmt.Errorf("read TypeText payload: %w", err)
+	}
+	s.injector.TypeText(string(buf))
+	return nil
+}
+
+// sendServerCutText sends clipboard text from the server to the client.
+func (s *session) sendServerCutText(text string) error {
+	data := []byte(text)
+	buf := make([]byte, 8+len(data))
+	buf[0] = serverCutText
+	// buf[1:4] = padding (zero)
+	binary.BigEndian.PutUint32(buf[4:8], uint32(len(data)))
+	copy(buf[8:], data)
+
+	s.writeMu.Lock()
+	_, err := s.conn.Write(buf)
+	s.writeMu.Unlock()
+	return err
+}
+
+// drainRequests consumes any pending requests so the sender's close completes
+// cleanly after the encoder loop has decided to exit on error. Returns the
+// number of drained requests to defeat empty-block lints; callers ignore it.
+func drainRequests(ch chan fbRequest) int {
+	var drained int
+	for range ch {
+		drained++
+	}
+	return drained
+}
+
+// pfIsTightCompatible reports whether the negotiated client pixel format
+// matches Tight's TPIXEL constraint: 32 bpp true colour with 8-bit RGB
+// channels at standard shifts (R=16, G=8, B=0). For anything else we fall
+// back to Zlib/Hextile/Raw which respect pf in full.
+func pfIsTightCompatible(pf clientPixelFormat) bool {
+	return pf.bpp == 32 &&
+		pf.rMax == 255 && pf.gMax == 255 && pf.bMax == 255 &&
+		pf.rShift == 16 && pf.gShift == 8 && pf.bShift == 0
+}

client/vnc/server/shutdown_state.go

@@ -0,0 +1,80 @@
+//go:build unix
+
+package server
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"syscall"
+
+	log "github.com/sirupsen/logrus"
+)
+
+// ShutdownState tracks VNC virtual session processes for crash recovery.
+// Persisted by the state manager; on restart, residual processes are killed.
+type ShutdownState struct {
+	// Processes maps a description to its PID (e.g., "xvfb:50" -> 1234).
+	Processes map[string]int `json:"processes,omitempty"`
+}
+
+// Name returns the state name for the state manager.
+func (s *ShutdownState) Name() string {
+	return "vnc_sessions_state"
+}
+
+// Cleanup kills any residual VNC session processes left from a crash.
+func (s *ShutdownState) Cleanup() error {
+	if len(s.Processes) == 0 {
+		return nil
+	}
+
+	for desc, pid := range s.Processes {
+		if pid <= 0 {
+			continue
+		}
+		if !isOurProcess(pid, desc) {
+			log.Debugf("cleanup:skipping PID %d (%s), not ours", pid, desc)
+			continue
+		}
+		log.Infof("cleanup:killing residual process %d (%s)", pid, desc)
+		// Kill the process group (negative PID) to get children too.
+		if err := syscall.Kill(-pid, syscall.SIGTERM); err != nil {
+			// Try individual process if group kill fails.
+			if killErr := syscall.Kill(pid, syscall.SIGKILL); killErr != nil {
+				log.Debugf("cleanup: kill pid %d (%s): group kill: %v, single kill: %v", pid, desc, err, killErr)
+			}
+		}
+	}
+
+	s.Processes = nil
+	return nil
+}
+
+// isOurProcess verifies the PID still belongs to a VNC-related process
+// by checking /proc/<pid>/cmdline (Linux) or the process name.
+func isOurProcess(pid int, desc string) bool {
+	// Check if the process exists at all.
+	if err := syscall.Kill(pid, 0); err != nil {
+		return false
+	}
+
+	// On Linux, verify via /proc cmdline.
+	cmdline, err := os.ReadFile(fmt.Sprintf("/proc/%d/cmdline", pid))
+	if err != nil {
+		log.Debugf("cleanup: cannot read /proc/%d/cmdline: %v, treating PID as foreign", pid, err)
+		return false
+	}
+
+	cmd := string(cmdline)
+	// Match against expected process types.
+	if strings.Contains(desc, "xvfb") || strings.Contains(desc, "xorg") {
+		return strings.Contains(cmd, "Xvfb") || strings.Contains(cmd, "Xorg")
+	}
+	if strings.Contains(desc, "desktop") {
+		return strings.Contains(cmd, "session") || strings.Contains(cmd, "plasma") ||
+			strings.Contains(cmd, "gnome") || strings.Contains(cmd, "xfce") ||
+			strings.Contains(cmd, "dbus-launch")
+	}
+	return false
+}

client/vnc/server/stubs.go

@@ -0,0 +1,46 @@
+package server
+
+import (
+	"fmt"
+	"image"
+)
+
+// StubCapturer is a placeholder for platforms without screen capture support.
+type StubCapturer struct{}
+
+// Width returns 0 on unsupported platforms.
+func (c *StubCapturer) Width() int { return 0 }
+
+// Height returns 0 on unsupported platforms.
+func (c *StubCapturer) Height() int { return 0 }
+
+// Capture returns an error on unsupported platforms.
+func (c *StubCapturer) Capture() (*image.RGBA, error) {
+	return nil, fmt.Errorf("screen capture not supported on this platform")
+}
+
+// StubInputInjector is a placeholder for platforms without input injection support.
+type StubInputInjector struct{}
+
+// InjectKey is a no-op on unsupported platforms.
+func (s *StubInputInjector) InjectKey(_ uint32, _ bool) {
+	// no-op
+}
+
+// InjectPointer is a no-op on unsupported platforms.
+func (s *StubInputInjector) InjectPointer(_ uint8, _, _, _, _ int) {
+	// no-op
+}
+
+// SetClipboard is a no-op on unsupported platforms.
+func (s *StubInputInjector) SetClipboard(_ string) {
+	// no-op
+}
+
+// GetClipboard returns empty on unsupported platforms.
+func (s *StubInputInjector) GetClipboard() string { return "" }
+
+// TypeText is a no-op on unsupported platforms.
+func (s *StubInputInjector) TypeText(_ string) {
+	// no-op
+}

client/vnc/server/swizzle.go

@@ -0,0 +1,29 @@
+package server
+
+import "unsafe"
+
+// swizzleBGRAtoRGBA swaps B and R channels in a BGRA pixel buffer and copies
+// into dst in-place (dst and src may alias). Operates on uint32 words: one
+// read-modify-write per pixel, which is meaningfully faster than the naive
+// three-byte-store per pixel for large buffers like framebuffers.
+//
+// The alpha byte is forced to 0xff so callers that capture from X11 GetImage
+// (where the X server leaves the pad byte as zero) still get an opaque image.
+func swizzleBGRAtoRGBA(dst, src []byte) {
+	n := len(dst) / 4
+	if len(src)/4 < n {
+		n = len(src) / 4
+	}
+	if n == 0 {
+		return
+	}
+	dp := unsafe.Slice((*uint32)(unsafe.Pointer(&dst[0])), n)
+	sp := unsafe.Slice((*uint32)(unsafe.Pointer(&src[0])), n)
+	for i := range n {
+		p := sp[i]
+		// p in memory: B, G, R, A -> as uint32 little-endian: 0xAARRGGBB
+		// Want memory: R, G, B, 0xFF -> uint32 little-endian: 0xFFBBGGRR
+		dp[i] = 0xFF000000 | (p & 0x0000FF00) | ((p & 0x00FF0000) >> 16) | ((p & 0x000000FF) << 16)
+	}
+}
+

client/vnc/server/tight_test.go

@@ -0,0 +1,84 @@
+package server
+
+import (
+	"bytes"
+	"image/jpeg"
+	"testing"
+)
+
+func decodeTightLength(buf []byte) (n, consumed int) {
+	b0 := buf[0]
+	n = int(b0 & 0x7f)
+	if b0&0x80 == 0 {
+		return n, 1
+	}
+	b1 := buf[1]
+	n |= int(b1&0x7f) << 7
+	if b1&0x80 == 0 {
+		return n, 2
+	}
+	b2 := buf[2]
+	n |= int(b2) << 14
+	return n, 3
+}
+
+func TestEncodeTightFill(t *testing.T) {
+	pf := defaultClientPixelFormat()
+	img := makeUniformImage(64, 64, 0x12, 0x34, 0x56)
+	tstate := newTightState()
+	buf := encodeTightRect(img, pf, 0, 0, 64, 64, tstate)
+	if len(buf) != 12+1+3 {
+		t.Fatalf("fill rect should be 16 bytes, got %d", len(buf))
+	}
+	if buf[12] != tightFillSubenc {
+		t.Fatalf("expected fill subenc, got 0x%02x", buf[12])
+	}
+	if buf[13] != 0x12 || buf[14] != 0x34 || buf[15] != 0x56 {
+		t.Fatalf("wrong fill colour: %v", buf[13:16])
+	}
+}
+
+func TestEncodeTightBasic(t *testing.T) {
+	pf := defaultClientPixelFormat()
+	img := makeTwoColorImage(64, 64)
+	tstate := newTightState()
+	buf := encodeTightRect(img, pf, 0, 0, 64, 64, tstate)
+	if buf[12]&0xf0 != tightBasicFilter {
+		t.Fatalf("expected basic+filter subenc, got 0x%02x", buf[12])
+	}
+	if buf[13] != tightFilterCopy {
+		t.Fatalf("expected copy filter, got 0x%02x", buf[13])
+	}
+	// Length prefix and zlib stream follow.
+	n, _ := decodeTightLength(buf[14:])
+	if n == 0 {
+		t.Fatalf("zero-length basic stream")
+	}
+}
+
+func TestEncodeTightJPEG(t *testing.T) {
+	pf := defaultClientPixelFormat()
+	img := makeBenchImage(128, 128, 7) // random → many colours
+	tstate := newTightState()
+	buf := encodeTightRect(img, pf, 0, 0, 128, 128, tstate)
+	if buf[12] != tightJPEGSubenc {
+		t.Fatalf("expected JPEG subenc, got 0x%02x", buf[12])
+	}
+	n, consumed := decodeTightLength(buf[13:])
+	jpegBytes := buf[13+consumed : 13+consumed+n]
+	if _, err := jpeg.Decode(bytes.NewReader(jpegBytes)); err != nil {
+		t.Fatalf("emitted JPEG bytes do not decode: %v", err)
+	}
+}
+
+func TestSampledColorCount(t *testing.T) {
+	uniform := makeUniformImage(64, 64, 0x10, 0x20, 0x30)
+	if c := sampledColorCountInto(map[uint32]struct{}{},uniform, 0, 0, 64, 64, 32); c != 1 {
+		t.Fatalf("uniform should be 1 colour, got %d", c)
+	}
+	rnd := makeBenchImage(128, 128, 1)
+	if c := sampledColorCountInto(map[uint32]struct{}{},rnd, 0, 0, 128, 128, 16); c <= 16 {
+		t.Fatalf("random image should exceed colour cap, got %d", c)
+	}
+}
+

client/vnc/server/virtual_x11.go

@@ -0,0 +1,723 @@
+//go:build (linux && !android) || freebsd
+
+package server
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"os/user"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+	"syscall"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+)
+
+// VirtualSession manages a virtual X11 display (Xvfb) with a desktop session
+// running as a target user. It implements ScreenCapturer and InputInjector by
+// delegating to an X11Capturer/X11InputInjector pointed at the virtual display.
+const (
+	sessionIdleTimeout = 5 * time.Minute
+
+	defaultSessionWidth  uint16 = 1280
+	defaultSessionHeight uint16 = 800
+)
+
+type VirtualSession struct {
+	mu        sync.Mutex
+	display   string
+	user      *user.User
+	uid       uint32
+	gid       uint32
+	groups    []uint32
+	width     uint16
+	height    uint16
+	xvfb      *exec.Cmd
+	desktop   *exec.Cmd
+	poller    *X11Poller
+	injector  *X11InputInjector
+	log       *log.Entry
+	stopped   bool
+	clients   int
+	idleTimer *time.Timer
+	onIdle    func() // called when idle timeout fires or Xvfb dies
+}
+
+// StartVirtualSession creates and starts a virtual X11 session for the given
+// user. Requires root privileges to create sessions as other users. width and
+// height request the virtual display geometry; 0 values fall back to the
+// defaults.
+func StartVirtualSession(username string, width, height uint16, logger *log.Entry) (*VirtualSession, error) {
+	if os.Getuid() != 0 {
+		return nil, fmt.Errorf("virtual sessions require root privileges")
+	}
+
+	if _, err := exec.LookPath("Xvfb"); err != nil {
+		if _, err := exec.LookPath("Xorg"); err != nil {
+			return nil, fmt.Errorf("neither Xvfb nor Xorg found (install xvfb or xserver-xorg)")
+		}
+		if !hasDummyDriver() {
+			return nil, fmt.Errorf("xvfb not found and xorg dummy driver not installed (install xvfb or xf86-video-dummy)")
+		}
+	}
+
+	u, err := user.Lookup(username)
+	if err != nil {
+		return nil, fmt.Errorf("lookup user %s: %w", username, err)
+	}
+
+	uid, err := strconv.ParseUint(u.Uid, 10, 32)
+	if err != nil {
+		return nil, fmt.Errorf("parse uid: %w", err)
+	}
+	gid, err := strconv.ParseUint(u.Gid, 10, 32)
+	if err != nil {
+		return nil, fmt.Errorf("parse gid: %w", err)
+	}
+
+	groups, err := supplementaryGroups(u)
+	if err != nil {
+		logger.Debugf("supplementary groups for %s: %v", username, err)
+	}
+
+	if width == 0 {
+		width = defaultSessionWidth
+	}
+	if height == 0 {
+		height = defaultSessionHeight
+	}
+
+	vs := &VirtualSession{
+		user:   u,
+		uid:    uint32(uid),
+		gid:    uint32(gid),
+		groups: groups,
+		width:  width,
+		height: height,
+		log:    logger.WithField("vnc_user", username),
+	}
+
+	if err := vs.start(); err != nil {
+		return nil, err
+	}
+	return vs, nil
+}
+
+func (vs *VirtualSession) start() error {
+	display, err := findFreeDisplay()
+	if err != nil {
+		return fmt.Errorf("find free display: %w", err)
+	}
+	vs.display = display
+
+	if err := vs.startXvfb(); err != nil {
+		return err
+	}
+
+	socketPath := fmt.Sprintf("/tmp/.X11-unix/X%s", vs.display[1:])
+	if err := waitForPath(socketPath, 5*time.Second); err != nil {
+		vs.stopXvfb()
+		return fmt.Errorf("wait for X11 socket %s: %w", socketPath, err)
+	}
+
+	// Grant the target user access to the display via xhost.
+	xhostCmd := exec.Command("xhost", "+SI:localuser:"+vs.user.Username)
+	xhostCmd.Env = []string{"DISPLAY=" + vs.display}
+	if out, err := xhostCmd.CombinedOutput(); err != nil {
+		vs.log.Debugf("xhost: %s (%v)", strings.TrimSpace(string(out)), err)
+	}
+
+	vs.poller = NewX11Poller(vs.display)
+
+	injector, err := NewX11InputInjector(vs.display)
+	if err != nil {
+		vs.stopXvfb()
+		return fmt.Errorf("create X11 injector for %s: %w", vs.display, err)
+	}
+	vs.injector = injector
+
+	if err := vs.startDesktop(); err != nil {
+		vs.injector.Close()
+		vs.stopXvfb()
+		return fmt.Errorf("start desktop: %w", err)
+	}
+
+	vs.log.Infof("virtual session started: display=%s user=%s", vs.display, vs.user.Username)
+	return nil
+}
+
+// ClientConnect increments the client count and cancels any idle timer.
+func (vs *VirtualSession) ClientConnect() {
+	vs.mu.Lock()
+	defer vs.mu.Unlock()
+	vs.clients++
+	if vs.idleTimer != nil {
+		vs.idleTimer.Stop()
+		vs.idleTimer = nil
+	}
+}
+
+// ClientDisconnect decrements the client count. When the last client
+// disconnects, starts an idle timer that destroys the session.
+func (vs *VirtualSession) ClientDisconnect() {
+	vs.mu.Lock()
+	defer vs.mu.Unlock()
+	vs.clients--
+	if vs.clients <= 0 {
+		vs.clients = 0
+		vs.log.Infof("no VNC clients connected, session will be destroyed in %s", sessionIdleTimeout)
+		vs.idleTimer = time.AfterFunc(sessionIdleTimeout, vs.idleExpired)
+	}
+}
+
+// idleExpired is called by the idle timer. It stops the session and
+// notifies the session manager via onIdle so it removes us from the map.
+func (vs *VirtualSession) idleExpired() {
+	vs.log.Info("idle timeout reached, destroying virtual session")
+	vs.Stop()
+	// onIdle acquires sessionManager.mu; safe because Stop() has released vs.mu.
+	if vs.onIdle != nil {
+		vs.onIdle()
+	}
+}
+
+// isAlive returns true if the session is running and its X server socket exists.
+func (vs *VirtualSession) isAlive() bool {
+	vs.mu.Lock()
+	stopped := vs.stopped
+	display := vs.display
+	vs.mu.Unlock()
+
+	if stopped {
+		return false
+	}
+	// Verify the X socket still exists on disk.
+	socketPath := fmt.Sprintf("/tmp/.X11-unix/X%s", display[1:])
+	if _, err := os.Stat(socketPath); err != nil {
+		return false
+	}
+	return true
+}
+
+// Capturer returns the screen capturer for this virtual session.
+func (vs *VirtualSession) Capturer() ScreenCapturer {
+	return vs.poller
+}
+
+// Injector returns the input injector for this virtual session.
+func (vs *VirtualSession) Injector() InputInjector {
+	return vs.injector
+}
+
+// Display returns the X11 display string (e.g., ":99").
+func (vs *VirtualSession) Display() string {
+	return vs.display
+}
+
+// Stop terminates the virtual session, killing the desktop and Xvfb.
+func (vs *VirtualSession) Stop() {
+	vs.mu.Lock()
+	defer vs.mu.Unlock()
+
+	if vs.stopped {
+		return
+	}
+	vs.stopped = true
+
+	if vs.injector != nil {
+		vs.injector.Close()
+	}
+
+	vs.stopDesktop()
+	vs.stopXvfb()
+
+	vs.log.Info("virtual session stopped")
+}
+
+func (vs *VirtualSession) startXvfb() error {
+	if _, err := exec.LookPath("Xvfb"); err == nil {
+		return vs.startXvfbDirect()
+	}
+	return vs.startXorgDummy()
+}
+
+func (vs *VirtualSession) startXvfbDirect() error {
+	geom := fmt.Sprintf("%dx%dx24", vs.width, vs.height)
+	vs.xvfb = exec.Command("Xvfb", vs.display,
+		"-screen", "0", geom,
+		"-nolisten", "tcp",
+	)
+	vs.xvfb.SysProcAttr = &syscall.SysProcAttr{Setsid: true, Pdeathsig: syscall.SIGTERM}
+
+	if err := vs.xvfb.Start(); err != nil {
+		return fmt.Errorf("start Xvfb on %s: %w", vs.display, err)
+	}
+	vs.log.Infof("Xvfb started on %s (pid=%d)", vs.display, vs.xvfb.Process.Pid)
+
+	go vs.monitorXvfb()
+
+	return nil
+}
+
+// startXorgDummy starts Xorg with the dummy video driver as a fallback when
+// Xvfb is not installed. Most systems with a desktop have Xorg available.
+func (vs *VirtualSession) startXorgDummy() error {
+	conf := fmt.Sprintf(`Section "Device"
+    Identifier "dummy"
+    Driver "dummy"
+    VideoRam 256000
+EndSection
+Section "Screen"
+    Identifier "screen"
+    Device "dummy"
+    DefaultDepth 24
+    SubSection "Display"
+        Depth 24
+        Modes "%dx%d"
+    EndSubSection
+EndSection
+`, vs.width, vs.height)
+	f, err := os.CreateTemp("", fmt.Sprintf("nbvnc-dummy-%s-*.conf", vs.display[1:]))
+	if err != nil {
+		return fmt.Errorf("create Xorg dummy config: %w", err)
+	}
+	confPath := f.Name()
+	if _, err := f.WriteString(conf); err != nil {
+		f.Close()
+		os.Remove(confPath)
+		return fmt.Errorf("write Xorg dummy config: %w", err)
+	}
+	if err := f.Chmod(0600); err != nil {
+		f.Close()
+		os.Remove(confPath)
+		return fmt.Errorf("chmod Xorg dummy config: %w", err)
+	}
+	if err := f.Close(); err != nil {
+		os.Remove(confPath)
+		return fmt.Errorf("close Xorg dummy config: %w", err)
+	}
+
+	vs.xvfb = exec.Command("Xorg", vs.display,
+		"-config", confPath,
+		"-noreset",
+		"-nolisten", "tcp",
+	)
+	vs.xvfb.SysProcAttr = &syscall.SysProcAttr{Setsid: true, Pdeathsig: syscall.SIGTERM}
+
+	if err := vs.xvfb.Start(); err != nil {
+		os.Remove(confPath)
+		return fmt.Errorf("start Xorg dummy on %s: %w", vs.display, err)
+	}
+	vs.log.Infof("Xorg (dummy driver) started on %s (pid=%d)", vs.display, vs.xvfb.Process.Pid)
+
+	go func() {
+		vs.monitorXvfb()
+		os.Remove(confPath)
+	}()
+
+	return nil
+}
+
+// monitorXvfb waits for the Xvfb/Xorg process to exit. If it exits
+// unexpectedly (not via Stop), the session is marked as dead and the
+// onIdle callback fires so the session manager removes it from the map.
+// The next GetOrCreate call for this user will create a fresh session.
+func (vs *VirtualSession) monitorXvfb() {
+	if err := vs.xvfb.Wait(); err != nil {
+		vs.log.Debugf("X server exited: %v", err)
+	}
+
+	vs.mu.Lock()
+	alreadyStopped := vs.stopped
+	if !alreadyStopped {
+		vs.log.Warn("X server exited unexpectedly, marking session as dead")
+		vs.stopped = true
+		if vs.idleTimer != nil {
+			vs.idleTimer.Stop()
+			vs.idleTimer = nil
+		}
+		if vs.injector != nil {
+			vs.injector.Close()
+		}
+		vs.stopDesktop()
+	}
+	onIdle := vs.onIdle
+	vs.mu.Unlock()
+
+	if !alreadyStopped && onIdle != nil {
+		onIdle()
+	}
+}
+
+func (vs *VirtualSession) stopXvfb() {
+	if vs.xvfb == nil || vs.xvfb.Process == nil {
+		return
+	}
+	if err := syscall.Kill(-vs.xvfb.Process.Pid, syscall.SIGTERM); err != nil {
+		vs.log.Debugf("SIGTERM xvfb group: %v", err)
+	}
+	time.Sleep(200 * time.Millisecond)
+	if err := syscall.Kill(-vs.xvfb.Process.Pid, syscall.SIGKILL); err != nil {
+		vs.log.Debugf("SIGKILL xvfb group: %v", err)
+	}
+}
+
+func (vs *VirtualSession) startDesktop() error {
+	session := detectDesktopSession()
+
+	// Wrap the desktop command with dbus-launch to provide a session bus.
+	// Without this, most desktop environments (XFCE, MATE, etc.) fail immediately.
+	var args []string
+	if _, err := exec.LookPath("dbus-launch"); err == nil {
+		args = append([]string{"dbus-launch", "--exit-with-session"}, session...)
+	} else {
+		args = session
+	}
+
+	vs.desktop = exec.Command(args[0], args[1:]...)
+	vs.desktop.Dir = vs.user.HomeDir
+	vs.desktop.Env = vs.buildUserEnv()
+	vs.desktop.SysProcAttr = &syscall.SysProcAttr{
+		Credential: &syscall.Credential{
+			Uid:    vs.uid,
+			Gid:    vs.gid,
+			Groups: vs.groups,
+		},
+		Setsid:    true,
+		Pdeathsig: syscall.SIGTERM,
+	}
+
+	if err := vs.desktop.Start(); err != nil {
+		return fmt.Errorf("start desktop session (%v): %w", args, err)
+	}
+	vs.log.Infof("desktop session started: %v (pid=%d)", args, vs.desktop.Process.Pid)
+
+	go vs.monitorDesktop()
+
+	return nil
+}
+
+// monitorDesktop waits for the desktop-session process to exit. When the user
+// logs out of GNOME/KDE/XFCE/etc., the session process terminates while Xvfb
+// keeps running, leaving a blank root window. Tear the whole virtual session
+// down so the next connect starts fresh with a login.
+func (vs *VirtualSession) monitorDesktop() {
+	if err := vs.desktop.Wait(); err != nil {
+		vs.log.Debugf("desktop session exited: %v", err)
+	}
+
+	vs.mu.Lock()
+	alreadyStopped := vs.stopped
+	if !alreadyStopped {
+		vs.log.Info("desktop session exited (logout), tearing down virtual session")
+		vs.stopped = true
+		if vs.idleTimer != nil {
+			vs.idleTimer.Stop()
+			vs.idleTimer = nil
+		}
+		if vs.injector != nil {
+			vs.injector.Close()
+		}
+		vs.stopXvfb()
+	}
+	onIdle := vs.onIdle
+	vs.mu.Unlock()
+
+	if !alreadyStopped && onIdle != nil {
+		onIdle()
+	}
+}
+
+func (vs *VirtualSession) stopDesktop() {
+	if vs.desktop == nil || vs.desktop.Process == nil {
+		return
+	}
+	if err := syscall.Kill(-vs.desktop.Process.Pid, syscall.SIGTERM); err != nil {
+		vs.log.Debugf("SIGTERM desktop group: %v", err)
+	}
+	time.Sleep(200 * time.Millisecond)
+	if err := syscall.Kill(-vs.desktop.Process.Pid, syscall.SIGKILL); err != nil {
+		vs.log.Debugf("SIGKILL desktop group: %v", err)
+	}
+}
+
+func (vs *VirtualSession) buildUserEnv() []string {
+	return []string{
+		"DISPLAY=" + vs.display,
+		"HOME=" + vs.user.HomeDir,
+		"USER=" + vs.user.Username,
+		"LOGNAME=" + vs.user.Username,
+		"SHELL=" + getUserShell(vs.user.Uid),
+		"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
+		"XDG_RUNTIME_DIR=/run/user/" + vs.user.Uid,
+		"DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/" + vs.user.Uid + "/bus",
+	}
+}
+
+// detectDesktopSession discovers available desktop sessions from the standard
+// /usr/share/xsessions/*.desktop files (FreeDesktop standard, used by all
+// display managers). Falls back to a hardcoded list if no .desktop files found.
+func detectDesktopSession() []string {
+	// Scan xsessions directories (Linux: /usr/share, FreeBSD: /usr/local/share).
+	for _, dir := range []string{"/usr/share/xsessions", "/usr/local/share/xsessions"} {
+		if cmd := findXSession(dir); cmd != nil {
+			return cmd
+		}
+	}
+
+	// Fallback: try common session commands directly.
+	fallbacks := [][]string{
+		{"startplasma-x11"},
+		{"gnome-session"},
+		{"xfce4-session"},
+		{"mate-session"},
+		{"cinnamon-session"},
+		{"openbox-session"},
+		{"xterm"},
+	}
+	for _, s := range fallbacks {
+		if _, err := exec.LookPath(s[0]); err == nil {
+			return s
+		}
+	}
+	return []string{"xterm"}
+}
+
+// sessionPriority defines preference order for desktop environments.
+// Lower number = higher priority. Unknown sessions get 100.
+var sessionPriority = map[string]int{
+	"plasma":   1, // KDE
+	"gnome":    2,
+	"xfce":     3,
+	"mate":     4,
+	"cinnamon": 5,
+	"lxqt":     6,
+	"lxde":     7,
+	"budgie":   8,
+	"openbox":  20,
+	"fluxbox":  21,
+	"i3":       22,
+	"xinit":    50, // generic user session
+	"lightdm":  50,
+	"default":  50,
+}
+
+func findXSession(dir string) []string {
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		return nil
+	}
+	candidates := collectSessionCandidates(dir, entries)
+	if len(candidates) == 0 {
+		return nil
+	}
+	best := bestSessionCandidate(candidates)
+	parts := strings.Fields(best.cmd)
+	if _, err := exec.LookPath(parts[0]); err != nil {
+		return nil
+	}
+	return parts
+}
+
+type sessionCandidate struct {
+	cmd      string
+	priority int
+}
+
+func collectSessionCandidates(dir string, entries []os.DirEntry) []sessionCandidate {
+	var out []sessionCandidate
+	for _, e := range entries {
+		c, ok := parseSessionEntry(dir, e)
+		if ok {
+			out = append(out, c)
+		}
+	}
+	return out
+}
+
+// parseSessionEntry reads a single .desktop file and extracts its Exec
+// command plus the priority hint to be used when picking the best session.
+func parseSessionEntry(dir string, e os.DirEntry) (sessionCandidate, bool) {
+	if !strings.HasSuffix(e.Name(), ".desktop") {
+		return sessionCandidate{}, false
+	}
+	data, err := os.ReadFile(filepath.Join(dir, e.Name()))
+	if err != nil {
+		return sessionCandidate{}, false
+	}
+	execCmd := extractExecLine(data)
+	if execCmd == "" || execCmd == "default" {
+		return sessionCandidate{}, false
+	}
+	return sessionCandidate{cmd: execCmd, priority: sessionPriorityFor(e.Name(), execCmd)}, true
+}
+
+func extractExecLine(data []byte) string {
+	for _, line := range strings.Split(string(data), "\n") {
+		if strings.HasPrefix(line, "Exec=") {
+			return strings.TrimSpace(strings.TrimPrefix(line, "Exec="))
+		}
+	}
+	return ""
+}
+
+func sessionPriorityFor(name, execCmd string) int {
+	pri := 100
+	lower := strings.ToLower(name + " " + execCmd)
+	for keyword, p := range sessionPriority {
+		if strings.Contains(lower, keyword) && p < pri {
+			pri = p
+		}
+	}
+	return pri
+}
+
+func bestSessionCandidate(candidates []sessionCandidate) sessionCandidate {
+	best := candidates[0]
+	for _, c := range candidates[1:] {
+		if c.priority < best.priority {
+			best = c
+		}
+	}
+	return best
+}
+
+// findFreeDisplay scans for an unused X11 display number.
+func findFreeDisplay() (string, error) {
+	for n := 50; n < 200; n++ {
+		lockFile := fmt.Sprintf("/tmp/.X%d-lock", n)
+		socketFile := fmt.Sprintf("/tmp/.X11-unix/X%d", n)
+		if _, err := os.Stat(lockFile); err == nil {
+			continue
+		}
+		if _, err := os.Stat(socketFile); err == nil {
+			continue
+		}
+		return fmt.Sprintf(":%d", n), nil
+	}
+	return "", fmt.Errorf("no free X11 display found (checked :50-:199)")
+}
+
+// waitForPath polls until a filesystem path exists or the timeout expires.
+func waitForPath(path string, timeout time.Duration) error {
+	deadline := time.Now().Add(timeout)
+	for time.Now().Before(deadline) {
+		if _, err := os.Stat(path); err == nil {
+			return nil
+		}
+		time.Sleep(50 * time.Millisecond)
+	}
+	return fmt.Errorf("timeout waiting for %s", path)
+}
+
+// getUserShell returns the login shell for the given UID.
+func getUserShell(uid string) string {
+	data, err := os.ReadFile("/etc/passwd")
+	if err != nil {
+		return "/bin/sh"
+	}
+	for _, line := range strings.Split(string(data), "\n") {
+		fields := strings.Split(line, ":")
+		if len(fields) >= 7 && fields[2] == uid {
+			return fields[6]
+		}
+	}
+	return "/bin/sh"
+}
+
+// supplementaryGroups returns the supplementary group IDs for a user.
+func supplementaryGroups(u *user.User) ([]uint32, error) {
+	gids, err := u.GroupIds()
+	if err != nil {
+		return nil, err
+	}
+	var groups []uint32
+	for _, g := range gids {
+		id, err := strconv.ParseUint(g, 10, 32)
+		if err != nil {
+			continue
+		}
+		groups = append(groups, uint32(id))
+	}
+	return groups, nil
+}
+
+// sessionManager tracks active virtual sessions by username.
+type sessionManager struct {
+	mu       sync.Mutex
+	sessions map[string]*VirtualSession
+	log      *log.Entry
+}
+
+func newSessionManager(logger *log.Entry) *sessionManager {
+	return &sessionManager{
+		sessions: make(map[string]*VirtualSession),
+		log:      logger,
+	}
+}
+
+// GetOrCreate returns an existing virtual session or creates a new one with
+// the requested geometry. If a previous session for this user is alive it is
+// reused regardless of the requested geometry; the first caller's size wins
+// until the session idles out. If a previous session is stopped or its X
+// server died, it is replaced.
+func (sm *sessionManager) GetOrCreate(username string, width, height uint16) (vncSession, error) {
+	sm.mu.Lock()
+	defer sm.mu.Unlock()
+
+	if vs, ok := sm.sessions[username]; ok {
+		if vs.isAlive() {
+			return vs, nil
+		}
+		sm.log.Infof("replacing dead virtual session for %s", username)
+		vs.Stop()
+		delete(sm.sessions, username)
+	}
+
+	vs, err := StartVirtualSession(username, width, height, sm.log)
+	if err != nil {
+		return nil, err
+	}
+	vs.onIdle = func() {
+		sm.mu.Lock()
+		defer sm.mu.Unlock()
+		if cur, ok := sm.sessions[username]; ok && cur == vs {
+			delete(sm.sessions, username)
+			sm.log.Infof("removed idle virtual session for %s", username)
+		}
+	}
+	sm.sessions[username] = vs
+	return vs, nil
+}
+
+// hasDummyDriver checks common paths for the Xorg dummy video driver.
+func hasDummyDriver() bool {
+	paths := []string{
+		"/usr/lib/xorg/modules/drivers/dummy_drv.so",                  // Debian/Ubuntu
+		"/usr/lib64/xorg/modules/drivers/dummy_drv.so",                // RHEL/Fedora
+		"/usr/local/lib/xorg/modules/drivers/dummy_drv.so",            // FreeBSD
+		"/usr/lib/x86_64-linux-gnu/xorg/modules/drivers/dummy_drv.so", // Debian multiarch
+	}
+	for _, p := range paths {
+		if _, err := os.Stat(p); err == nil {
+			return true
+		}
+	}
+	return false
+}
+
+// StopAll terminates all active virtual sessions.
+func (sm *sessionManager) StopAll() {
+	sm.mu.Lock()
+	defer sm.mu.Unlock()
+
+	for username, vs := range sm.sessions {
+		vs.Stop()
+		delete(sm.sessions, username)
+		sm.log.Infof("stopped virtual session for %s", username)
+	}
+}

client/wasm/cmd/main.go

@@ -19,8 +19,8 @@ import (
 	nbstatus "github.com/netbirdio/netbird/client/status"
 	wasmcapture "github.com/netbirdio/netbird/client/wasm/internal/capture"
 	"github.com/netbirdio/netbird/client/wasm/internal/http"
-	"github.com/netbirdio/netbird/client/wasm/internal/rdp"
 	"github.com/netbirdio/netbird/client/wasm/internal/ssh"
+	"github.com/netbirdio/netbird/client/wasm/internal/vnc"
 	"github.com/netbirdio/netbird/util"
 )
 
@@ -364,29 +364,133 @@ func createProxyRequestMethod(client *netbird.Client) js.Func {
 	})
 }
 
-// createRDPProxyMethod creates the RDP proxy method
-func createRDPProxyMethod(client *netbird.Client) js.Func {
+// createVNCProxyMethod creates the VNC proxy method for raw TCP-over-WebSocket bridging.
+// JS signature: createVNCProxy(hostname, port, mode?, username?, jwt?, sessionID?, width?, height?)
+// mode: "attach" (default) or "session"
+// username: required when mode is "session"
+// jwt: authentication token (from OIDC session)
+// sessionID: Windows session ID (0 = console/auto)
+// width/height: requested viewport size for session mode (0 = server default)
+func createVNCProxyMethod(client *netbird.Client) js.Func {
 	return js.FuncOf(func(_ js.Value, args []js.Value) any {
-		if len(args) < 2 {
-			return js.ValueOf("error: hostname and port required")
+		params, err := parseVNCProxyArgs(args)
+		if err != nil {
+			if params.rejectViaPromise {
+				return createPromise(func(resolve, reject js.Value) {
+					reject.Invoke(js.ValueOf(err.Error()))
+				})
+			}
+			return js.ValueOf(err.Error())
 		}
-
-		if args[0].Type() != js.TypeString {
-			return createPromise(func(resolve, reject js.Value) {
-				reject.Invoke(js.ValueOf("hostname parameter must be a string"))
-			})
-		}
-		if args[1].Type() != js.TypeString {
-			return createPromise(func(resolve, reject js.Value) {
-				reject.Invoke(js.ValueOf("port parameter must be a string"))
-			})
-		}
-
-		proxy := rdp.NewRDCleanPathProxy(client)
-		return proxy.CreateProxy(args[0].String(), args[1].String())
+		proxy := vnc.NewVNCProxy(client)
+		return proxy.CreateProxy(vnc.ProxyRequest{
+			Hostname:  params.hostname,
+			Port:      params.port,
+			Mode:      params.mode,
+			Username:  params.username,
+			JWT:       params.jwt,
+			SessionID: params.sessionID,
+			Width:     params.width,
+			Height:    params.height,
+		})
 	})
 }
 
+type vncProxyParams struct {
+	hostname         string
+	port             string
+	mode             string
+	username         string
+	jwt              string
+	sessionID        uint32
+	width            uint16
+	height           uint16
+	rejectViaPromise bool // true when the JS caller expects a rejected Promise instead of a plain string return
+}
+
+// parseVNCProxyArgs validates JS args for createVNCProxyMethod and returns
+// the parsed params plus the first validation error (nil on success).
+// vncProxyParams.rejectViaPromise tells the caller which JS-side response
+// path to use for the returned error.
+func parseVNCProxyArgs(args []js.Value) (vncProxyParams, error) {
+	var p vncProxyParams
+	if err := parseVNCProxyRequiredArgs(args, &p); err != nil {
+		return p, err
+	}
+	if err := parseVNCProxyOptionalStrings(args, &p); err != nil {
+		return p, err
+	}
+	if err := parseVNCProxyOptionalNumbers(args, &p); err != nil {
+		return p, err
+	}
+	return p, nil
+}
+
+func parseVNCProxyRequiredArgs(args []js.Value, p *vncProxyParams) error {
+	if len(args) < 2 {
+		return fmt.Errorf("hostname and port required")
+	}
+	if args[0].Type() != js.TypeString {
+		p.rejectViaPromise = true
+		return fmt.Errorf("hostname parameter must be a string")
+	}
+	if args[1].Type() != js.TypeString {
+		p.rejectViaPromise = true
+		return fmt.Errorf("port parameter must be a string")
+	}
+	p.hostname = args[0].String()
+	p.port = args[1].String()
+	p.mode = "attach"
+	return nil
+}
+
+func parseVNCProxyOptionalStrings(args []js.Value, p *vncProxyParams) error {
+	if len(args) > 2 && args[2].Type() == js.TypeString {
+		p.mode = args[2].String()
+	}
+	if p.mode != "attach" && p.mode != "session" {
+		p.rejectViaPromise = true
+		return fmt.Errorf("invalid mode %q: expected \"attach\" or \"session\"", p.mode)
+	}
+	if len(args) > 3 && args[3].Type() == js.TypeString {
+		p.username = args[3].String()
+	}
+	if len(args) > 4 && args[4].Type() == js.TypeString {
+		p.jwt = args[4].String()
+	}
+	return nil
+}
+
+func parseVNCProxyOptionalNumbers(args []js.Value, p *vncProxyParams) error {
+	if len(args) > 5 && args[5].Type() == js.TypeNumber {
+		v := args[5].Int()
+		if v < 0 || v > 0xFFFFFFFF {
+			p.rejectViaPromise = true
+			return fmt.Errorf("invalid sessionID %d: must be 0..0xFFFFFFFF", v)
+		}
+		p.sessionID = uint32(v)
+	}
+	// width=0 / height=0 mean "use server default"; reject only out-of-range
+	// non-zero values so attach mode (which omits width/height) still works.
+	if len(args) > 6 && args[6].Type() == js.TypeNumber {
+		v := args[6].Int()
+		if v < 0 || v > 0xFFFF {
+			p.rejectViaPromise = true
+			return fmt.Errorf("invalid width %d: must be 0..65535", v)
+		}
+		p.width = uint16(v)
+	}
+	if len(args) > 7 && args[7].Type() == js.TypeNumber {
+		v := args[7].Int()
+		if v < 0 || v > 0xFFFF {
+			p.rejectViaPromise = true
+			return fmt.Errorf("invalid height %d: must be 0..65535", v)
+		}
+		p.height = uint16(v)
+	}
+	return nil
+}
+
 // getStatusOverview is a helper to get the status overview
 func getStatusOverview(client *netbird.Client) (nbstatus.OutputOverview, error) {
 	fullStatus, err := client.Status()
@@ -676,7 +780,7 @@ func createClientObject(client *netbird.Client) js.Value {
 	obj["detectSSHServerType"] = createDetectSSHServerMethod(client)
 	obj["createSSHConnection"] = createSSHMethod(client)
 	obj["proxyRequest"] = createProxyRequestMethod(client)
-	obj["createRDPProxy"] = createRDPProxyMethod(client)
+	obj["createVNCProxy"] = createVNCProxyMethod(client)
 	obj["status"] = createStatusMethod(client)
 	obj["statusSummary"] = createStatusSummaryMethod(client)
 	obj["statusDetail"] = createStatusDetailMethod(client)

client/wasm/internal/vnc/proxy.go

@@ -0,0 +1,427 @@
+//go:build js
+
+package vnc
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"sync"
+	"sync/atomic"
+	"syscall/js"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	vncProxyHost   = "vnc.proxy.local"
+	vncProxyScheme = "ws"
+	vncDialTimeout = 15 * time.Second
+
+	// Connection modes matching server/server.go constants.
+	modeAttach  byte = 0
+	modeSession byte = 1
+)
+
+// VNCProxy bridges WebSocket connections from noVNC in the browser
+// to TCP VNC server connections through the NetBird tunnel.
+type VNCProxy struct {
+	nbClient interface {
+		Dial(ctx context.Context, network, address string) (net.Conn, error)
+	}
+	activeConnections map[string]*vncConnection
+	destinations      map[string]vncDestination
+	// pendingHandlers holds the js.Func for handleVNCWebSocket_<id> between
+	// CreateProxy and handleWebSocketConnection so we can move it onto the
+	// vncConnection for later release.
+	pendingHandlers map[string]js.Func
+	mu              sync.Mutex
+	nextID          atomic.Uint64
+}
+
+type vncDestination struct {
+	address   string
+	mode      byte
+	username  string
+	jwt       string
+	sessionID uint32 // Windows session ID (0 = auto/console)
+	width     uint16 // Requested viewport width for session mode (0 = default)
+	height    uint16 // Requested viewport height for session mode (0 = default)
+}
+
+type vncConnection struct {
+	id          string
+	destination vncDestination
+	mu          sync.Mutex
+	vncConn     net.Conn
+	wsHandlers  js.Value
+	ctx         context.Context
+	cancel      context.CancelFunc
+	// Go-side callbacks exposed to JS. js.FuncOf pins the Go closure in a
+	// global handle map and MUST be released, otherwise every connection
+	// leaks the Go memory the closure captures.
+	wsHandlerFn js.Func
+	onMessageFn js.Func
+	onCloseFn   js.Func
+}
+
+// NewVNCProxy creates a new VNC proxy.
+func NewVNCProxy(client interface {
+	Dial(ctx context.Context, network, address string) (net.Conn, error)
+}) *VNCProxy {
+	return &VNCProxy{
+		nbClient:          client,
+		activeConnections: make(map[string]*vncConnection),
+	}
+}
+
+// ProxyRequest bundles the per-call parameters for CreateProxy so the JS
+// boundary doesn't drown callers in a wide positional argument list.
+type ProxyRequest struct {
+	Hostname  string
+	Port      string
+	Mode      string
+	Username  string
+	JWT       string
+	SessionID uint32
+	Width     uint16
+	Height    uint16
+}
+
+// CreateProxy creates a new proxy endpoint for the given VNC destination.
+// req.Mode is "attach" (capture current display) or "session" (virtual session).
+// req.Username is required for session mode. req.Width/Height request the
+// virtual display geometry for session mode; 0 means use the server default.
+// Returns a JS Promise that resolves to the WebSocket proxy URL.
+func (p *VNCProxy) CreateProxy(req ProxyRequest) js.Value {
+	hostname, port, mode, username, jwt := req.Hostname, req.Port, req.Mode, req.Username, req.JWT
+	sessionID, width, height := req.SessionID, req.Width, req.Height
+	address := net.JoinHostPort(hostname, port)
+
+	var m byte
+	if mode == "session" {
+		m = modeSession
+	}
+
+	dest := vncDestination{
+		address:   address,
+		mode:      m,
+		username:  username,
+		jwt:       jwt,
+		sessionID: sessionID,
+		width:     width,
+		height:    height,
+	}
+	return p.newProxyPromise(address, mode, username, dest)
+}
+
+// newProxyPromise wraps the JS Promise creation + executor lifecycle so
+// CreateProxy stays a thin parameter-bundling entrypoint.
+func (p *VNCProxy) newProxyPromise(address, mode, username string, dest vncDestination) js.Value {
+
+	var executor js.Func
+	executor = js.FuncOf(func(_ js.Value, args []js.Value) any {
+		resolve := args[0]
+
+		go func() {
+			defer executor.Release()
+
+			proxyID := fmt.Sprintf("vnc_proxy_%d", p.nextID.Add(1))
+
+			p.mu.Lock()
+			if p.destinations == nil {
+				p.destinations = make(map[string]vncDestination)
+			}
+			p.destinations[proxyID] = dest
+			p.mu.Unlock()
+
+			proxyURL := fmt.Sprintf("%s://%s/%s", vncProxyScheme, vncProxyHost, proxyID)
+
+			handlerFn := js.FuncOf(func(_ js.Value, args []js.Value) any {
+				if len(args) < 1 {
+					return js.ValueOf("error: requires WebSocket argument")
+				}
+				p.handleWebSocketConnection(args[0], proxyID)
+				return nil
+			})
+			p.mu.Lock()
+			if p.pendingHandlers == nil {
+				p.pendingHandlers = make(map[string]js.Func)
+			}
+			p.pendingHandlers[proxyID] = handlerFn
+			p.mu.Unlock()
+			js.Global().Set(fmt.Sprintf("handleVNCWebSocket_%s", proxyID), handlerFn)
+
+			log.Infof("created VNC proxy: %s -> %s (mode=%s, user=%s)", proxyURL, address, mode, username)
+			resolve.Invoke(proxyURL)
+		}()
+
+		return nil
+	})
+	return js.Global().Get("Promise").New(executor)
+}
+
+func (p *VNCProxy) handleWebSocketConnection(ws js.Value, proxyID string) {
+	p.mu.Lock()
+	dest, ok := p.destinations[proxyID]
+	handlerFn := p.pendingHandlers[proxyID]
+	delete(p.pendingHandlers, proxyID)
+	p.mu.Unlock()
+
+	if !ok {
+		log.Errorf("no destination for VNC proxy %s", proxyID)
+		return
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	conn := &vncConnection{
+		id:          proxyID,
+		destination: dest,
+		wsHandlers:  ws,
+		ctx:         ctx,
+		cancel:      cancel,
+		wsHandlerFn: handlerFn,
+	}
+
+	p.mu.Lock()
+	p.activeConnections[proxyID] = conn
+	p.mu.Unlock()
+
+	p.setupWebSocketHandlers(ws, conn)
+	go p.connectToVNC(conn)
+
+	log.Infof("VNC proxy WebSocket connection established for %s", proxyID)
+}
+
+func (p *VNCProxy) setupWebSocketHandlers(ws js.Value, conn *vncConnection) {
+	conn.onMessageFn = js.FuncOf(func(_ js.Value, args []js.Value) any {
+		if len(args) < 1 {
+			return nil
+		}
+		data := args[0]
+		go p.handleWebSocketMessage(conn, data)
+		return nil
+	})
+	ws.Set("onGoMessage", conn.onMessageFn)
+
+	conn.onCloseFn = js.FuncOf(func(_ js.Value, _ []js.Value) any {
+		log.Debug("VNC WebSocket closed by JavaScript")
+		conn.cancel()
+		return nil
+	})
+	ws.Set("onGoClose", conn.onCloseFn)
+}
+
+func (p *VNCProxy) handleWebSocketMessage(conn *vncConnection, data js.Value) {
+	if !data.InstanceOf(js.Global().Get("Uint8Array")) {
+		return
+	}
+
+	length := data.Get("length").Int()
+	buf := make([]byte, length)
+	js.CopyBytesToGo(buf, data)
+
+	conn.mu.Lock()
+	vncConn := conn.vncConn
+	conn.mu.Unlock()
+
+	if vncConn == nil {
+		return
+	}
+
+	if _, err := vncConn.Write(buf); err != nil {
+		log.Debugf("write to VNC server: %v", err)
+	}
+}
+
+func (p *VNCProxy) connectToVNC(conn *vncConnection) {
+	ctx, cancel := context.WithTimeout(conn.ctx, vncDialTimeout)
+	defer cancel()
+
+	vncConn, err := p.nbClient.Dial(ctx, "tcp", conn.destination.address)
+	if err != nil {
+		log.Errorf("VNC connect to %s: %v", conn.destination.address, err)
+		// Close the WebSocket so noVNC fires a disconnect event.
+		if conn.wsHandlers.Get("close").Truthy() {
+			conn.wsHandlers.Call("close", 1006, fmt.Sprintf("connect to peer: %v", err))
+		}
+		p.cleanupConnection(conn)
+		return
+	}
+	conn.mu.Lock()
+	conn.vncConn = vncConn
+	conn.mu.Unlock()
+
+	// Send the NetBird VNC session header before the RFB handshake.
+	if err := p.sendSessionHeader(vncConn, conn.destination); err != nil {
+		log.Errorf("send VNC session header: %v", err)
+		if conn.wsHandlers.Get("close").Truthy() {
+			conn.wsHandlers.Call("close", 1006, fmt.Sprintf("send session header: %v", err))
+		}
+		p.cleanupConnection(conn)
+		return
+	}
+
+	// WS→TCP is handled by the onGoMessage handler set in setupWebSocketHandlers,
+	// which writes directly to the VNC connection as data arrives from JS.
+	// Only the TCP→WS direction needs a read loop here.
+	go p.forwardConnToWS(conn)
+
+	<-conn.ctx.Done()
+	p.cleanupConnection(conn)
+}
+
+// sendSessionHeader writes mode, username, JWT, Windows session ID, and the
+// requested viewport size to the VNC server.
+// Format: [mode:1] [username_len:2] [username:N] [jwt_len:2] [jwt:N]
+//
+//	[session_id:4] [width:2] [height:2]
+func (p *VNCProxy) sendSessionHeader(conn net.Conn, dest vncDestination) error {
+	usernameBytes := []byte(dest.username)
+	jwtBytes := []byte(dest.jwt)
+	if len(usernameBytes) > 0xFFFF {
+		return fmt.Errorf("username too long: %d bytes (max %d)", len(usernameBytes), 0xFFFF)
+	}
+	if len(jwtBytes) > 0xFFFF {
+		return fmt.Errorf("jwt too long: %d bytes (max %d)", len(jwtBytes), 0xFFFF)
+	}
+	hdr := make([]byte, 3+len(usernameBytes)+2+len(jwtBytes)+4+4)
+	hdr[0] = dest.mode
+	hdr[1] = byte(len(usernameBytes) >> 8)
+	hdr[2] = byte(len(usernameBytes))
+	off := 3
+	copy(hdr[off:], usernameBytes)
+	off += len(usernameBytes)
+	hdr[off] = byte(len(jwtBytes) >> 8)
+	hdr[off+1] = byte(len(jwtBytes))
+	off += 2
+	copy(hdr[off:], jwtBytes)
+	off += len(jwtBytes)
+	hdr[off] = byte(dest.sessionID >> 24)
+	hdr[off+1] = byte(dest.sessionID >> 16)
+	hdr[off+2] = byte(dest.sessionID >> 8)
+	hdr[off+3] = byte(dest.sessionID)
+	off += 4
+	hdr[off] = byte(dest.width >> 8)
+	hdr[off+1] = byte(dest.width)
+	hdr[off+2] = byte(dest.height >> 8)
+	hdr[off+3] = byte(dest.height)
+
+	for off := 0; off < len(hdr); {
+		n, err := conn.Write(hdr[off:])
+		if err != nil {
+			return fmt.Errorf("write session header: %w", err)
+		}
+		off += n
+	}
+	return nil
+}
+
+func (p *VNCProxy) forwardConnToWS(conn *vncConnection) {
+	buf := make([]byte, 32*1024)
+
+	for {
+		if conn.ctx.Err() != nil {
+			return
+		}
+		vc, ok := conn.snapshotVNC()
+		if !ok {
+			return
+		}
+		if err := vc.SetReadDeadline(time.Now().Add(30 * time.Second)); err != nil {
+			log.Debugf("set VNC read deadline: %v", err)
+		}
+		n, err := vc.Read(buf)
+		if err != nil {
+			if p.handleConnReadError(conn, err) {
+				return
+			}
+			continue
+		}
+		if n > 0 {
+			p.sendToWebSocket(conn, buf[:n])
+		}
+	}
+}
+
+// snapshotVNC returns the current vncConn under conn.mu, with ok=false when
+// the connection has already been cleaned up.
+func (c *vncConnection) snapshotVNC() (net.Conn, bool) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.vncConn == nil {
+		return nil, false
+	}
+	return c.vncConn, true
+}
+
+// handleConnReadError classifies an error from the VNC read loop. Returns
+// true if the caller should exit; false to retry (transient timeout).
+func (p *VNCProxy) handleConnReadError(conn *vncConnection, err error) bool {
+	if conn.ctx.Err() != nil {
+		return true
+	}
+	if netErr, ok := err.(interface{ Timeout() bool }); ok && netErr.Timeout() {
+		// Read timeout: connection might be stale. The next iteration will
+		// fail too and trigger the close path.
+		return false
+	}
+	if err != io.EOF {
+		log.Debugf("read from VNC connection: %v", err)
+	}
+	// Close the WebSocket to notify noVNC, and cancel the local context so
+	// cleanupConnection isn't left waiting on the JS close callback that
+	// may never fire on hard errors.
+	if conn.wsHandlers.Get("close").Truthy() {
+		conn.wsHandlers.Call("close", 1006, "VNC connection lost")
+	}
+	conn.cancel()
+	return true
+}
+
+func (p *VNCProxy) sendToWebSocket(conn *vncConnection, data []byte) {
+	if conn.wsHandlers.Get("receiveFromGo").Truthy() {
+		uint8Array := js.Global().Get("Uint8Array").New(len(data))
+		js.CopyBytesToJS(uint8Array, data)
+		conn.wsHandlers.Call("receiveFromGo", uint8Array.Get("buffer"))
+	} else if conn.wsHandlers.Get("send").Truthy() {
+		uint8Array := js.Global().Get("Uint8Array").New(len(data))
+		js.CopyBytesToJS(uint8Array, data)
+		conn.wsHandlers.Call("send", uint8Array.Get("buffer"))
+	}
+}
+
+func (p *VNCProxy) cleanupConnection(conn *vncConnection) {
+	log.Debugf("cleaning up VNC connection %s", conn.id)
+	conn.cancel()
+
+	conn.mu.Lock()
+	vncConn := conn.vncConn
+	conn.vncConn = nil
+	conn.mu.Unlock()
+
+	if vncConn != nil {
+		if err := vncConn.Close(); err != nil {
+			log.Debugf("close VNC connection: %v", err)
+		}
+	}
+
+	// Remove the global JS handler registered in CreateProxy.
+	globalName := fmt.Sprintf("handleVNCWebSocket_%s", conn.id)
+	js.Global().Delete(globalName)
+
+	// Release all js.Func handles; js.FuncOf pins the Go closure and the
+	// allocations it captures until Release is called.
+	conn.wsHandlerFn.Release()
+	conn.onMessageFn.Release()
+	conn.onCloseFn.Release()
+
+	p.mu.Lock()
+	delete(p.activeConnections, conn.id)
+	delete(p.destinations, conn.id)
+	delete(p.pendingHandlers, conn.id)
+	p.mu.Unlock()
+}

go.mod

@@ -66,6 +66,8 @@ require (
 	github.com/hashicorp/go-secure-stdlib/base62 v0.1.2
 	github.com/hashicorp/go-version v1.7.0
 	github.com/jackc/pgx/v5 v5.5.5
+	github.com/jezek/xgb v1.3.0
+	github.com/kirides/go-d3d v1.0.1
 	github.com/libdns/route53 v1.5.0
 	github.com/libp2p/go-nat v0.2.0
 	github.com/libp2p/go-netroute v0.4.0

go.sum

@@ -378,6 +378,8 @@ github.com/jcmturner/rpc/v2 v2.0.3 h1:7FXXj8Ti1IaVFpSAziCZWNzbNuZmnvw/i6CqLNdWfZ
 github.com/jcmturner/rpc/v2 v2.0.3/go.mod h1:VUJYCIDm3PVOEHw8sgt091/20OJjskO/YJki3ELg/Hc=
 github.com/jeandeaual/go-locale v0.0.0-20250612000132-0ef82f21eade h1:FmusiCI1wHw+XQbvL9M+1r/C3SPqKrmBaIOYwVfQoDE=
 github.com/jeandeaual/go-locale v0.0.0-20250612000132-0ef82f21eade/go.mod h1:ZDXo8KHryOWSIqnsb/CiDq7hQUYryCgdVnxbj8tDG7o=
+github.com/jezek/xgb v1.3.0 h1:Wa1pn4GVtcmNVAVB6/pnQVJ7xPFZVZ/W1Tc27msDhgI=
+github.com/jezek/xgb v1.3.0/go.mod h1:nrhwO0FX/enq75I7Y7G8iN1ubpSGZEiA3v9e9GyRFlk=
 github.com/jinzhu/inflection v1.0.0 h1:K317FqzuhWc8YvSVlFMCCUb36O/S9MCKRDI7QkRKD/E=
 github.com/jinzhu/inflection v1.0.0/go.mod h1:h+uFLlag+Qp1Va5pdKtLDYj+kHp5pxUVkryuEj+Srlc=
 github.com/jinzhu/now v1.1.5 h1:/o9tlHleP7gOFmsnYNz3RGnqzefHA47wQpKrrdTIwXQ=
@@ -396,6 +398,8 @@ github.com/jsummers/gobmp v0.0.0-20230614200233-a9de23ed2e25/go.mod h1:kLgvv7o6U
 github.com/juju/gnuflag v0.0.0-20171113085948-2ce1bb71843d/go.mod h1:2PavIy+JPciBPrBUjwbNvtwB6RQlve+hkpll6QSNmOE=
 github.com/kelseyhightower/envconfig v1.4.0 h1:Im6hONhd3pLkfDFsbRgu68RDNkGF1r3dvMUtDTo2cv8=
 github.com/kelseyhightower/envconfig v1.4.0/go.mod h1:cccZRl6mQpaq41TPp5QxidR+Sa3axMbJDNb//FQX6Gg=
+github.com/kirides/go-d3d v1.0.1 h1:ZDANfvo34vskBMET1uwUUMNw8545Kbe8qYSiRwlNIuA=
+github.com/kirides/go-d3d v1.0.1/go.mod h1:99AjD+5mRTFEnkpRWkwq8UYMQDljGIIvLn2NyRdVImY=
 github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
 github.com/klauspost/compress v1.18.0 h1:c/Cqfb0r+Yi+JtIEq73FWXVkRonBlf0CRNYc8Zttxdo=

management/internals/modules/peers/ephemeral/manager/ephemeral.go

@@ -11,7 +11,6 @@ import (
 	"github.com/netbirdio/netbird/management/internals/modules/peers/ephemeral"
 	"github.com/netbirdio/netbird/management/server/activity"
 	nbpeer "github.com/netbirdio/netbird/management/server/peer"
-	"github.com/netbirdio/netbird/management/server/telemetry"
 
 	"github.com/netbirdio/netbird/management/server/store"
 )
@@ -48,11 +47,6 @@ type EphemeralManager struct {
 
 	lifeTime      time.Duration
 	cleanupWindow time.Duration
-
-	// metrics is nil-safe; methods on telemetry.EphemeralPeersMetrics
-	// no-op when the receiver is nil so deployments without an app
-	// metrics provider work unchanged.
-	metrics *telemetry.EphemeralPeersMetrics
 }
 
 // NewEphemeralManager instantiate new EphemeralManager
@@ -66,15 +60,6 @@ func NewEphemeralManager(store store.Store, peersManager peers.Manager) *Ephemer
 	}
 }
 
-// SetMetrics attaches a metrics collector. Safe to call once before
-// LoadInitialPeers; later attachment is fine but earlier loads won't be
-// reflected in the gauge. Pass nil to detach.
-func (e *EphemeralManager) SetMetrics(m *telemetry.EphemeralPeersMetrics) {
-	e.peersLock.Lock()
-	e.metrics = m
-	e.peersLock.Unlock()
-}
-
 // LoadInitialPeers load from the database the ephemeral type of peers and schedule a cleanup procedure to the head
 // of the linked list (to the most deprecated peer). At the end of cleanup it schedules the next cleanup to the new
 // head.
@@ -112,9 +97,7 @@ func (e *EphemeralManager) OnPeerConnected(ctx context.Context, peer *nbpeer.Pee
 	e.peersLock.Lock()
 	defer e.peersLock.Unlock()
 
-	if e.removePeer(peer.ID) {
-		e.metrics.DecPending(1)
-	}
+	e.removePeer(peer.ID)
 
 	// stop the unnecessary timer
 	if e.headPeer == nil && e.timer != nil {
@@ -140,7 +123,6 @@ func (e *EphemeralManager) OnPeerDisconnected(ctx context.Context, peer *nbpeer.
 	}
 
 	e.addPeer(peer.AccountID, peer.ID, e.newDeadLine())
-	e.metrics.IncPending()
 	if e.timer == nil {
 		delay := e.headPeer.deadline.Sub(timeNow()) + e.cleanupWindow
 		if delay < 0 {
@@ -163,7 +145,6 @@ func (e *EphemeralManager) loadEphemeralPeers(ctx context.Context) {
 	for _, p := range peers {
 		e.addPeer(p.AccountID, p.ID, t)
 	}
-	e.metrics.AddPending(int64(len(peers)))
 
 	log.WithContext(ctx).Debugf("loaded ephemeral peer(s): %d", len(peers))
 }
@@ -200,15 +181,6 @@ func (e *EphemeralManager) cleanup(ctx context.Context) {
 
 	e.peersLock.Unlock()
 
-	// Drop the gauge by the number of entries we just took off the list,
-	// regardless of whether the subsequent DeletePeers call succeeds. The
-	// list invariant is what the gauge tracks; failed delete batches are
-	// counted separately via CountCleanupError so we can still see them.
-	if len(deletePeers) > 0 {
-		e.metrics.CountCleanupRun()
-		e.metrics.DecPending(int64(len(deletePeers)))
-	}
-
 	peerIDsPerAccount := make(map[string][]string)
 	for id, p := range deletePeers {
 		peerIDsPerAccount[p.accountID] = append(peerIDsPerAccount[p.accountID], id)
@@ -219,10 +191,7 @@ func (e *EphemeralManager) cleanup(ctx context.Context) {
 		err := e.peersManager.DeletePeers(ctx, accountID, peerIDs, activity.SystemInitiator, true)
 		if err != nil {
 			log.WithContext(ctx).Errorf("failed to delete ephemeral peers: %s", err)
-			e.metrics.CountCleanupError()
-			continue
 		}
-		e.metrics.CountPeersCleaned(int64(len(peerIDs)))
 	}
 }
 
@@ -242,12 +211,9 @@ func (e *EphemeralManager) addPeer(accountID string, peerID string, deadline tim
 	e.tailPeer = ep
 }
 
-// removePeer drops the entry from the linked list. Returns true if a
-// matching entry was found and removed so callers can keep the pending
-// metric gauge in sync.
-func (e *EphemeralManager) removePeer(id string) bool {
+func (e *EphemeralManager) removePeer(id string) {
 	if e.headPeer == nil {
-		return false
+		return
 	}
 
 	if e.headPeer.id == id {
@@ -255,7 +221,7 @@ func (e *EphemeralManager) removePeer(id string) bool {
 		if e.tailPeer.id == id {
 			e.tailPeer = nil
 		}
-		return true
+		return
 	}
 
 	for p := e.headPeer; p.next != nil; p = p.next {
@@ -265,10 +231,9 @@ func (e *EphemeralManager) removePeer(id string) bool {
 				e.tailPeer = p
 			}
 			p.next = p.next.next
-			return true
+			return
 		}
 	}
-	return false
 }
 
 func (e *EphemeralManager) isPeerOnList(id string) bool {

management/internals/modules/reverseproxy/proxy/manager/manager.go

@@ -17,7 +17,7 @@ type store interface {
 	UpdateProxyHeartbeat(ctx context.Context, p *proxy.Proxy) error
 	GetActiveProxyClusterAddresses(ctx context.Context) ([]string, error)
 	GetActiveProxyClusterAddressesForAccount(ctx context.Context, accountID string) ([]string, error)
-	GetProxyClusters(ctx context.Context, accountID string) ([]proxy.Cluster, error)
+	GetActiveProxyClusters(ctx context.Context, accountID string) ([]proxy.Cluster, error)
 	GetClusterSupportsCustomPorts(ctx context.Context, clusterAddr string) *bool
 	GetClusterRequireSubdomain(ctx context.Context, clusterAddr string) *bool
 	GetClusterSupportsCrowdSec(ctx context.Context, clusterAddr string) *bool

management/internals/modules/reverseproxy/proxy/manager/manager_test.go

@@ -57,7 +57,7 @@ func (m *mockStore) GetActiveProxyClusterAddressesForAccount(ctx context.Context
 	}
 	return nil, nil
 }
-func (m *mockStore) GetProxyClusters(_ context.Context, _ string) ([]proxy.Cluster, error) {
+func (m *mockStore) GetActiveProxyClusters(_ context.Context, _ string) ([]proxy.Cluster, error) {
 	return nil, nil
 }
 func (m *mockStore) CleanupStaleProxies(ctx context.Context, d time.Duration) error {

management/internals/modules/reverseproxy/proxy/proxy.go

@@ -42,35 +42,10 @@ func (Proxy) TableName() string {
 	return "proxies"
 }
 
-// ClusterType is the source of a proxy cluster.
-type ClusterType string
-
-const (
-	// ClusterTypeAccount is a cluster operated by the account itself (BYOP) —
-	// at least one proxy row in the cluster carries a non-NULL account_id.
-	ClusterTypeAccount ClusterType = "account"
-	// ClusterTypeShared is a cluster operated by NetBird and shared across
-	// accounts — all proxy rows in the cluster have account_id IS NULL.
-	ClusterTypeShared ClusterType = "shared"
-)
-
 // Cluster represents a group of proxy nodes serving the same address.
-//
-// Online and ConnectedProxies derive from the same 2-min active window
-// the rest of the module uses, but Cluster rows are not gated on it —
-// the cluster listing surfaces offline clusters too so operators can
-// see and clean them up. The 1-hour heartbeat reaper still bounds the
-// table eventually.
 type Cluster struct {
 	ID               string
 	Address          string
-	Type             ClusterType
-	Online           bool
 	ConnectedProxies int
-	// Capability flags. *bool because nil means "no proxy reported a
-	// capability for this cluster" — the dashboard renders these as
-	// unknown rather than false.
-	SupportsCustomPorts *bool
-	RequireSubdomain    *bool
-	SupportsCrowdSec    *bool
+	SelfHosted       bool
 }

management/internals/modules/reverseproxy/service/interface.go

@@ -9,7 +9,7 @@ import (
 )
 
 type Manager interface {
-	GetClusters(ctx context.Context, accountID, userID string) ([]proxy.Cluster, error)
+	GetActiveClusters(ctx context.Context, accountID, userID string) ([]proxy.Cluster, error)
 	DeleteAccountCluster(ctx context.Context, accountID, userID, clusterAddress string) error
 	GetAllServices(ctx context.Context, accountID, userID string) ([]*Service, error)
 	GetService(ctx context.Context, accountID, userID, serviceID string) (*Service, error)

management/internals/modules/reverseproxy/service/interface_mock.go

@@ -65,20 +65,6 @@ func (mr *MockManagerMockRecorder) CreateServiceFromPeer(ctx, accountID, peerID,
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "CreateServiceFromPeer", reflect.TypeOf((*MockManager)(nil).CreateServiceFromPeer), ctx, accountID, peerID, req)
 }
 
-// DeleteAccountCluster mocks base method.
-func (m *MockManager) DeleteAccountCluster(ctx context.Context, accountID, userID, clusterAddress string) error {
-	m.ctrl.T.Helper()
-	ret := m.ctrl.Call(m, "DeleteAccountCluster", ctx, accountID, userID, clusterAddress)
-	ret0, _ := ret[0].(error)
-	return ret0
-}
-
-// DeleteAccountCluster indicates an expected call of DeleteAccountCluster.
-func (mr *MockManagerMockRecorder) DeleteAccountCluster(ctx, accountID, userID, clusterAddress interface{}) *gomock.Call {
-	mr.mock.ctrl.T.Helper()
-	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "DeleteAccountCluster", reflect.TypeOf((*MockManager)(nil).DeleteAccountCluster), ctx, accountID, userID, clusterAddress)
-}
-
 // DeleteAllServices mocks base method.
 func (m *MockManager) DeleteAllServices(ctx context.Context, accountID, userID string) error {
 	m.ctrl.T.Helper()
@@ -93,6 +79,20 @@ func (mr *MockManagerMockRecorder) DeleteAllServices(ctx, accountID, userID inte
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "DeleteAllServices", reflect.TypeOf((*MockManager)(nil).DeleteAllServices), ctx, accountID, userID)
 }
 
+// DeleteAccountCluster mocks base method.
+func (m *MockManager) DeleteAccountCluster(ctx context.Context, accountID, userID, clusterAddress string) error {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "DeleteAccountCluster", ctx, accountID, userID, clusterAddress)
+	ret0, _ := ret[0].(error)
+	return ret0
+}
+
+// DeleteAccountCluster indicates an expected call of DeleteAccountCluster.
+func (mr *MockManagerMockRecorder) DeleteAccountCluster(ctx, accountID, userID, clusterAddress interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "DeleteAccountCluster", reflect.TypeOf((*MockManager)(nil).DeleteAccountCluster), ctx, accountID, userID, clusterAddress)
+}
+
 // DeleteService mocks base method.
 func (m *MockManager) DeleteService(ctx context.Context, accountID, userID, serviceID string) error {
 	m.ctrl.T.Helper()
@@ -122,6 +122,21 @@ func (mr *MockManagerMockRecorder) GetAccountServices(ctx, accountID interface{}
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetAccountServices", reflect.TypeOf((*MockManager)(nil).GetAccountServices), ctx, accountID)
 }
 
+// GetActiveClusters mocks base method.
+func (m *MockManager) GetActiveClusters(ctx context.Context, accountID, userID string) ([]proxy.Cluster, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "GetActiveClusters", ctx, accountID, userID)
+	ret0, _ := ret[0].([]proxy.Cluster)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// GetActiveClusters indicates an expected call of GetActiveClusters.
+func (mr *MockManagerMockRecorder) GetActiveClusters(ctx, accountID, userID interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetActiveClusters", reflect.TypeOf((*MockManager)(nil).GetActiveClusters), ctx, accountID, userID)
+}
+
 // GetAllServices mocks base method.
 func (m *MockManager) GetAllServices(ctx context.Context, accountID, userID string) ([]*Service, error) {
 	m.ctrl.T.Helper()
@@ -137,19 +152,19 @@ func (mr *MockManagerMockRecorder) GetAllServices(ctx, accountID, userID interfa
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetAllServices", reflect.TypeOf((*MockManager)(nil).GetAllServices), ctx, accountID, userID)
 }
 
-// GetClusters mocks base method.
-func (m *MockManager) GetClusters(ctx context.Context, accountID, userID string) ([]proxy.Cluster, error) {
+// GetServiceByDomain mocks base method.
+func (m *MockManager) GetServiceByDomain(ctx context.Context, domain string) (*Service, error) {
 	m.ctrl.T.Helper()
-	ret := m.ctrl.Call(m, "GetClusters", ctx, accountID, userID)
-	ret0, _ := ret[0].([]proxy.Cluster)
+	ret := m.ctrl.Call(m, "GetServiceByDomain", ctx, domain)
+	ret0, _ := ret[0].(*Service)
 	ret1, _ := ret[1].(error)
 	return ret0, ret1
 }
 
-// GetClusters indicates an expected call of GetClusters.
-func (mr *MockManagerMockRecorder) GetClusters(ctx, accountID, userID interface{}) *gomock.Call {
+// GetServiceByDomain indicates an expected call of GetServiceByDomain.
+func (mr *MockManagerMockRecorder) GetServiceByDomain(ctx, domain interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
-	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetClusters", reflect.TypeOf((*MockManager)(nil).GetClusters), ctx, accountID, userID)
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetServiceByDomain", reflect.TypeOf((*MockManager)(nil).GetServiceByDomain), ctx, domain)
 }
 
 // GetGlobalServices mocks base method.
@@ -182,21 +197,6 @@ func (mr *MockManagerMockRecorder) GetService(ctx, accountID, userID, serviceID
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetService", reflect.TypeOf((*MockManager)(nil).GetService), ctx, accountID, userID, serviceID)
 }
 
-// GetServiceByDomain mocks base method.
-func (m *MockManager) GetServiceByDomain(ctx context.Context, domain string) (*Service, error) {
-	m.ctrl.T.Helper()
-	ret := m.ctrl.Call(m, "GetServiceByDomain", ctx, domain)
-	ret0, _ := ret[0].(*Service)
-	ret1, _ := ret[1].(error)
-	return ret0, ret1
-}
-
-// GetServiceByDomain indicates an expected call of GetServiceByDomain.
-func (mr *MockManagerMockRecorder) GetServiceByDomain(ctx, domain interface{}) *gomock.Call {
-	mr.mock.ctrl.T.Helper()
-	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetServiceByDomain", reflect.TypeOf((*MockManager)(nil).GetServiceByDomain), ctx, domain)
-}
-
 // GetServiceByID mocks base method.
 func (m *MockManager) GetServiceByID(ctx context.Context, accountID, serviceID string) (*Service, error) {
 	m.ctrl.T.Helper()

management/internals/modules/reverseproxy/service/manager/api.go

@@ -187,7 +187,7 @@ func (h *handler) getClusters(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	clusters, err := h.manager.GetClusters(r.Context(), userAuth.AccountId, userAuth.UserId)
+	clusters, err := h.manager.GetActiveClusters(r.Context(), userAuth.AccountId, userAuth.UserId)
 	if err != nil {
 		util.WriteError(r.Context(), err, w)
 		return
@@ -196,14 +196,10 @@ func (h *handler) getClusters(w http.ResponseWriter, r *http.Request) {
 	apiClusters := make([]api.ProxyCluster, 0, len(clusters))
 	for _, c := range clusters {
 		apiClusters = append(apiClusters, api.ProxyCluster{
-			Id:                  c.ID,
-			Address:             c.Address,
-			Type:                api.ProxyClusterType(c.Type),
-			Online:              c.Online,
-			ConnectedProxies:    c.ConnectedProxies,
-			SupportsCustomPorts: c.SupportsCustomPorts,
-			RequireSubdomain:    c.RequireSubdomain,
-			SupportsCrowdsec:    c.SupportsCrowdSec,
+			Id:               c.ID,
+			Address:          c.Address,
+			ConnectedProxies: c.ConnectedProxies,
+			SelfHosted:       c.SelfHosted,
 		})
 	}
 

management/internals/modules/reverseproxy/service/manager/manager.go

@@ -81,7 +81,6 @@ type ClusterDeriver interface {
 type CapabilityProvider interface {
 	ClusterSupportsCustomPorts(ctx context.Context, clusterAddr string) *bool
 	ClusterRequireSubdomain(ctx context.Context, clusterAddr string) *bool
-	ClusterSupportsCrowdSec(ctx context.Context, clusterAddr string) *bool
 }
 
 type Manager struct {
@@ -113,12 +112,8 @@ func (m *Manager) StartExposeReaper(ctx context.Context) {
 	m.exposeReaper.StartExposeReaper(ctx)
 }
 
-// GetClusters returns every proxy cluster visible to the account
-// (shared + its own BYOP), regardless of whether any proxy in the
-// cluster is currently heartbeating. Each cluster is enriched with the
-// capability flags reported by its active proxies so the dashboard can
-// render feature support without a second round-trip.
-func (m *Manager) GetClusters(ctx context.Context, accountID, userID string) ([]proxy.Cluster, error) {
+// GetActiveClusters returns all active proxy clusters with their connected proxy count.
+func (m *Manager) GetActiveClusters(ctx context.Context, accountID, userID string) ([]proxy.Cluster, error) {
 	ok, err := m.permissionsManager.ValidateUserPermissions(ctx, accountID, userID, modules.Services, operations.Read)
 	if err != nil {
 		return nil, status.NewPermissionValidationError(err)
@@ -127,18 +122,7 @@ func (m *Manager) GetClusters(ctx context.Context, accountID, userID string) ([]
 		return nil, status.NewPermissionDeniedError()
 	}
 
-	clusters, err := m.store.GetProxyClusters(ctx, accountID)
-	if err != nil {
-		return nil, err
-	}
-
-	for i := range clusters {
-		clusters[i].SupportsCustomPorts = m.capabilities.ClusterSupportsCustomPorts(ctx, clusters[i].Address)
-		clusters[i].RequireSubdomain = m.capabilities.ClusterRequireSubdomain(ctx, clusters[i].Address)
-		clusters[i].SupportsCrowdSec = m.capabilities.ClusterSupportsCrowdSec(ctx, clusters[i].Address)
-	}
-
-	return clusters, nil
+	return m.store.GetActiveProxyClusters(ctx, accountID)
 }
 
 // DeleteAccountCluster removes all proxy registrations for the given cluster address

management/internals/server/controllers.go

@@ -112,11 +112,7 @@ func (s *BaseServer) AuthManager() auth.Manager {
 
 func (s *BaseServer) EphemeralManager() ephemeral.Manager {
 	return Create(s, func() ephemeral.Manager {
-		em := manager.NewEphemeralManager(s.Store(), s.PeersManager())
-		if metrics := s.Metrics(); metrics != nil {
-			em.SetMetrics(metrics.EphemeralPeersMetrics())
-		}
-		return em
+		return manager.NewEphemeralManager(s.Store(), s.PeersManager())
 	})
 }
 

management/internals/shared/grpc/conversion.go

@@ -98,10 +98,7 @@ func toPeerConfig(peer *nbpeer.Peer, network *types.Network, dnsName string, set
 
 	sshConfig := &proto.SSHConfig{
 		SshEnabled: peer.SSHEnabled || enableSSH,
-	}
-
-	if sshConfig.SshEnabled {
-		sshConfig.JwtConfig = buildJWTConfig(httpConfig, deviceFlowConfig)
+		JwtConfig:  buildJWTConfig(httpConfig, deviceFlowConfig),
 	}
 
 	peerConfig := &proto.PeerConfig{
@@ -134,13 +131,14 @@ func ToSyncResponse(ctx context.Context, config *nbconfig.Config, httpConfig *nb
 	includeIPv6 := peer.SupportsIPv6() && peer.IPv6.IsValid()
 	useSourcePrefixes := peer.SupportsSourcePrefixes()
 
+	peerConfig := toPeerConfig(peer, networkMap.Network, dnsName, settings, httpConfig, deviceFlowConfig, networkMap.EnableSSH)
 	response := &proto.SyncResponse{
-		PeerConfig: toPeerConfig(peer, networkMap.Network, dnsName, settings, httpConfig, deviceFlowConfig, networkMap.EnableSSH),
+		PeerConfig: peerConfig,
 		NetworkMap: &proto.NetworkMap{
 			Serial:     networkMap.Network.CurrentSerial(),
 			Routes:     toProtocolRoutes(networkMap.Routes),
 			DNSConfig:  toProtocolDNSConfig(networkMap.DNSConfig, dnsCache, dnsFwdPort),
-			PeerConfig: toPeerConfig(peer, networkMap.Network, dnsName, settings, httpConfig, deviceFlowConfig, networkMap.EnableSSH),
+			PeerConfig: peerConfig,
 		},
 		Checks: toProtocolChecks(ctx, checks),
 	}
@@ -149,8 +147,6 @@ func ToSyncResponse(ctx context.Context, config *nbconfig.Config, httpConfig *nb
 	extendedConfig := integrationsConfig.ExtendNetBirdConfig(peer.ID, peerGroups, nbConfig, extraSettings)
 	response.NetbirdConfig = extendedConfig
 
-	response.NetworkMap.PeerConfig = response.PeerConfig
-
 	remotePeers := make([]*proto.RemotePeerConfig, 0, len(networkMap.Peers)+len(networkMap.OfflinePeers))
 	remotePeers = appendRemotePeerConfig(remotePeers, networkMap.Peers, dnsName, includeIPv6)
 	response.RemotePeers = remotePeers
@@ -176,15 +172,21 @@ func ToSyncResponse(ctx context.Context, config *nbconfig.Config, httpConfig *nb
 		response.NetworkMap.ForwardingRules = forwardingRules
 	}
 
+	userIDClaim := auth.DefaultUserIDClaim
+	if httpConfig != nil && httpConfig.AuthUserIDClaim != "" {
+		userIDClaim = httpConfig.AuthUserIDClaim
+	}
+
 	if networkMap.AuthorizedUsers != nil {
 		hashedUsers, machineUsers := buildAuthorizedUsersProto(ctx, networkMap.AuthorizedUsers)
-		userIDClaim := auth.DefaultUserIDClaim
-		if httpConfig != nil && httpConfig.AuthUserIDClaim != "" {
-			userIDClaim = httpConfig.AuthUserIDClaim
-		}
 		response.NetworkMap.SshAuth = &proto.SSHAuth{AuthorizedUsers: hashedUsers, MachineUsers: machineUsers, UserIDClaim: userIDClaim}
 	}
 
+	if networkMap.VNCAuthorizedUsers != nil {
+		hashedUsers, machineUsers := buildAuthorizedUsersProto(ctx, networkMap.VNCAuthorizedUsers)
+		response.NetworkMap.VncAuth = &proto.VNCAuth{AuthorizedUsers: hashedUsers, MachineUsers: machineUsers, UserIDClaim: userIDClaim}
+	}
+
 	return response
 }
 

management/internals/shared/grpc/proxy.go

@@ -9,7 +9,6 @@ import (
 	"encoding/hex"
 	"errors"
 	"fmt"
-	"io"
 	"net"
 	"net/http"
 	"net/url"
@@ -137,12 +136,9 @@ type proxyConnection struct {
 	tokenID      string
 	capabilities *proto.ProxyCapabilities
 	stream       proto.ProxyService_GetMappingUpdateServer
-	// syncStream is set when the proxy connected via SyncMappings.
-	// When non-nil, the sender goroutine uses this instead of stream.
-	syncStream proto.ProxyService_SyncMappingsServer
-	sendChan   chan *proto.GetMappingUpdateResponse
-	ctx        context.Context
-	cancel     context.CancelFunc
+	sendChan     chan *proto.GetMappingUpdateResponse
+	ctx          context.Context
+	cancel       context.CancelFunc
 }
 
 func enforceAccountScope(ctx context.Context, requestAccountID string) error {
@@ -210,322 +206,145 @@ func (s *ProxyServiceServer) SetProxyController(proxyController proxy.Controller
 	s.proxyController = proxyController
 }
 
-// proxyConnectParams holds the validated parameters extracted from either
-// a GetMappingUpdateRequest or a SyncMappingsInit message.
-type proxyConnectParams struct {
-	proxyID      string
-	address      string
-	capabilities *proto.ProxyCapabilities
-}
-
 // GetMappingUpdate handles the control stream with proxy clients
 func (s *ProxyServiceServer) GetMappingUpdate(req *proto.GetMappingUpdateRequest, stream proto.ProxyService_GetMappingUpdateServer) error {
-	params, err := s.validateProxyConnect(req.GetProxyId(), req.GetAddress(), stream.Context())
-	if err != nil {
-		return err
-	}
-	params.capabilities = req.GetCapabilities()
+	ctx := stream.Context()
 
-	conn, proxyRecord, err := s.registerProxyConnection(stream.Context(), params, &proxyConnection{
-		stream: stream,
-	})
-	if err != nil {
-		return err
-	}
-
-	if err := s.sendSnapshot(stream.Context(), conn); err != nil {
-		s.cleanupFailedSnapshot(stream.Context(), conn)
-		return fmt.Errorf("send snapshot to proxy %s: %w", params.proxyID, err)
-	}
-
-	errChan := make(chan error, 2)
-	go s.sender(conn, errChan)
-
-	return s.serveProxyConnection(conn, proxyRecord, errChan, false)
-}
-
-// SyncMappings implements the bidirectional SyncMappings RPC.
-// It mirrors GetMappingUpdate but provides application-level back-pressure:
-// management waits for an ack from the proxy before sending the next batch.
-func (s *ProxyServiceServer) SyncMappings(stream proto.ProxyService_SyncMappingsServer) error {
-	init, err := recvSyncInit(stream)
-	if err != nil {
-		return err
-	}
-
-	params, err := s.validateProxyConnect(init.GetProxyId(), init.GetAddress(), stream.Context())
-	if err != nil {
-		return err
-	}
-	params.capabilities = init.GetCapabilities()
-
-	conn, proxyRecord, err := s.registerProxyConnection(stream.Context(), params, &proxyConnection{
-		syncStream: stream,
-	})
-	if err != nil {
-		return err
-	}
-
-	if err := s.sendSnapshotSync(stream.Context(), conn, stream); err != nil {
-		s.cleanupFailedSnapshot(stream.Context(), conn)
-		return fmt.Errorf("send snapshot to proxy %s: %w", params.proxyID, err)
-	}
-
-	errChan := make(chan error, 2)
-	go s.sender(conn, errChan)
-	go s.drainRecv(stream, errChan)
-
-	return s.serveProxyConnection(conn, proxyRecord, errChan, true)
-}
-
-// recvSyncInit receives and validates the first message on a SyncMappings stream.
-func recvSyncInit(stream proto.ProxyService_SyncMappingsServer) (*proto.SyncMappingsInit, error) {
-	firstMsg, err := stream.Recv()
-	if err != nil {
-		return nil, status.Errorf(codes.Internal, "receive init: %v", err)
-	}
-	init := firstMsg.GetInit()
-	if init == nil {
-		return nil, status.Errorf(codes.InvalidArgument, "first message must be init")
-	}
-	return init, nil
-}
-
-// validateProxyConnect validates the proxy ID and address, and checks cluster
-// address availability for account-scoped tokens.
-func (s *ProxyServiceServer) validateProxyConnect(proxyID, address string, ctx context.Context) (proxyConnectParams, error) {
-	if proxyID == "" {
-		return proxyConnectParams{}, status.Errorf(codes.InvalidArgument, "proxy_id is required")
-	}
-	if !isProxyAddressValid(address) {
-		return proxyConnectParams{}, status.Errorf(codes.InvalidArgument, "proxy address is invalid")
-	}
-
-	token := GetProxyTokenFromContext(ctx)
-	if token != nil && token.AccountID != nil {
-		available, err := s.proxyManager.IsClusterAddressAvailable(ctx, address, *token.AccountID)
-		if err != nil {
-			return proxyConnectParams{}, status.Errorf(codes.Internal, "check cluster address: %v", err)
-		}
-		if !available {
-			return proxyConnectParams{}, status.Errorf(codes.AlreadyExists, "cluster address %s is already in use", address)
-		}
-	}
-
-	return proxyConnectParams{proxyID: proxyID, address: address}, nil
-}
-
-// registerProxyConnection creates a proxyConnection, registers it with the
-// proxy manager and cluster, and stores it in connectedProxies. The caller
-// provides a partially initialised connSeed with stream-specific fields set;
-// the remaining fields are filled in here.
-func (s *ProxyServiceServer) registerProxyConnection(ctx context.Context, params proxyConnectParams, connSeed *proxyConnection) (*proxyConnection, *proxy.Proxy, error) {
 	peerInfo := PeerIPFromContext(ctx)
+	log.Infof("New proxy connection from %s", peerInfo)
+
+	proxyID := req.GetProxyId()
+	if proxyID == "" {
+		return status.Errorf(codes.InvalidArgument, "proxy_id is required")
+	}
+
+	proxyAddress := req.GetAddress()
+	if !isProxyAddressValid(proxyAddress) {
+		return status.Errorf(codes.InvalidArgument, "proxy address is invalid")
+	}
 
 	var accountID *string
-	var tokenID string
-	if token := GetProxyTokenFromContext(ctx); token != nil {
-		if token.AccountID != nil {
-			accountID = token.AccountID
+	token := GetProxyTokenFromContext(ctx)
+	if token != nil && token.AccountID != nil {
+		accountID = token.AccountID
+
+		available, err := s.proxyManager.IsClusterAddressAvailable(ctx, proxyAddress, *accountID)
+		if err != nil {
+			return status.Errorf(codes.Internal, "check cluster address: %v", err)
 		}
+		if !available {
+			return status.Errorf(codes.AlreadyExists, "cluster address %s is already in use", proxyAddress)
+		}
+	}
+
+	var tokenID string
+	if token != nil {
 		tokenID = token.ID
 	}
 
 	sessionID := uuid.NewString()
-	s.supersedePriorConnection(params.proxyID, sessionID)
+
+	if old, loaded := s.connectedProxies.Load(proxyID); loaded {
+		oldConn := old.(*proxyConnection)
+		log.WithFields(log.Fields{
+			"proxy_id":       proxyID,
+			"old_session_id": oldConn.sessionID,
+			"new_session_id": sessionID,
+		}).Info("Superseding existing proxy connection")
+		oldConn.cancel()
+	}
 
 	connCtx, cancel := context.WithCancel(ctx)
-	connSeed.proxyID = params.proxyID
-	connSeed.sessionID = sessionID
-	connSeed.address = params.address
-	connSeed.accountID = accountID
-	connSeed.tokenID = tokenID
-	connSeed.capabilities = params.capabilities
-	connSeed.sendChan = make(chan *proto.GetMappingUpdateResponse, 100)
-	connSeed.ctx = connCtx
-	connSeed.cancel = cancel
+	conn := &proxyConnection{
+		proxyID:      proxyID,
+		sessionID:    sessionID,
+		address:      proxyAddress,
+		accountID:    accountID,
+		tokenID:      tokenID,
+		capabilities: req.GetCapabilities(),
+		stream:       stream,
+		sendChan:     make(chan *proto.GetMappingUpdateResponse, 100),
+		ctx:          connCtx,
+		cancel:       cancel,
+	}
 
 	var caps *proxy.Capabilities
-	if c := params.capabilities; c != nil {
+	if c := req.GetCapabilities(); c != nil {
 		caps = &proxy.Capabilities{
 			SupportsCustomPorts: c.SupportsCustomPorts,
 			RequireSubdomain:    c.RequireSubdomain,
 			SupportsCrowdsec:    c.SupportsCrowdsec,
 		}
 	}
-
-	proxyRecord, err := s.proxyManager.Connect(ctx, params.proxyID, sessionID, params.address, peerInfo, accountID, caps)
+	proxyRecord, err := s.proxyManager.Connect(ctx, proxyID, sessionID, proxyAddress, peerInfo, accountID, caps)
 	if err != nil {
 		cancel()
 		if accountID != nil {
-			return nil, nil, status.Errorf(codes.Internal, "failed to register BYOP proxy: %v", err)
+			return status.Errorf(codes.Internal, "failed to register BYOP proxy: %v", err)
 		}
-		log.WithContext(ctx).Warnf("failed to register proxy %s in database: %v", params.proxyID, err)
-		return nil, nil, status.Errorf(codes.Internal, "register proxy in database: %v", err)
+		log.WithContext(ctx).Warnf("failed to register proxy %s in database: %v", proxyID, err)
+		return status.Errorf(codes.Internal, "register proxy in database: %v", err)
 	}
 
-	s.connectedProxies.Store(params.proxyID, connSeed)
-	if err := s.proxyController.RegisterProxyToCluster(ctx, params.address, params.proxyID); err != nil {
-		log.WithContext(ctx).Warnf("Failed to register proxy %s in cluster: %v", params.proxyID, err)
+	s.connectedProxies.Store(proxyID, conn)
+	if err := s.proxyController.RegisterProxyToCluster(ctx, conn.address, proxyID); err != nil {
+		log.WithContext(ctx).Warnf("Failed to register proxy %s in cluster: %v", proxyID, err)
 	}
 
-	return connSeed, proxyRecord, nil
-}
-
-// supersedePriorConnection cancels any existing connection for the given proxy.
-func (s *ProxyServiceServer) supersedePriorConnection(proxyID, newSessionID string) {
-	if old, loaded := s.connectedProxies.Load(proxyID); loaded {
-		oldConn := old.(*proxyConnection)
-		log.WithFields(log.Fields{
-			"proxy_id":       proxyID,
-			"old_session_id": oldConn.sessionID,
-			"new_session_id": newSessionID,
-		}).Info("Superseding existing proxy connection")
-		oldConn.cancel()
-	}
-}
-
-// cleanupFailedSnapshot removes the connection from the cluster and store
-// after a snapshot send failure.
-func (s *ProxyServiceServer) cleanupFailedSnapshot(ctx context.Context, conn *proxyConnection) {
-	if s.connectedProxies.CompareAndDelete(conn.proxyID, conn) {
-		if err := s.proxyController.UnregisterProxyFromCluster(context.Background(), conn.address, conn.proxyID); err != nil {
-			log.WithContext(ctx).Debugf("cleanup after snapshot failure for proxy %s: %v", conn.proxyID, err)
+	if err := s.sendSnapshot(ctx, conn); err != nil {
+		if s.connectedProxies.CompareAndDelete(proxyID, conn) {
+			if unregErr := s.proxyController.UnregisterProxyFromCluster(context.Background(), conn.address, proxyID); unregErr != nil {
+				log.WithContext(ctx).Debugf("cleanup after snapshot failure for proxy %s: %v", proxyID, unregErr)
+			}
 		}
-	}
-	conn.cancel()
-	if err := s.proxyManager.Disconnect(context.Background(), conn.proxyID, conn.sessionID); err != nil {
-		log.WithContext(ctx).Debugf("cleanup after snapshot failure for proxy %s: %v", conn.proxyID, err)
-	}
-}
-
-// drainRecv consumes and discards messages from a bidirectional stream.
-// The proxy sends an ack for every incremental update; we don't need them
-// after the snapshot phase. Recv errors are forwarded to errChan.
-func (s *ProxyServiceServer) drainRecv(stream proto.ProxyService_SyncMappingsServer, errChan chan<- error) {
-	for {
-		if _, err := stream.Recv(); err != nil {
-			errChan <- err
-			return
+		cancel()
+		if disconnErr := s.proxyManager.Disconnect(context.Background(), proxyID, sessionID); disconnErr != nil {
+			log.WithContext(ctx).Debugf("cleanup after snapshot failure for proxy %s: %v", proxyID, disconnErr)
 		}
+		return fmt.Errorf("send snapshot to proxy %s: %w", proxyID, err)
 	}
-}
 
-// serveProxyConnection runs the post-snapshot lifecycle: heartbeat, sender,
-// and wait for termination. When bidi is true, normal stream closure (EOF,
-// canceled) is treated as a clean disconnect rather than an error.
-func (s *ProxyServiceServer) serveProxyConnection(conn *proxyConnection, proxyRecord *proxy.Proxy, errChan <-chan error, bidi bool) error {
+	errChan := make(chan error, 2)
+	go s.sender(conn, errChan)
+
 	log.WithFields(log.Fields{
-		"proxy_id":      conn.proxyID,
-		"session_id":    conn.sessionID,
-		"address":       conn.address,
-		"cluster_addr":  conn.address,
-		"account_id":    conn.accountID,
+		"proxy_id":      proxyID,
+		"session_id":    sessionID,
+		"address":       proxyAddress,
+		"cluster_addr":  proxyAddress,
+		"account_id":    accountID,
 		"total_proxies": len(s.GetConnectedProxies()),
 	}).Info("Proxy registered in cluster")
+	defer func() {
+		if !s.connectedProxies.CompareAndDelete(proxyID, conn) {
+			log.Infof("Proxy %s session %s: skipping cleanup, superseded by new connection", proxyID, sessionID)
+			cancel()
+			return
+		}
 
-	defer s.disconnectProxy(conn)
-	go s.heartbeat(conn.ctx, conn, proxyRecord)
+		if err := s.proxyController.UnregisterProxyFromCluster(context.Background(), conn.address, proxyID); err != nil {
+			log.Warnf("Failed to unregister proxy %s from cluster: %v", proxyID, err)
+		}
+		if err := s.proxyManager.Disconnect(context.Background(), proxyID, sessionID); err != nil {
+			log.Warnf("Failed to mark proxy %s as disconnected: %v", proxyID, err)
+		}
+
+		cancel()
+		log.Infof("Proxy %s session %s disconnected", proxyID, sessionID)
+	}()
+
+	go s.heartbeat(connCtx, conn, proxyRecord)
 
 	select {
 	case err := <-errChan:
-		if bidi && isStreamClosed(err) {
-			log.Infof("Proxy %s stream closed", conn.proxyID)
-			return nil
-		}
-		log.Warnf("Failed to send update: %v", err)
-		return fmt.Errorf("send update to proxy %s: %w", conn.proxyID, err)
-	case <-conn.ctx.Done():
-		log.Infof("Proxy %s context canceled", conn.proxyID)
-		return conn.ctx.Err()
+		log.WithContext(ctx).Warnf("Failed to send update: %v", err)
+		return fmt.Errorf("send update to proxy %s: %w", proxyID, err)
+	case <-connCtx.Done():
+		log.WithContext(ctx).Infof("Proxy %s context canceled", proxyID)
+		return connCtx.Err()
 	}
 }
 
-// disconnectProxy removes the connection from cluster and store, unless it
-// has already been superseded by a newer connection.
-func (s *ProxyServiceServer) disconnectProxy(conn *proxyConnection) {
-	if !s.connectedProxies.CompareAndDelete(conn.proxyID, conn) {
-		log.Infof("Proxy %s session %s: skipping cleanup, superseded by new connection", conn.proxyID, conn.sessionID)
-		conn.cancel()
-		return
-	}
-
-	if err := s.proxyController.UnregisterProxyFromCluster(context.Background(), conn.address, conn.proxyID); err != nil {
-		log.Warnf("Failed to unregister proxy %s from cluster: %v", conn.proxyID, err)
-	}
-	if err := s.proxyManager.Disconnect(context.Background(), conn.proxyID, conn.sessionID); err != nil {
-		log.Warnf("Failed to mark proxy %s as disconnected: %v", conn.proxyID, err)
-	}
-
-	conn.cancel()
-	log.Infof("Proxy %s session %s disconnected", conn.proxyID, conn.sessionID)
-}
-
-// sendSnapshotSync sends the initial snapshot with back-pressure: it sends
-// one batch, then waits for the proxy to ack before sending the next.
-func (s *ProxyServiceServer) sendSnapshotSync(ctx context.Context, conn *proxyConnection, stream proto.ProxyService_SyncMappingsServer) error {
-	if !isProxyAddressValid(conn.address) {
-		return fmt.Errorf("proxy address is invalid")
-	}
-	if s.snapshotBatchSize <= 0 {
-		return fmt.Errorf("invalid snapshot batch size: %d", s.snapshotBatchSize)
-	}
-
-	mappings, err := s.snapshotServiceMappings(ctx, conn)
-	if err != nil {
-		return err
-	}
-
-	for i := 0; i < len(mappings); i += s.snapshotBatchSize {
-		end := i + s.snapshotBatchSize
-		if end > len(mappings) {
-			end = len(mappings)
-		}
-		for _, m := range mappings[i:end] {
-			token, err := s.tokenStore.GenerateToken(m.AccountId, m.Id, s.proxyTokenTTL())
-			if err != nil {
-				return fmt.Errorf("generate auth token for service %s: %w", m.Id, err)
-			}
-			m.AuthToken = token
-		}
-		if err := stream.Send(&proto.SyncMappingsResponse{
-			Mapping:             mappings[i:end],
-			InitialSyncComplete: end == len(mappings),
-		}); err != nil {
-			return fmt.Errorf("send snapshot batch: %w", err)
-		}
-
-		if err := waitForAck(stream); err != nil {
-			return err
-		}
-	}
-
-	if len(mappings) == 0 {
-		if err := stream.Send(&proto.SyncMappingsResponse{
-			InitialSyncComplete: true,
-		}); err != nil {
-			return fmt.Errorf("send snapshot completion: %w", err)
-		}
-
-		if err := waitForAck(stream); err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-func waitForAck(stream proto.ProxyService_SyncMappingsServer) error {
-	msg, err := stream.Recv()
-	if err != nil {
-		return fmt.Errorf("receive ack: %w", err)
-	}
-	if msg.GetAck() == nil {
-		return fmt.Errorf("expected ack, got %T", msg.GetMsg())
-	}
-	return nil
-}
-
 // heartbeat updates the proxy's last_seen timestamp every minute and
 // disconnects the proxy if its access token has been revoked.
 func (s *ProxyServiceServer) heartbeat(ctx context.Context, conn *proxyConnection, p *proxy.Proxy) {
@@ -562,9 +381,6 @@ func (s *ProxyServiceServer) sendSnapshot(ctx context.Context, conn *proxyConnec
 	if !isProxyAddressValid(conn.address) {
 		return fmt.Errorf("proxy address is invalid")
 	}
-	if s.snapshotBatchSize <= 0 {
-		return fmt.Errorf("invalid snapshot batch size: %d", s.snapshotBatchSize)
-	}
 
 	mappings, err := s.snapshotServiceMappings(ctx, conn)
 	if err != nil {
@@ -644,26 +460,12 @@ func isProxyAddressValid(addr string) bool {
 	return err == nil
 }
 
-// isStreamClosed returns true for errors that indicate normal stream
-// termination: io.EOF, context cancellation, or gRPC Canceled.
-func isStreamClosed(err error) bool {
-	if err == nil {
-		return false
-	}
-	if errors.Is(err, io.EOF) || errors.Is(err, context.Canceled) {
-		return true
-	}
-	return status.Code(err) == codes.Canceled
-}
-
-// sender handles sending messages to proxy.
-// When conn.syncStream is set the message is sent as SyncMappingsResponse;
-// otherwise the legacy GetMappingUpdateResponse stream is used.
+// sender handles sending messages to proxy
 func (s *ProxyServiceServer) sender(conn *proxyConnection, errChan chan<- error) {
 	for {
 		select {
 		case resp := <-conn.sendChan:
-			if err := conn.sendResponse(resp); err != nil {
+			if err := conn.stream.Send(resp); err != nil {
 				errChan <- err
 				return
 			}
@@ -673,17 +475,6 @@ func (s *ProxyServiceServer) sender(conn *proxyConnection, errChan chan<- error)
 	}
 }
 
-// sendResponse sends a mapping update on whichever stream the proxy connected with.
-func (conn *proxyConnection) sendResponse(resp *proto.GetMappingUpdateResponse) error {
-	if conn.syncStream != nil {
-		return conn.syncStream.Send(&proto.SyncMappingsResponse{
-			Mapping:             resp.Mapping,
-			InitialSyncComplete: resp.InitialSyncComplete,
-		})
-	}
-	return conn.stream.Send(resp)
-}
-
 // SendAccessLog processes access log from proxy
 func (s *ProxyServiceServer) SendAccessLog(ctx context.Context, req *proto.SendAccessLogRequest) (*proto.SendAccessLogResponse, error) {
 	accessLog := req.GetLog()
@@ -750,8 +541,8 @@ func (s *ProxyServiceServer) SendServiceUpdate(update *proto.GetMappingUpdateRes
 				return true
 			}
 			connUpdate = &proto.GetMappingUpdateResponse{
-				Mapping:             filtered,
-				InitialSyncComplete: update.InitialSyncComplete,
+				Mapping:              filtered,
+				InitialSyncComplete:  update.InitialSyncComplete,
 			}
 		}
 		resp := s.perProxyMessage(connUpdate, conn.proxyID)

management/internals/shared/grpc/proxy_group_access_test.go

@@ -109,7 +109,7 @@ func (m *mockReverseProxyManager) GetServiceByDomain(_ context.Context, domain s
 	return nil, errors.New("service not found for domain: " + domain)
 }
 
-func (m *mockReverseProxyManager) GetClusters(_ context.Context, _, _ string) ([]proxy.Cluster, error) {
+func (m *mockReverseProxyManager) GetActiveClusters(_ context.Context, _, _ string) ([]proxy.Cluster, error) {
 	return nil, nil
 }
 

management/internals/shared/grpc/server.go

@@ -674,6 +674,7 @@ func extractPeerMeta(ctx context.Context, meta *proto.PeerSystemMeta) nbpeer.Pee
 			RosenpassEnabled:      meta.GetFlags().GetRosenpassEnabled(),
 			RosenpassPermissive:   meta.GetFlags().GetRosenpassPermissive(),
 			ServerSSHAllowed:      meta.GetFlags().GetServerSSHAllowed(),
+			ServerVNCAllowed:      meta.GetFlags().GetServerVNCAllowed(),
 			DisableClientRoutes:   meta.GetFlags().GetDisableClientRoutes(),
 			DisableServerRoutes:   meta.GetFlags().GetDisableServerRoutes(),
 			DisableDNS:            meta.GetFlags().GetDisableDNS(),

management/internals/shared/grpc/sync_mappings_test.go

@@ -1,411 +0,0 @@
-package grpc
-
-import (
-	"context"
-	"fmt"
-	"sync"
-	"testing"
-	"time"
-
-	"github.com/golang/mock/gomock"
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-	"google.golang.org/grpc"
-	"google.golang.org/grpc/metadata"
-
-	rpservice "github.com/netbirdio/netbird/management/internals/modules/reverseproxy/service"
-	"github.com/netbirdio/netbird/shared/management/proto"
-)
-
-// syncRecordingStream is a mock ProxyService_SyncMappingsServer that records
-// sent messages and returns pre-loaded ack responses from Recv.
-type syncRecordingStream struct {
-	grpc.ServerStream
-
-	mu       sync.Mutex
-	sent     []*proto.SyncMappingsResponse
-	recvMsgs []*proto.SyncMappingsRequest
-	recvIdx  int
-}
-
-func (s *syncRecordingStream) Send(m *proto.SyncMappingsResponse) error {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-	s.sent = append(s.sent, m)
-	return nil
-}
-
-func (s *syncRecordingStream) Recv() (*proto.SyncMappingsRequest, error) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-	if s.recvIdx >= len(s.recvMsgs) {
-		return nil, fmt.Errorf("no more recv messages")
-	}
-	msg := s.recvMsgs[s.recvIdx]
-	s.recvIdx++
-	return msg, nil
-}
-
-func (s *syncRecordingStream) Context() context.Context     { return context.Background() }
-func (s *syncRecordingStream) SetHeader(metadata.MD) error  { return nil }
-func (s *syncRecordingStream) SendHeader(metadata.MD) error { return nil }
-func (s *syncRecordingStream) SetTrailer(metadata.MD)       {}
-func (s *syncRecordingStream) SendMsg(any) error            { return nil }
-func (s *syncRecordingStream) RecvMsg(any) error            { return nil }
-
-func ackMsg() *proto.SyncMappingsRequest {
-	return &proto.SyncMappingsRequest{
-		Msg: &proto.SyncMappingsRequest_Ack{Ack: &proto.SyncMappingsAck{}},
-	}
-}
-
-func TestSendSnapshotSync_BatchesWithAcks(t *testing.T) {
-	const cluster = "cluster.example.com"
-	const batchSize = 3
-	const totalServices = 7 // 3 + 3 + 1 → 3 batches, 3 acks (one per batch, including final)
-
-	ctrl := gomock.NewController(t)
-	mgr := rpservice.NewMockManager(ctrl)
-	mgr.EXPECT().GetGlobalServices(gomock.Any()).Return(makeServices(totalServices, cluster), nil)
-
-	s := newSnapshotTestServer(t, batchSize)
-	s.serviceManager = mgr
-
-	stream := &syncRecordingStream{
-		recvMsgs: []*proto.SyncMappingsRequest{ackMsg(), ackMsg(), ackMsg()},
-	}
-	conn := &proxyConnection{
-		proxyID:    "proxy-a",
-		address:    cluster,
-		syncStream: stream,
-	}
-
-	err := s.sendSnapshotSync(context.Background(), conn, stream)
-	require.NoError(t, err)
-
-	require.Len(t, stream.sent, 3, "should send ceil(7/3) = 3 batches")
-
-	assert.Len(t, stream.sent[0].Mapping, 3)
-	assert.False(t, stream.sent[0].InitialSyncComplete)
-
-	assert.Len(t, stream.sent[1].Mapping, 3)
-	assert.False(t, stream.sent[1].InitialSyncComplete)
-
-	assert.Len(t, stream.sent[2].Mapping, 1)
-	assert.True(t, stream.sent[2].InitialSyncComplete)
-
-	// All 3 acks consumed — including the final batch.
-	assert.Equal(t, 3, stream.recvIdx)
-}
-
-func TestSendSnapshotSync_SingleBatchWaitsForAck(t *testing.T) {
-	const cluster = "cluster.example.com"
-	const batchSize = 100
-	const totalServices = 5
-
-	ctrl := gomock.NewController(t)
-	mgr := rpservice.NewMockManager(ctrl)
-	mgr.EXPECT().GetGlobalServices(gomock.Any()).Return(makeServices(totalServices, cluster), nil)
-
-	s := newSnapshotTestServer(t, batchSize)
-	s.serviceManager = mgr
-
-	stream := &syncRecordingStream{
-		recvMsgs: []*proto.SyncMappingsRequest{ackMsg()},
-	}
-	conn := &proxyConnection{
-		proxyID:    "proxy-a",
-		address:    cluster,
-		syncStream: stream,
-	}
-
-	err := s.sendSnapshotSync(context.Background(), conn, stream)
-	require.NoError(t, err)
-
-	require.Len(t, stream.sent, 1)
-	assert.Len(t, stream.sent[0].Mapping, totalServices)
-	assert.True(t, stream.sent[0].InitialSyncComplete)
-	assert.Equal(t, 1, stream.recvIdx, "final batch ack must be consumed")
-}
-
-func TestSendSnapshotSync_EmptySnapshot(t *testing.T) {
-	const cluster = "cluster.example.com"
-
-	ctrl := gomock.NewController(t)
-	mgr := rpservice.NewMockManager(ctrl)
-	mgr.EXPECT().GetGlobalServices(gomock.Any()).Return(nil, nil)
-
-	s := newSnapshotTestServer(t, 500)
-	s.serviceManager = mgr
-
-	stream := &syncRecordingStream{
-		recvMsgs: []*proto.SyncMappingsRequest{ackMsg()},
-	}
-	conn := &proxyConnection{
-		proxyID:    "proxy-a",
-		address:    cluster,
-		syncStream: stream,
-	}
-
-	err := s.sendSnapshotSync(context.Background(), conn, stream)
-	require.NoError(t, err)
-
-	require.Len(t, stream.sent, 1, "empty snapshot must still send sync-complete")
-	assert.Empty(t, stream.sent[0].Mapping)
-	assert.True(t, stream.sent[0].InitialSyncComplete)
-	assert.Equal(t, 1, stream.recvIdx, "empty snapshot ack must be consumed")
-}
-
-func TestSendSnapshotSync_MissingAckReturnsError(t *testing.T) {
-	const cluster = "cluster.example.com"
-	const batchSize = 2
-	const totalServices = 4 // 2 batches → 1 ack needed, but we provide none
-
-	ctrl := gomock.NewController(t)
-	mgr := rpservice.NewMockManager(ctrl)
-	mgr.EXPECT().GetGlobalServices(gomock.Any()).Return(makeServices(totalServices, cluster), nil)
-
-	s := newSnapshotTestServer(t, batchSize)
-	s.serviceManager = mgr
-
-	// No acks available — Recv will return error.
-	stream := &syncRecordingStream{}
-	conn := &proxyConnection{
-		proxyID:    "proxy-a",
-		address:    cluster,
-		syncStream: stream,
-	}
-
-	err := s.sendSnapshotSync(context.Background(), conn, stream)
-	require.Error(t, err)
-	assert.Contains(t, err.Error(), "receive ack")
-	// First batch should have been sent before the error.
-	require.Len(t, stream.sent, 1)
-}
-
-func TestSendSnapshotSync_WrongMessageInsteadOfAck(t *testing.T) {
-	const cluster = "cluster.example.com"
-	const batchSize = 2
-	const totalServices = 4
-
-	ctrl := gomock.NewController(t)
-	mgr := rpservice.NewMockManager(ctrl)
-	mgr.EXPECT().GetGlobalServices(gomock.Any()).Return(makeServices(totalServices, cluster), nil)
-
-	s := newSnapshotTestServer(t, batchSize)
-	s.serviceManager = mgr
-
-	// Send an init message instead of an ack.
-	stream := &syncRecordingStream{
-		recvMsgs: []*proto.SyncMappingsRequest{
-			{Msg: &proto.SyncMappingsRequest_Init{Init: &proto.SyncMappingsInit{ProxyId: "bad"}}},
-		},
-	}
-	conn := &proxyConnection{
-		proxyID:    "proxy-a",
-		address:    cluster,
-		syncStream: stream,
-	}
-
-	err := s.sendSnapshotSync(context.Background(), conn, stream)
-	require.Error(t, err)
-	assert.Contains(t, err.Error(), "expected ack")
-}
-
-func TestSendSnapshotSync_BackPressureOrdering(t *testing.T) {
-	// Verify batches are sent strictly sequentially — batch N+1 is not sent
-	// until the ack for batch N is received, including the final batch.
-	const cluster = "cluster.example.com"
-	const batchSize = 2
-	const totalServices = 6 // 3 batches, 3 acks
-
-	ctrl := gomock.NewController(t)
-	mgr := rpservice.NewMockManager(ctrl)
-	mgr.EXPECT().GetGlobalServices(gomock.Any()).Return(makeServices(totalServices, cluster), nil)
-
-	s := newSnapshotTestServer(t, batchSize)
-	s.serviceManager = mgr
-
-	var mu sync.Mutex
-	var events []string
-
-	// Build a stream that logs send/recv events so we can verify ordering.
-	ackCh := make(chan struct{}, 3)
-	stream := &orderTrackingStream{
-		mu:     &mu,
-		events: &events,
-		ackCh:  ackCh,
-	}
-	conn := &proxyConnection{
-		proxyID:    "proxy-a",
-		address:    cluster,
-		syncStream: stream,
-	}
-
-	// Feed acks asynchronously after a short delay to simulate real proxy.
-	go func() {
-		for range 3 {
-			time.Sleep(10 * time.Millisecond)
-			ackCh <- struct{}{}
-		}
-	}()
-
-	err := s.sendSnapshotSync(context.Background(), conn, stream)
-	require.NoError(t, err)
-
-	mu.Lock()
-	defer mu.Unlock()
-
-	// Expected: send, recv-ack, send, recv-ack, send, recv-ack.
-	require.Len(t, events, 6)
-	assert.Equal(t, "send", events[0])
-	assert.Equal(t, "recv", events[1])
-	assert.Equal(t, "send", events[2])
-	assert.Equal(t, "recv", events[3])
-	assert.Equal(t, "send", events[4])
-	assert.Equal(t, "recv", events[5])
-}
-
-// orderTrackingStream logs "send" and "recv" events and blocks Recv until
-// an ack is signaled via ackCh.
-type orderTrackingStream struct {
-	grpc.ServerStream
-	mu     *sync.Mutex
-	events *[]string
-	ackCh  chan struct{}
-}
-
-func (s *orderTrackingStream) Send(_ *proto.SyncMappingsResponse) error {
-	s.mu.Lock()
-	*s.events = append(*s.events, "send")
-	s.mu.Unlock()
-	return nil
-}
-
-func (s *orderTrackingStream) Recv() (*proto.SyncMappingsRequest, error) {
-	<-s.ackCh
-	s.mu.Lock()
-	*s.events = append(*s.events, "recv")
-	s.mu.Unlock()
-	return ackMsg(), nil
-}
-
-func (s *orderTrackingStream) Context() context.Context     { return context.Background() }
-func (s *orderTrackingStream) SetHeader(metadata.MD) error  { return nil }
-func (s *orderTrackingStream) SendHeader(metadata.MD) error { return nil }
-func (s *orderTrackingStream) SetTrailer(metadata.MD)       {}
-func (s *orderTrackingStream) SendMsg(any) error            { return nil }
-func (s *orderTrackingStream) RecvMsg(any) error            { return nil }
-
-func TestSendSnapshotSync_TokensGeneratedPerBatch(t *testing.T) {
-	const cluster = "cluster.example.com"
-	const batchSize = 2
-	const totalServices = 4
-	const ttl = 100 * time.Millisecond
-	const ackDelay = 200 * time.Millisecond
-
-	ctrl := gomock.NewController(t)
-	mgr := rpservice.NewMockManager(ctrl)
-	mgr.EXPECT().GetGlobalServices(gomock.Any()).Return(makeServices(totalServices, cluster), nil)
-
-	s := newSnapshotTestServer(t, batchSize)
-	s.serviceManager = mgr
-	s.tokenTTL = ttl
-
-	// Build a stream that validates tokens immediately on Send, then
-	// delays the ack to ensure the next batch's tokens are generated fresh.
-	var validateErrs []error
-	ackCh := make(chan struct{}, 2)
-	stream := &tokenValidatingSyncStream{
-		tokenStore:   s.tokenStore,
-		validateErrs: &validateErrs,
-		ackCh:        ackCh,
-	}
-	conn := &proxyConnection{
-		proxyID:    "proxy-a",
-		address:    cluster,
-		syncStream: stream,
-	}
-
-	go func() {
-		// Delay first ack so that if tokens were all generated upfront they'd expire.
-		time.Sleep(ackDelay)
-		ackCh <- struct{}{}
-		// Final batch ack — immediate.
-		ackCh <- struct{}{}
-	}()
-
-	err := s.sendSnapshotSync(context.Background(), conn, stream)
-	require.NoError(t, err)
-	require.Empty(t, validateErrs,
-		"tokens must remain valid: per-batch generation guarantees freshness")
-}
-
-type tokenValidatingSyncStream struct {
-	grpc.ServerStream
-	tokenStore   *OneTimeTokenStore
-	validateErrs *[]error
-	ackCh        chan struct{}
-}
-
-func (s *tokenValidatingSyncStream) Send(m *proto.SyncMappingsResponse) error {
-	for _, mapping := range m.Mapping {
-		if err := s.tokenStore.ValidateAndConsume(mapping.AuthToken, mapping.AccountId, mapping.Id); err != nil {
-			*s.validateErrs = append(*s.validateErrs, fmt.Errorf("svc %s: %w", mapping.Id, err))
-		}
-	}
-	return nil
-}
-
-func (s *tokenValidatingSyncStream) Recv() (*proto.SyncMappingsRequest, error) {
-	<-s.ackCh
-	return ackMsg(), nil
-}
-
-func (s *tokenValidatingSyncStream) Context() context.Context     { return context.Background() }
-func (s *tokenValidatingSyncStream) SetHeader(metadata.MD) error  { return nil }
-func (s *tokenValidatingSyncStream) SendHeader(metadata.MD) error { return nil }
-func (s *tokenValidatingSyncStream) SetTrailer(metadata.MD)       {}
-func (s *tokenValidatingSyncStream) SendMsg(any) error            { return nil }
-func (s *tokenValidatingSyncStream) RecvMsg(any) error            { return nil }
-
-func TestConnectionSendResponse_RoutesToSyncStream(t *testing.T) {
-	stream := &syncRecordingStream{}
-	conn := &proxyConnection{
-		syncStream: stream,
-	}
-
-	resp := &proto.GetMappingUpdateResponse{
-		Mapping: []*proto.ProxyMapping{
-			{Id: "svc-1", AccountId: "acct-1", Domain: "example.com"},
-		},
-		InitialSyncComplete: true,
-	}
-
-	err := conn.sendResponse(resp)
-	require.NoError(t, err)
-
-	require.Len(t, stream.sent, 1)
-	assert.Len(t, stream.sent[0].Mapping, 1)
-	assert.Equal(t, "svc-1", stream.sent[0].Mapping[0].Id)
-	assert.True(t, stream.sent[0].InitialSyncComplete)
-}
-
-func TestConnectionSendResponse_RoutesToLegacyStream(t *testing.T) {
-	stream := &recordingStream{}
-	conn := &proxyConnection{
-		stream: stream,
-	}
-
-	resp := &proto.GetMappingUpdateResponse{
-		Mapping: []*proto.ProxyMapping{
-			{Id: "svc-2", AccountId: "acct-2"},
-		},
-	}
-
-	err := conn.sendResponse(resp)
-	require.NoError(t, err)
-
-	require.Len(t, stream.messages, 1)
-	assert.Equal(t, "svc-2", stream.messages[0].Mapping[0].Id)
-}

management/internals/shared/grpc/validate_session_test.go

@@ -322,7 +322,7 @@ func (m *testValidateSessionServiceManager) GetServiceByDomain(ctx context.Conte
 	return m.store.GetServiceByDomain(ctx, domain)
 }
 
-func (m *testValidateSessionServiceManager) GetClusters(_ context.Context, _, _ string) ([]proxy.Cluster, error) {
+func (m *testValidateSessionServiceManager) GetActiveClusters(_ context.Context, _, _ string) ([]proxy.Cluster, error) {
 	return nil, nil
 }