Zoltán Papp 77ec25796e client/dns/mgmt: bypass overlay for control-plane FQDN resolution
When an exit-node peer's network-map installs a 0.0.0.0/0 default route
on the overlay interface before that peer's WireGuard key material is
active, any UDP socket dialing an off-link address is routed into wt0
and the kernel returns ENOKEY.

Two places needed fixing:

 1. The mgmt cache refresh path. It reactively refreshes the
    control-plane FQDNs advertised by the mgmt (api/signal/stun/turn/
    the Relay pool root) after the daemon has installed its own
    resolv.conf pointing at the overlay listener. Previously the
    refresh dial followed the chain's upstream handler, which followed
    the overlay default route and deadlocked on ENOKEY.

 2. Foreign relay FQDN resolution. When a remote peer is homed on a
    different relay instance than us, we need to resolve a streamline-*
    subdomain that is not in the cache. That lookup went through the
    same overlay-routed upstream and failed identically, deadlocking
    the exit-node test whenever the relay LB put the two peers on
    different instances.

Fix both by giving the mgmt cache a dedicated net.Resolver that dials
the original pre-NetBird system nameservers through nbnet.NewDialer.
The dialer marks the socket as control-plane (SO_MARK on Linux,
IP_BOUND_IF on darwin, IP_UNICAST_IF on Windows); the routemanager's
policy rules keep those sockets on the underlay regardless of the
overlay default.

Pool-root domains (the Relay entries in ServerDomains) now register
through a subdomain-matching wrapper so that instance subdomains like
streamline-de-fra1-0.relay.netbird.io also hit the mgmt cache handler.
On cache miss under a pool root, ServeDNS resolves the FQDN on demand
through the bypass resolver, caches the result, and returns it.

Pool-root membership is derived dynamically from mgmt-advertised
ServerDomains.Relay[] — no hardcoded domain lists, no protocol change.
No hardcoded fallback nameservers: if the host had no original system
resolver at all, the bypass resolver stays nil and the stale-while-
revalidate cache keeps serving. The general upstream forwarder and
the user DNS path are unchanged.
2026-04-24 17:40:33 +02:00
2022-10-22 16:19:16 +02:00
2025-04-09 20:18:52 +01:00
2024-10-30 17:18:27 +01:00
2022-12-02 13:54:22 +01:00

Start using NetBird at netbird.io
See Documentation
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New: NetBird terraform provider


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)

Watch the video

Key features

Connectivity Management Security Automation Platforms
  • - [x] Kernel WireGuard
  • - [x] Linux
  • - [x] Peer-to-peer connections
  • - [x] Auto peer discovery and configuration
  • - [x] Mac
  • - [x] Connection relay fallback
  • - [x] Windows
  • - [x] IdP groups sync with JWT
  • - [x] Android
  • - [x] NAT traversal with BPF
  • - [x] Peer-to-peer encryption
  • - [x] iOS
  • - [x] OpenWRT
  • - [x] Docker

Quickstart with NetBird Cloud

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 for installations with different IDPs.

Infrastructure requirements:

  • 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 installed on the VM with the docker-compose plugin (Docker installation guide) or docker with docker-compose in version 2 or higher.
  • 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 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:
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 NetBird Agent (or Client) that manages WireGuard.
  • Every agent connects to Management Service that holds network state, manages peer IPs, and distributes network updates to agents (peers).
  • NetBird agent uses WebRTC ICE implemented in pion/ice library to discover connection candidates when establishing a peer-to-peer connection between machines.
  • Connection candidates are discovered with the help of STUN servers.
  • Agents negotiate a connection through Signal Service 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, and a secure WireGuard tunnel is established via the TURN server.

Coturn is the one that has been successfully used for STUN and TURN in NetBird setups.

See a complete architecture overview for details.

Community projects

Note: The main branch may be in an unstable or even broken state during development. For stable versions, see releases.

Support acknowledgement

In November 2022, NetBird joined the StartUpSecure program sponsored by The Federal Ministry of Education and Research of The Federal Republic of Germany. Together with CISPA Helmholtz Center for Information Security NetBird brings the security best practices and simplicity to private networking.

CISPA_Logo_BLACK_EN_RZ_RGB (1)

Testimonials

We use open-source technologies like WireGuard®, Pion ICE (WebRTC), Coturn, and Rosenpass. 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).

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 of Jason A. Donenfeld.

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