Merge pull request #192 from fosrl/dev

Add robust client connectivity support

.gitignore

@@ -6,3 +6,4 @@ nohup.out
 *.iml
 certs/
 newt_arm64
+key

README.md

@@ -47,13 +47,11 @@ When Newt receives WireGuard control messages, it will use the information encod
 -   `docker-socket` (optional): Set the Docker socket to use the container discovery integration
 -   `docker-enforce-network-validation` (optional): Validate the container target is on the same network as the newt process. Default: false
 
-### Accpet Client Connection 
+### Client Connections
 
--   `accept-clients` (optional): Enable WireGuard server mode to accept incoming newt client connections. Default: false
+-   `disable-clients` (optional): Disable clients on the WireGuard interface. Default: false (clients enabled)
-    -   `generateAndSaveKeyTo` (optional): Path to save generated private key
+-   `native` (optional): Use native WireGuard interface (requires WireGuard kernel module and Linux, must run as root). Default: false (uses userspace netstack)
-    -   `native` (optional): Use native WireGuard interface when accepting clients (requires WireGuard kernel module and Linux, must run as root). Default: false (uses userspace netstack)
+-   `interface` (optional): Name of the WireGuard interface. Default: newt
-        -   `interface` (optional): Name of the WireGuard interface. Default: newt
-        -   `keep-interface` (optional): Keep the WireGuard interface. Default: false
 
 ### Metrics & Observability
 
@@ -73,9 +71,11 @@ When Newt receives WireGuard control messages, it will use the information encod
 ### Security & TLS
 
 -   `enforce-hc-cert` (optional): Enforce certificate validation for health checks. Default: false (accepts any cert)
--   `tls-client-cert` (optional): Client certificate (p12 or pfx) for mTLS or path to client certificate (PEM format). See [mTLS](#mtls)
+-   `tls-client-cert-file` (optional): Path to client certificate file (PEM/DER format) for mTLS. See [mTLS](#mtls)
--   `tls-client-key` (optional): Path to private key for mTLS (PEM format, optional if using PKCS12)
+-   `tls-client-key` (optional): Path to client private key file (PEM/DER format) for mTLS
--   `tls-ca-cert` (optional): Path to CA certificate to verify server (PEM format, optional if using PKCS12)
+-   `tls-client-ca` (optional): Path to CA certificate file for validating remote certificates (can be specified multiple times)
+-   `tls-client-cert` (optional): Path to client certificate (PKCS12 format) - DEPRECATED: use `--tls-client-cert-file` and `--tls-client-key` instead
+-   `prefer-endpoint` (optional): Prefer this endpoint for the connection (if set, will override the endpoint from the server)
 
 ### Monitoring & Health
 
@@ -101,13 +101,11 @@ All CLI arguments can be set using environment variables as an alternative to co
 -   `DOCKER_SOCKET`: Path to Docker socket for container discovery (equivalent to `--docker-socket`)
 -   `DOCKER_ENFORCE_NETWORK_VALIDATION`: Validate container targets are on same network. Default: false (equivalent to `--docker-enforce-network-validation`)
 
-### Accept Client Connections
+### Client Connections
 
--   `ACCEPT_CLIENTS`: Enable WireGuard server mode. Default: false (equivalent to `--accept-clients`)
+-   `DISABLE_CLIENTS`: Disable clients on the WireGuard interface. Default: false (equivalent to `--disable-clients`)
--   `GENERATE_AND_SAVE_KEY_TO`: Path to save generated private key (equivalent to `--generateAndSaveKeyTo`)
 -   `USE_NATIVE_INTERFACE`: Use native WireGuard interface (Linux only). Default: false (equivalent to `--native`)
 -   `INTERFACE`: Name of the WireGuard interface. Default: newt (equivalent to `--interface`)
--   `KEEP_INTERFACE`: Keep the WireGuard interface after shutdown. Default: false (equivalent to `--keep-interface`)
 
 ### Monitoring & Health
 
@@ -132,10 +130,10 @@ All CLI arguments can be set using environment variables as an alternative to co
 ### Security & TLS
 
 -   `ENFORCE_HC_CERT`: Enforce certificate validation for health checks. Default: false (equivalent to `--enforce-hc-cert`)
--   `TLS_CLIENT_CERT`: Path to client certificate for mTLS (equivalent to `--tls-client-cert`)
+-   `TLS_CLIENT_CERT`: Path to client certificate file (PEM/DER format) for mTLS (equivalent to `--tls-client-cert-file`)
--   `TLS_CLIENT_KEY`: Path to private key for mTLS (equivalent to `--tls-client-key`)
+-   `TLS_CLIENT_KEY`: Path to client private key file (PEM/DER format) for mTLS (equivalent to `--tls-client-key`)
--   `TLS_CA_CERT`: Path to CA certificate to verify server (equivalent to `--tls-ca-cert`)
+-   `TLS_CLIENT_CAS`: Comma-separated list of CA certificate file paths for validating remote certificates (equivalent to multiple `--tls-client-ca` flags)
--   `SKIP_TLS_VERIFY`: Skip TLS verification for server connections. Default: false
+-   `TLS_CLIENT_CERT_PKCS12`: Path to client certificate (PKCS12 format) - DEPRECATED: use `TLS_CLIENT_CERT` and `TLS_CLIENT_KEY` instead
 
 ## Loading secrets from files
 
@@ -202,9 +200,9 @@ services:
             - --health-file /tmp/healthy
 ```
 
-## Accept Client Connections
+## Client Connections
 
-When the `--accept-clients` flag is enabled (or `ACCEPT_CLIENTS=true` environment variable is set), Newt operates as a WireGuard server that can accept incoming client connections from other devices. This enables peer-to-peer connectivity through the Newt instance.
+By default, Newt can accept incoming client connections from other devices, enabling peer-to-peer connectivity through the Newt instance. This behavior can be disabled with the `--disable-clients` flag (or `DISABLE_CLIENTS=true` environment variable).
 
 ### How It Works
 
@@ -260,7 +258,7 @@ To use native mode:
 3. Run Newt as root (`sudo`)
 4. Ensure the system allows creation of network interfaces
 
-Docker Compose example:
+Docker Compose example (with clients enabled by default):
 
 ```yaml
 services:
@@ -272,7 +270,6 @@ services:
             - PANGOLIN_ENDPOINT=https://example.com
             - NEWT_ID=2ix2t8xk22ubpfy
             - NEWT_SECRET=nnisrfsdfc7prqsp9ewo1dvtvci50j5uiqotez00dgap0ii2
-            - ACCEPT_CLIENTS=true
 ```
 
 ### Technical Details
@@ -394,9 +391,9 @@ newt \
 
 You can now provide separate files for:
 
-* `--tls-client-cert`: client certificate (`.crt` or `.pem`)
+* `--tls-client-cert-file`: client certificate (`.crt` or `.pem`)
 * `--tls-client-key`: client private key (`.key` or `.pem`)
-* `--tls-ca-cert`: CA cert to verify the server
+* `--tls-client-ca`: CA cert to verify the server (can be specified multiple times)
 
 Example:
 
@@ -405,9 +402,9 @@ newt \
 --id 31frd0uzbjvp721 \
 --secret h51mmlknrvrwv8s4r1i210azhumt6isgbpyavxodibx1k2d6 \
 --endpoint https://example.com \
---tls-client-cert ./client.crt \
+--tls-client-cert-file ./client.crt \
 --tls-client-key ./client.key \
---tls-ca-cert ./ca.crt
+--tls-client-ca ./ca.crt
 ```
 
 

bind/shared_bind.go

@@ -0,0 +1,675 @@
+//go:build !js
+
+package bind
+
+import (
+	"bytes"
+	"fmt"
+	"net"
+	"net/netip"
+	"runtime"
+	"sync"
+	"sync/atomic"
+
+	"github.com/fosrl/newt/logger"
+	"golang.org/x/net/ipv4"
+	"golang.org/x/net/ipv6"
+	wgConn "golang.zx2c4.com/wireguard/conn"
+)
+
+// Magic packet constants for connection testing
+// These packets are intercepted by SharedBind and responded to directly,
+// without being passed to the WireGuard device.
+var (
+	// MagicTestRequest is the prefix for a test request packet
+	// Format: PANGOLIN_TEST_REQ + 8 bytes of random data (for echo)
+	MagicTestRequest = []byte("PANGOLIN_TEST_REQ")
+
+	// MagicTestResponse is the prefix for a test response packet
+	// Format: PANGOLIN_TEST_RSP + 8 bytes echoed from request
+	MagicTestResponse = []byte("PANGOLIN_TEST_RSP")
+)
+
+const (
+	// MagicPacketDataLen is the length of random data included in test packets
+	MagicPacketDataLen = 8
+
+	// MagicTestRequestLen is the total length of a test request packet
+	MagicTestRequestLen = 17 + MagicPacketDataLen // len("PANGOLIN_TEST_REQ") + 8
+
+	// MagicTestResponseLen is the total length of a test response packet
+	MagicTestResponseLen = 17 + MagicPacketDataLen // len("PANGOLIN_TEST_RSP") + 8
+)
+
+// PacketSource identifies where a packet came from
+type PacketSource uint8
+
+const (
+	SourceSocket   PacketSource = iota // From physical UDP socket (hole-punched clients)
+	SourceNetstack                     // From netstack (relay through main tunnel)
+)
+
+// SourceAwareEndpoint wraps an endpoint with source information
+type SourceAwareEndpoint struct {
+	wgConn.Endpoint
+	source PacketSource
+}
+
+// GetSource returns the source of this endpoint
+func (e *SourceAwareEndpoint) GetSource() PacketSource {
+	return e.source
+}
+
+// injectedPacket represents a packet injected into the SharedBind from an internal source
+type injectedPacket struct {
+	data     []byte
+	endpoint wgConn.Endpoint
+}
+
+// Endpoint represents a network endpoint for the SharedBind
+type Endpoint struct {
+	AddrPort netip.AddrPort
+}
+
+// ClearSrc implements the wgConn.Endpoint interface
+func (e *Endpoint) ClearSrc() {}
+
+// DstIP implements the wgConn.Endpoint interface
+func (e *Endpoint) DstIP() netip.Addr {
+	return e.AddrPort.Addr()
+}
+
+// SrcIP implements the wgConn.Endpoint interface
+func (e *Endpoint) SrcIP() netip.Addr {
+	return netip.Addr{}
+}
+
+// DstToBytes implements the wgConn.Endpoint interface
+func (e *Endpoint) DstToBytes() []byte {
+	b, _ := e.AddrPort.MarshalBinary()
+	return b
+}
+
+// DstToString implements the wgConn.Endpoint interface
+func (e *Endpoint) DstToString() string {
+	return e.AddrPort.String()
+}
+
+// SrcToString implements the wgConn.Endpoint interface
+func (e *Endpoint) SrcToString() string {
+	return ""
+}
+
+// SharedBind is a thread-safe UDP bind that can be shared between WireGuard
+// and hole punch senders. It wraps a single UDP connection and implements
+// reference counting to prevent premature closure.
+// It also supports receiving packets from a netstack and routing responses
+// back through the appropriate source.
+type SharedBind struct {
+	mu sync.RWMutex
+
+	// The underlying UDP connection (for hole-punched clients)
+	udpConn *net.UDPConn
+
+	// IPv4 and IPv6 packet connections for advanced features
+	ipv4PC *ipv4.PacketConn
+	ipv6PC *ipv6.PacketConn
+
+	// Reference counting to prevent closing while in use
+	refCount atomic.Int32
+	closed   atomic.Bool
+
+	// Channels for receiving data
+	recvFuncs []wgConn.ReceiveFunc
+
+	// Port binding information
+	port uint16
+
+	// Channel for packets from netstack (from direct relay) - larger buffer for throughput
+	netstackPackets chan injectedPacket
+
+	// Netstack connection for sending responses back through the tunnel
+	// Using atomic.Pointer for lock-free access in hot path
+	netstackConn atomic.Pointer[net.PacketConn]
+
+	// Track which endpoints came from netstack (key: netip.AddrPort, value: struct{})
+	// Using netip.AddrPort directly as key is more efficient than string
+	netstackEndpoints sync.Map
+
+	// Pre-allocated message buffers for batch operations (Linux only)
+	ipv4Msgs []ipv4.Message
+
+	// Shutdown signal for receive goroutines
+	closeChan chan struct{}
+
+	// Callback for magic test responses (used for holepunch testing)
+	magicResponseCallback atomic.Pointer[func(addr netip.AddrPort, echoData []byte)]
+}
+
+// MagicResponseCallback is the function signature for magic packet response callbacks
+type MagicResponseCallback func(addr netip.AddrPort, echoData []byte)
+
+// New creates a new SharedBind from an existing UDP connection.
+// The SharedBind takes ownership of the connection and will close it
+// when all references are released.
+func New(udpConn *net.UDPConn) (*SharedBind, error) {
+	if udpConn == nil {
+		return nil, fmt.Errorf("udpConn cannot be nil")
+	}
+
+	bind := &SharedBind{
+		udpConn:         udpConn,
+		netstackPackets: make(chan injectedPacket, 1024), // Larger buffer for better throughput
+		closeChan:       make(chan struct{}),
+	}
+
+	// Initialize reference count to 1 (the creator holds the first reference)
+	bind.refCount.Store(1)
+
+	// Get the local port
+	if addr, ok := udpConn.LocalAddr().(*net.UDPAddr); ok {
+		bind.port = uint16(addr.Port)
+	}
+
+	return bind, nil
+}
+
+// SetNetstackConn sets the netstack connection for receiving/sending packets through the tunnel.
+// This connection is used for relay traffic that should go back through the main tunnel.
+func (b *SharedBind) SetNetstackConn(conn net.PacketConn) {
+	b.netstackConn.Store(&conn)
+}
+
+// GetNetstackConn returns the netstack connection if set
+func (b *SharedBind) GetNetstackConn() net.PacketConn {
+	ptr := b.netstackConn.Load()
+	if ptr == nil {
+		return nil
+	}
+	return *ptr
+}
+
+// InjectPacket allows injecting a packet directly into the SharedBind's receive path.
+// This is used for direct relay from netstack without going through the host network.
+// The fromAddr should be the address the packet appears to come from.
+func (b *SharedBind) InjectPacket(data []byte, fromAddr netip.AddrPort) error {
+	if b.closed.Load() {
+		return net.ErrClosed
+	}
+
+	// Unmap IPv4-in-IPv6 addresses to ensure consistency with parsed endpoints
+	if fromAddr.Addr().Is4In6() {
+		fromAddr = netip.AddrPortFrom(fromAddr.Addr().Unmap(), fromAddr.Port())
+	}
+
+	// Track this endpoint as coming from netstack so responses go back the same way
+	// Use AddrPort directly as key (more efficient than string)
+	b.netstackEndpoints.Store(fromAddr, struct{}{})
+
+	// Make a copy of the data to avoid issues with buffer reuse
+	dataCopy := make([]byte, len(data))
+	copy(dataCopy, data)
+
+	select {
+	case b.netstackPackets <- injectedPacket{
+		data:     dataCopy,
+		endpoint: &wgConn.StdNetEndpoint{AddrPort: fromAddr},
+	}:
+		return nil
+	case <-b.closeChan:
+		return net.ErrClosed
+	default:
+		// Channel full, drop the packet
+		return fmt.Errorf("netstack packet buffer full")
+	}
+}
+
+// AddRef increments the reference count. Call this when sharing
+// the bind with another component.
+func (b *SharedBind) AddRef() {
+	newCount := b.refCount.Add(1)
+	// Optional: Add logging for debugging
+	_ = newCount // Placeholder for potential logging
+}
+
+// Release decrements the reference count. When it reaches zero,
+// the underlying UDP connection is closed.
+func (b *SharedBind) Release() error {
+	newCount := b.refCount.Add(-1)
+	// Optional: Add logging for debugging
+	_ = newCount // Placeholder for potential logging
+
+	if newCount < 0 {
+		// This should never happen with proper usage
+		b.refCount.Store(0)
+		return fmt.Errorf("SharedBind reference count went negative")
+	}
+
+	if newCount == 0 {
+		return b.closeConnection()
+	}
+
+	return nil
+}
+
+// closeConnection actually closes the UDP connection
+func (b *SharedBind) closeConnection() error {
+	if !b.closed.CompareAndSwap(false, true) {
+		// Already closed
+		return nil
+	}
+
+	// Signal all goroutines to stop
+	close(b.closeChan)
+
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	var err error
+	if b.udpConn != nil {
+		err = b.udpConn.Close()
+		b.udpConn = nil
+	}
+
+	b.ipv4PC = nil
+	b.ipv6PC = nil
+
+	// Clear netstack connection (but don't close it - it's managed externally)
+	b.netstackConn.Store(nil)
+
+	// Clear tracked netstack endpoints
+	b.netstackEndpoints = sync.Map{}
+
+	return err
+}
+
+// ClearNetstackConn clears the netstack connection and tracked endpoints.
+// Call this when stopping the relay.
+func (b *SharedBind) ClearNetstackConn() {
+	b.netstackConn.Store(nil)
+
+	// Clear tracked netstack endpoints
+	b.netstackEndpoints = sync.Map{}
+}
+
+// GetUDPConn returns the underlying UDP connection.
+// The caller must not close this connection directly.
+func (b *SharedBind) GetUDPConn() *net.UDPConn {
+	b.mu.RLock()
+	defer b.mu.RUnlock()
+	return b.udpConn
+}
+
+// GetRefCount returns the current reference count (for debugging)
+func (b *SharedBind) GetRefCount() int32 {
+	return b.refCount.Load()
+}
+
+// IsClosed returns whether the bind is closed
+func (b *SharedBind) IsClosed() bool {
+	return b.closed.Load()
+}
+
+// SetMagicResponseCallback sets a callback function that will be called when
+// a magic test response packet is received. This is used for holepunch testing.
+// Pass nil to clear the callback.
+func (b *SharedBind) SetMagicResponseCallback(callback MagicResponseCallback) {
+	if callback == nil {
+		b.magicResponseCallback.Store(nil)
+	} else {
+		// Convert to the function type the atomic.Pointer expects
+		fn := func(addr netip.AddrPort, echoData []byte) {
+			callback(addr, echoData)
+		}
+		b.magicResponseCallback.Store(&fn)
+	}
+}
+
+// WriteToUDP writes data to a specific UDP address.
+// This is thread-safe and can be used by hole punch senders.
+func (b *SharedBind) WriteToUDP(data []byte, addr *net.UDPAddr) (int, error) {
+	if b.closed.Load() {
+		return 0, net.ErrClosed
+	}
+
+	b.mu.RLock()
+	conn := b.udpConn
+	b.mu.RUnlock()
+
+	if conn == nil {
+		return 0, net.ErrClosed
+	}
+
+	return conn.WriteToUDP(data, addr)
+}
+
+// Close implements the WireGuard Bind interface.
+// It decrements the reference count and closes the connection if no references remain.
+func (b *SharedBind) Close() error {
+	return b.Release()
+}
+
+// Open implements the WireGuard Bind interface.
+// Since the connection is already open, this just sets up the receive functions.
+func (b *SharedBind) Open(uport uint16) ([]wgConn.ReceiveFunc, uint16, error) {
+	if b.closed.Load() {
+		return nil, 0, net.ErrClosed
+	}
+
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if b.udpConn == nil {
+		return nil, 0, net.ErrClosed
+	}
+
+	// Set up IPv4 and IPv6 packet connections for advanced features
+	if runtime.GOOS == "linux" || runtime.GOOS == "android" {
+		b.ipv4PC = ipv4.NewPacketConn(b.udpConn)
+		b.ipv6PC = ipv6.NewPacketConn(b.udpConn)
+
+		// Pre-allocate message buffers for batch operations
+		batchSize := wgConn.IdealBatchSize
+		b.ipv4Msgs = make([]ipv4.Message, batchSize)
+		for i := range b.ipv4Msgs {
+			b.ipv4Msgs[i].OOB = make([]byte, 0)
+		}
+	}
+
+	// Create receive functions - one for socket, one for netstack
+	recvFuncs := make([]wgConn.ReceiveFunc, 0, 2)
+
+	// Add socket receive function (reads from physical UDP socket)
+	recvFuncs = append(recvFuncs, b.makeReceiveSocket())
+
+	// Add netstack receive function (reads from injected packets channel)
+	recvFuncs = append(recvFuncs, b.makeReceiveNetstack())
+
+	b.recvFuncs = recvFuncs
+	return recvFuncs, b.port, nil
+}
+
+// makeReceiveSocket creates a receive function for physical UDP socket packets
+func (b *SharedBind) makeReceiveSocket() wgConn.ReceiveFunc {
+	return func(bufs [][]byte, sizes []int, eps []wgConn.Endpoint) (n int, err error) {
+		if b.closed.Load() {
+			return 0, net.ErrClosed
+		}
+
+		b.mu.RLock()
+		conn := b.udpConn
+		pc := b.ipv4PC
+		b.mu.RUnlock()
+
+		if conn == nil {
+			return 0, net.ErrClosed
+		}
+
+		// Use batch reading on Linux for performance
+		if pc != nil && (runtime.GOOS == "linux" || runtime.GOOS == "android") {
+			return b.receiveIPv4Batch(pc, bufs, sizes, eps)
+		}
+		return b.receiveIPv4Simple(conn, bufs, sizes, eps)
+	}
+}
+
+// makeReceiveNetstack creates a receive function for netstack-injected packets
+func (b *SharedBind) makeReceiveNetstack() wgConn.ReceiveFunc {
+	return func(bufs [][]byte, sizes []int, eps []wgConn.Endpoint) (n int, err error) {
+		select {
+		case <-b.closeChan:
+			return 0, net.ErrClosed
+		case pkt := <-b.netstackPackets:
+			if len(pkt.data) <= len(bufs[0]) {
+				copy(bufs[0], pkt.data)
+				sizes[0] = len(pkt.data)
+				eps[0] = pkt.endpoint
+				return 1, nil
+			}
+			// Packet too large for buffer, skip it
+			return 0, nil
+		}
+	}
+}
+
+// receiveIPv4Batch uses batch reading for better performance on Linux
+func (b *SharedBind) receiveIPv4Batch(pc *ipv4.PacketConn, bufs [][]byte, sizes []int, eps []wgConn.Endpoint) (int, error) {
+	// Use pre-allocated messages, just update buffer pointers
+	numBufs := len(bufs)
+	if numBufs > len(b.ipv4Msgs) {
+		numBufs = len(b.ipv4Msgs)
+	}
+
+	for i := 0; i < numBufs; i++ {
+		b.ipv4Msgs[i].Buffers = [][]byte{bufs[i]}
+	}
+
+	numMsgs, err := pc.ReadBatch(b.ipv4Msgs[:numBufs], 0)
+	if err != nil {
+		return 0, err
+	}
+
+	// Process messages and filter out magic packets
+	writeIdx := 0
+	for i := 0; i < numMsgs; i++ {
+		if b.ipv4Msgs[i].N == 0 {
+			continue
+		}
+
+		// Check for magic packet
+		if b.ipv4Msgs[i].Addr != nil {
+			if udpAddr, ok := b.ipv4Msgs[i].Addr.(*net.UDPAddr); ok {
+				data := bufs[i][:b.ipv4Msgs[i].N]
+				if b.handleMagicPacket(data, udpAddr) {
+					// Magic packet handled, skip this message
+					continue
+				}
+			}
+		}
+
+		// Not a magic packet, include in output
+		if writeIdx != i {
+			// Need to copy data to the correct position
+			copy(bufs[writeIdx], bufs[i][:b.ipv4Msgs[i].N])
+		}
+		sizes[writeIdx] = b.ipv4Msgs[i].N
+
+		if b.ipv4Msgs[i].Addr != nil {
+			if udpAddr, ok := b.ipv4Msgs[i].Addr.(*net.UDPAddr); ok {
+				addrPort := udpAddr.AddrPort()
+				// Unmap IPv4-in-IPv6 addresses to ensure consistency with parsed endpoints
+				if addrPort.Addr().Is4In6() {
+					addrPort = netip.AddrPortFrom(addrPort.Addr().Unmap(), addrPort.Port())
+				}
+				eps[writeIdx] = &wgConn.StdNetEndpoint{AddrPort: addrPort}
+			}
+		}
+		writeIdx++
+	}
+
+	return writeIdx, nil
+}
+
+// receiveIPv4Simple uses simple ReadFromUDP for non-Linux platforms
+func (b *SharedBind) receiveIPv4Simple(conn *net.UDPConn, bufs [][]byte, sizes []int, eps []wgConn.Endpoint) (int, error) {
+	for {
+		n, addr, err := conn.ReadFromUDP(bufs[0])
+		if err != nil {
+			return 0, err
+		}
+
+		// Check for magic test packet and handle it directly
+		if b.handleMagicPacket(bufs[0][:n], addr) {
+			// Magic packet was handled, read another packet
+			continue
+		}
+
+		sizes[0] = n
+		if addr != nil {
+			addrPort := addr.AddrPort()
+			// Unmap IPv4-in-IPv6 addresses to ensure consistency with parsed endpoints
+			if addrPort.Addr().Is4In6() {
+				addrPort = netip.AddrPortFrom(addrPort.Addr().Unmap(), addrPort.Port())
+			}
+			eps[0] = &wgConn.StdNetEndpoint{AddrPort: addrPort}
+		}
+
+		return 1, nil
+	}
+}
+
+// handleMagicPacket checks if the packet is a magic test packet and responds if so.
+// Returns true if the packet was a magic packet and was handled (should not be passed to WireGuard).
+func (b *SharedBind) handleMagicPacket(data []byte, addr *net.UDPAddr) bool {
+	// Check if this is a test request packet
+	if len(data) >= MagicTestRequestLen && bytes.HasPrefix(data, MagicTestRequest) {
+		logger.Debug("Received magic test REQUEST from %s, sending response", addr.String())
+		// Extract the random data portion to echo back
+		echoData := data[len(MagicTestRequest) : len(MagicTestRequest)+MagicPacketDataLen]
+
+		// Build response packet
+		response := make([]byte, MagicTestResponseLen)
+		copy(response, MagicTestResponse)
+		copy(response[len(MagicTestResponse):], echoData)
+
+		// Send response back to sender
+		b.mu.RLock()
+		conn := b.udpConn
+		b.mu.RUnlock()
+
+		if conn != nil {
+			_, _ = conn.WriteToUDP(response, addr)
+		}
+
+		return true
+	}
+
+	// Check if this is a test response packet
+	if len(data) >= MagicTestResponseLen && bytes.HasPrefix(data, MagicTestResponse) {
+		logger.Debug("Received magic test RESPONSE from %s", addr.String())
+		// Extract the echoed data
+		echoData := data[len(MagicTestResponse) : len(MagicTestResponse)+MagicPacketDataLen]
+
+		// Call the callback if set
+		callbackPtr := b.magicResponseCallback.Load()
+		if callbackPtr != nil {
+			callback := *callbackPtr
+			addrPort := addr.AddrPort()
+			// Unmap IPv4-in-IPv6 addresses to ensure consistency
+			if addrPort.Addr().Is4In6() {
+				addrPort = netip.AddrPortFrom(addrPort.Addr().Unmap(), addrPort.Port())
+			}
+			callback(addrPort, echoData)
+		} else {
+			logger.Debug("Magic response received but no callback registered")
+		}
+
+		return true
+	}
+
+	return false
+}
+
+// Send implements the WireGuard Bind interface.
+// It sends packets to the specified endpoint, routing through the appropriate
+// source (netstack or physical socket) based on where the endpoint's packets came from.
+func (b *SharedBind) Send(bufs [][]byte, ep wgConn.Endpoint) error {
+	if b.closed.Load() {
+		return net.ErrClosed
+	}
+
+	// Extract the destination address from the endpoint
+	var destAddrPort netip.AddrPort
+
+	// Try to cast to StdNetEndpoint first (most common case, avoid allocations)
+	if stdEp, ok := ep.(*wgConn.StdNetEndpoint); ok {
+		destAddrPort = stdEp.AddrPort
+	} else {
+		// Fallback: construct from DstIP and DstToBytes
+		dstBytes := ep.DstToBytes()
+		if len(dstBytes) >= 6 { // Minimum for IPv4 (4 bytes) + port (2 bytes)
+			var addr netip.Addr
+			var port uint16
+
+			if len(dstBytes) >= 18 { // IPv6 (16 bytes) + port (2 bytes)
+				addr, _ = netip.AddrFromSlice(dstBytes[:16])
+				port = uint16(dstBytes[16]) | uint16(dstBytes[17])<<8
+			} else { // IPv4
+				addr, _ = netip.AddrFromSlice(dstBytes[:4])
+				port = uint16(dstBytes[4]) | uint16(dstBytes[5])<<8
+			}
+
+			if addr.IsValid() {
+				destAddrPort = netip.AddrPortFrom(addr, port)
+			}
+		}
+	}
+
+	if !destAddrPort.IsValid() {
+		return fmt.Errorf("could not extract destination address from endpoint")
+	}
+
+	// Check if this endpoint came from netstack - if so, send through netstack
+	// Use AddrPort directly as key (more efficient than string conversion)
+	if _, isNetstackEndpoint := b.netstackEndpoints.Load(destAddrPort); isNetstackEndpoint {
+		connPtr := b.netstackConn.Load()
+		if connPtr != nil && *connPtr != nil {
+			netstackConn := *connPtr
+			destAddr := net.UDPAddrFromAddrPort(destAddrPort)
+			// Send all buffers through netstack
+			for _, buf := range bufs {
+				_, err := netstackConn.WriteTo(buf, destAddr)
+				if err != nil {
+					return err
+				}
+			}
+			return nil
+		}
+		// Fall through to socket if netstack conn not available
+	}
+
+	// Send through the physical UDP socket (for hole-punched clients)
+	b.mu.RLock()
+	conn := b.udpConn
+	b.mu.RUnlock()
+
+	if conn == nil {
+		return net.ErrClosed
+	}
+
+	destAddr := net.UDPAddrFromAddrPort(destAddrPort)
+
+	// Send all buffers to the destination
+	for _, buf := range bufs {
+		_, err := conn.WriteToUDP(buf, destAddr)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// SetMark implements the WireGuard Bind interface.
+// It's a no-op for this implementation.
+func (b *SharedBind) SetMark(mark uint32) error {
+	// Not implemented for this use case
+	return nil
+}
+
+// BatchSize returns the preferred batch size for sending packets.
+func (b *SharedBind) BatchSize() int {
+	if runtime.GOOS == "linux" || runtime.GOOS == "android" {
+		return wgConn.IdealBatchSize
+	}
+	return 1
+}
+
+// ParseEndpoint creates a new endpoint from a string address.
+func (b *SharedBind) ParseEndpoint(s string) (wgConn.Endpoint, error) {
+	addrPort, err := netip.ParseAddrPort(s)
+	if err != nil {
+		return nil, err
+	}
+	return &wgConn.StdNetEndpoint{AddrPort: addrPort}, nil
+}

bind/shared_bind_test.go

@@ -0,0 +1,605 @@
+//go:build !js
+
+package bind
+
+import (
+	"net"
+	"net/netip"
+	"sync"
+	"testing"
+	"time"
+
+	wgConn "golang.zx2c4.com/wireguard/conn"
+)
+
+// TestSharedBindCreation tests basic creation and initialization
+func TestSharedBindCreation(t *testing.T) {
+	// Create a UDP connection
+	udpConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create UDP connection: %v", err)
+	}
+	defer udpConn.Close()
+
+	// Create SharedBind
+	bind, err := New(udpConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+
+	if bind == nil {
+		t.Fatal("SharedBind is nil")
+	}
+
+	// Verify initial reference count
+	if bind.refCount.Load() != 1 {
+		t.Errorf("Expected initial refCount to be 1, got %d", bind.refCount.Load())
+	}
+
+	// Clean up
+	if err := bind.Close(); err != nil {
+		t.Errorf("Failed to close SharedBind: %v", err)
+	}
+}
+
+// TestSharedBindReferenceCount tests reference counting
+func TestSharedBindReferenceCount(t *testing.T) {
+	udpConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create UDP connection: %v", err)
+	}
+
+	bind, err := New(udpConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+
+	// Add references
+	bind.AddRef()
+	if bind.refCount.Load() != 2 {
+		t.Errorf("Expected refCount to be 2, got %d", bind.refCount.Load())
+	}
+
+	bind.AddRef()
+	if bind.refCount.Load() != 3 {
+		t.Errorf("Expected refCount to be 3, got %d", bind.refCount.Load())
+	}
+
+	// Release references
+	bind.Release()
+	if bind.refCount.Load() != 2 {
+		t.Errorf("Expected refCount to be 2 after release, got %d", bind.refCount.Load())
+	}
+
+	bind.Release()
+	bind.Release() // This should close the connection
+
+	if !bind.closed.Load() {
+		t.Error("Expected bind to be closed after all references released")
+	}
+}
+
+// TestSharedBindWriteToUDP tests the WriteToUDP functionality
+func TestSharedBindWriteToUDP(t *testing.T) {
+	// Create sender
+	senderConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create sender UDP connection: %v", err)
+	}
+
+	senderBind, err := New(senderConn)
+	if err != nil {
+		t.Fatalf("Failed to create sender SharedBind: %v", err)
+	}
+	defer senderBind.Close()
+
+	// Create receiver
+	receiverConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create receiver UDP connection: %v", err)
+	}
+	defer receiverConn.Close()
+
+	receiverAddr := receiverConn.LocalAddr().(*net.UDPAddr)
+
+	// Send data
+	testData := []byte("Hello, SharedBind!")
+	n, err := senderBind.WriteToUDP(testData, receiverAddr)
+	if err != nil {
+		t.Fatalf("WriteToUDP failed: %v", err)
+	}
+
+	if n != len(testData) {
+		t.Errorf("Expected to send %d bytes, sent %d", len(testData), n)
+	}
+
+	// Receive data
+	buf := make([]byte, 1024)
+	receiverConn.SetReadDeadline(time.Now().Add(2 * time.Second))
+	n, _, err = receiverConn.ReadFromUDP(buf)
+	if err != nil {
+		t.Fatalf("Failed to receive data: %v", err)
+	}
+
+	if string(buf[:n]) != string(testData) {
+		t.Errorf("Expected to receive %q, got %q", testData, buf[:n])
+	}
+}
+
+// TestSharedBindConcurrentWrites tests thread-safety
+func TestSharedBindConcurrentWrites(t *testing.T) {
+	// Create sender
+	senderConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create sender UDP connection: %v", err)
+	}
+
+	senderBind, err := New(senderConn)
+	if err != nil {
+		t.Fatalf("Failed to create sender SharedBind: %v", err)
+	}
+	defer senderBind.Close()
+
+	// Create receiver
+	receiverConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create receiver UDP connection: %v", err)
+	}
+	defer receiverConn.Close()
+
+	receiverAddr := receiverConn.LocalAddr().(*net.UDPAddr)
+
+	// Launch concurrent writes
+	numGoroutines := 100
+	var wg sync.WaitGroup
+	wg.Add(numGoroutines)
+
+	for i := 0; i < numGoroutines; i++ {
+		go func(id int) {
+			defer wg.Done()
+			data := []byte{byte(id)}
+			_, err := senderBind.WriteToUDP(data, receiverAddr)
+			if err != nil {
+				t.Errorf("WriteToUDP failed in goroutine %d: %v", id, err)
+			}
+		}(i)
+	}
+
+	wg.Wait()
+}
+
+// TestSharedBindWireGuardInterface tests WireGuard Bind interface implementation
+func TestSharedBindWireGuardInterface(t *testing.T) {
+	udpConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create UDP connection: %v", err)
+	}
+
+	bind, err := New(udpConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+	defer bind.Close()
+
+	// Test Open
+	recvFuncs, port, err := bind.Open(0)
+	if err != nil {
+		t.Fatalf("Open failed: %v", err)
+	}
+
+	if len(recvFuncs) == 0 {
+		t.Error("Expected at least one receive function")
+	}
+
+	if port == 0 {
+		t.Error("Expected non-zero port")
+	}
+
+	// Test SetMark (should be a no-op)
+	if err := bind.SetMark(0); err != nil {
+		t.Errorf("SetMark failed: %v", err)
+	}
+
+	// Test BatchSize
+	batchSize := bind.BatchSize()
+	if batchSize <= 0 {
+		t.Error("Expected positive batch size")
+	}
+}
+
+// TestSharedBindSend tests the Send method with WireGuard endpoints
+func TestSharedBindSend(t *testing.T) {
+	// Create sender
+	senderConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create sender UDP connection: %v", err)
+	}
+
+	senderBind, err := New(senderConn)
+	if err != nil {
+		t.Fatalf("Failed to create sender SharedBind: %v", err)
+	}
+	defer senderBind.Close()
+
+	// Create receiver
+	receiverConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create receiver UDP connection: %v", err)
+	}
+	defer receiverConn.Close()
+
+	receiverAddr := receiverConn.LocalAddr().(*net.UDPAddr)
+
+	// Create an endpoint
+	addrPort := receiverAddr.AddrPort()
+	endpoint := &wgConn.StdNetEndpoint{AddrPort: addrPort}
+
+	// Send data
+	testData := []byte("WireGuard packet")
+	bufs := [][]byte{testData}
+	err = senderBind.Send(bufs, endpoint)
+	if err != nil {
+		t.Fatalf("Send failed: %v", err)
+	}
+
+	// Receive data
+	buf := make([]byte, 1024)
+	receiverConn.SetReadDeadline(time.Now().Add(2 * time.Second))
+	n, _, err := receiverConn.ReadFromUDP(buf)
+	if err != nil {
+		t.Fatalf("Failed to receive data: %v", err)
+	}
+
+	if string(buf[:n]) != string(testData) {
+		t.Errorf("Expected to receive %q, got %q", testData, buf[:n])
+	}
+}
+
+// TestSharedBindMultipleUsers simulates WireGuard and hole punch using the same bind
+func TestSharedBindMultipleUsers(t *testing.T) {
+	// Create shared bind
+	udpConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create UDP connection: %v", err)
+	}
+
+	sharedBind, err := New(udpConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+
+	// Add reference for hole punch sender
+	sharedBind.AddRef()
+
+	// Create receiver
+	receiverConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create receiver UDP connection: %v", err)
+	}
+	defer receiverConn.Close()
+
+	receiverAddr := receiverConn.LocalAddr().(*net.UDPAddr)
+
+	var wg sync.WaitGroup
+
+	// Simulate WireGuard using the bind
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		addrPort := receiverAddr.AddrPort()
+		endpoint := &wgConn.StdNetEndpoint{AddrPort: addrPort}
+
+		for i := 0; i < 10; i++ {
+			data := []byte("WireGuard packet")
+			bufs := [][]byte{data}
+			if err := sharedBind.Send(bufs, endpoint); err != nil {
+				t.Errorf("WireGuard Send failed: %v", err)
+			}
+			time.Sleep(10 * time.Millisecond)
+		}
+	}()
+
+	// Simulate hole punch sender using the bind
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		for i := 0; i < 10; i++ {
+			data := []byte("Hole punch packet")
+			if _, err := sharedBind.WriteToUDP(data, receiverAddr); err != nil {
+				t.Errorf("Hole punch WriteToUDP failed: %v", err)
+			}
+			time.Sleep(10 * time.Millisecond)
+		}
+	}()
+
+	wg.Wait()
+
+	// Release the hole punch reference
+	sharedBind.Release()
+
+	// Close WireGuard's reference (should close the connection)
+	sharedBind.Close()
+
+	if !sharedBind.closed.Load() {
+		t.Error("Expected bind to be closed after all users released it")
+	}
+}
+
+// TestEndpoint tests the Endpoint implementation
+func TestEndpoint(t *testing.T) {
+	addr := netip.MustParseAddr("192.168.1.1")
+	addrPort := netip.AddrPortFrom(addr, 51820)
+
+	ep := &Endpoint{AddrPort: addrPort}
+
+	// Test DstIP
+	if ep.DstIP() != addr {
+		t.Errorf("Expected DstIP to be %v, got %v", addr, ep.DstIP())
+	}
+
+	// Test DstToString
+	expected := "192.168.1.1:51820"
+	if ep.DstToString() != expected {
+		t.Errorf("Expected DstToString to be %q, got %q", expected, ep.DstToString())
+	}
+
+	// Test DstToBytes
+	bytes := ep.DstToBytes()
+	if len(bytes) == 0 {
+		t.Error("Expected DstToBytes to return non-empty slice")
+	}
+
+	// Test SrcIP (should be zero)
+	if ep.SrcIP().IsValid() {
+		t.Error("Expected SrcIP to be invalid")
+	}
+
+	// Test ClearSrc (should not panic)
+	ep.ClearSrc()
+}
+
+// TestParseEndpoint tests the ParseEndpoint method
+func TestParseEndpoint(t *testing.T) {
+	udpConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create UDP connection: %v", err)
+	}
+
+	bind, err := New(udpConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+	defer bind.Close()
+
+	tests := []struct {
+		name      string
+		input     string
+		wantErr   bool
+		checkAddr func(*testing.T, wgConn.Endpoint)
+	}{
+		{
+			name:    "valid IPv4",
+			input:   "192.168.1.1:51820",
+			wantErr: false,
+			checkAddr: func(t *testing.T, ep wgConn.Endpoint) {
+				if ep.DstToString() != "192.168.1.1:51820" {
+					t.Errorf("Expected 192.168.1.1:51820, got %s", ep.DstToString())
+				}
+			},
+		},
+		{
+			name:    "valid IPv6",
+			input:   "[::1]:51820",
+			wantErr: false,
+			checkAddr: func(t *testing.T, ep wgConn.Endpoint) {
+				if ep.DstToString() != "[::1]:51820" {
+					t.Errorf("Expected [::1]:51820, got %s", ep.DstToString())
+				}
+			},
+		},
+		{
+			name:    "invalid - missing port",
+			input:   "192.168.1.1",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - bad format",
+			input:   "not-an-address",
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ep, err := bind.ParseEndpoint(tt.input)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ParseEndpoint() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !tt.wantErr && tt.checkAddr != nil {
+				tt.checkAddr(t, ep)
+			}
+		})
+	}
+}
+
+// TestNetstackRouting tests that packets from netstack endpoints are routed back through netstack
+func TestNetstackRouting(t *testing.T) {
+	// Create the SharedBind with a physical UDP socket
+	physicalConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create physical UDP connection: %v", err)
+	}
+
+	sharedBind, err := New(physicalConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+	defer sharedBind.Close()
+
+	// Create a mock "netstack" connection (just another UDP socket for testing)
+	netstackConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create netstack UDP connection: %v", err)
+	}
+	defer netstackConn.Close()
+
+	// Set the netstack connection
+	sharedBind.SetNetstackConn(netstackConn)
+
+	// Create a "client" that would receive packets
+	clientConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create client UDP connection: %v", err)
+	}
+	defer clientConn.Close()
+
+	clientAddr := clientConn.LocalAddr().(*net.UDPAddr)
+	clientAddrPort := clientAddr.AddrPort()
+
+	// Inject a packet from the "netstack" source - this should track the endpoint
+	testData := []byte("test packet from netstack")
+	err = sharedBind.InjectPacket(testData, clientAddrPort)
+	if err != nil {
+		t.Fatalf("InjectPacket failed: %v", err)
+	}
+
+	// Now when we send a response to this endpoint, it should go through netstack
+	endpoint := &wgConn.StdNetEndpoint{AddrPort: clientAddrPort}
+	responseData := []byte("response packet")
+	err = sharedBind.Send([][]byte{responseData}, endpoint)
+	if err != nil {
+		t.Fatalf("Send failed: %v", err)
+	}
+
+	// The packet should be received by the client from the netstack connection
+	buf := make([]byte, 1024)
+	clientConn.SetReadDeadline(time.Now().Add(2 * time.Second))
+	n, fromAddr, err := clientConn.ReadFromUDP(buf)
+	if err != nil {
+		t.Fatalf("Failed to receive response: %v", err)
+	}
+
+	if string(buf[:n]) != string(responseData) {
+		t.Errorf("Expected to receive %q, got %q", responseData, buf[:n])
+	}
+
+	// Verify the response came from the netstack connection, not the physical one
+	netstackAddr := netstackConn.LocalAddr().(*net.UDPAddr)
+	if fromAddr.Port != netstackAddr.Port {
+		t.Errorf("Expected response from netstack port %d, got %d", netstackAddr.Port, fromAddr.Port)
+	}
+}
+
+// TestSocketRouting tests that packets from socket endpoints are routed through socket
+func TestSocketRouting(t *testing.T) {
+	// Create the SharedBind with a physical UDP socket
+	physicalConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create physical UDP connection: %v", err)
+	}
+
+	sharedBind, err := New(physicalConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+	defer sharedBind.Close()
+
+	// Create a mock "netstack" connection
+	netstackConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create netstack UDP connection: %v", err)
+	}
+	defer netstackConn.Close()
+
+	// Set the netstack connection
+	sharedBind.SetNetstackConn(netstackConn)
+
+	// Create a "client" that would receive packets (this simulates a hole-punched client)
+	clientConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create client UDP connection: %v", err)
+	}
+	defer clientConn.Close()
+
+	clientAddr := clientConn.LocalAddr().(*net.UDPAddr)
+	clientAddrPort := clientAddr.AddrPort()
+
+	// Don't inject from netstack - this endpoint is NOT tracked as netstack-sourced
+	// So Send should use the physical socket
+
+	endpoint := &wgConn.StdNetEndpoint{AddrPort: clientAddrPort}
+	responseData := []byte("response packet via socket")
+	err = sharedBind.Send([][]byte{responseData}, endpoint)
+	if err != nil {
+		t.Fatalf("Send failed: %v", err)
+	}
+
+	// The packet should be received by the client from the physical connection
+	buf := make([]byte, 1024)
+	clientConn.SetReadDeadline(time.Now().Add(2 * time.Second))
+	n, fromAddr, err := clientConn.ReadFromUDP(buf)
+	if err != nil {
+		t.Fatalf("Failed to receive response: %v", err)
+	}
+
+	if string(buf[:n]) != string(responseData) {
+		t.Errorf("Expected to receive %q, got %q", responseData, buf[:n])
+	}
+
+	// Verify the response came from the physical connection, not the netstack one
+	physicalAddr := physicalConn.LocalAddr().(*net.UDPAddr)
+	if fromAddr.Port != physicalAddr.Port {
+		t.Errorf("Expected response from physical port %d, got %d", physicalAddr.Port, fromAddr.Port)
+	}
+}
+
+// TestClearNetstackConn tests that clearing the netstack connection works correctly
+func TestClearNetstackConn(t *testing.T) {
+	physicalConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create physical UDP connection: %v", err)
+	}
+
+	sharedBind, err := New(physicalConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+	defer sharedBind.Close()
+
+	// Set a netstack connection
+	netstackConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create netstack UDP connection: %v", err)
+	}
+	defer netstackConn.Close()
+
+	sharedBind.SetNetstackConn(netstackConn)
+
+	// Inject a packet to track an endpoint
+	testAddrPort := netip.MustParseAddrPort("192.168.1.100:51820")
+	err = sharedBind.InjectPacket([]byte("test"), testAddrPort)
+	if err != nil {
+		t.Fatalf("InjectPacket failed: %v", err)
+	}
+
+	// Verify the endpoint is tracked
+	_, tracked := sharedBind.netstackEndpoints.Load(testAddrPort.String())
+	if !tracked {
+		t.Error("Expected endpoint to be tracked as netstack-sourced")
+	}
+
+	// Clear the netstack connection
+	sharedBind.ClearNetstackConn()
+
+	// Verify the netstack connection is cleared
+	if sharedBind.GetNetstackConn() != nil {
+		t.Error("Expected netstack connection to be nil after clear")
+	}
+
+	// Verify the tracked endpoints are cleared
+	_, stillTracked := sharedBind.netstackEndpoints.Load(testAddrPort.String())
+	if stillTracked {
+		t.Error("Expected endpoint tracking to be cleared")
+	}
+}

clients.go

@@ -1,20 +1,17 @@
 package main
 
 import (
-	"fmt"
 	"strings"
 
+	"github.com/fosrl/newt/clients"
+	wgnetstack "github.com/fosrl/newt/clients"
+	"github.com/fosrl/newt/clients/permissions"
 	"github.com/fosrl/newt/logger"
-	"github.com/fosrl/newt/proxy"
 	"github.com/fosrl/newt/websocket"
 	"golang.zx2c4.com/wireguard/tun/netstack"
-
-	"github.com/fosrl/newt/wgnetstack"
-	"github.com/fosrl/newt/wgtester"
 )
 
-var wgService *wgnetstack.WireGuardService
+var wgService *clients.WireGuardService
-var wgTesterServer *wgtester.Server
 var ready bool
 
 func setupClients(client *websocket.Client) {
@@ -27,43 +24,29 @@ func setupClients(client *websocket.Client) {
 
 	host = strings.TrimSuffix(host, "/")
 
+	logger.Info("Setting up clients with netstack2...")
+
+	// if useNativeInterface is true make sure we have permission to use native interface
 	if useNativeInterface {
-		setupClientsNative(client, host)
+		logger.Debug("Checking permissions for native interface")
-	} else {
+		err := permissions.CheckNativeInterfacePermissions()
-		setupClientsNetstack(client, host)
+		if err != nil {
+			logger.Fatal("Insufficient permissions to create native TUN interface: %v", err)
+			return
+		}
 	}
 
-	ready = true
-}
-
-func setupClientsNetstack(client *websocket.Client, host string) {
-	logger.Info("Setting up clients with netstack...")
 	// Create WireGuard service
-	wgService, err = wgnetstack.NewWireGuardService(interfaceName, mtuInt, generateAndSaveKeyTo, host, id, client, "9.9.9.9")
+	wgService, err = wgnetstack.NewWireGuardService(interfaceName, mtuInt, host, id, client, dns, useNativeInterface)
 	if err != nil {
 		logger.Fatal("Failed to create WireGuard service: %v", err)
 	}
 
-	// // Set up callback to restart wgtester with netstack when WireGuard is ready
-	wgService.SetOnNetstackReady(func(tnet *netstack.Net) {
-
-		wgTesterServer = wgtester.NewServerWithNetstack("0.0.0.0", wgService.Port, id, tnet) // TODO: maybe make this the same ip of the wg server?
-		err := wgTesterServer.Start()
-		if err != nil {
-			logger.Error("Failed to start WireGuard tester server: %v", err)
-		}
-	})
-
-	wgService.SetOnNetstackClose(func() {
-		if wgTesterServer != nil {
-			wgTesterServer.Stop()
-			wgTesterServer = nil
-		}
-	})
-
 	client.OnTokenUpdate(func(token string) {
 		wgService.SetToken(token)
 	})
+
+	ready = true
 }
 
 func setDownstreamTNetstack(tnet *netstack.Net) {
@@ -75,16 +58,9 @@ func setDownstreamTNetstack(tnet *netstack.Net) {
 func closeClients() {
 	logger.Info("Closing clients...")
 	if wgService != nil {
-		wgService.Close(!keepInterface)
+		wgService.Close()
 		wgService = nil
 	}
-
-	closeWgServiceNative()
-
-	if wgTesterServer != nil {
-		wgTesterServer.Stop()
-		wgTesterServer = nil
-	}
 }
 
 func clientsHandleNewtConnection(publicKey string, endpoint string) {
@@ -103,8 +79,6 @@ func clientsHandleNewtConnection(publicKey string, endpoint string) {
 	if wgService != nil {
 		wgService.StartHolepunch(publicKey, endpoint)
 	}
-
-	clientsHandleNewtConnectionNative(publicKey, endpoint)
 }
 
 func clientsOnConnect() {
@@ -114,19 +88,17 @@ func clientsOnConnect() {
 	if wgService != nil {
 		wgService.LoadRemoteConfig()
 	}
-
-	clientsOnConnectNative()
 }
 
-func clientsAddProxyTarget(pm *proxy.ProxyManager, tunnelIp string) {
+// clientsStartDirectRelay starts a direct UDP relay from the main tunnel netstack
+// to the clients' WireGuard, bypassing the proxy for better performance.
+func clientsStartDirectRelay(tunnelIP string) {
 	if !ready {
 		return
 	}
-	// add a udp proxy for localost and the wgService port
-	// TODO: make sure this port is not used in a target
 	if wgService != nil {
-		pm.AddTarget("udp", tunnelIp, int(wgService.Port), fmt.Sprintf("127.0.0.1:%d", wgService.Port))
+		if err := wgService.StartDirectUDPRelay(tunnelIP); err != nil {
+			logger.Error("Failed to start direct UDP relay: %v", err)
+		}
 	}
-
-	clientsAddProxyTargetNative(pm, tunnelIp)
 }

clients/permissions/permissions_darwin.go

@@ -0,0 +1,18 @@
+//go:build darwin
+
+package permissions
+
+import (
+	"fmt"
+	"os"
+)
+
+// CheckNativeInterfacePermissions checks if the process has sufficient
+// permissions to create a native TUN interface on macOS.
+// This typically requires root privileges.
+func CheckNativeInterfacePermissions() error {
+	if os.Geteuid() == 0 {
+		return nil
+	}
+	return fmt.Errorf("insufficient permissions: need root to create TUN interface on macOS")
+}

clients/permissions/permissions_linux.go

@@ -0,0 +1,96 @@
+//go:build linux
+
+package permissions
+
+import (
+	"fmt"
+	"os"
+	"unsafe"
+
+	"github.com/fosrl/newt/logger"
+	"golang.org/x/sys/unix"
+)
+
+const (
+	// TUN device constants
+	tunDevice = "/dev/net/tun"
+	ifnamsiz  = 16
+	iffTun    = 0x0001
+	iffNoPi   = 0x1000
+	tunSetIff = 0x400454ca
+)
+
+// ifReq is the structure for TUNSETIFF ioctl
+type ifReq struct {
+	Name  [ifnamsiz]byte
+	Flags uint16
+	_     [22]byte // padding to match kernel structure
+}
+
+// CheckNativeInterfacePermissions checks if the process has sufficient
+// permissions to create a native TUN interface on Linux.
+// This requires either root privileges (UID 0) or CAP_NET_ADMIN capability.
+func CheckNativeInterfacePermissions() error {
+	logger.Debug("Checking native interface permissions on Linux")
+
+	// Check if running as root
+	if os.Geteuid() == 0 {
+		logger.Debug("Running as root, sufficient permissions for native TUN interface")
+		return nil
+	}
+
+	// Check for CAP_NET_ADMIN capability
+	caps := unix.CapUserHeader{
+		Version: unix.LINUX_CAPABILITY_VERSION_3,
+		Pid:     0, // 0 means current process
+	}
+
+	var data [2]unix.CapUserData
+	if err := unix.Capget(&caps, &data[0]); err != nil {
+		logger.Debug("Failed to get capabilities: %v, will try creating test TUN", err)
+	} else {
+		// CAP_NET_ADMIN is capability bit 12
+		const CAP_NET_ADMIN = 12
+		if data[0].Effective&(1<<CAP_NET_ADMIN) != 0 {
+			logger.Debug("Process has CAP_NET_ADMIN capability, sufficient permissions for native TUN interface")
+			return nil
+		}
+		logger.Debug("Process does not have CAP_NET_ADMIN capability in effective set")
+	}
+
+	// Actually try to create a TUN interface to verify permissions
+	// This is the most reliable check as it tests the actual operation
+	return tryCreateTestTun()
+}
+
+// tryCreateTestTun attempts to create a temporary TUN interface to verify
+// we have the necessary permissions. This tests the actual ioctl call that
+// will be used when creating the real interface.
+func tryCreateTestTun() error {
+	f, err := os.OpenFile(tunDevice, os.O_RDWR, 0)
+	if err != nil {
+		return fmt.Errorf("cannot open %s: %v (need root or CAP_NET_ADMIN capability)", tunDevice, err)
+	}
+	defer f.Close()
+
+	// Try to create a TUN interface with a test name
+	// Using a random-ish name to avoid conflicts
+	var req ifReq
+	copy(req.Name[:], "tuntest0")
+	req.Flags = iffTun | iffNoPi
+
+	_, _, errno := unix.Syscall(
+		unix.SYS_IOCTL,
+		f.Fd(),
+		uintptr(tunSetIff),
+		uintptr(unsafe.Pointer(&req)),
+	)
+
+	if errno != 0 {
+		return fmt.Errorf("cannot create TUN interface (ioctl TUNSETIFF failed): %v (need root or CAP_NET_ADMIN capability)", errno)
+	}
+
+	// Success - the interface will be automatically destroyed when we close the fd
+	logger.Debug("Successfully created test TUN interface, sufficient permissions for native TUN interface")
+	return nil
+}

clients/permissions/permissions_windows.go

@@ -0,0 +1,38 @@
+//go:build windows
+
+package permissions
+
+import (
+	"fmt"
+
+	"golang.org/x/sys/windows"
+)
+
+// CheckNativeInterfacePermissions checks if the process has sufficient
+// permissions to create a native TUN interface on Windows.
+// This requires Administrator privileges.
+func CheckNativeInterfacePermissions() error {
+	var sid *windows.SID
+	err := windows.AllocateAndInitializeSid(
+		&windows.SECURITY_NT_AUTHORITY,
+		2,
+		windows.SECURITY_BUILTIN_DOMAIN_RID,
+		windows.DOMAIN_ALIAS_RID_ADMINS,
+		0, 0, 0, 0, 0, 0,
+		&sid)
+	if err != nil {
+		return fmt.Errorf("failed to initialize SID: %v", err)
+	}
+	defer windows.FreeSid(sid)
+
+	token := windows.Token(0)
+	member, err := token.IsMember(sid)
+	if err != nil {
+		return fmt.Errorf("failed to check admin group membership: %v", err)
+	}
+
+	if !member {
+		return fmt.Errorf("insufficient permissions: need Administrator to create TUN interface on Windows")
+	}
+	return nil
+}

common.go

@@ -3,11 +3,8 @@ package main
 import (
 	"bytes"
 	"context"
-	"encoding/base64"
-	"encoding/hex"
 	"encoding/json"
 	"fmt"
-	"net"
 	"os"
 	"os/exec"
 	"strings"
@@ -21,29 +18,14 @@ import (
 	"github.com/fosrl/newt/websocket"
 	"golang.org/x/net/icmp"
 	"golang.org/x/net/ipv4"
-	"golang.zx2c4.com/wireguard/device"
 	"golang.zx2c4.com/wireguard/tun/netstack"
 	"gopkg.in/yaml.v3"
 )
 
 const msgHealthFileWriteFailed = "Failed to write health file: %v"
 
-func fixKey(key string) string {
-	// Remove any whitespace
-	key = strings.TrimSpace(key)
-
-	// Decode from base64
-	decoded, err := base64.StdEncoding.DecodeString(key)
-	if err != nil {
-		logger.Fatal("Error decoding base64: %v", err)
-	}
-
-	// Convert to hex
-	return hex.EncodeToString(decoded)
-}
-
 func ping(tnet *netstack.Net, dst string, timeout time.Duration) (time.Duration, error) {
-	logger.Debug("Pinging %s", dst)
+	// logger.Debug("Pinging %s", dst)
 	socket, err := tnet.Dial("ping4", dst)
 	if err != nil {
 		return 0, fmt.Errorf("failed to create ICMP socket: %w", err)
@@ -102,7 +84,7 @@ func ping(tnet *netstack.Net, dst string, timeout time.Duration) (time.Duration,
 
 	latency := time.Since(start)
 
-	logger.Debug("Ping to %s successful, latency: %v", dst, latency)
+	// logger.Debug("Ping to %s successful, latency: %v", dst, latency)
 
 	return latency, nil
 }
@@ -140,7 +122,7 @@ func reliablePing(tnet *netstack.Net, dst string, baseTimeout time.Duration, max
 		// If we get at least one success, we can return early for health checks
 		if successCount > 0 {
 			avgLatency := totalLatency / time.Duration(successCount)
-			logger.Debug("Reliable ping succeeded after %d attempts, avg latency: %v", attempt, avgLatency)
+			// logger.Debug("Reliable ping succeeded after %d attempts, avg latency: %v", attempt, avgLatency)
 			return avgLatency, nil
 		}
 	}
@@ -366,89 +348,6 @@ func startPingCheck(tnet *netstack.Net, serverIP string, client *websocket.Clien
 	return pingStopChan
 }
 
-func parseLogLevel(level string) logger.LogLevel {
-	switch strings.ToUpper(level) {
-	case "DEBUG":
-		return logger.DEBUG
-	case "INFO":
-		return logger.INFO
-	case "WARN":
-		return logger.WARN
-	case "ERROR":
-		return logger.ERROR
-	case "FATAL":
-		return logger.FATAL
-	default:
-		return logger.INFO // default to INFO if invalid level provided
-	}
-}
-
-func mapToWireGuardLogLevel(level logger.LogLevel) int {
-	switch level {
-	case logger.DEBUG:
-		return device.LogLevelVerbose
-	// case logger.INFO:
-	// return device.LogLevel
-	case logger.WARN:
-		return device.LogLevelError
-	case logger.ERROR, logger.FATAL:
-		return device.LogLevelSilent
-	default:
-		return device.LogLevelSilent
-	}
-}
-
-func resolveDomain(domain string) (string, error) {
-	// Check if there's a port in the domain
-	host, port, err := net.SplitHostPort(domain)
-	if err != nil {
-		// No port found, use the domain as is
-		host = domain
-		port = ""
-	}
-
-	// Remove any protocol prefix if present
-	if strings.HasPrefix(host, "http://") {
-		host = strings.TrimPrefix(host, "http://")
-	} else if strings.HasPrefix(host, "https://") {
-		host = strings.TrimPrefix(host, "https://")
-	}
-
-	// if there are any trailing slashes, remove them
-	host = strings.TrimSuffix(host, "/")
-
-	// Lookup IP addresses
-	ips, err := net.LookupIP(host)
-	if err != nil {
-		return "", fmt.Errorf("DNS lookup failed: %v", err)
-	}
-
-	if len(ips) == 0 {
-		return "", fmt.Errorf("no IP addresses found for domain %s", host)
-	}
-
-	// Get the first IPv4 address if available
-	var ipAddr string
-	for _, ip := range ips {
-		if ipv4 := ip.To4(); ipv4 != nil {
-			ipAddr = ipv4.String()
-			break
-		}
-	}
-
-	// If no IPv4 found, use the first IP (might be IPv6)
-	if ipAddr == "" {
-		ipAddr = ips[0].String()
-	}
-
-	// Add port back if it existed
-	if port != "" {
-		ipAddr = net.JoinHostPort(ipAddr, port)
-	}
-
-	return ipAddr, nil
-}
-
 func parseTargetData(data interface{}) (TargetData, error) {
 	var targetData TargetData
 	jsonData, err := json.Marshal(data)

examples/README.md

@@ -0,0 +1,167 @@
+# Extensible Logger
+
+This logger package provides a flexible logging system that can be extended with custom log writers.
+
+## Basic Usage (Current Behavior)
+
+The logger works exactly as before with no changes required:
+
+```go
+package main
+
+import "your-project/logger"
+
+func main() {
+    // Use default logger
+    logger.Info("This works as before")
+    logger.Debug("Debug message")
+    logger.Error("Error message")
+    
+    // Or create a custom instance
+    log := logger.NewLogger()
+    log.SetLevel(logger.INFO)
+    log.Info("Custom logger instance")
+}
+```
+
+## Custom Log Writers
+
+To use a custom log backend, implement the `LogWriter` interface:
+
+```go
+type LogWriter interface {
+    Write(level LogLevel, timestamp time.Time, message string)
+}
+```
+
+### Example: OS Log Writer (macOS/iOS)
+
+```go
+package main
+
+import "your-project/logger"
+
+func main() {
+    // Create an OS log writer
+    osWriter := logger.NewOSLogWriter(
+        "net.pangolin.Pangolin.PacketTunnel",
+        "PangolinGo",
+        "MyApp",
+    )
+    
+    // Create a logger with the OS log writer
+    log := logger.NewLoggerWithWriter(osWriter)
+    log.SetLevel(logger.DEBUG)
+    
+    // Use it just like the standard logger
+    log.Info("This message goes to os_log")
+    log.Error("Error logged to os_log")
+}
+```
+
+### Example: Custom Writer
+
+```go
+package main
+
+import (
+    "fmt"
+    "time"
+    "your-project/logger"
+)
+
+// CustomWriter writes logs to a custom destination
+type CustomWriter struct {
+    // your custom fields
+}
+
+func (w *CustomWriter) Write(level logger.LogLevel, timestamp time.Time, message string) {
+    // Your custom logging logic
+    fmt.Printf("[CUSTOM] %s [%s] %s\n", timestamp.Format(time.RFC3339), level.String(), message)
+}
+
+func main() {
+    customWriter := &CustomWriter{}
+    log := logger.NewLoggerWithWriter(customWriter)
+    log.Info("Custom logging!")
+}
+```
+
+### Example: Multi-Writer (Log to Multiple Destinations)
+
+```go
+package main
+
+import (
+    "time"
+    "your-project/logger"
+)
+
+// MultiWriter writes to multiple log writers
+type MultiWriter struct {
+    writers []logger.LogWriter
+}
+
+func NewMultiWriter(writers ...logger.LogWriter) *MultiWriter {
+    return &MultiWriter{writers: writers}
+}
+
+func (w *MultiWriter) Write(level logger.LogLevel, timestamp time.Time, message string) {
+    for _, writer := range w.writers {
+        writer.Write(level, timestamp, message)
+    }
+}
+
+func main() {
+    // Log to both standard output and OS log
+    standardWriter := logger.NewStandardWriter()
+    osWriter := logger.NewOSLogWriter("com.example.app", "Main", "App")
+    
+    multiWriter := NewMultiWriter(standardWriter, osWriter)
+    log := logger.NewLoggerWithWriter(multiWriter)
+    
+    log.Info("This goes to both stdout and os_log!")
+}
+```
+
+## API Reference
+
+### Creating Loggers
+
+- `NewLogger()` - Creates a logger with the default StandardWriter
+- `NewLoggerWithWriter(writer LogWriter)` - Creates a logger with a custom writer
+
+### Built-in Writers
+
+- `NewStandardWriter()` - Standard writer that outputs to stdout (default)
+- `NewOSLogWriter(subsystem, category, prefix string)` - OS log writer for macOS/iOS (example)
+
+### Logger Methods
+
+- `SetLevel(level LogLevel)` - Set minimum log level
+- `SetOutput(output *os.File)` - Set output file (StandardWriter only)
+- `Debug(format string, args ...interface{})` - Log debug message
+- `Info(format string, args ...interface{})` - Log info message
+- `Warn(format string, args ...interface{})` - Log warning message
+- `Error(format string, args ...interface{})` - Log error message
+- `Fatal(format string, args ...interface{})` - Log fatal message and exit
+
+### Global Functions
+
+For convenience, you can use global functions that use the default logger:
+
+- `logger.Debug(format, args...)`
+- `logger.Info(format, args...)`
+- `logger.Warn(format, args...)`
+- `logger.Error(format, args...)`
+- `logger.Fatal(format, args...)`
+- `logger.SetOutput(output *os.File)`
+
+## Migration Guide
+
+No changes needed! The logger maintains 100% backward compatibility. Your existing code will continue to work without modifications.
+
+If you want to switch to a custom writer:
+1. Create your writer implementing `LogWriter`
+2. Use `NewLoggerWithWriter()` instead of `NewLogger()`
+3. That's it!

examples/logger_examples.go

@@ -0,0 +1,161 @@
+// Example usage patterns for the extensible logger
+package main
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/fosrl/newt/logger"
+)
+
+// Example 1: Using the default logger (works exactly as before)
+func exampleDefaultLogger() {
+	logger.Info("Starting application")
+	logger.Debug("Debug information")
+	logger.Warn("Warning message")
+	logger.Error("Error occurred")
+}
+
+// Example 2: Using a custom logger instance with standard writer
+func exampleCustomInstance() {
+	log := logger.NewLogger()
+	log.SetLevel(logger.INFO)
+	log.Info("This is from a custom instance")
+}
+
+// Example 3: Custom writer that adds JSON formatting
+type JSONWriter struct{}
+
+func (w *JSONWriter) Write(level logger.LogLevel, timestamp time.Time, message string) {
+	fmt.Printf("{\"time\":\"%s\",\"level\":\"%s\",\"message\":\"%s\"}\n",
+		timestamp.Format(time.RFC3339),
+		level.String(),
+		message)
+}
+
+func exampleJSONLogger() {
+	jsonWriter := &JSONWriter{}
+	log := logger.NewLoggerWithWriter(jsonWriter)
+	log.Info("This will be logged as JSON")
+}
+
+// Example 4: File writer
+type FileWriter struct {
+	file *os.File
+}
+
+func NewFileWriter(filename string) (*FileWriter, error) {
+	file, err := os.OpenFile(filename, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
+	if err != nil {
+		return nil, err
+	}
+	return &FileWriter{file: file}, nil
+}
+
+func (w *FileWriter) Write(level logger.LogLevel, timestamp time.Time, message string) {
+	fmt.Fprintf(w.file, "[%s] %s: %s\n",
+		timestamp.Format("2006-01-02 15:04:05"),
+		level.String(),
+		message)
+}
+
+func (w *FileWriter) Close() error {
+	return w.file.Close()
+}
+
+func exampleFileLogger() {
+	fileWriter, err := NewFileWriter("/tmp/app.log")
+	if err != nil {
+		panic(err)
+	}
+	defer fileWriter.Close()
+
+	log := logger.NewLoggerWithWriter(fileWriter)
+	log.Info("This goes to a file")
+}
+
+// Example 5: Multi-writer to log to multiple destinations
+type MultiWriter struct {
+	writers []logger.LogWriter
+}
+
+func NewMultiWriter(writers ...logger.LogWriter) *MultiWriter {
+	return &MultiWriter{writers: writers}
+}
+
+func (w *MultiWriter) Write(level logger.LogLevel, timestamp time.Time, message string) {
+	for _, writer := range w.writers {
+		writer.Write(level, timestamp, message)
+	}
+}
+
+func exampleMultiWriter() {
+	// Log to both stdout and a file
+	standardWriter := logger.NewStandardWriter()
+	fileWriter, _ := NewFileWriter("/tmp/app.log")
+
+	multiWriter := NewMultiWriter(standardWriter, fileWriter)
+	log := logger.NewLoggerWithWriter(multiWriter)
+
+	log.Info("This goes to both stdout and file!")
+}
+
+// Example 6: Conditional writer (only log errors to a specific destination)
+type ErrorOnlyWriter struct {
+	writer logger.LogWriter
+}
+
+func NewErrorOnlyWriter(writer logger.LogWriter) *ErrorOnlyWriter {
+	return &ErrorOnlyWriter{writer: writer}
+}
+
+func (w *ErrorOnlyWriter) Write(level logger.LogLevel, timestamp time.Time, message string) {
+	if level >= logger.ERROR {
+		w.writer.Write(level, timestamp, message)
+	}
+}
+
+func exampleConditionalWriter() {
+	errorWriter, _ := NewFileWriter("/tmp/errors.log")
+	errorOnlyWriter := NewErrorOnlyWriter(errorWriter)
+
+	log := logger.NewLoggerWithWriter(errorOnlyWriter)
+	log.Info("This won't be logged")
+	log.Error("This will be logged to errors.log")
+}
+
+/* Example 7: OS Log Writer (macOS/iOS only)
+// Uncomment on Darwin platforms
+
+func exampleOSLogWriter() {
+	osWriter := logger.NewOSLogWriter(
+		"net.pangolin.Pangolin.PacketTunnel",
+		"PangolinGo",
+		"MyApp",
+	)
+
+	log := logger.NewLoggerWithWriter(osWriter)
+	log.Info("This goes to os_log and can be viewed with Console.app")
+}
+*/
+
+func main() {
+	fmt.Println("=== Example 1: Default Logger ===")
+	exampleDefaultLogger()
+
+	fmt.Println("\n=== Example 2: Custom Instance ===")
+	exampleCustomInstance()
+
+	fmt.Println("\n=== Example 3: JSON Logger ===")
+	exampleJSONLogger()
+
+	fmt.Println("\n=== Example 4: File Logger ===")
+	exampleFileLogger()
+
+	fmt.Println("\n=== Example 5: Multi-Writer ===")
+	exampleMultiWriter()
+
+	fmt.Println("\n=== Example 6: Conditional Writer ===")
+	exampleConditionalWriter()
+}

examples/oslog_writer_example.go

@@ -0,0 +1,86 @@
+//go:build darwin
+// +build darwin
+
+package main
+
+/*
+#cgo CFLAGS: -I../PacketTunnel
+#include "../PacketTunnel/OSLogBridge.h"
+#include <stdlib.h>
+*/
+import "C"
+import (
+	"fmt"
+	"runtime"
+	"time"
+	"unsafe"
+)
+
+// OSLogWriter is a LogWriter implementation that writes to Apple's os_log
+type OSLogWriter struct {
+	subsystem string
+	category  string
+	prefix    string
+}
+
+// NewOSLogWriter creates a new OSLogWriter
+func NewOSLogWriter(subsystem, category, prefix string) *OSLogWriter {
+	writer := &OSLogWriter{
+		subsystem: subsystem,
+		category:  category,
+		prefix:    prefix,
+	}
+
+	// Initialize the OS log bridge
+	cSubsystem := C.CString(subsystem)
+	cCategory := C.CString(category)
+	defer C.free(unsafe.Pointer(cSubsystem))
+	defer C.free(unsafe.Pointer(cCategory))
+
+	C.initOSLogBridge(cSubsystem, cCategory)
+
+	return writer
+}
+
+// Write implements the LogWriter interface
+func (w *OSLogWriter) Write(level LogLevel, timestamp time.Time, message string) {
+	// Get caller information (skip 3 frames to get to the actual caller)
+	_, file, line, ok := runtime.Caller(3)
+	if !ok {
+		file = "unknown"
+		line = 0
+	} else {
+		// Get just the filename, not the full path
+		for i := len(file) - 1; i > 0; i-- {
+			if file[i] == '/' {
+				file = file[i+1:]
+				break
+			}
+		}
+	}
+
+	formattedTime := timestamp.Format("2006-01-02 15:04:05.000")
+	fullMessage := fmt.Sprintf("[%s] [%s] [%s] %s:%d - %s",
+		formattedTime, level.String(), w.prefix, file, line, message)
+
+	cMessage := C.CString(fullMessage)
+	defer C.free(unsafe.Pointer(cMessage))
+
+	// Map Go log levels to os_log levels:
+	// 0=DEBUG, 1=INFO, 2=DEFAULT (WARN), 3=ERROR
+	var osLogLevel C.int
+	switch level {
+	case DEBUG:
+		osLogLevel = 0 // DEBUG
+	case INFO:
+		osLogLevel = 1 // INFO
+	case WARN:
+		osLogLevel = 2 // DEFAULT
+	case ERROR, FATAL:
+		osLogLevel = 3 // ERROR
+	default:
+		osLogLevel = 2 // DEFAULT
+	}
+
+	C.logToOSLog(osLogLevel, cMessage)
+}

go.mod

@@ -4,7 +4,6 @@ go 1.25
 
 require (
 	github.com/docker/docker v28.5.2+incompatible
-	github.com/google/gopacket v1.1.19
 	github.com/gorilla/websocket v1.5.3
 	github.com/prometheus/client_golang v1.23.2
 	github.com/vishvananda/netlink v1.3.1
@@ -18,9 +17,12 @@ require (
 	go.opentelemetry.io/otel/sdk v1.38.0
 	go.opentelemetry.io/otel/sdk/metric v1.38.0
 	golang.org/x/crypto v0.45.0
+	golang.org/x/exp v0.0.0-20251113190631-e25ba8c21ef6
 	golang.org/x/net v0.47.0
+	golang.org/x/sys v0.38.0
 	golang.zx2c4.com/wireguard v0.0.0-20250521234502-f333402bd9cb
 	golang.zx2c4.com/wireguard/wgctrl v0.0.0-20241231184526-a9ab2273dd10
+	golang.zx2c4.com/wireguard/windows v0.5.3
 	google.golang.org/grpc v1.76.0
 	gopkg.in/yaml.v3 v3.0.1
 	gvisor.dev/gvisor v0.0.0-20250503011706-39ed1f5ac29c
@@ -41,14 +43,9 @@ require (
 	github.com/go-logr/logr v1.4.3 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/google/btree v1.1.3 // indirect
-	github.com/google/go-cmp v0.7.0 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/grafana/regexp v0.0.0-20240518133315-a468a5bfb3bc // indirect
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.27.2 // indirect
-	github.com/josharian/native v1.1.0 // indirect
-	github.com/mdlayher/genetlink v1.3.2 // indirect
-	github.com/mdlayher/netlink v1.7.2 // indirect
-	github.com/mdlayher/socket v0.5.1 // indirect
 	github.com/moby/docker-image-spec v1.3.1 // indirect
 	github.com/moby/sys/atomicwriter v0.1.0 // indirect
 	github.com/moby/term v0.5.2 // indirect
@@ -68,12 +65,11 @@ require (
 	go.opentelemetry.io/otel/trace v1.38.0 // indirect
 	go.opentelemetry.io/proto/otlp v1.7.1 // indirect
 	go.yaml.in/yaml/v2 v2.4.2 // indirect
-	golang.org/x/mod v0.29.0 // indirect
+	golang.org/x/mod v0.30.0 // indirect
 	golang.org/x/sync v0.18.0 // indirect
-	golang.org/x/sys v0.38.0 // indirect
 	golang.org/x/text v0.31.0 // indirect
 	golang.org/x/time v0.12.0 // indirect
-	golang.org/x/tools v0.38.0 // indirect
+	golang.org/x/tools v0.39.0 // indirect
 	golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2 // indirect
 	google.golang.org/genproto/googleapis/api v0.0.0-20250825161204-c5933d9347a5 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20250825161204-c5933d9347a5 // indirect

go.sum

@@ -37,8 +37,6 @@ github.com/google/btree v1.1.3 h1:CVpQJjYgC4VbzxeGVHfvZrv1ctoYCAI8vbl07Fcxlyg=
 github.com/google/btree v1.1.3/go.mod h1:qOPhT0dTNdNzV6Z/lhRX0YXUafgPLFUh+gZMl761Gm4=
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
-github.com/google/gopacket v1.1.19 h1:ves8RnFZPGiFnTS0uPQStjwru6uO6h+nlr9j6fL7kF8=
-github.com/google/gopacket v1.1.19/go.mod h1:iJ8V8n6KS+z2U1A8pUwu8bW5SyEMkXJB8Yo/Vo+TKTo=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aNNg=
@@ -47,8 +45,6 @@ github.com/grafana/regexp v0.0.0-20240518133315-a468a5bfb3bc h1:GN2Lv3MGO7AS6PrR
 github.com/grafana/regexp v0.0.0-20240518133315-a468a5bfb3bc/go.mod h1:+JKpmjMGhpgPL+rXZ5nsZieVzvarn86asRlBg4uNGnk=
 github.com/grpc-ecosystem/grpc-gateway/v2 v2.27.2 h1:8Tjv8EJ+pM1xP8mK6egEbD1OgnVTyacbefKhmbLhIhU=
 github.com/grpc-ecosystem/grpc-gateway/v2 v2.27.2/go.mod h1:pkJQ2tZHJ0aFOVEEot6oZmaVEZcRme73eIFmhiVuRWs=
-github.com/josharian/native v1.1.0 h1:uuaP0hAbW7Y4l0ZRQ6C9zfb7Mg1mbFKry/xzDAfmtLA=
-github.com/josharian/native v1.1.0/go.mod h1:7X/raswPFr05uY3HiLlYeyQntB6OO7E/d2Cu7qoaN2w=
 github.com/klauspost/compress v1.18.0 h1:c/Cqfb0r+Yi+JtIEq73FWXVkRonBlf0CRNYc8Zttxdo=
 github.com/klauspost/compress v1.18.0/go.mod h1:2Pp+KzxcywXVXMr50+X0Q/Lsb43OQHYWRCY2AiWywWQ=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
@@ -57,14 +53,6 @@ github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
 github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
-github.com/mdlayher/genetlink v1.3.2 h1:KdrNKe+CTu+IbZnm/GVUMXSqBBLqcGpRDa0xkQy56gw=
-github.com/mdlayher/genetlink v1.3.2/go.mod h1:tcC3pkCrPUGIKKsCsp0B3AdaaKuHtaxoJRz3cc+528o=
-github.com/mdlayher/netlink v1.7.2 h1:/UtM3ofJap7Vl4QWCPDGXY8d3GIY2UGSDbK+QWmY8/g=
-github.com/mdlayher/netlink v1.7.2/go.mod h1:xraEF7uJbxLhc5fpHL4cPe221LI2bdttWlU+ZGLfQSw=
-github.com/mdlayher/socket v0.5.1 h1:VZaqt6RkGkt2OE9l3GcC6nZkqD3xKeQLyfleW/uBcos=
-github.com/mdlayher/socket v0.5.1/go.mod h1:TjPLHI1UgwEv5J1B5q0zTZq12A/6H7nKmtTanQE37IQ=
-github.com/mikioh/ipaddr v0.0.0-20190404000644-d465c8ab6721 h1:RlZweED6sbSArvlE924+mUcZuXKLBHA35U7LN621Bws=
-github.com/mikioh/ipaddr v0.0.0-20190404000644-d465c8ab6721/go.mod h1:Ickgr2WtCLZ2MDGd4Gr0geeCH5HybhRJbonOgQpvSxc=
 github.com/moby/docker-image-spec v1.3.1 h1:jMKff3w6PgbfSa69GfNg+zN/XLhfXJGnEx3Nl2EsFP0=
 github.com/moby/docker-image-spec v1.3.1/go.mod h1:eKmb5VW8vQEh/BAr2yvVNvuiJuY6UIocYsFu/DxxRpo=
 github.com/moby/sys/atomicwriter v0.1.0 h1:kw5D/EqkBwsBFi0ss9v1VG3wIkVhzGvLklJ+w3A14Sw=
@@ -137,42 +125,34 @@ go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
 go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
 go.yaml.in/yaml/v2 v2.4.2 h1:DzmwEr2rDGHl7lsFgAHxmNz/1NlQ7xLIrlN2h5d1eGI=
 go.yaml.in/yaml/v2 v2.4.2/go.mod h1:081UH+NErpNdqlCXm3TtEran0rJZGxAYx9hb/ELlsPU=
-golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.45.0 h1:jMBrvKuj23MTlT0bQEOBcAE0mjg8mK9RXFhRH6nyF3Q=
 golang.org/x/crypto v0.45.0/go.mod h1:XTGrrkGJve7CYK7J8PEww4aY7gM3qMCElcJQ8n8JdX4=
-golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
+golang.org/x/exp v0.0.0-20251113190631-e25ba8c21ef6 h1:zfMcR1Cs4KNuomFFgGefv5N0czO2XZpUbxGUy8i8ug0=
-golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
+golang.org/x/exp v0.0.0-20251113190631-e25ba8c21ef6/go.mod h1:46edojNIoXTNOhySWIWdix628clX9ODXwPsQuG6hsK0=
-golang.org/x/mod v0.29.0 h1:HV8lRxZC4l2cr3Zq1LvtOsi/ThTgWnUk/y64QSs8GwA=
+golang.org/x/mod v0.30.0 h1:fDEXFVZ/fmCKProc/yAXXUijritrDzahmwwefnjoPFk=
-golang.org/x/mod v0.29.0/go.mod h1:NyhrlYXJ2H4eJiRy/WDBO6HMqZQ6q9nk4JzS3NuCK+w=
+golang.org/x/mod v0.30.0/go.mod h1:lAsf5O2EvJeSFMiBxXDki7sCgAxEUcZHXoXMKT4GJKc=
-golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.47.0 h1:Mx+4dIFzqraBXUugkia1OOvlD6LemFo1ALMHjrXDOhY=
 golang.org/x/net v0.47.0/go.mod h1:/jNxtkgq5yWUGYkaZGqo27cfGZ1c5Nen03aYrrKpVRU=
-golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.18.0 h1:kr88TuHDroi+UVf+0hZnirlk8o8T+4MrK6mr60WkH/I=
 golang.org/x/sync v0.18.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
-golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.10.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.38.0 h1:3yZWxaJjBmCWXqhN1qh02AkOnCQ1poK6oF+a7xWL6Gc=
 golang.org/x/sys v0.38.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
-golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.31.0 h1:aC8ghyu4JhP8VojJ2lEHBnochRno1sgL6nEi9WGFGMM=
 golang.org/x/text v0.31.0/go.mod h1:tKRAlv61yKIjGGHX/4tP1LTbc13YSec1pxVEWXzfoeM=
 golang.org/x/time v0.12.0 h1:ScB/8o8olJvc+CQPWrK3fPZNfh7qgwCrY0zJmoEQLSE=
 golang.org/x/time v0.12.0/go.mod h1:CDIdPxbZBQxdj6cxyCIdrNogrJKMJ7pr37NYpMcMDSg=
-golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
+golang.org/x/tools v0.39.0 h1:ik4ho21kwuQln40uelmciQPp9SipgNDdrafrYA4TmQQ=
-golang.org/x/tools v0.38.0 h1:Hx2Xv8hISq8Lm16jvBZ2VQf+RLmbd7wVUsALibYI/IQ=
+golang.org/x/tools v0.39.0/go.mod h1:JnefbkDPyD8UU2kI5fuf8ZX4/yUeh9W877ZeBONxUqQ=
-golang.org/x/tools v0.38.0/go.mod h1:yEsQ/d/YK8cjh0L6rZlY8tgtlKiBNTL14pGDJPJpYQs=
-golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2 h1:B82qJJgjvYKsXS9jeunTOisW56dUokqW/FOteYJJ/yg=
 golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2/go.mod h1:deeaetjYA+DHMHg+sMSMI58GrEteJUUzzw7en6TJQcI=
 golang.zx2c4.com/wireguard v0.0.0-20250521234502-f333402bd9cb h1:whnFRlWMcXI9d+ZbWg+4sHnLp52d5yiIPUxMBSt4X9A=
 golang.zx2c4.com/wireguard v0.0.0-20250521234502-f333402bd9cb/go.mod h1:rpwXGsirqLqN2L0JDJQlwOboGHmptD5ZD6T2VmcqhTw=
 golang.zx2c4.com/wireguard/wgctrl v0.0.0-20241231184526-a9ab2273dd10 h1:3GDAcqdIg1ozBNLgPy4SLT84nfcBjr6rhGtXYtrkWLU=
 golang.zx2c4.com/wireguard/wgctrl v0.0.0-20241231184526-a9ab2273dd10/go.mod h1:T97yPqesLiNrOYxkwmhMI0ZIlJDm+p0PMR8eRVeR5tQ=
+golang.zx2c4.com/wireguard/windows v0.5.3 h1:On6j2Rpn3OEMXqBq00QEDC7bWSZrPIHKIus8eIuExIE=
+golang.zx2c4.com/wireguard/windows v0.5.3/go.mod h1:9TEe8TJmtwyQebdFwAkEWOPr3prrtqm+REGFifP60hI=
 gonum.org/v1/gonum v0.16.0 h1:5+ul4Swaf3ESvrOnidPp4GZbzf0mxVQpDCYUQE7OJfk=
 gonum.org/v1/gonum v0.16.0/go.mod h1:fef3am4MQ93R2HHpKnLk4/Tbh/s0+wqD5nfa6Pnwy4E=
 google.golang.org/genproto/googleapis/api v0.0.0-20250825161204-c5933d9347a5 h1:BIRfGDEjiHRrk0QKZe3Xv2ieMhtgRGeLcZQ0mIVn4EY=

holepunch/holepunch.go

@@ -0,0 +1,517 @@
+package holepunch
+
+import (
+	"encoding/json"
+	"fmt"
+	"net"
+	"sync"
+	"time"
+
+	"github.com/fosrl/newt/bind"
+	"github.com/fosrl/newt/logger"
+	"github.com/fosrl/newt/util"
+	"golang.org/x/crypto/chacha20poly1305"
+	"golang.org/x/crypto/curve25519"
+	mrand "golang.org/x/exp/rand"
+	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
+)
+
+// ExitNode represents a WireGuard exit node for hole punching
+type ExitNode struct {
+	Endpoint  string `json:"endpoint"`
+	PublicKey string `json:"publicKey"`
+}
+
+// Manager handles UDP hole punching operations
+type Manager struct {
+	mu         sync.Mutex
+	running    bool
+	stopChan   chan struct{}
+	sharedBind *bind.SharedBind
+	ID         string
+	token      string
+	publicKey  string
+	clientType string
+	exitNodes  map[string]ExitNode // key is endpoint
+	updateChan chan struct{}       // signals the goroutine to refresh exit nodes
+
+	sendHolepunchInterval time.Duration
+}
+
+const sendHolepunchIntervalMax = 60 * time.Second
+const sendHolepunchIntervalMin = 1 * time.Second
+
+// NewManager creates a new hole punch manager
+func NewManager(sharedBind *bind.SharedBind, ID string, clientType string, publicKey string) *Manager {
+	return &Manager{
+		sharedBind:            sharedBind,
+		ID:                    ID,
+		clientType:            clientType,
+		publicKey:             publicKey,
+		exitNodes:             make(map[string]ExitNode),
+		sendHolepunchInterval: sendHolepunchIntervalMin,
+	}
+}
+
+// SetToken updates the authentication token used for hole punching
+func (m *Manager) SetToken(token string) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	m.token = token
+}
+
+// IsRunning returns whether hole punching is currently active
+func (m *Manager) IsRunning() bool {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	return m.running
+}
+
+// Stop stops any ongoing hole punch operations
+func (m *Manager) Stop() {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if !m.running {
+		return
+	}
+
+	if m.stopChan != nil {
+		close(m.stopChan)
+		m.stopChan = nil
+	}
+
+	if m.updateChan != nil {
+		close(m.updateChan)
+		m.updateChan = nil
+	}
+
+	m.running = false
+	logger.Info("Hole punch manager stopped")
+}
+
+// AddExitNode adds a new exit node to the rotation if it doesn't already exist
+func (m *Manager) AddExitNode(exitNode ExitNode) bool {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if _, exists := m.exitNodes[exitNode.Endpoint]; exists {
+		logger.Debug("Exit node %s already exists in rotation", exitNode.Endpoint)
+		return false
+	}
+
+	m.exitNodes[exitNode.Endpoint] = exitNode
+	logger.Info("Added exit node %s to hole punch rotation", exitNode.Endpoint)
+
+	// Signal the goroutine to refresh if running
+	if m.running && m.updateChan != nil {
+		select {
+		case m.updateChan <- struct{}{}:
+		default:
+			// Channel full or closed, skip
+		}
+	}
+
+	return true
+}
+
+// RemoveExitNode removes an exit node from the rotation
+func (m *Manager) RemoveExitNode(endpoint string) bool {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if _, exists := m.exitNodes[endpoint]; !exists {
+		logger.Debug("Exit node %s not found in rotation", endpoint)
+		return false
+	}
+
+	delete(m.exitNodes, endpoint)
+	logger.Info("Removed exit node %s from hole punch rotation", endpoint)
+
+	// Signal the goroutine to refresh if running
+	if m.running && m.updateChan != nil {
+		select {
+		case m.updateChan <- struct{}{}:
+		default:
+			// Channel full or closed, skip
+		}
+	}
+
+	return true
+}
+
+// GetExitNodes returns a copy of the current exit nodes
+func (m *Manager) GetExitNodes() []ExitNode {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	nodes := make([]ExitNode, 0, len(m.exitNodes))
+	for _, node := range m.exitNodes {
+		nodes = append(nodes, node)
+	}
+	return nodes
+}
+
+// ResetInterval resets the hole punch interval back to the minimum value,
+// allowing it to climb back up through exponential backoff.
+// This is useful when network conditions change or connectivity is restored.
+func (m *Manager) ResetInterval() {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if m.sendHolepunchInterval != sendHolepunchIntervalMin {
+		m.sendHolepunchInterval = sendHolepunchIntervalMin
+		logger.Info("Reset hole punch interval to minimum (%v)", sendHolepunchIntervalMin)
+	}
+
+	// Signal the goroutine to apply the new interval if running
+	if m.running && m.updateChan != nil {
+		select {
+		case m.updateChan <- struct{}{}:
+		default:
+			// Channel full or closed, skip
+		}
+	}
+}
+
+// TriggerHolePunch sends an immediate hole punch packet to all configured exit nodes
+// This is useful for triggering hole punching on demand without waiting for the interval
+func (m *Manager) TriggerHolePunch() error {
+	m.mu.Lock()
+
+	if len(m.exitNodes) == 0 {
+		m.mu.Unlock()
+		return fmt.Errorf("no exit nodes configured")
+	}
+
+	// Get a copy of exit nodes to work with
+	currentExitNodes := make([]ExitNode, 0, len(m.exitNodes))
+	for _, node := range m.exitNodes {
+		currentExitNodes = append(currentExitNodes, node)
+	}
+	m.mu.Unlock()
+
+	logger.Info("Triggering on-demand hole punch to %d exit nodes", len(currentExitNodes))
+
+	// Send hole punch to all exit nodes
+	successCount := 0
+	for _, exitNode := range currentExitNodes {
+		host, err := util.ResolveDomain(exitNode.Endpoint)
+		if err != nil {
+			logger.Warn("Failed to resolve endpoint %s: %v", exitNode.Endpoint, err)
+			continue
+		}
+
+		serverAddr := net.JoinHostPort(host, "21820")
+		remoteAddr, err := net.ResolveUDPAddr("udp", serverAddr)
+		if err != nil {
+			logger.Error("Failed to resolve UDP address %s: %v", serverAddr, err)
+			continue
+		}
+
+		if err := m.sendHolePunch(remoteAddr, exitNode.PublicKey); err != nil {
+			logger.Warn("Failed to send on-demand hole punch to %s: %v", exitNode.Endpoint, err)
+			continue
+		}
+
+		logger.Debug("Sent on-demand hole punch to %s", exitNode.Endpoint)
+		successCount++
+	}
+
+	if successCount == 0 {
+		return fmt.Errorf("failed to send hole punch to any exit node")
+	}
+
+	logger.Info("Successfully sent on-demand hole punch to %d/%d exit nodes", successCount, len(currentExitNodes))
+	return nil
+}
+
+// StartMultipleExitNodes starts hole punching to multiple exit nodes
+func (m *Manager) StartMultipleExitNodes(exitNodes []ExitNode) error {
+	m.mu.Lock()
+
+	if m.running {
+		m.mu.Unlock()
+		logger.Debug("UDP hole punch already running, skipping new request")
+		return fmt.Errorf("hole punch already running")
+	}
+
+	// Populate exit nodes map
+	m.exitNodes = make(map[string]ExitNode)
+	for _, node := range exitNodes {
+		m.exitNodes[node.Endpoint] = node
+	}
+
+	m.running = true
+	m.stopChan = make(chan struct{})
+	m.updateChan = make(chan struct{}, 1)
+	m.mu.Unlock()
+
+	logger.Info("Starting UDP hole punch to %d exit nodes with shared bind", len(exitNodes))
+
+	go m.runMultipleExitNodes()
+
+	return nil
+}
+
+// Start starts hole punching with the current set of exit nodes
+func (m *Manager) Start() error {
+	m.mu.Lock()
+
+	if m.running {
+		m.mu.Unlock()
+		logger.Debug("UDP hole punch already running")
+		return fmt.Errorf("hole punch already running")
+	}
+
+	m.running = true
+	m.stopChan = make(chan struct{})
+	m.updateChan = make(chan struct{}, 1)
+	nodeCount := len(m.exitNodes)
+	m.mu.Unlock()
+
+	if nodeCount == 0 {
+		logger.Info("Starting UDP hole punch manager (waiting for exit nodes to be added)")
+	} else {
+		logger.Info("Starting UDP hole punch with %d exit nodes", nodeCount)
+	}
+
+	go m.runMultipleExitNodes()
+
+	return nil
+}
+
+// runMultipleExitNodes performs hole punching to multiple exit nodes
+func (m *Manager) runMultipleExitNodes() {
+	defer func() {
+		m.mu.Lock()
+		m.running = false
+		m.mu.Unlock()
+		logger.Info("UDP hole punch goroutine ended for all exit nodes")
+	}()
+
+	// Resolve all endpoints upfront
+	type resolvedExitNode struct {
+		remoteAddr   *net.UDPAddr
+		publicKey    string
+		endpointName string
+	}
+
+	resolveNodes := func() []resolvedExitNode {
+		m.mu.Lock()
+		currentExitNodes := make([]ExitNode, 0, len(m.exitNodes))
+		for _, node := range m.exitNodes {
+			currentExitNodes = append(currentExitNodes, node)
+		}
+		m.mu.Unlock()
+
+		var resolvedNodes []resolvedExitNode
+		for _, exitNode := range currentExitNodes {
+			host, err := util.ResolveDomain(exitNode.Endpoint)
+			if err != nil {
+				logger.Warn("Failed to resolve endpoint %s: %v", exitNode.Endpoint, err)
+				continue
+			}
+
+			serverAddr := net.JoinHostPort(host, "21820")
+			remoteAddr, err := net.ResolveUDPAddr("udp", serverAddr)
+			if err != nil {
+				logger.Error("Failed to resolve UDP address %s: %v", serverAddr, err)
+				continue
+			}
+
+			resolvedNodes = append(resolvedNodes, resolvedExitNode{
+				remoteAddr:   remoteAddr,
+				publicKey:    exitNode.PublicKey,
+				endpointName: exitNode.Endpoint,
+			})
+			logger.Info("Resolved exit node: %s -> %s", exitNode.Endpoint, remoteAddr.String())
+		}
+		return resolvedNodes
+	}
+
+	resolvedNodes := resolveNodes()
+
+	if len(resolvedNodes) == 0 {
+		logger.Info("No exit nodes available yet, waiting for nodes to be added")
+	} else {
+		// Send initial hole punch to all exit nodes
+		for _, node := range resolvedNodes {
+			if err := m.sendHolePunch(node.remoteAddr, node.publicKey); err != nil {
+				logger.Warn("Failed to send initial hole punch to %s: %v", node.endpointName, err)
+			}
+		}
+	}
+
+	// Start with minimum interval
+	m.mu.Lock()
+	m.sendHolepunchInterval = sendHolepunchIntervalMin
+	m.mu.Unlock()
+
+	ticker := time.NewTicker(m.sendHolepunchInterval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-m.stopChan:
+			logger.Debug("Hole punch stopped by signal")
+			return
+		case <-m.updateChan:
+			// Re-resolve exit nodes when update is signaled
+			logger.Info("Refreshing exit nodes for hole punching")
+			resolvedNodes = resolveNodes()
+			if len(resolvedNodes) == 0 {
+				logger.Warn("No exit nodes available after refresh")
+			} else {
+				logger.Info("Updated resolved nodes count: %d", len(resolvedNodes))
+			}
+			// Reset interval to minimum on update
+			m.mu.Lock()
+			m.sendHolepunchInterval = sendHolepunchIntervalMin
+			m.mu.Unlock()
+			ticker.Reset(m.sendHolepunchInterval)
+			// Send immediate hole punch to newly resolved nodes
+			for _, node := range resolvedNodes {
+				if err := m.sendHolePunch(node.remoteAddr, node.publicKey); err != nil {
+					logger.Debug("Failed to send hole punch to %s: %v", node.endpointName, err)
+				}
+			}
+		case <-ticker.C:
+			// Send hole punch to all exit nodes (if any are available)
+			if len(resolvedNodes) > 0 {
+				for _, node := range resolvedNodes {
+					if err := m.sendHolePunch(node.remoteAddr, node.publicKey); err != nil {
+						logger.Debug("Failed to send hole punch to %s: %v", node.endpointName, err)
+					}
+				}
+				// Exponential backoff: double the interval up to max
+				m.mu.Lock()
+				newInterval := m.sendHolepunchInterval * 2
+				if newInterval > sendHolepunchIntervalMax {
+					newInterval = sendHolepunchIntervalMax
+				}
+				if newInterval != m.sendHolepunchInterval {
+					m.sendHolepunchInterval = newInterval
+					ticker.Reset(m.sendHolepunchInterval)
+					logger.Debug("Increased hole punch interval to %v", m.sendHolepunchInterval)
+				}
+				m.mu.Unlock()
+			}
+		}
+	}
+}
+
+// sendHolePunch sends an encrypted hole punch packet using the shared bind
+func (m *Manager) sendHolePunch(remoteAddr *net.UDPAddr, serverPubKey string) error {
+	m.mu.Lock()
+	token := m.token
+	ID := m.ID
+	m.mu.Unlock()
+
+	if serverPubKey == "" || token == "" {
+		return fmt.Errorf("server public key or OLM token is empty")
+	}
+
+	var payload interface{}
+	if m.clientType == "newt" {
+		payload = struct {
+			ID        string `json:"newtId"`
+			Token     string `json:"token"`
+			PublicKey string `json:"publicKey"`
+		}{
+			ID:        ID,
+			Token:     token,
+			PublicKey: m.publicKey,
+		}
+	} else {
+		payload = struct {
+			ID        string `json:"olmId"`
+			Token     string `json:"token"`
+			PublicKey string `json:"publicKey"`
+		}{
+			ID:        ID,
+			Token:     token,
+			PublicKey: m.publicKey,
+		}
+	}
+
+	// Convert payload to JSON
+	payloadBytes, err := json.Marshal(payload)
+	if err != nil {
+		return fmt.Errorf("failed to marshal payload: %w", err)
+	}
+
+	// Encrypt the payload using the server's WireGuard public key
+	encryptedPayload, err := encryptPayload(payloadBytes, serverPubKey)
+	if err != nil {
+		return fmt.Errorf("failed to encrypt payload: %w", err)
+	}
+
+	jsonData, err := json.Marshal(encryptedPayload)
+	if err != nil {
+		return fmt.Errorf("failed to marshal encrypted payload: %w", err)
+	}
+
+	_, err = m.sharedBind.WriteToUDP(jsonData, remoteAddr)
+	if err != nil {
+		return fmt.Errorf("failed to write to UDP: %w", err)
+	}
+
+	logger.Debug("Sent UDP hole punch to %s: %s", remoteAddr.String(), string(jsonData))
+
+	return nil
+}
+
+// encryptPayload encrypts the payload using ChaCha20-Poly1305 AEAD with X25519 key exchange
+func encryptPayload(payload []byte, serverPublicKey string) (interface{}, error) {
+	// Generate an ephemeral keypair for this message
+	ephemeralPrivateKey, err := wgtypes.GeneratePrivateKey()
+	if err != nil {
+		return nil, fmt.Errorf("failed to generate ephemeral private key: %v", err)
+	}
+	ephemeralPublicKey := ephemeralPrivateKey.PublicKey()
+
+	// Parse the server's public key
+	serverPubKey, err := wgtypes.ParseKey(serverPublicKey)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse server public key: %v", err)
+	}
+
+	// Use X25519 for key exchange
+	var ephPrivKeyFixed [32]byte
+	copy(ephPrivKeyFixed[:], ephemeralPrivateKey[:])
+
+	// Perform X25519 key exchange
+	sharedSecret, err := curve25519.X25519(ephPrivKeyFixed[:], serverPubKey[:])
+	if err != nil {
+		return nil, fmt.Errorf("failed to perform X25519 key exchange: %v", err)
+	}
+
+	// Create an AEAD cipher using the shared secret
+	aead, err := chacha20poly1305.New(sharedSecret)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create AEAD cipher: %v", err)
+	}
+
+	// Generate a random nonce
+	nonce := make([]byte, aead.NonceSize())
+	if _, err := mrand.Read(nonce); err != nil {
+		return nil, fmt.Errorf("failed to generate nonce: %v", err)
+	}
+
+	// Encrypt the payload
+	ciphertext := aead.Seal(nil, nonce, payload, nil)
+
+	// Prepare the final encrypted message
+	encryptedMsg := struct {
+		EphemeralPublicKey string `json:"ephemeralPublicKey"`
+		Nonce              []byte `json:"nonce"`
+		Ciphertext         []byte `json:"ciphertext"`
+	}{
+		EphemeralPublicKey: ephemeralPublicKey.String(),
+		Nonce:              nonce,
+		Ciphertext:         ciphertext,
+	}
+
+	return encryptedMsg, nil
+}

holepunch/tester.go

@@ -0,0 +1,343 @@
+package holepunch
+
+import (
+	"crypto/rand"
+	"fmt"
+	"net"
+	"net/netip"
+	"sync"
+	"time"
+
+	"github.com/fosrl/newt/bind"
+	"github.com/fosrl/newt/logger"
+	"github.com/fosrl/newt/util"
+)
+
+// TestResult represents the result of a connection test
+type TestResult struct {
+	// Success indicates whether the test was successful
+	Success bool
+	// RTT is the round-trip time of the test packet
+	RTT time.Duration
+	// Endpoint is the endpoint that was tested
+	Endpoint string
+	// Error contains any error that occurred during the test
+	Error error
+}
+
+// TestConnectionOptions configures the connection test
+type TestConnectionOptions struct {
+	// Timeout is how long to wait for a response (default: 5 seconds)
+	Timeout time.Duration
+	// Retries is the number of times to retry on failure (default: 0)
+	Retries int
+}
+
+// DefaultTestOptions returns the default test options
+func DefaultTestOptions() TestConnectionOptions {
+	return TestConnectionOptions{
+		Timeout: 5 * time.Second,
+		Retries: 0,
+	}
+}
+
+// HolepunchTester monitors holepunch connectivity using magic packets
+type HolepunchTester struct {
+	sharedBind *bind.SharedBind
+	mu         sync.RWMutex
+	running    bool
+	stopChan   chan struct{}
+
+	// Pending requests waiting for responses (key: echo data as string)
+	pendingRequests sync.Map // map[string]*pendingRequest
+
+	// Callback when connection status changes
+	callback HolepunchStatusCallback
+}
+
+// HolepunchStatus represents the status of a holepunch connection
+type HolepunchStatus struct {
+	Endpoint  string
+	Connected bool
+	RTT       time.Duration
+}
+
+// HolepunchStatusCallback is called when holepunch status changes
+type HolepunchStatusCallback func(status HolepunchStatus)
+
+// pendingRequest tracks a pending test request
+type pendingRequest struct {
+	endpoint  string
+	sentAt    time.Time
+	replyChan chan time.Duration
+}
+
+// NewHolepunchTester creates a new holepunch tester using the given SharedBind
+func NewHolepunchTester(sharedBind *bind.SharedBind) *HolepunchTester {
+	return &HolepunchTester{
+		sharedBind: sharedBind,
+	}
+}
+
+// SetCallback sets the callback for connection status changes
+func (t *HolepunchTester) SetCallback(callback HolepunchStatusCallback) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.callback = callback
+}
+
+// Start begins listening for magic packet responses
+func (t *HolepunchTester) Start() error {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	if t.running {
+		return fmt.Errorf("tester already running")
+	}
+
+	if t.sharedBind == nil {
+		return fmt.Errorf("sharedBind is nil")
+	}
+
+	t.running = true
+	t.stopChan = make(chan struct{})
+
+	// Register our callback with the SharedBind to receive magic responses
+	t.sharedBind.SetMagicResponseCallback(t.handleResponse)
+
+	logger.Debug("HolepunchTester started")
+	return nil
+}
+
+// Stop stops the tester
+func (t *HolepunchTester) Stop() {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	if !t.running {
+		return
+	}
+
+	t.running = false
+	close(t.stopChan)
+
+	// Clear the callback
+	if t.sharedBind != nil {
+		t.sharedBind.SetMagicResponseCallback(nil)
+	}
+
+	// Cancel all pending requests
+	t.pendingRequests.Range(func(key, value interface{}) bool {
+		if req, ok := value.(*pendingRequest); ok {
+			close(req.replyChan)
+		}
+		t.pendingRequests.Delete(key)
+		return true
+	})
+
+	logger.Debug("HolepunchTester stopped")
+}
+
+// handleResponse is called by SharedBind when a magic response is received
+func (t *HolepunchTester) handleResponse(addr netip.AddrPort, echoData []byte) {
+	logger.Debug("Received magic response from %s", addr.String())
+	key := string(echoData)
+
+	value, ok := t.pendingRequests.LoadAndDelete(key)
+	if !ok {
+		// No matching request found
+		logger.Debug("No pending request found for magic response from %s", addr.String())
+		return
+	}
+
+	req := value.(*pendingRequest)
+	rtt := time.Since(req.sentAt)
+	logger.Debug("Magic response matched pending request for %s (RTT: %v)", req.endpoint, rtt)
+
+	// Send RTT to the waiting goroutine (non-blocking)
+	select {
+	case req.replyChan <- rtt:
+	default:
+	}
+}
+
+// TestEndpoint sends a magic test packet to the endpoint and waits for a response.
+// This uses the SharedBind so packets come from the same source port as WireGuard.
+func (t *HolepunchTester) TestEndpoint(endpoint string, timeout time.Duration) TestResult {
+	result := TestResult{
+		Endpoint: endpoint,
+	}
+
+	t.mu.RLock()
+	running := t.running
+	sharedBind := t.sharedBind
+	t.mu.RUnlock()
+
+	if !running {
+		result.Error = fmt.Errorf("tester not running")
+		return result
+	}
+
+	if sharedBind == nil || sharedBind.IsClosed() {
+		result.Error = fmt.Errorf("sharedBind is nil or closed")
+		return result
+	}
+
+	// Resolve the endpoint
+	host, err := util.ResolveDomain(endpoint)
+	if err != nil {
+		host = endpoint
+	}
+
+	_, _, err = net.SplitHostPort(host)
+	if err != nil {
+		host = net.JoinHostPort(host, "21820")
+	}
+
+	remoteAddr, err := net.ResolveUDPAddr("udp", host)
+	if err != nil {
+		result.Error = fmt.Errorf("failed to resolve UDP address %s: %w", host, err)
+		return result
+	}
+
+	// Generate random data for the test packet
+	randomData := make([]byte, bind.MagicPacketDataLen)
+	if _, err := rand.Read(randomData); err != nil {
+		result.Error = fmt.Errorf("failed to generate random data: %w", err)
+		return result
+	}
+
+	// Create a pending request
+	req := &pendingRequest{
+		endpoint:  endpoint,
+		sentAt:    time.Now(),
+		replyChan: make(chan time.Duration, 1),
+	}
+
+	key := string(randomData)
+	t.pendingRequests.Store(key, req)
+
+	// Build the test request packet
+	request := make([]byte, bind.MagicTestRequestLen)
+	copy(request, bind.MagicTestRequest)
+	copy(request[len(bind.MagicTestRequest):], randomData)
+
+	// Send the test packet
+	_, err = sharedBind.WriteToUDP(request, remoteAddr)
+	if err != nil {
+		t.pendingRequests.Delete(key)
+		result.Error = fmt.Errorf("failed to send test packet: %w", err)
+		return result
+	}
+
+	// Wait for response with timeout
+	select {
+	case rtt, ok := <-req.replyChan:
+		if ok {
+			result.Success = true
+			result.RTT = rtt
+		} else {
+			result.Error = fmt.Errorf("request cancelled")
+		}
+	case <-time.After(timeout):
+		t.pendingRequests.Delete(key)
+		result.Error = fmt.Errorf("timeout waiting for response")
+	}
+
+	return result
+}
+
+// TestConnectionWithBind sends a magic test packet using an existing SharedBind.
+// This is useful when you want to test the connection through the same socket
+// that WireGuard is using, which tests the actual hole-punched path.
+func TestConnectionWithBind(sharedBind *bind.SharedBind, endpoint string, opts *TestConnectionOptions) TestResult {
+	if opts == nil {
+		defaultOpts := DefaultTestOptions()
+		opts = &defaultOpts
+	}
+
+	result := TestResult{
+		Endpoint: endpoint,
+	}
+
+	if sharedBind == nil {
+		result.Error = fmt.Errorf("sharedBind is nil")
+		return result
+	}
+
+	if sharedBind.IsClosed() {
+		result.Error = fmt.Errorf("sharedBind is closed")
+		return result
+	}
+
+	// Resolve the endpoint
+	host, err := util.ResolveDomain(endpoint)
+	if err != nil {
+		host = endpoint
+	}
+
+	_, _, err = net.SplitHostPort(host)
+	if err != nil {
+		host = net.JoinHostPort(host, "21820")
+	}
+
+	remoteAddr, err := net.ResolveUDPAddr("udp", host)
+	if err != nil {
+		result.Error = fmt.Errorf("failed to resolve UDP address %s: %w", host, err)
+		return result
+	}
+
+	// Generate random data for the test packet
+	randomData := make([]byte, bind.MagicPacketDataLen)
+	if _, err := rand.Read(randomData); err != nil {
+		result.Error = fmt.Errorf("failed to generate random data: %w", err)
+		return result
+	}
+
+	// Build the test request packet
+	request := make([]byte, bind.MagicTestRequestLen)
+	copy(request, bind.MagicTestRequest)
+	copy(request[len(bind.MagicTestRequest):], randomData)
+
+	// Get the underlying UDP connection to set read deadline and read response
+	udpConn := sharedBind.GetUDPConn()
+	if udpConn == nil {
+		result.Error = fmt.Errorf("could not get UDP connection from SharedBind")
+		return result
+	}
+
+	attempts := opts.Retries + 1
+	for attempt := 0; attempt < attempts; attempt++ {
+		if attempt > 0 {
+			logger.Debug("Retrying connection test to %s (attempt %d/%d)", endpoint, attempt+1, attempts)
+		}
+
+		// Note: We can't easily set a read deadline on the shared connection
+		// without affecting WireGuard, so we use a goroutine with timeout instead
+		startTime := time.Now()
+
+		// Send the test packet through the shared bind
+		_, err = sharedBind.WriteToUDP(request, remoteAddr)
+		if err != nil {
+			result.Error = fmt.Errorf("failed to send test packet: %w", err)
+			if attempt < attempts-1 {
+				continue
+			}
+			return result
+		}
+
+		// For shared bind test, we send the packet but can't easily wait for
+		// response without interfering with WireGuard's receive loop.
+		// The response will be handled by SharedBind automatically.
+		// We consider the test successful if the send succeeded.
+		// For a full round-trip test, use TestConnection() with a separate socket.
+
+		result.RTT = time.Since(startTime)
+		result.Success = true
+		result.Error = nil
+		logger.Debug("Test packet sent to %s via SharedBind", endpoint)
+		return result
+	}
+
+	return result
+}

key

@@ -1 +0,0 @@
-oBvcoMJZXGzTZ4X+aNSCCQIjroREFBeRCs+a328xWGA=

linux.go

@@ -1,74 +0,0 @@
-//go:build linux
-
-package main
-
-import (
-	"fmt"
-	"os"
-	"runtime"
-
-	"github.com/fosrl/newt/logger"
-	"github.com/fosrl/newt/proxy"
-	"github.com/fosrl/newt/websocket"
-	"github.com/fosrl/newt/wg"
-	"github.com/fosrl/newt/wgtester"
-)
-
-var wgServiceNative *wg.WireGuardService
-
-func setupClientsNative(client *websocket.Client, host string) {
-
-	if runtime.GOOS != "linux" {
-		logger.Fatal("Tunnel management is only supported on Linux right now!")
-		os.Exit(1)
-	}
-
-	// make sure we are sudo
-	if os.Geteuid() != 0 {
-		logger.Fatal("You must run this program as root to manage tunnels on Linux.")
-		os.Exit(1)
-	}
-
-	// Create WireGuard service
-	wgServiceNative, err = wg.NewWireGuardService(interfaceName, mtuInt, generateAndSaveKeyTo, host, id, client)
-	if err != nil {
-		logger.Fatal("Failed to create WireGuard service: %v", err)
-	}
-
-	wgTesterServer = wgtester.NewServer("0.0.0.0", wgServiceNative.Port, id) // TODO: maybe make this the same ip of the wg server?
-	err := wgTesterServer.Start()
-	if err != nil {
-		logger.Error("Failed to start WireGuard tester server: %v", err)
-	}
-
-	client.OnTokenUpdate(func(token string) {
-		wgServiceNative.SetToken(token)
-	})
-}
-
-func closeWgServiceNative() {
-	if wgServiceNative != nil {
-		wgServiceNative.Close(!keepInterface)
-		wgServiceNative = nil
-	}
-}
-
-func clientsOnConnectNative() {
-	if wgServiceNative != nil {
-		wgServiceNative.LoadRemoteConfig()
-	}
-}
-
-func clientsHandleNewtConnectionNative(publicKey, endpoint string) {
-	if wgServiceNative != nil {
-		wgServiceNative.StartHolepunch(publicKey, endpoint)
-	}
-}
-
-func clientsAddProxyTargetNative(pm *proxy.ProxyManager, tunnelIp string) {
-	// add a udp proxy for localost and the wgService port
-	// TODO: make sure this port is not used in a target
-	if wgServiceNative != nil {
-		pm.AddTarget("udp", tunnelIp, int(wgServiceNative.Port), fmt.Sprintf("127.0.0.1:%d", wgServiceNative.Port))
-	}
-}

logger/logger.go

@@ -2,16 +2,15 @@ package logger
 
 import (
 	"fmt"
-	"io"
-	"log"
 	"os"
+	"strings"
 	"sync"
 	"time"
 )
 
 // Logger struct holds the logger instance
 type Logger struct {
-	logger *log.Logger
+	writer LogWriter
 	level  LogLevel
 }
 
@@ -20,17 +19,29 @@ var (
 	once          sync.Once
 )
 
-// NewLogger creates a new logger instance
+// NewLogger creates a new logger instance with the default StandardWriter
 func NewLogger() *Logger {
 	return &Logger{
-		logger: log.New(os.Stdout, "", 0),
+		writer: NewStandardWriter(),
+		level:  DEBUG,
+	}
+}
+
+// NewLoggerWithWriter creates a new logger instance with a custom LogWriter
+func NewLoggerWithWriter(writer LogWriter) *Logger {
+	return &Logger{
+		writer: writer,
 		level:  DEBUG,
 	}
 }
 
 // Init initializes the default logger
-func Init() *Logger {
+func Init(logger *Logger) *Logger {
 	once.Do(func() {
+		if logger != nil {
+			defaultLogger = logger
+			return
+		}
 		defaultLogger = NewLogger()
 	})
 	return defaultLogger
@@ -39,7 +50,7 @@ func Init() *Logger {
 // GetLogger returns the default logger instance
 func GetLogger() *Logger {
 	if defaultLogger == nil {
-		Init()
+		Init(nil)
 	}
 	return defaultLogger
 }
@@ -49,9 +60,11 @@ func (l *Logger) SetLevel(level LogLevel) {
 	l.level = level
 }
 
-// SetOutput sets the output destination for the logger
+// SetOutput sets the output destination for the logger (only works with StandardWriter)
-func (l *Logger) SetOutput(w io.Writer) {
+func (l *Logger) SetOutput(output *os.File) {
-	l.logger.SetOutput(w)
+	if sw, ok := l.writer.(*StandardWriter); ok {
+		sw.SetOutput(output)
+	}
 }
 
 // log handles the actual logging
@@ -60,24 +73,8 @@ func (l *Logger) log(level LogLevel, format string, args ...interface{}) {
 		return
 	}
 
-	// Get timezone from environment variable or use local timezone
-	timezone := os.Getenv("LOGGER_TIMEZONE")
-	var location *time.Location
-	var err error
-
-	if timezone != "" {
-		location, err = time.LoadLocation(timezone)
-		if err != nil {
-			// If invalid timezone, fall back to local
-			location = time.Local
-		}
-	} else {
-		location = time.Local
-	}
-
-	timestamp := time.Now().In(location).Format("2006/01/02 15:04:05")
 	message := fmt.Sprintf(format, args...)
-	l.logger.Printf("%s: %s %s", level.String(), timestamp, message)
+	l.writer.Write(level, time.Now(), message)
 }
 
 // Debug logs debug level messages
@@ -128,6 +125,29 @@ func Fatal(format string, args ...interface{}) {
 }
 
 // SetOutput sets the output destination for the default logger
-func SetOutput(w io.Writer) {
+func SetOutput(output *os.File) {
-	GetLogger().SetOutput(w)
+	GetLogger().SetOutput(output)
+}
+
+// WireGuardLogger is a wrapper type that matches WireGuard's Logger interface
+type WireGuardLogger struct {
+	Verbosef func(format string, args ...any)
+	Errorf   func(format string, args ...any)
+}
+
+// GetWireGuardLogger returns a WireGuard-compatible logger that writes to the newt logger
+// The prepend string is added as a prefix to all log messages
+func (l *Logger) GetWireGuardLogger(prepend string) *WireGuardLogger {
+	return &WireGuardLogger{
+		Verbosef: func(format string, args ...any) {
+			// if the format string contains "Sending keepalive packet", skip debug logging to reduce noise
+			if strings.Contains(format, "Sending keepalive packet") {
+				return
+			}
+			l.Debug(prepend+format, args...)
+		},
+		Errorf: func(format string, args ...any) {
+			l.Error(prepend+format, args...)
+		},
+	}
 }

logger/writer.go

@@ -0,0 +1,54 @@
+package logger
+
+import (
+	"fmt"
+	"os"
+	"time"
+)
+
+// LogWriter is an interface for writing log messages
+// Implement this interface to create custom log backends (OS log, syslog, etc.)
+type LogWriter interface {
+	// Write writes a log message with the given level, timestamp, and formatted message
+	Write(level LogLevel, timestamp time.Time, message string)
+}
+
+// StandardWriter is the default log writer that writes to an io.Writer
+type StandardWriter struct {
+	output   *os.File
+	timezone *time.Location
+}
+
+// NewStandardWriter creates a new standard writer with the default configuration
+func NewStandardWriter() *StandardWriter {
+	// Get timezone from environment variable or use local timezone
+	timezone := os.Getenv("LOGGER_TIMEZONE")
+	var location *time.Location
+	var err error
+
+	if timezone != "" {
+		location, err = time.LoadLocation(timezone)
+		if err != nil {
+			// If invalid timezone, fall back to local
+			location = time.Local
+		}
+	} else {
+		location = time.Local
+	}
+
+	return &StandardWriter{
+		output:   os.Stdout,
+		timezone: location,
+	}
+}
+
+// SetOutput sets the output destination
+func (w *StandardWriter) SetOutput(output *os.File) {
+	w.output = output
+}
+
+// Write implements the LogWriter interface
+func (w *StandardWriter) Write(level LogLevel, timestamp time.Time, message string) {
+	formattedTime := timestamp.In(w.timezone).Format("2006/01/02 15:04:05")
+	fmt.Fprintf(w.output, "%s: %s %s\n", level.String(), formattedTime, message)
+}

main.go

@@ -22,6 +22,7 @@ import (
 	"github.com/fosrl/newt/logger"
 	"github.com/fosrl/newt/proxy"
 	"github.com/fosrl/newt/updates"
+	"github.com/fosrl/newt/util"
 	"github.com/fosrl/newt/websocket"
 
 	"github.com/fosrl/newt/internal/state"
@@ -115,9 +116,7 @@ var (
 	err                                error
 	logLevel                           string
 	interfaceName                      string
-	generateAndSaveKeyTo               string
+	disableClients                     bool
-	keepInterface                      bool
-	acceptClients                      bool
 	updownScript                       string
 	dockerSocket                       string
 	dockerEnforceNetworkValidation     string
@@ -168,7 +167,6 @@ func main() {
 	logLevel = os.Getenv("LOG_LEVEL")
 	updownScript = os.Getenv("UPDOWN_SCRIPT")
 	interfaceName = os.Getenv("INTERFACE")
-	generateAndSaveKeyTo = os.Getenv("GENERATE_AND_SAVE_KEY_TO")
 
 	// Metrics/observability env mirrors
 	metricsEnabledEnv := os.Getenv("NEWT_METRICS_PROMETHEUS_ENABLED")
@@ -177,10 +175,8 @@ func main() {
 	regionEnv := os.Getenv("NEWT_REGION")
 	asyncBytesEnv := os.Getenv("NEWT_METRICS_ASYNC_BYTES")
 
-	keepInterfaceEnv := os.Getenv("KEEP_INTERFACE")
+	disableClientsEnv := os.Getenv("DISABLE_CLIENTS")
-	keepInterface = keepInterfaceEnv == "true"
+	disableClients = disableClientsEnv == "true"
-	acceptClientsEnv := os.Getenv("ACCEPT_CLIENTS")
-	acceptClients = acceptClientsEnv == "true"
 	useNativeInterfaceEnv := os.Getenv("USE_NATIVE_INTERFACE")
 	useNativeInterface = useNativeInterfaceEnv == "true"
 	enforceHealthcheckCertEnv := os.Getenv("ENFORCE_HC_CERT")
@@ -239,17 +235,11 @@ func main() {
 	if interfaceName == "" {
 		flag.StringVar(&interfaceName, "interface", "newt", "Name of the WireGuard interface")
 	}
-	if generateAndSaveKeyTo == "" {
-		flag.StringVar(&generateAndSaveKeyTo, "generateAndSaveKeyTo", "", "Path to save generated private key")
-	}
-	if keepInterfaceEnv == "" {
-		flag.BoolVar(&keepInterface, "keep-interface", false, "Keep the WireGuard interface")
-	}
 	if useNativeInterfaceEnv == "" {
-		flag.BoolVar(&useNativeInterface, "native", false, "Use native WireGuard interface (requires WireGuard kernel module) and linux")
+		flag.BoolVar(&useNativeInterface, "native", false, "Use native WireGuard interface")
 	}
-	if acceptClientsEnv == "" {
+	if disableClientsEnv == "" {
-		flag.BoolVar(&acceptClients, "accept-clients", false, "Accept clients on the WireGuard interface")
+		flag.BoolVar(&disableClients, "disable-clients", false, "Disable clients on the WireGuard interface")
 	}
 	if enforceHealthcheckCertEnv == "" {
 		flag.BoolVar(&enforceHealthcheckCert, "enforce-hc-cert", false, "Enforce certificate validation for health checks (default: false, accepts any cert)")
@@ -367,9 +357,9 @@ func main() {
 		tlsClientCAs = append(tlsClientCAs, tlsClientCAsFlag...)
 	}
 
-	logger.Init()
+	logger.Init(nil)
-	loggerLevel := parseLogLevel(logLevel)
+	loggerLevel := util.ParseLogLevel(logLevel)
-	logger.GetLogger().SetLevel(parseLogLevel(logLevel))
+	logger.GetLogger().SetLevel(loggerLevel)
 
 	// Initialize telemetry after flags are parsed (so flags override env)
 	tcfg := telemetry.FromEnv()
@@ -538,7 +528,7 @@ func main() {
 	var wgData WgData
 	var dockerEventMonitor *docker.EventMonitor
 
-	if acceptClients {
+	if !disableClients {
 		setupClients(client)
 	}
 
@@ -650,7 +640,7 @@ func main() {
 
 		// Create WireGuard device
 		dev = device.NewDevice(tun, conn.NewDefaultBind(), device.NewLogger(
-			mapToWireGuardLogLevel(loggerLevel),
+			util.MapToWireGuardLogLevel(loggerLevel),
 			"wireguard: ",
 		))
 
@@ -663,7 +653,7 @@ func main() {
 
 		logger.Info("Connecting to endpoint: %s", host)
 
-		endpoint, err := resolveDomain(wgData.Endpoint)
+		endpoint, err := util.ResolveDomain(wgData.Endpoint)
 		if err != nil {
 			logger.Error("Failed to resolve endpoint: %v", err)
 			regResult = "failure"
@@ -677,7 +667,7 @@ func main() {
 public_key=%s
 allowed_ip=%s/32
 endpoint=%s
-persistent_keepalive_interval=5`, fixKey(privateKey.String()), fixKey(wgData.PublicKey), wgData.ServerIP, endpoint)
+persistent_keepalive_interval=5`, util.FixKey(privateKey.String()), util.FixKey(wgData.PublicKey), wgData.ServerIP, endpoint)
 
 		err = dev.IpcSet(config)
 		if err != nil {
@@ -747,7 +737,8 @@ persistent_keepalive_interval=5`, fixKey(privateKey.String()), fixKey(wgData.Pub
 			// }
 		}
 
-		clientsAddProxyTarget(pm, wgData.TunnelIP)
+		// Start direct UDP relay from main tunnel to clients' WireGuard (bypasses proxy)
+		clientsStartDirectRelay(wgData.TunnelIP)
 
 		if err := healthMonitor.AddTargets(wgData.HealthCheckTargets); err != nil {
 			logger.Error("Failed to bulk add health check targets: %v", err)
@@ -800,6 +791,7 @@ persistent_keepalive_interval=5`, fixKey(privateKey.String()), fixKey(wgData.Pub
 
 		// Close the WireGuard device and TUN
 		closeWgTunnel()
+		closeClients()
 
 		if stopFunc != nil {
 			stopFunc()     // stop the ws from sending more requests
@@ -1397,7 +1389,12 @@ persistent_keepalive_interval=5`, fixKey(privateKey.String()), fixKey(wgData.Pub
 				"noCloud": noCloud,
 			}, 3*time.Second)
 			logger.Debug("Requesting exit nodes from server")
-			clientsOnConnect()
+
+			if client.GetServerVersion() != "" { // to prevent issues with running newt > 1.7 versions with older servers
+				clientsOnConnect()
+			} else {
+				logger.Warn("CLIENTS WILL NOT WORK ON THIS VERSION OF NEWT WITH THIS VERSION OF PANGOLIN, PLEASE UPDATE THE SERVER TO 1.13 OR HIGHER OR DOWNGRADE NEWT")
+			}
 		}
 
 		// Send registration message to the server for backward compatibility

netstack2/handlers.go

@@ -0,0 +1,350 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2017-2025 WireGuard LLC. All Rights Reserved.
+ */
+
+package netstack2
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"sync"
+	"time"
+
+	"github.com/fosrl/newt/logger"
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/adapters/gonet"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
+	"gvisor.dev/gvisor/pkg/waiter"
+)
+
+const (
+	// defaultWndSize if set to zero, the default
+	// receive window buffer size is used instead.
+	defaultWndSize = 0
+
+	// maxConnAttempts specifies the maximum number
+	// of in-flight tcp connection attempts.
+	maxConnAttempts = 2 << 10
+
+	// tcpKeepaliveCount is the maximum number of
+	// TCP keep-alive probes to send before giving up
+	// and killing the connection if no response is
+	// obtained from the other end.
+	tcpKeepaliveCount = 9
+
+	// tcpKeepaliveIdle specifies the time a connection
+	// must remain idle before the first TCP keepalive
+	// packet is sent. Once this time is reached,
+	// tcpKeepaliveInterval option is used instead.
+	tcpKeepaliveIdle = 60 * time.Second
+
+	// tcpKeepaliveInterval specifies the interval
+	// time between sending TCP keepalive packets.
+	tcpKeepaliveInterval = 30 * time.Second
+
+	// tcpConnectTimeout is the default timeout for TCP handshakes.
+	tcpConnectTimeout = 5 * time.Second
+
+	// tcpWaitTimeout implements a TCP half-close timeout.
+	tcpWaitTimeout = 60 * time.Second
+
+	// udpSessionTimeout is the default timeout for UDP sessions.
+	udpSessionTimeout = 60 * time.Second
+
+	// Buffer size for copying data
+	bufferSize = 32 * 1024
+)
+
+// TCPHandler handles TCP connections from netstack
+type TCPHandler struct {
+	stack        *stack.Stack
+	proxyHandler *ProxyHandler
+}
+
+// UDPHandler handles UDP connections from netstack
+type UDPHandler struct {
+	stack        *stack.Stack
+	proxyHandler *ProxyHandler
+}
+
+// NewTCPHandler creates a new TCP handler
+func NewTCPHandler(s *stack.Stack, ph *ProxyHandler) *TCPHandler {
+	return &TCPHandler{stack: s, proxyHandler: ph}
+}
+
+// NewUDPHandler creates a new UDP handler
+func NewUDPHandler(s *stack.Stack, ph *ProxyHandler) *UDPHandler {
+	return &UDPHandler{stack: s, proxyHandler: ph}
+}
+
+// InstallTCPHandler installs the TCP forwarder on the stack
+func (h *TCPHandler) InstallTCPHandler() error {
+	tcpForwarder := tcp.NewForwarder(h.stack, defaultWndSize, maxConnAttempts, func(r *tcp.ForwarderRequest) {
+		var (
+			wq  waiter.Queue
+			ep  tcpip.Endpoint
+			err tcpip.Error
+			id  = r.ID()
+		)
+
+		// Perform a TCP three-way handshake
+		ep, err = r.CreateEndpoint(&wq)
+		if err != nil {
+			// RST: prevent potential half-open TCP connection leak
+			r.Complete(true)
+			return
+		}
+		defer r.Complete(false)
+
+		// Set socket options
+		setTCPSocketOptions(h.stack, ep)
+
+		// Create TCP connection from netstack endpoint
+		netstackConn := gonet.NewTCPConn(&wq, ep)
+
+		// Handle the connection in a goroutine
+		go h.handleTCPConn(netstackConn, id)
+	})
+
+	h.stack.SetTransportProtocolHandler(tcp.ProtocolNumber, tcpForwarder.HandlePacket)
+	return nil
+}
+
+// handleTCPConn handles a TCP connection by proxying it to the actual target
+func (h *TCPHandler) handleTCPConn(netstackConn *gonet.TCPConn, id stack.TransportEndpointID) {
+	defer netstackConn.Close()
+
+	// Extract source and target address from the connection ID
+	srcIP := id.RemoteAddress.String()
+	srcPort := id.RemotePort
+	dstIP := id.LocalAddress.String()
+	dstPort := id.LocalPort
+
+	logger.Info("TCP Forwarder: Handling connection %s:%d -> %s:%d", srcIP, srcPort, dstIP, dstPort)
+
+	// Check if there's a destination rewrite for this connection (e.g., localhost targets)
+	actualDstIP := dstIP
+	if h.proxyHandler != nil {
+		if rewrittenAddr, ok := h.proxyHandler.LookupDestinationRewrite(srcIP, dstIP, dstPort, uint8(tcp.ProtocolNumber)); ok {
+			actualDstIP = rewrittenAddr.String()
+			logger.Info("TCP Forwarder: Using rewritten destination %s (original: %s)", actualDstIP, dstIP)
+		}
+	}
+
+	targetAddr := fmt.Sprintf("%s:%d", actualDstIP, dstPort)
+
+	// Create context with timeout for connection establishment
+	ctx, cancel := context.WithTimeout(context.Background(), tcpConnectTimeout)
+	defer cancel()
+
+	// Dial the actual target using standard net package
+	var d net.Dialer
+	targetConn, err := d.DialContext(ctx, "tcp", targetAddr)
+	if err != nil {
+		logger.Info("TCP Forwarder: Failed to connect to %s: %v", targetAddr, err)
+		// Connection failed, netstack will handle RST
+		return
+	}
+	defer targetConn.Close()
+
+	logger.Info("TCP Forwarder: Successfully connected to %s, starting bidirectional copy", targetAddr)
+
+	// Bidirectional copy between netstack and target
+	pipeTCP(netstackConn, targetConn)
+}
+
+// pipeTCP copies data bidirectionally between two connections
+func pipeTCP(origin, remote net.Conn) {
+	wg := sync.WaitGroup{}
+	wg.Add(2)
+
+	go unidirectionalStreamTCP(remote, origin, "origin->remote", &wg)
+	go unidirectionalStreamTCP(origin, remote, "remote->origin", &wg)
+
+	wg.Wait()
+}
+
+// unidirectionalStreamTCP copies data in one direction
+func unidirectionalStreamTCP(dst, src net.Conn, dir string, wg *sync.WaitGroup) {
+	defer wg.Done()
+
+	buf := make([]byte, bufferSize)
+	_, _ = io.CopyBuffer(dst, src, buf)
+
+	// Do the upload/download side TCP half-close
+	if cr, ok := src.(interface{ CloseRead() error }); ok {
+		cr.CloseRead()
+	}
+	if cw, ok := dst.(interface{ CloseWrite() error }); ok {
+		cw.CloseWrite()
+	}
+
+	// Set TCP half-close timeout
+	dst.SetReadDeadline(time.Now().Add(tcpWaitTimeout))
+}
+
+// setTCPSocketOptions sets TCP socket options for better performance
+func setTCPSocketOptions(s *stack.Stack, ep tcpip.Endpoint) {
+	// TCP keepalive options
+	ep.SocketOptions().SetKeepAlive(true)
+
+	idle := tcpip.KeepaliveIdleOption(tcpKeepaliveIdle)
+	ep.SetSockOpt(&idle)
+
+	interval := tcpip.KeepaliveIntervalOption(tcpKeepaliveInterval)
+	ep.SetSockOpt(&interval)
+
+	ep.SetSockOptInt(tcpip.KeepaliveCountOption, tcpKeepaliveCount)
+
+	// TCP send/recv buffer size
+	var ss tcpip.TCPSendBufferSizeRangeOption
+	if err := s.TransportProtocolOption(tcp.ProtocolNumber, &ss); err == nil {
+		ep.SocketOptions().SetSendBufferSize(int64(ss.Default), false)
+	}
+
+	var rs tcpip.TCPReceiveBufferSizeRangeOption
+	if err := s.TransportProtocolOption(tcp.ProtocolNumber, &rs); err == nil {
+		ep.SocketOptions().SetReceiveBufferSize(int64(rs.Default), false)
+	}
+}
+
+// InstallUDPHandler installs the UDP forwarder on the stack
+func (h *UDPHandler) InstallUDPHandler() error {
+	udpForwarder := udp.NewForwarder(h.stack, func(r *udp.ForwarderRequest) {
+		var (
+			wq waiter.Queue
+			id = r.ID()
+		)
+
+		ep, err := r.CreateEndpoint(&wq)
+		if err != nil {
+			return
+		}
+
+		// Create UDP connection from netstack endpoint
+		netstackConn := gonet.NewUDPConn(&wq, ep)
+
+		// Handle the connection in a goroutine
+		go h.handleUDPConn(netstackConn, id)
+	})
+
+	h.stack.SetTransportProtocolHandler(udp.ProtocolNumber, udpForwarder.HandlePacket)
+	return nil
+}
+
+// handleUDPConn handles a UDP connection by proxying it to the actual target
+func (h *UDPHandler) handleUDPConn(netstackConn *gonet.UDPConn, id stack.TransportEndpointID) {
+	defer netstackConn.Close()
+
+	// Extract source and target address from the connection ID
+	srcIP := id.RemoteAddress.String()
+	srcPort := id.RemotePort
+	dstIP := id.LocalAddress.String()
+	dstPort := id.LocalPort
+
+	logger.Info("UDP Forwarder: Handling connection %s:%d -> %s:%d", srcIP, srcPort, dstIP, dstPort)
+
+	// Check if there's a destination rewrite for this connection (e.g., localhost targets)
+	actualDstIP := dstIP
+	if h.proxyHandler != nil {
+		if rewrittenAddr, ok := h.proxyHandler.LookupDestinationRewrite(srcIP, dstIP, dstPort, uint8(udp.ProtocolNumber)); ok {
+			actualDstIP = rewrittenAddr.String()
+			logger.Info("UDP Forwarder: Using rewritten destination %s (original: %s)", actualDstIP, dstIP)
+		}
+	}
+
+	targetAddr := fmt.Sprintf("%s:%d", actualDstIP, dstPort)
+
+	// Resolve target address
+	remoteUDPAddr, err := net.ResolveUDPAddr("udp", targetAddr)
+	if err != nil {
+		logger.Info("UDP Forwarder: Failed to resolve %s: %v", targetAddr, err)
+		return
+	}
+
+	// Resolve client address (for sending responses back)
+	clientAddr, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", srcIP, srcPort))
+	if err != nil {
+		logger.Info("UDP Forwarder: Failed to resolve client %s:%d: %v", srcIP, srcPort, err)
+		return
+	}
+
+	// Create unconnected UDP socket (so we can use WriteTo)
+	targetConn, err := net.ListenUDP("udp", nil)
+	if err != nil {
+		logger.Info("UDP Forwarder: Failed to create UDP socket: %v", err)
+		return
+	}
+	defer targetConn.Close()
+
+	logger.Info("UDP Forwarder: Successfully created UDP socket for %s, starting bidirectional copy", targetAddr)
+
+	// Bidirectional copy between netstack and target
+	pipeUDP(netstackConn, targetConn, remoteUDPAddr, clientAddr, udpSessionTimeout)
+}
+
+// pipeUDP copies UDP packets bidirectionally
+func pipeUDP(origin, remote net.PacketConn, serverAddr, clientAddr net.Addr, timeout time.Duration) {
+	wg := sync.WaitGroup{}
+	wg.Add(2)
+
+	// Read from origin (netstack), write to remote (target server)
+	go unidirectionalPacketStream(remote, origin, serverAddr, "origin->remote", &wg, timeout)
+	// Read from remote (target server), write to origin (netstack) with client address
+	go unidirectionalPacketStream(origin, remote, clientAddr, "remote->origin", &wg, timeout)
+
+	wg.Wait()
+}
+
+// unidirectionalPacketStream copies packets in one direction
+func unidirectionalPacketStream(dst, src net.PacketConn, to net.Addr, dir string, wg *sync.WaitGroup, timeout time.Duration) {
+	defer wg.Done()
+
+	logger.Info("UDP %s: Starting packet stream (to=%v)", dir, to)
+	err := copyPacketData(dst, src, to, timeout)
+	if err != nil {
+		logger.Info("UDP %s: Stream ended with error: %v", dir, err)
+	} else {
+		logger.Info("UDP %s: Stream ended (timeout)", dir)
+	}
+}
+
+// copyPacketData copies UDP packet data with timeout
+func copyPacketData(dst, src net.PacketConn, to net.Addr, timeout time.Duration) error {
+	buf := make([]byte, 65535) // Max UDP packet size
+
+	for {
+		src.SetReadDeadline(time.Now().Add(timeout))
+		n, srcAddr, err := src.ReadFrom(buf)
+		if ne, ok := err.(net.Error); ok && ne.Timeout() {
+			return nil // ignore I/O timeout
+		} else if err == io.EOF {
+			return nil // ignore EOF
+		} else if err != nil {
+			return err
+		}
+
+		logger.Info("UDP copyPacketData: Read %d bytes from %v", n, srcAddr)
+
+		// Determine write destination
+		writeAddr := to
+		if writeAddr == nil {
+			// If no destination specified, use the source address from the packet
+			writeAddr = srcAddr
+		}
+
+		written, err := dst.WriteTo(buf[:n], writeAddr)
+		if err != nil {
+			logger.Info("UDP copyPacketData: Write error to %v: %v", writeAddr, err)
+			return err
+		}
+		logger.Info("UDP copyPacketData: Wrote %d bytes to %v", written, writeAddr)
+
+		dst.SetReadDeadline(time.Now().Add(timeout))
+	}
+}

netstack2/proxy.go

@@ -0,0 +1,710 @@
+package netstack2
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/netip"
+	"sync"
+	"time"
+
+	"github.com/fosrl/newt/logger"
+	"gvisor.dev/gvisor/pkg/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/checksum"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
+	"gvisor.dev/gvisor/pkg/tcpip/link/channel"
+	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
+	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
+)
+
+// PortRange represents an allowed range of ports (inclusive)
+type PortRange struct {
+	Min uint16
+	Max uint16
+}
+
+// SubnetRule represents a subnet with optional port restrictions and source address
+// When RewriteTo is set, DNAT (Destination Network Address Translation) is performed:
+//   - Incoming packets: destination IP is rewritten to the resolved RewriteTo address
+//   - Outgoing packets: source IP is rewritten back to the original destination
+//
+// RewriteTo can be either:
+//   - An IP address with CIDR notation (e.g., "192.168.1.1/32")
+//   - A domain name (e.g., "example.com") which will be resolved at request time
+//
+// This allows transparent proxying where traffic appears to come from the rewritten address
+type SubnetRule struct {
+	SourcePrefix netip.Prefix // Source IP prefix (who is sending)
+	DestPrefix   netip.Prefix // Destination IP prefix (where it's going)
+	RewriteTo    string       // Optional rewrite address for DNAT - can be IP/CIDR or domain name
+	PortRanges   []PortRange  // empty slice means all ports allowed
+}
+
+// ruleKey is used as a map key for fast O(1) lookups
+type ruleKey struct {
+	sourcePrefix string
+	destPrefix   string
+}
+
+// SubnetLookup provides fast IP subnet and port matching with O(1) lookup performance
+type SubnetLookup struct {
+	mu    sync.RWMutex
+	rules map[ruleKey]*SubnetRule // Map for O(1) lookups by prefix combination
+}
+
+// NewSubnetLookup creates a new subnet lookup table
+func NewSubnetLookup() *SubnetLookup {
+	return &SubnetLookup{
+		rules: make(map[ruleKey]*SubnetRule),
+	}
+}
+
+// AddSubnet adds a subnet rule with source and destination prefixes and optional port restrictions
+// If portRanges is nil or empty, all ports are allowed for this subnet
+// rewriteTo can be either an IP/CIDR (e.g., "192.168.1.1/32") or a domain name (e.g., "example.com")
+func (sl *SubnetLookup) AddSubnet(sourcePrefix, destPrefix netip.Prefix, rewriteTo string, portRanges []PortRange) {
+	sl.mu.Lock()
+	defer sl.mu.Unlock()
+
+	key := ruleKey{
+		sourcePrefix: sourcePrefix.String(),
+		destPrefix:   destPrefix.String(),
+	}
+
+	sl.rules[key] = &SubnetRule{
+		SourcePrefix: sourcePrefix,
+		DestPrefix:   destPrefix,
+		RewriteTo:    rewriteTo,
+		PortRanges:   portRanges,
+	}
+}
+
+// RemoveSubnet removes a subnet rule from the lookup table
+func (sl *SubnetLookup) RemoveSubnet(sourcePrefix, destPrefix netip.Prefix) {
+	sl.mu.Lock()
+	defer sl.mu.Unlock()
+
+	key := ruleKey{
+		sourcePrefix: sourcePrefix.String(),
+		destPrefix:   destPrefix.String(),
+	}
+
+	delete(sl.rules, key)
+}
+
+// Match checks if a source IP, destination IP, and port match any subnet rule
+// Returns the matched rule if BOTH:
+//   - The source IP is in the rule's source prefix
+//   - The destination IP is in the rule's destination prefix
+//   - The port is in an allowed range (or no port restrictions exist)
+//
+// Returns nil if no rule matches
+func (sl *SubnetLookup) Match(srcIP, dstIP netip.Addr, port uint16) *SubnetRule {
+	sl.mu.RLock()
+	defer sl.mu.RUnlock()
+
+	// Iterate through all rules to find matching source and destination prefixes
+	// This is O(n) but necessary since we need to check prefix containment, not exact match
+	for _, rule := range sl.rules {
+		// Check if source and destination IPs match their respective prefixes
+		if !rule.SourcePrefix.Contains(srcIP) {
+			continue
+		}
+		if !rule.DestPrefix.Contains(dstIP) {
+			continue
+		}
+
+		// Both IPs match - now check port restrictions
+		// If no port ranges specified, all ports are allowed
+		if len(rule.PortRanges) == 0 {
+			return rule
+		}
+
+		// Check if port is in any of the allowed ranges
+		for _, pr := range rule.PortRanges {
+			if port >= pr.Min && port <= pr.Max {
+				return rule
+			}
+		}
+	}
+
+	return nil
+}
+
+// connKey uniquely identifies a connection for NAT tracking
+type connKey struct {
+	srcIP   string
+	srcPort uint16
+	dstIP   string
+	dstPort uint16
+	proto   uint8
+}
+
+// destKey identifies a destination for handler lookups (without source port since it may change)
+type destKey struct {
+	srcIP   string
+	dstIP   string
+	dstPort uint16
+	proto   uint8
+}
+
+// natState tracks NAT translation state for reverse translation
+type natState struct {
+	originalDst netip.Addr // Original destination before DNAT
+	rewrittenTo netip.Addr // The address we rewrote to
+}
+
+// ProxyHandler handles packet injection and extraction for promiscuous mode
+type ProxyHandler struct {
+	proxyStack        *stack.Stack
+	proxyEp           *channel.Endpoint
+	proxyNotifyHandle *channel.NotificationHandle
+	tcpHandler        *TCPHandler
+	udpHandler        *UDPHandler
+	subnetLookup      *SubnetLookup
+	natTable          map[connKey]*natState
+	destRewriteTable  map[destKey]netip.Addr // Maps original dest to rewritten dest for handler lookups
+	natMu             sync.RWMutex
+	enabled           bool
+}
+
+// ProxyHandlerOptions configures the proxy handler
+type ProxyHandlerOptions struct {
+	EnableTCP bool
+	EnableUDP bool
+	MTU       int
+}
+
+// NewProxyHandler creates a new proxy handler for promiscuous mode
+func NewProxyHandler(options ProxyHandlerOptions) (*ProxyHandler, error) {
+	if !options.EnableTCP && !options.EnableUDP {
+		return nil, nil // No proxy needed
+	}
+
+	handler := &ProxyHandler{
+		enabled:          true,
+		subnetLookup:     NewSubnetLookup(),
+		natTable:         make(map[connKey]*natState),
+		destRewriteTable: make(map[destKey]netip.Addr),
+		proxyEp:          channel.New(1024, uint32(options.MTU), ""),
+		proxyStack: stack.New(stack.Options{
+			NetworkProtocols: []stack.NetworkProtocolFactory{
+				ipv4.NewProtocol,
+				ipv6.NewProtocol,
+			},
+			TransportProtocols: []stack.TransportProtocolFactory{
+				tcp.NewProtocol,
+				udp.NewProtocol,
+				icmp.NewProtocol4,
+				icmp.NewProtocol6,
+			},
+		}),
+	}
+
+	// Initialize TCP handler if enabled
+	if options.EnableTCP {
+		handler.tcpHandler = NewTCPHandler(handler.proxyStack, handler)
+		if err := handler.tcpHandler.InstallTCPHandler(); err != nil {
+			return nil, fmt.Errorf("failed to install TCP handler: %v", err)
+		}
+	}
+
+	// Initialize UDP handler if enabled
+	if options.EnableUDP {
+		handler.udpHandler = NewUDPHandler(handler.proxyStack, handler)
+		if err := handler.udpHandler.InstallUDPHandler(); err != nil {
+			return nil, fmt.Errorf("failed to install UDP handler: %v", err)
+		}
+	}
+
+	// // Example 1: Add a rule with no port restrictions (all ports allowed)
+	// // This accepts all traffic FROM 10.0.0.0/24 TO 10.20.20.0/24
+	// sourceSubnet := netip.MustParsePrefix("10.0.0.0/24")
+	// destSubnet := netip.MustParsePrefix("10.20.20.0/24")
+	// handler.AddSubnetRule(sourceSubnet, destSubnet, nil)
+
+	// // Example 2: Add a rule with specific port ranges
+	// // This accepts traffic FROM 10.0.0.5/32 TO 10.20.21.21/32 only on ports 80, 443, and 8000-9000
+	// sourceIP := netip.MustParsePrefix("10.0.0.5/32")
+	// destIP := netip.MustParsePrefix("10.20.21.21/32")
+	// handler.AddSubnetRule(sourceIP, destIP, []PortRange{
+	// 	{Min: 80, Max: 80},
+	// 	{Min: 443, Max: 443},
+	// 	{Min: 8000, Max: 9000},
+	// })
+
+	return handler, nil
+}
+
+// AddSubnetRule adds a subnet with optional port restrictions to the proxy handler
+// sourcePrefix: The IP prefix of the peer sending the data
+// destPrefix: The IP prefix of the destination
+// rewriteTo: Optional address to rewrite destination to - can be IP/CIDR or domain name
+// If portRanges is nil or empty, all ports are allowed for this subnet
+func (p *ProxyHandler) AddSubnetRule(sourcePrefix, destPrefix netip.Prefix, rewriteTo string, portRanges []PortRange) {
+	if p == nil || !p.enabled {
+		return
+	}
+	p.subnetLookup.AddSubnet(sourcePrefix, destPrefix, rewriteTo, portRanges)
+}
+
+// RemoveSubnetRule removes a subnet from the proxy handler
+func (p *ProxyHandler) RemoveSubnetRule(sourcePrefix, destPrefix netip.Prefix) {
+	if p == nil || !p.enabled {
+		return
+	}
+	p.subnetLookup.RemoveSubnet(sourcePrefix, destPrefix)
+}
+
+// LookupDestinationRewrite looks up the rewritten destination for a connection
+// This is used by TCP/UDP handlers to find the actual target address
+func (p *ProxyHandler) LookupDestinationRewrite(srcIP, dstIP string, dstPort uint16, proto uint8) (netip.Addr, bool) {
+	if p == nil || !p.enabled {
+		return netip.Addr{}, false
+	}
+
+	key := destKey{
+		srcIP:   srcIP,
+		dstIP:   dstIP,
+		dstPort: dstPort,
+		proto:   proto,
+	}
+
+	p.natMu.RLock()
+	defer p.natMu.RUnlock()
+
+	addr, ok := p.destRewriteTable[key]
+	return addr, ok
+}
+
+// resolveRewriteAddress resolves a rewrite address which can be either:
+// - An IP address with CIDR notation (e.g., "192.168.1.1/32") - returns the IP directly
+// - A plain IP address (e.g., "192.168.1.1") - returns the IP directly
+// - A domain name (e.g., "example.com") - performs DNS lookup
+func (p *ProxyHandler) resolveRewriteAddress(rewriteTo string) (netip.Addr, error) {
+	logger.Debug("Resolving rewrite address: %s", rewriteTo)
+
+	// First, try to parse as a CIDR prefix (e.g., "192.168.1.1/32")
+	if prefix, err := netip.ParsePrefix(rewriteTo); err == nil {
+		return prefix.Addr(), nil
+	}
+
+	// Try to parse as a plain IP address (e.g., "192.168.1.1")
+	if addr, err := netip.ParseAddr(rewriteTo); err == nil {
+		return addr, nil
+	}
+
+	// Not an IP address, treat as domain name - perform DNS lookup
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	ips, err := net.DefaultResolver.LookupIP(ctx, "ip4", rewriteTo)
+	if err != nil {
+		return netip.Addr{}, fmt.Errorf("failed to resolve domain %s: %w", rewriteTo, err)
+	}
+
+	if len(ips) == 0 {
+		return netip.Addr{}, fmt.Errorf("no IP addresses found for domain %s", rewriteTo)
+	}
+
+	// Use the first resolved IP address
+	ip := ips[0]
+	if ip4 := ip.To4(); ip4 != nil {
+		addr := netip.AddrFrom4([4]byte{ip4[0], ip4[1], ip4[2], ip4[3]})
+		logger.Debug("Resolved %s to %s", rewriteTo, addr)
+		return addr, nil
+	}
+
+	return netip.Addr{}, fmt.Errorf("no IPv4 address found for domain %s", rewriteTo)
+}
+
+// Initialize sets up the promiscuous NIC with the netTun's notification system
+func (p *ProxyHandler) Initialize(notifiable channel.Notification) error {
+	if p == nil || !p.enabled {
+		return nil
+	}
+
+	// Add notification handler
+	p.proxyNotifyHandle = p.proxyEp.AddNotify(notifiable)
+
+	// Create NIC with promiscuous mode
+	tcpipErr := p.proxyStack.CreateNICWithOptions(1, p.proxyEp, stack.NICOptions{
+		Disabled: false,
+		QDisc:    nil,
+	})
+	if tcpipErr != nil {
+		return fmt.Errorf("CreateNIC (proxy): %v", tcpipErr)
+	}
+
+	// Enable promiscuous mode - accepts packets for any destination IP
+	if tcpipErr := p.proxyStack.SetPromiscuousMode(1, true); tcpipErr != nil {
+		return fmt.Errorf("SetPromiscuousMode: %v", tcpipErr)
+	}
+
+	// Enable spoofing - allows sending packets from any source IP
+	if tcpipErr := p.proxyStack.SetSpoofing(1, true); tcpipErr != nil {
+		return fmt.Errorf("SetSpoofing: %v", tcpipErr)
+	}
+
+	// Add default route
+	p.proxyStack.AddRoute(tcpip.Route{
+		Destination: header.IPv4EmptySubnet,
+		NIC:         1,
+	})
+
+	return nil
+}
+
+// HandleIncomingPacket processes incoming packets and determines if they should
+// be injected into the proxy stack
+func (p *ProxyHandler) HandleIncomingPacket(packet []byte) bool {
+	if p == nil || !p.enabled {
+		return false
+	}
+
+	// Check minimum packet size
+	if len(packet) < header.IPv4MinimumSize {
+		return false
+	}
+
+	// Only handle IPv4 for now
+	if packet[0]>>4 != 4 {
+		return false
+	}
+
+	// Parse IPv4 header
+	ipv4Header := header.IPv4(packet)
+	srcIP := ipv4Header.SourceAddress()
+	dstIP := ipv4Header.DestinationAddress()
+
+	// Convert gvisor tcpip.Address to netip.Addr
+	srcBytes := srcIP.As4()
+	srcAddr := netip.AddrFrom4(srcBytes)
+	dstBytes := dstIP.As4()
+	dstAddr := netip.AddrFrom4(dstBytes)
+
+	// Parse transport layer to get destination port
+	var dstPort uint16
+	protocol := ipv4Header.TransportProtocol()
+	headerLen := int(ipv4Header.HeaderLength())
+
+	// Extract port based on protocol
+	switch protocol {
+	case header.TCPProtocolNumber:
+		if len(packet) < headerLen+header.TCPMinimumSize {
+			return false
+		}
+		tcpHeader := header.TCP(packet[headerLen:])
+		dstPort = tcpHeader.DestinationPort()
+	case header.UDPProtocolNumber:
+		if len(packet) < headerLen+header.UDPMinimumSize {
+			return false
+		}
+		udpHeader := header.UDP(packet[headerLen:])
+		dstPort = udpHeader.DestinationPort()
+	default:
+		// For other protocols (ICMP, etc.), use port 0 (must match rules with no port restrictions)
+		dstPort = 0
+	}
+
+	// Check if the source IP, destination IP, and port match any subnet rule
+	matchedRule := p.subnetLookup.Match(srcAddr, dstAddr, dstPort)
+	if matchedRule != nil {
+		// Check if we need to perform DNAT
+		if matchedRule.RewriteTo != "" {
+			// Create connection tracking key using original destination
+			// This allows us to check if we've already resolved for this connection
+			var srcPort uint16
+			switch protocol {
+			case header.TCPProtocolNumber:
+				tcpHeader := header.TCP(packet[headerLen:])
+				srcPort = tcpHeader.SourcePort()
+			case header.UDPProtocolNumber:
+				udpHeader := header.UDP(packet[headerLen:])
+				srcPort = udpHeader.SourcePort()
+			}
+
+			// Key using original destination to track the connection
+			key := connKey{
+				srcIP:   srcAddr.String(),
+				srcPort: srcPort,
+				dstIP:   dstAddr.String(),
+				dstPort: dstPort,
+				proto:   uint8(protocol),
+			}
+
+			// Key for handler lookups (doesn't include srcPort for flexibility)
+			dKey := destKey{
+				srcIP:   srcAddr.String(),
+				dstIP:   dstAddr.String(),
+				dstPort: dstPort,
+				proto:   uint8(protocol),
+			}
+
+			// Check if we already have a NAT entry for this connection
+			p.natMu.RLock()
+			existingEntry, exists := p.natTable[key]
+			p.natMu.RUnlock()
+
+			var newDst netip.Addr
+			if exists {
+				// Use the previously resolved address for this connection
+				newDst = existingEntry.rewrittenTo
+				logger.Debug("Using existing NAT entry for connection: %s -> %s", dstAddr, newDst)
+			} else {
+				// New connection - resolve the rewrite address
+				var err error
+				newDst, err = p.resolveRewriteAddress(matchedRule.RewriteTo)
+				if err != nil {
+					// Failed to resolve, skip DNAT but still proxy the packet
+					logger.Debug("Failed to resolve rewrite address: %v", err)
+					pkb := stack.NewPacketBuffer(stack.PacketBufferOptions{
+						Payload: buffer.MakeWithData(packet),
+					})
+					p.proxyEp.InjectInbound(header.IPv4ProtocolNumber, pkb)
+					return true
+				}
+
+				// Store NAT state for this connection
+				p.natMu.Lock()
+				p.natTable[key] = &natState{
+					originalDst: dstAddr,
+					rewrittenTo: newDst,
+				}
+				// Store destination rewrite for handler lookups
+				p.destRewriteTable[dKey] = newDst
+				p.natMu.Unlock()
+				logger.Debug("New NAT entry for connection: %s -> %s", dstAddr, newDst)
+			}
+
+			// Check if target is loopback - if so, don't rewrite packet destination
+			// as gVisor will drop martian packets. Instead, the handlers will use
+			// destRewriteTable to find the actual target address.
+			if !newDst.IsLoopback() {
+				// Rewrite the packet only for non-loopback destinations
+				packet = p.rewritePacketDestination(packet, newDst)
+				if packet == nil {
+					return false
+				}
+			} else {
+				logger.Debug("Target is loopback, not rewriting packet - handlers will use rewrite table")
+			}
+		}
+
+		// Inject into proxy stack
+		pkb := stack.NewPacketBuffer(stack.PacketBufferOptions{
+			Payload: buffer.MakeWithData(packet),
+		})
+		p.proxyEp.InjectInbound(header.IPv4ProtocolNumber, pkb)
+		return true
+	}
+
+	return false
+}
+
+// rewritePacketDestination rewrites the destination IP in a packet and recalculates checksums
+func (p *ProxyHandler) rewritePacketDestination(packet []byte, newDst netip.Addr) []byte {
+	if len(packet) < header.IPv4MinimumSize {
+		return nil
+	}
+
+	// Make a copy to avoid modifying the original
+	pkt := make([]byte, len(packet))
+	copy(pkt, packet)
+
+	ipv4Header := header.IPv4(pkt)
+	headerLen := int(ipv4Header.HeaderLength())
+
+	// Rewrite destination IP
+	newDstBytes := newDst.As4()
+	newDstAddr := tcpip.AddrFrom4(newDstBytes)
+	ipv4Header.SetDestinationAddress(newDstAddr)
+
+	// Recalculate IP checksum
+	ipv4Header.SetChecksum(0)
+	ipv4Header.SetChecksum(^ipv4Header.CalculateChecksum())
+
+	// Update transport layer checksum if needed
+	protocol := ipv4Header.TransportProtocol()
+	switch protocol {
+	case header.TCPProtocolNumber:
+		if len(pkt) >= headerLen+header.TCPMinimumSize {
+			tcpHeader := header.TCP(pkt[headerLen:])
+			tcpHeader.SetChecksum(0)
+			xsum := header.PseudoHeaderChecksum(
+				header.TCPProtocolNumber,
+				ipv4Header.SourceAddress(),
+				ipv4Header.DestinationAddress(),
+				uint16(len(pkt)-headerLen),
+			)
+			xsum = checksum.Checksum(pkt[headerLen:], xsum)
+			tcpHeader.SetChecksum(^xsum)
+		}
+	case header.UDPProtocolNumber:
+		if len(pkt) >= headerLen+header.UDPMinimumSize {
+			udpHeader := header.UDP(pkt[headerLen:])
+			udpHeader.SetChecksum(0)
+			xsum := header.PseudoHeaderChecksum(
+				header.UDPProtocolNumber,
+				ipv4Header.SourceAddress(),
+				ipv4Header.DestinationAddress(),
+				uint16(len(pkt)-headerLen),
+			)
+			xsum = checksum.Checksum(pkt[headerLen:], xsum)
+			udpHeader.SetChecksum(^xsum)
+		}
+	}
+
+	return pkt
+}
+
+// rewritePacketSource rewrites the source IP in a packet and recalculates checksums (for reverse NAT)
+func (p *ProxyHandler) rewritePacketSource(packet []byte, newSrc netip.Addr) []byte {
+	if len(packet) < header.IPv4MinimumSize {
+		return nil
+	}
+
+	// Make a copy to avoid modifying the original
+	pkt := make([]byte, len(packet))
+	copy(pkt, packet)
+
+	ipv4Header := header.IPv4(pkt)
+	headerLen := int(ipv4Header.HeaderLength())
+
+	// Rewrite source IP
+	newSrcBytes := newSrc.As4()
+	newSrcAddr := tcpip.AddrFrom4(newSrcBytes)
+	ipv4Header.SetSourceAddress(newSrcAddr)
+
+	// Recalculate IP checksum
+	ipv4Header.SetChecksum(0)
+	ipv4Header.SetChecksum(^ipv4Header.CalculateChecksum())
+
+	// Update transport layer checksum if needed
+	protocol := ipv4Header.TransportProtocol()
+	switch protocol {
+	case header.TCPProtocolNumber:
+		if len(pkt) >= headerLen+header.TCPMinimumSize {
+			tcpHeader := header.TCP(pkt[headerLen:])
+			tcpHeader.SetChecksum(0)
+			xsum := header.PseudoHeaderChecksum(
+				header.TCPProtocolNumber,
+				ipv4Header.SourceAddress(),
+				ipv4Header.DestinationAddress(),
+				uint16(len(pkt)-headerLen),
+			)
+			xsum = checksum.Checksum(pkt[headerLen:], xsum)
+			tcpHeader.SetChecksum(^xsum)
+		}
+	case header.UDPProtocolNumber:
+		if len(pkt) >= headerLen+header.UDPMinimumSize {
+			udpHeader := header.UDP(pkt[headerLen:])
+			udpHeader.SetChecksum(0)
+			xsum := header.PseudoHeaderChecksum(
+				header.UDPProtocolNumber,
+				ipv4Header.SourceAddress(),
+				ipv4Header.DestinationAddress(),
+				uint16(len(pkt)-headerLen),
+			)
+			xsum = checksum.Checksum(pkt[headerLen:], xsum)
+			udpHeader.SetChecksum(^xsum)
+		}
+	}
+
+	return pkt
+}
+
+// ReadOutgoingPacket reads packets from the proxy stack that need to be
+// sent back through the tunnel
+func (p *ProxyHandler) ReadOutgoingPacket() *buffer.View {
+	if p == nil || !p.enabled {
+		return nil
+	}
+
+	pkt := p.proxyEp.Read()
+	if pkt != nil {
+		view := pkt.ToView()
+		pkt.DecRef()
+
+		// Check if we need to perform reverse NAT
+		packet := view.AsSlice()
+		if len(packet) >= header.IPv4MinimumSize && packet[0]>>4 == 4 {
+			ipv4Header := header.IPv4(packet)
+			srcIP := ipv4Header.SourceAddress()
+			dstIP := ipv4Header.DestinationAddress()
+			protocol := ipv4Header.TransportProtocol()
+			headerLen := int(ipv4Header.HeaderLength())
+
+			// Extract ports
+			var srcPort, dstPort uint16
+			switch protocol {
+			case header.TCPProtocolNumber:
+				if len(packet) >= headerLen+header.TCPMinimumSize {
+					tcpHeader := header.TCP(packet[headerLen:])
+					srcPort = tcpHeader.SourcePort()
+					dstPort = tcpHeader.DestinationPort()
+				}
+			case header.UDPProtocolNumber:
+				if len(packet) >= headerLen+header.UDPMinimumSize {
+					udpHeader := header.UDP(packet[headerLen:])
+					srcPort = udpHeader.SourcePort()
+					dstPort = udpHeader.DestinationPort()
+				}
+			}
+
+			// Look up NAT state for reverse translation
+			// The key uses the original dst (before rewrite), so for replies we need to
+			// find the entry where the rewritten address matches the current source
+			p.natMu.RLock()
+			var natEntry *natState
+			for k, entry := range p.natTable {
+				// Match: reply's dst should be original src, reply's src should be rewritten dst
+				if k.srcIP == dstIP.String() && k.srcPort == dstPort &&
+					entry.rewrittenTo.String() == srcIP.String() && k.dstPort == srcPort &&
+					k.proto == uint8(protocol) {
+					natEntry = entry
+					break
+				}
+			}
+			p.natMu.RUnlock()
+
+			if natEntry != nil {
+				// Perform reverse NAT - rewrite source to original destination
+				packet = p.rewritePacketSource(packet, natEntry.originalDst)
+				if packet != nil {
+					return buffer.NewViewWithData(packet)
+				}
+			}
+		}
+
+		return view
+	}
+
+	return nil
+}
+
+// Close cleans up the proxy handler resources
+func (p *ProxyHandler) Close() error {
+	if p == nil || !p.enabled {
+		return nil
+	}
+
+	if p.proxyStack != nil {
+		p.proxyStack.RemoveNIC(1)
+		p.proxyStack.Close()
+	}
+
+	if p.proxyEp != nil {
+		if p.proxyNotifyHandle != nil {
+			p.proxyEp.RemoveNotify(p.proxyNotifyHandle)
+		}
+		p.proxyEp.Close()
+	}
+
+	return nil
+}

network/interface.go

@@ -0,0 +1,165 @@
+package network
+
+import (
+	"fmt"
+	"net"
+	"os/exec"
+	"regexp"
+	"runtime"
+	"strconv"
+	"time"
+
+	"github.com/fosrl/newt/logger"
+	"github.com/vishvananda/netlink"
+)
+
+// ConfigureInterface configures a network interface with an IP address and brings it up
+func ConfigureInterface(interfaceName string, tunnelIp string, mtu int) error {
+	logger.Info("The tunnel IP is: %s", tunnelIp)
+
+	// Parse the IP address and network
+	ip, ipNet, err := net.ParseCIDR(tunnelIp)
+	if err != nil {
+		return fmt.Errorf("invalid IP address: %v", err)
+	}
+
+	// Convert CIDR mask to dotted decimal format (e.g., 255.255.255.0)
+	mask := net.IP(ipNet.Mask).String()
+	destinationAddress := ip.String()
+
+	logger.Debug("The destination address is: %s", destinationAddress)
+
+	// network.SetTunnelRemoteAddress() // what does this do?
+	SetIPv4Settings([]string{destinationAddress}, []string{mask})
+	SetMTU(mtu)
+
+	if interfaceName == "" {
+		return nil
+	}
+
+	switch runtime.GOOS {
+	case "linux":
+		return configureLinux(interfaceName, ip, ipNet)
+	case "darwin":
+		return configureDarwin(interfaceName, ip, ipNet)
+	case "windows":
+		return configureWindows(interfaceName, ip, ipNet)
+	default:
+		return fmt.Errorf("unsupported operating system: %s", runtime.GOOS)
+	}
+}
+
+// waitForInterfaceUp polls the network interface until it's up or times out
+func waitForInterfaceUp(interfaceName string, expectedIP net.IP, timeout time.Duration) error {
+	logger.Info("Waiting for interface %s to be up with IP %s", interfaceName, expectedIP)
+	deadline := time.Now().Add(timeout)
+	pollInterval := 500 * time.Millisecond
+
+	for time.Now().Before(deadline) {
+		// Check if interface exists and is up
+		iface, err := net.InterfaceByName(interfaceName)
+		if err == nil {
+			// Check if interface is up
+			if iface.Flags&net.FlagUp != 0 {
+				// Check if it has the expected IP
+				addrs, err := iface.Addrs()
+				if err == nil {
+					for _, addr := range addrs {
+						ipNet, ok := addr.(*net.IPNet)
+						if ok && ipNet.IP.Equal(expectedIP) {
+							logger.Info("Interface %s is up with correct IP", interfaceName)
+							return nil // Interface is up with correct IP
+						}
+					}
+					logger.Info("Interface %s is up but doesn't have expected IP yet", interfaceName)
+				}
+			} else {
+				logger.Info("Interface %s exists but is not up yet", interfaceName)
+			}
+		} else {
+			logger.Info("Interface %s not found yet: %v", interfaceName, err)
+		}
+
+		// Wait before next check
+		time.Sleep(pollInterval)
+	}
+
+	return fmt.Errorf("timed out waiting for interface %s to be up with IP %s", interfaceName, expectedIP)
+}
+
+func FindUnusedUTUN() (string, error) {
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return "", fmt.Errorf("failed to list interfaces: %v", err)
+	}
+	used := make(map[int]bool)
+	re := regexp.MustCompile(`^utun(\d+)$`)
+	for _, iface := range ifaces {
+		if matches := re.FindStringSubmatch(iface.Name); len(matches) == 2 {
+			if num, err := strconv.Atoi(matches[1]); err == nil {
+				used[num] = true
+			}
+		}
+	}
+	// Try utun0 up to utun255.
+	for i := 0; i < 256; i++ {
+		if !used[i] {
+			return fmt.Sprintf("utun%d", i), nil
+		}
+	}
+	return "", fmt.Errorf("no unused utun interface found")
+}
+
+func configureDarwin(interfaceName string, ip net.IP, ipNet *net.IPNet) error {
+	logger.Info("Configuring darwin interface: %s", interfaceName)
+
+	prefix, _ := ipNet.Mask.Size()
+	ipStr := fmt.Sprintf("%s/%d", ip.String(), prefix)
+
+	cmd := exec.Command("ifconfig", interfaceName, "inet", ipStr, ip.String(), "alias")
+	logger.Info("Running command: %v", cmd)
+
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("ifconfig command failed: %v, output: %s", err, out)
+	}
+
+	// Bring up the interface
+	cmd = exec.Command("ifconfig", interfaceName, "up")
+	logger.Info("Running command: %v", cmd)
+
+	out, err = cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("ifconfig up command failed: %v, output: %s", err, out)
+	}
+
+	return nil
+}
+
+func configureLinux(interfaceName string, ip net.IP, ipNet *net.IPNet) error {
+	// Get the interface
+	link, err := netlink.LinkByName(interfaceName)
+	if err != nil {
+		return fmt.Errorf("failed to get interface %s: %v", interfaceName, err)
+	}
+
+	// Create the IP address attributes
+	addr := &netlink.Addr{
+		IPNet: &net.IPNet{
+			IP:   ip,
+			Mask: ipNet.Mask,
+		},
+	}
+
+	// Add the IP address to the interface
+	if err := netlink.AddrAdd(link, addr); err != nil {
+		return fmt.Errorf("failed to add IP address: %v", err)
+	}
+
+	// Bring up the interface
+	if err := netlink.LinkSetUp(link); err != nil {
+		return fmt.Errorf("failed to bring up interface: %v", err)
+	}
+
+	return nil
+}

network/interface_notwindows.go

@@ -0,0 +1,12 @@
+//go:build !windows
+
+package network
+
+import (
+	"fmt"
+	"net"
+)
+
+func configureWindows(interfaceName string, ip net.IP, ipNet *net.IPNet) error {
+	return fmt.Errorf("configureWindows called on non-Windows platform")
+}

network/interface_windows.go

@@ -0,0 +1,63 @@
+//go:build windows
+
+package network
+
+import (
+	"fmt"
+	"net"
+	"net/netip"
+
+	"github.com/fosrl/newt/logger"
+	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
+)
+
+func configureWindows(interfaceName string, ip net.IP, ipNet *net.IPNet) error {
+	logger.Info("Configuring Windows interface: %s", interfaceName)
+
+	// Get the LUID for the interface
+	iface, err := net.InterfaceByName(interfaceName)
+	if err != nil {
+		return fmt.Errorf("failed to get interface %s: %v", interfaceName, err)
+	}
+
+	luid, err := winipcfg.LUIDFromIndex(uint32(iface.Index))
+	if err != nil {
+		return fmt.Errorf("failed to get LUID for interface %s: %v", interfaceName, err)
+	}
+
+	// Create the IP address prefix
+	maskBits, _ := ipNet.Mask.Size()
+
+	// Ensure we convert to the correct IP version (IPv4 vs IPv6)
+	var addr netip.Addr
+	if ip4 := ip.To4(); ip4 != nil {
+		// IPv4 address
+		addr, _ = netip.AddrFromSlice(ip4)
+	} else {
+		// IPv6 address
+		addr, _ = netip.AddrFromSlice(ip)
+	}
+	if !addr.IsValid() {
+		return fmt.Errorf("failed to convert IP address")
+	}
+	prefix := netip.PrefixFrom(addr, maskBits)
+
+	// Add the IP address to the interface
+	logger.Info("Adding IP address %s to interface %s", prefix.String(), interfaceName)
+	err = luid.AddIPAddress(prefix)
+	if err != nil {
+		return fmt.Errorf("failed to add IP address: %v", err)
+	}
+
+	// This was required when we were using the subprocess "netsh" command to bring up the interface.
+	// With the winipcfg library, the interface should already be up after adding the IP so we dont
+	// need this step anymore as far as I can tell.
+
+	// // Wait for the interface to be up and have the correct IP
+	// err = waitForInterfaceUp(interfaceName, ip, 30*time.Second)
+	// if err != nil {
+	// 	return fmt.Errorf("interface did not come up within timeout: %v", err)
+	// }
+
+	return nil
+}

network/network.go

@@ -1,195 +0,0 @@
-package network
-
-import (
-	"encoding/binary"
-	"encoding/json"
-	"fmt"
-	"log"
-	"net"
-	"time"
-
-	"github.com/google/gopacket"
-	"github.com/google/gopacket/layers"
-	"github.com/vishvananda/netlink"
-	"golang.org/x/net/bpf"
-	"golang.org/x/net/ipv4"
-)
-
-const (
-	udpProtocol = 17
-	// EmptyUDPSize is the size of an empty UDP packet
-	EmptyUDPSize = 28
-	timeout      = time.Second * 10
-)
-
-// Server stores data relating to the server
-type Server struct {
-	Hostname string
-	Addr     *net.IPAddr
-	Port     uint16
-}
-
-// PeerNet stores data about a peer's endpoint
-type PeerNet struct {
-	Resolved bool
-	IP       net.IP
-	Port     uint16
-	NewtID   string
-}
-
-// GetClientIP gets source ip address that will be used when sending data to dstIP
-func GetClientIP(dstIP net.IP) net.IP {
-	routes, err := netlink.RouteGet(dstIP)
-	if err != nil {
-		log.Fatalln("Error getting route:", err)
-	}
-	return routes[0].Src
-}
-
-// HostToAddr resolves a hostname, whether DNS or IP to a valid net.IPAddr
-func HostToAddr(hostStr string) *net.IPAddr {
-	remoteAddrs, err := net.LookupHost(hostStr)
-	if err != nil {
-		log.Fatalln("Error parsing remote address:", err)
-	}
-
-	for _, addrStr := range remoteAddrs {
-		if remoteAddr, err := net.ResolveIPAddr("ip4", addrStr); err == nil {
-			return remoteAddr
-		}
-	}
-	return nil
-}
-
-// SetupRawConn creates an ipv4 and udp only RawConn and applies packet filtering
-func SetupRawConn(server *Server, client *PeerNet) *ipv4.RawConn {
-	packetConn, err := net.ListenPacket("ip4:udp", client.IP.String())
-	if err != nil {
-		log.Fatalln("Error creating packetConn:", err)
-	}
-
-	rawConn, err := ipv4.NewRawConn(packetConn)
-	if err != nil {
-		log.Fatalln("Error creating rawConn:", err)
-	}
-
-	ApplyBPF(rawConn, server, client)
-
-	return rawConn
-}
-
-// ApplyBPF constructs a BPF program and applies it to the RawConn
-func ApplyBPF(rawConn *ipv4.RawConn, server *Server, client *PeerNet) {
-	const ipv4HeaderLen = 20
-	const srcIPOffset = 12
-	const srcPortOffset = ipv4HeaderLen + 0
-	const dstPortOffset = ipv4HeaderLen + 2
-
-	ipArr := []byte(server.Addr.IP.To4())
-	ipInt := uint32(ipArr[0])<<(3*8) + uint32(ipArr[1])<<(2*8) + uint32(ipArr[2])<<8 + uint32(ipArr[3])
-
-	bpfRaw, err := bpf.Assemble([]bpf.Instruction{
-		bpf.LoadAbsolute{Off: srcIPOffset, Size: 4},
-		bpf.JumpIf{Cond: bpf.JumpEqual, Val: ipInt, SkipFalse: 5, SkipTrue: 0},
-
-		bpf.LoadAbsolute{Off: srcPortOffset, Size: 2},
-		bpf.JumpIf{Cond: bpf.JumpEqual, Val: uint32(server.Port), SkipFalse: 3, SkipTrue: 0},
-
-		bpf.LoadAbsolute{Off: dstPortOffset, Size: 2},
-		bpf.JumpIf{Cond: bpf.JumpEqual, Val: uint32(client.Port), SkipFalse: 1, SkipTrue: 0},
-
-		bpf.RetConstant{Val: 1<<(8*4) - 1},
-		bpf.RetConstant{Val: 0},
-	})
-
-	if err != nil {
-		log.Fatalln("Error assembling BPF:", err)
-	}
-
-	err = rawConn.SetBPF(bpfRaw)
-	if err != nil {
-		log.Fatalln("Error setting BPF:", err)
-	}
-}
-
-// MakePacket constructs a request packet to send to the server
-func MakePacket(payload []byte, server *Server, client *PeerNet) []byte {
-	buf := gopacket.NewSerializeBuffer()
-
-	opts := gopacket.SerializeOptions{
-		FixLengths:       true,
-		ComputeChecksums: true,
-	}
-
-	ipHeader := layers.IPv4{
-		SrcIP:    client.IP,
-		DstIP:    server.Addr.IP,
-		Version:  4,
-		TTL:      64,
-		Protocol: layers.IPProtocolUDP,
-	}
-
-	udpHeader := layers.UDP{
-		SrcPort: layers.UDPPort(client.Port),
-		DstPort: layers.UDPPort(server.Port),
-	}
-
-	payloadLayer := gopacket.Payload(payload)
-
-	udpHeader.SetNetworkLayerForChecksum(&ipHeader)
-
-	gopacket.SerializeLayers(buf, opts, &ipHeader, &udpHeader, &payloadLayer)
-
-	return buf.Bytes()
-}
-
-// SendPacket sends packet to the Server
-func SendPacket(packet []byte, conn *ipv4.RawConn, server *Server, client *PeerNet) error {
-	fullPacket := MakePacket(packet, server, client)
-	_, err := conn.WriteToIP(fullPacket, server.Addr)
-	return err
-}
-
-// SendDataPacket sends a JSON payload to the Server
-func SendDataPacket(data interface{}, conn *ipv4.RawConn, server *Server, client *PeerNet) error {
-	jsonData, err := json.Marshal(data)
-	if err != nil {
-		return fmt.Errorf("failed to marshal payload: %v", err)
-	}
-
-	return SendPacket(jsonData, conn, server, client)
-}
-
-// RecvPacket receives a UDP packet from server
-func RecvPacket(conn *ipv4.RawConn, server *Server, client *PeerNet) ([]byte, int, error) {
-	err := conn.SetReadDeadline(time.Now().Add(timeout))
-	if err != nil {
-		return nil, 0, err
-	}
-
-	response := make([]byte, 4096)
-	n, err := conn.Read(response)
-	if err != nil {
-		return nil, n, err
-	}
-	return response, n, nil
-}
-
-// RecvDataPacket receives and unmarshals a JSON packet from server
-func RecvDataPacket(conn *ipv4.RawConn, server *Server, client *PeerNet) ([]byte, error) {
-	response, n, err := RecvPacket(conn, server, client)
-	if err != nil {
-		return nil, err
-	}
-
-	// Extract payload from UDP packet
-	payload := response[EmptyUDPSize:n]
-	return payload, nil
-}
-
-// ParseResponse takes a response packet and parses it into an IP and port
-func ParseResponse(response []byte) (net.IP, uint16) {
-	ip := net.IP(response[:4])
-	port := binary.BigEndian.Uint16(response[4:6])
-	return ip, port
-}

network/route.go

@@ -0,0 +1,282 @@
+package network
+
+import (
+	"fmt"
+	"net"
+	"os/exec"
+	"runtime"
+	"strings"
+
+	"github.com/fosrl/newt/logger"
+	"github.com/vishvananda/netlink"
+)
+
+func DarwinAddRoute(destination string, gateway string, interfaceName string) error {
+	if runtime.GOOS != "darwin" {
+		return nil
+	}
+
+	var cmd *exec.Cmd
+
+	if gateway != "" {
+		// Route with specific gateway
+		cmd = exec.Command("route", "-q", "-n", "add", "-inet", destination, "-gateway", gateway)
+	} else if interfaceName != "" {
+		// Route via interface
+		cmd = exec.Command("route", "-q", "-n", "add", "-inet", destination, "-interface", interfaceName)
+	} else {
+		return fmt.Errorf("either gateway or interface must be specified")
+	}
+
+	logger.Info("Running command: %v", cmd)
+
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("route command failed: %v, output: %s", err, out)
+	}
+
+	return nil
+}
+
+func DarwinRemoveRoute(destination string) error {
+	if runtime.GOOS != "darwin" {
+		return nil
+	}
+
+	cmd := exec.Command("route", "-q", "-n", "delete", "-inet", destination)
+	logger.Info("Running command: %v", cmd)
+
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("route delete command failed: %v, output: %s", err, out)
+	}
+
+	return nil
+}
+
+func LinuxAddRoute(destination string, gateway string, interfaceName string) error {
+	if runtime.GOOS != "linux" {
+		return nil
+	}
+
+	// Parse destination CIDR
+	_, ipNet, err := net.ParseCIDR(destination)
+	if err != nil {
+		return fmt.Errorf("invalid destination address: %v", err)
+	}
+
+	// Create route
+	route := &netlink.Route{
+		Dst: ipNet,
+	}
+
+	if gateway != "" {
+		// Route with specific gateway
+		gw := net.ParseIP(gateway)
+		if gw == nil {
+			return fmt.Errorf("invalid gateway address: %s", gateway)
+		}
+		route.Gw = gw
+		logger.Info("Adding route to %s via gateway %s", destination, gateway)
+	} else if interfaceName != "" {
+		// Route via interface
+		link, err := netlink.LinkByName(interfaceName)
+		if err != nil {
+			return fmt.Errorf("failed to get interface %s: %v", interfaceName, err)
+		}
+		route.LinkIndex = link.Attrs().Index
+		logger.Info("Adding route to %s via interface %s", destination, interfaceName)
+	} else {
+		return fmt.Errorf("either gateway or interface must be specified")
+	}
+
+	// Add the route
+	if err := netlink.RouteAdd(route); err != nil {
+		return fmt.Errorf("failed to add route: %v", err)
+	}
+
+	return nil
+}
+
+func LinuxRemoveRoute(destination string) error {
+	if runtime.GOOS != "linux" {
+		return nil
+	}
+
+	// Parse destination CIDR
+	_, ipNet, err := net.ParseCIDR(destination)
+	if err != nil {
+		return fmt.Errorf("invalid destination address: %v", err)
+	}
+
+	// Create route to delete
+	route := &netlink.Route{
+		Dst: ipNet,
+	}
+
+	logger.Info("Removing route to %s", destination)
+
+	// Delete the route
+	if err := netlink.RouteDel(route); err != nil {
+		return fmt.Errorf("failed to delete route: %v", err)
+	}
+
+	return nil
+}
+
+// addRouteForServerIP adds an OS-specific route for the server IP
+func AddRouteForServerIP(serverIP, interfaceName string) error {
+	if err := AddRouteForNetworkConfig(serverIP); err != nil {
+		return err
+	}
+	if interfaceName == "" {
+		return nil
+	}
+	if runtime.GOOS == "darwin" {
+		return DarwinAddRoute(serverIP, "", interfaceName)
+	}
+	// else if runtime.GOOS == "windows" {
+	//	return WindowsAddRoute(serverIP, "", interfaceName)
+	// } else if runtime.GOOS == "linux" {
+	//	return LinuxAddRoute(serverIP, "", interfaceName)
+	// }
+	return nil
+}
+
+// removeRouteForServerIP removes an OS-specific route for the server IP
+func RemoveRouteForServerIP(serverIP string, interfaceName string) error {
+	if err := RemoveRouteForNetworkConfig(serverIP); err != nil {
+		return err
+	}
+	if interfaceName == "" {
+		return nil
+	}
+	if runtime.GOOS == "darwin" {
+		return DarwinRemoveRoute(serverIP)
+	}
+	// else if runtime.GOOS == "windows" {
+	// 	return WindowsRemoveRoute(serverIP)
+	// } else if runtime.GOOS == "linux" {
+	// 	return LinuxRemoveRoute(serverIP)
+	// }
+	return nil
+}
+
+func AddRouteForNetworkConfig(destination string) error {
+	// Parse the subnet to extract IP and mask
+	_, ipNet, err := net.ParseCIDR(destination)
+	if err != nil {
+		return fmt.Errorf("failed to parse subnet %s: %v", destination, err)
+	}
+
+	// Convert CIDR mask to dotted decimal format (e.g., 255.255.255.0)
+	mask := net.IP(ipNet.Mask).String()
+	destinationAddress := ipNet.IP.String()
+
+	AddIPv4IncludedRoute(IPv4Route{DestinationAddress: destinationAddress, SubnetMask: mask})
+
+	return nil
+}
+
+func RemoveRouteForNetworkConfig(destination string) error {
+	// Parse the subnet to extract IP and mask
+	_, ipNet, err := net.ParseCIDR(destination)
+	if err != nil {
+		return fmt.Errorf("failed to parse subnet %s: %v", destination, err)
+	}
+
+	// Convert CIDR mask to dotted decimal format (e.g., 255.255.255.0)
+	mask := net.IP(ipNet.Mask).String()
+	destinationAddress := ipNet.IP.String()
+
+	RemoveIPv4IncludedRoute(IPv4Route{DestinationAddress: destinationAddress, SubnetMask: mask})
+
+	return nil
+}
+
+// addRoutes adds routes for each subnet in RemoteSubnets
+func AddRoutes(remoteSubnets []string, interfaceName string) error {
+	if len(remoteSubnets) == 0 {
+		return nil
+	}
+
+	// Add routes for each subnet
+	for _, subnet := range remoteSubnets {
+		subnet = strings.TrimSpace(subnet)
+		if subnet == "" {
+			continue
+		}
+
+		if err := AddRouteForNetworkConfig(subnet); err != nil {
+			logger.Error("Failed to add network config for subnet %s: %v", subnet, err)
+			continue
+		}
+
+		// Add route based on operating system
+		if interfaceName == "" {
+			continue
+		}
+
+		if runtime.GOOS == "darwin" {
+			if err := DarwinAddRoute(subnet, "", interfaceName); err != nil {
+				logger.Error("Failed to add Darwin route for subnet %s: %v", subnet, err)
+				return err
+			}
+		} else if runtime.GOOS == "windows" {
+			if err := WindowsAddRoute(subnet, "", interfaceName); err != nil {
+				logger.Error("Failed to add Windows route for subnet %s: %v", subnet, err)
+				return err
+			}
+		} else if runtime.GOOS == "linux" {
+			if err := LinuxAddRoute(subnet, "", interfaceName); err != nil {
+				logger.Error("Failed to add Linux route for subnet %s: %v", subnet, err)
+				return err
+			}
+		}
+
+		logger.Info("Added route for remote subnet: %s", subnet)
+	}
+	return nil
+}
+
+// removeRoutesForRemoteSubnets removes routes for each subnet in RemoteSubnets
+func RemoveRoutes(remoteSubnets []string) error {
+	if len(remoteSubnets) == 0 {
+		return nil
+	}
+
+	// Remove routes for each subnet
+	for _, subnet := range remoteSubnets {
+		subnet = strings.TrimSpace(subnet)
+		if subnet == "" {
+			continue
+		}
+
+		if err := RemoveRouteForNetworkConfig(subnet); err != nil {
+			logger.Error("Failed to remove network config for subnet %s: %v", subnet, err)
+			continue
+		}
+
+		// Remove route based on operating system
+		if runtime.GOOS == "darwin" {
+			if err := DarwinRemoveRoute(subnet); err != nil {
+				logger.Error("Failed to remove Darwin route for subnet %s: %v", subnet, err)
+				return err
+			}
+		} else if runtime.GOOS == "windows" {
+			if err := WindowsRemoveRoute(subnet); err != nil {
+				logger.Error("Failed to remove Windows route for subnet %s: %v", subnet, err)
+				return err
+			}
+		} else if runtime.GOOS == "linux" {
+			if err := LinuxRemoveRoute(subnet); err != nil {
+				logger.Error("Failed to remove Linux route for subnet %s: %v", subnet, err)
+				return err
+			}
+		}
+
+		logger.Info("Removed route for remote subnet: %s", subnet)
+	}
+
+	return nil
+}

network/route_notwindows.go

@@ -0,0 +1,11 @@
+//go:build !windows
+
+package network
+
+func WindowsAddRoute(destination string, gateway string, interfaceName string) error {
+	return nil
+}
+
+func WindowsRemoveRoute(destination string) error {
+	return nil
+}

network/route_windows.go

@@ -0,0 +1,148 @@
+//go:build windows
+
+package network
+
+import (
+	"fmt"
+	"net"
+	"net/netip"
+	"runtime"
+
+	"github.com/fosrl/newt/logger"
+	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
+)
+
+func WindowsAddRoute(destination string, gateway string, interfaceName string) error {
+	if runtime.GOOS != "windows" {
+		return nil
+	}
+
+	// Parse destination CIDR
+	_, ipNet, err := net.ParseCIDR(destination)
+	if err != nil {
+		return fmt.Errorf("invalid destination address: %v", err)
+	}
+
+	// Convert to netip.Prefix
+	maskBits, _ := ipNet.Mask.Size()
+
+	// Ensure we convert to the correct IP version (IPv4 vs IPv6)
+	var addr netip.Addr
+	if ip4 := ipNet.IP.To4(); ip4 != nil {
+		// IPv4 address
+		addr, _ = netip.AddrFromSlice(ip4)
+	} else {
+		// IPv6 address
+		addr, _ = netip.AddrFromSlice(ipNet.IP)
+	}
+	if !addr.IsValid() {
+		return fmt.Errorf("failed to convert destination IP")
+	}
+	prefix := netip.PrefixFrom(addr, maskBits)
+
+	var luid winipcfg.LUID
+	var nextHop netip.Addr
+
+	if interfaceName != "" {
+		// Get the interface LUID - needed for both gateway and interface-only routes
+		iface, err := net.InterfaceByName(interfaceName)
+		if err != nil {
+			return fmt.Errorf("failed to get interface %s: %v", interfaceName, err)
+		}
+
+		luid, err = winipcfg.LUIDFromIndex(uint32(iface.Index))
+		if err != nil {
+			return fmt.Errorf("failed to get LUID for interface %s: %v", interfaceName, err)
+		}
+	}
+
+	if gateway != "" {
+		// Route with specific gateway
+		gwIP := net.ParseIP(gateway)
+		if gwIP == nil {
+			return fmt.Errorf("invalid gateway address: %s", gateway)
+		}
+		// Convert to correct IP version
+		if ip4 := gwIP.To4(); ip4 != nil {
+			nextHop, _ = netip.AddrFromSlice(ip4)
+		} else {
+			nextHop, _ = netip.AddrFromSlice(gwIP)
+		}
+		if !nextHop.IsValid() {
+			return fmt.Errorf("failed to convert gateway IP")
+		}
+		logger.Info("Adding route to %s via gateway %s on interface %s", destination, gateway, interfaceName)
+	} else if interfaceName != "" {
+		// Route via interface only
+		if addr.Is4() {
+			nextHop = netip.IPv4Unspecified()
+		} else {
+			nextHop = netip.IPv6Unspecified()
+		}
+		logger.Info("Adding route to %s via interface %s", destination, interfaceName)
+	} else {
+		return fmt.Errorf("either gateway or interface must be specified")
+	}
+
+	// Add the route using winipcfg
+	err = luid.AddRoute(prefix, nextHop, 1)
+	if err != nil {
+		return fmt.Errorf("failed to add route: %v", err)
+	}
+
+	return nil
+}
+
+func WindowsRemoveRoute(destination string) error {
+	// Parse destination CIDR
+	_, ipNet, err := net.ParseCIDR(destination)
+	if err != nil {
+		return fmt.Errorf("invalid destination address: %v", err)
+	}
+
+	// Convert to netip.Prefix
+	maskBits, _ := ipNet.Mask.Size()
+
+	// Ensure we convert to the correct IP version (IPv4 vs IPv6)
+	var addr netip.Addr
+	if ip4 := ipNet.IP.To4(); ip4 != nil {
+		// IPv4 address
+		addr, _ = netip.AddrFromSlice(ip4)
+	} else {
+		// IPv6 address
+		addr, _ = netip.AddrFromSlice(ipNet.IP)
+	}
+	if !addr.IsValid() {
+		return fmt.Errorf("failed to convert destination IP")
+	}
+	prefix := netip.PrefixFrom(addr, maskBits)
+
+	// Get all routes and find the one to delete
+	// We need to get the LUID from the existing route
+	var family winipcfg.AddressFamily
+	if addr.Is4() {
+		family = 2 // AF_INET
+	} else {
+		family = 23 // AF_INET6
+	}
+
+	routes, err := winipcfg.GetIPForwardTable2(family)
+	if err != nil {
+		return fmt.Errorf("failed to get route table: %v", err)
+	}
+
+	// Find and delete matching route
+	for _, route := range routes {
+		routePrefix := route.DestinationPrefix.Prefix()
+		if routePrefix == prefix {
+			logger.Info("Removing route to %s", destination)
+			err = route.Delete()
+			if err != nil {
+				return fmt.Errorf("failed to delete route: %v", err)
+			}
+			return nil
+		}
+	}
+
+	return fmt.Errorf("route to %s not found", destination)
+}

network/settings.go

@@ -0,0 +1,190 @@
+package network
+
+import (
+	"encoding/json"
+	"sync"
+
+	"github.com/fosrl/newt/logger"
+)
+
+// NetworkSettings represents the network configuration for the tunnel
+type NetworkSettings struct {
+	TunnelRemoteAddress string      `json:"tunnel_remote_address,omitempty"`
+	MTU                 *int        `json:"mtu,omitempty"`
+	DNSServers          []string    `json:"dns_servers,omitempty"`
+	IPv4Addresses       []string    `json:"ipv4_addresses,omitempty"`
+	IPv4SubnetMasks     []string    `json:"ipv4_subnet_masks,omitempty"`
+	IPv4IncludedRoutes  []IPv4Route `json:"ipv4_included_routes,omitempty"`
+	IPv4ExcludedRoutes  []IPv4Route `json:"ipv4_excluded_routes,omitempty"`
+	IPv6Addresses       []string    `json:"ipv6_addresses,omitempty"`
+	IPv6NetworkPrefixes []string    `json:"ipv6_network_prefixes,omitempty"`
+	IPv6IncludedRoutes  []IPv6Route `json:"ipv6_included_routes,omitempty"`
+	IPv6ExcludedRoutes  []IPv6Route `json:"ipv6_excluded_routes,omitempty"`
+}
+
+// IPv4Route represents an IPv4 route
+type IPv4Route struct {
+	DestinationAddress string `json:"destination_address"`
+	SubnetMask         string `json:"subnet_mask,omitempty"`
+	GatewayAddress     string `json:"gateway_address,omitempty"`
+	IsDefault          bool   `json:"is_default,omitempty"`
+}
+
+// IPv6Route represents an IPv6 route
+type IPv6Route struct {
+	DestinationAddress  string `json:"destination_address"`
+	NetworkPrefixLength int    `json:"network_prefix_length,omitempty"`
+	GatewayAddress      string `json:"gateway_address,omitempty"`
+	IsDefault           bool   `json:"is_default,omitempty"`
+}
+
+var (
+	networkSettings      NetworkSettings
+	networkSettingsMutex sync.RWMutex
+	incrementor          int
+)
+
+// SetTunnelRemoteAddress sets the tunnel remote address
+func SetTunnelRemoteAddress(address string) {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+	networkSettings.TunnelRemoteAddress = address
+	incrementor++
+	logger.Info("Set tunnel remote address: %s", address)
+}
+
+// SetMTU sets the MTU value
+func SetMTU(mtu int) {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+	networkSettings.MTU = &mtu
+	incrementor++
+	logger.Info("Set MTU: %d", mtu)
+}
+
+// SetDNSServers sets the DNS servers
+func SetDNSServers(servers []string) {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+	networkSettings.DNSServers = servers
+	incrementor++
+	logger.Info("Set DNS servers: %v", servers)
+}
+
+// SetIPv4Settings sets IPv4 addresses and subnet masks
+func SetIPv4Settings(addresses []string, subnetMasks []string) {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+	networkSettings.IPv4Addresses = addresses
+	networkSettings.IPv4SubnetMasks = subnetMasks
+	incrementor++
+	logger.Info("Set IPv4 addresses: %v, subnet masks: %v", addresses, subnetMasks)
+}
+
+// SetIPv4IncludedRoutes sets the included IPv4 routes
+func SetIPv4IncludedRoutes(routes []IPv4Route) {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+	networkSettings.IPv4IncludedRoutes = routes
+	incrementor++
+	logger.Info("Set IPv4 included routes: %d routes", len(routes))
+}
+
+func AddIPv4IncludedRoute(route IPv4Route) {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+
+	// make sure it does not already exist
+	for _, r := range networkSettings.IPv4IncludedRoutes {
+		if r == route {
+			logger.Info("IPv4 included route already exists: %+v", route)
+			return
+		}
+	}
+
+	networkSettings.IPv4IncludedRoutes = append(networkSettings.IPv4IncludedRoutes, route)
+	incrementor++
+	logger.Info("Added IPv4 included route: %+v", route)
+}
+
+func RemoveIPv4IncludedRoute(route IPv4Route) {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+	routes := networkSettings.IPv4IncludedRoutes
+	for i, r := range routes {
+		if r == route {
+			networkSettings.IPv4IncludedRoutes = append(routes[:i], routes[i+1:]...)
+			logger.Info("Removed IPv4 included route: %+v", route)
+			return
+		}
+	}
+	incrementor++
+	logger.Info("IPv4 included route not found for removal: %+v", route)
+}
+
+func SetIPv4ExcludedRoutes(routes []IPv4Route) {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+	networkSettings.IPv4ExcludedRoutes = routes
+	incrementor++
+	logger.Info("Set IPv4 excluded routes: %d routes", len(routes))
+}
+
+// SetIPv6Settings sets IPv6 addresses and network prefixes
+func SetIPv6Settings(addresses []string, networkPrefixes []string) {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+	networkSettings.IPv6Addresses = addresses
+	networkSettings.IPv6NetworkPrefixes = networkPrefixes
+	incrementor++
+	logger.Info("Set IPv6 addresses: %v, network prefixes: %v", addresses, networkPrefixes)
+}
+
+// SetIPv6IncludedRoutes sets the included IPv6 routes
+func SetIPv6IncludedRoutes(routes []IPv6Route) {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+	networkSettings.IPv6IncludedRoutes = routes
+	incrementor++
+	logger.Info("Set IPv6 included routes: %d routes", len(routes))
+}
+
+// SetIPv6ExcludedRoutes sets the excluded IPv6 routes
+func SetIPv6ExcludedRoutes(routes []IPv6Route) {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+	networkSettings.IPv6ExcludedRoutes = routes
+	incrementor++
+	logger.Info("Set IPv6 excluded routes: %d routes", len(routes))
+}
+
+// ClearNetworkSettings clears all network settings
+func ClearNetworkSettings() {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+	networkSettings = NetworkSettings{}
+	incrementor++
+	logger.Info("Cleared all network settings")
+}
+
+func GetJSON() (string, error) {
+	networkSettingsMutex.RLock()
+	defer networkSettingsMutex.RUnlock()
+	data, err := json.MarshalIndent(networkSettings, "", "  ")
+	if err != nil {
+		return "", err
+	}
+	return string(data), nil
+}
+
+func GetSettings() NetworkSettings {
+	networkSettingsMutex.RLock()
+	defer networkSettingsMutex.RUnlock()
+	return networkSettings
+}
+
+func GetIncrementor() int {
+	networkSettingsMutex.Lock()
+	defer networkSettingsMutex.Unlock()
+	return incrementor
+}

stub.go

@@ -32,3 +32,8 @@ func clientsAddProxyTargetNative(pm *proxy.ProxyManager, tunnelIp string) {
 	_ = tunnelIp
 	// No-op for non-Linux systems
 }
+
+func clientsStartDirectRelayNative(tunnelIP string) {
+	_ = tunnelIP
+	// No-op for non-Linux systems
+}

util/util.go

@@ -0,0 +1,213 @@
+package util
+
+import (
+	"encoding/base64"
+	"encoding/binary"
+	"encoding/hex"
+	"fmt"
+	"net"
+	"strings"
+
+	mathrand "math/rand/v2"
+
+	"github.com/fosrl/newt/logger"
+	"golang.zx2c4.com/wireguard/device"
+)
+
+func ResolveDomain(domain string) (string, error) {
+	// trim whitespace
+	domain = strings.TrimSpace(domain)
+
+	// Remove any protocol prefix if present (do this first, before splitting host/port)
+	domain = strings.TrimPrefix(domain, "http://")
+	domain = strings.TrimPrefix(domain, "https://")
+
+	// if there are any trailing slashes, remove them
+	domain = strings.TrimSuffix(domain, "/")
+
+	// Check if there's a port in the domain
+	host, port, err := net.SplitHostPort(domain)
+	if err != nil {
+		// No port found, use the domain as is
+		host = domain
+		port = ""
+	}
+
+	// Lookup IP addresses
+	ips, err := net.LookupIP(host)
+	if err != nil {
+		return "", fmt.Errorf("DNS lookup failed: %v", err)
+	}
+
+	if len(ips) == 0 {
+		return "", fmt.Errorf("no IP addresses found for domain %s", host)
+	}
+
+	// Get the first IPv4 address if available
+	var ipAddr string
+	for _, ip := range ips {
+		if ipv4 := ip.To4(); ipv4 != nil {
+			ipAddr = ipv4.String()
+			break
+		}
+	}
+
+	// If no IPv4 found, use the first IP (might be IPv6)
+	if ipAddr == "" {
+		ipAddr = ips[0].String()
+	}
+
+	// Add port back if it existed
+	if port != "" {
+		ipAddr = net.JoinHostPort(ipAddr, port)
+	}
+
+	return ipAddr, nil
+}
+
+func ParseLogLevel(level string) logger.LogLevel {
+	switch strings.ToUpper(level) {
+	case "DEBUG":
+		return logger.DEBUG
+	case "INFO":
+		return logger.INFO
+	case "WARN":
+		return logger.WARN
+	case "ERROR":
+		return logger.ERROR
+	case "FATAL":
+		return logger.FATAL
+	default:
+		return logger.INFO // default to INFO if invalid level provided
+	}
+}
+
+// find an available UDP port in the range [minPort, maxPort] and also the next port for the wgtester
+func FindAvailableUDPPort(minPort, maxPort uint16) (uint16, error) {
+	if maxPort < minPort {
+		return 0, fmt.Errorf("invalid port range: min=%d, max=%d", minPort, maxPort)
+	}
+
+	// We need to check port+1 as well, so adjust the max port to avoid going out of range
+	adjustedMaxPort := maxPort - 1
+	if adjustedMaxPort < minPort {
+		return 0, fmt.Errorf("insufficient port range to find consecutive ports: min=%d, max=%d", minPort, maxPort)
+	}
+
+	// Create a slice of all ports in the range (excluding the last one)
+	portRange := make([]uint16, adjustedMaxPort-minPort+1)
+	for i := range portRange {
+		portRange[i] = minPort + uint16(i)
+	}
+
+	// Fisher-Yates shuffle to randomize the port order
+	for i := len(portRange) - 1; i > 0; i-- {
+		j := mathrand.IntN(i + 1)
+		portRange[i], portRange[j] = portRange[j], portRange[i]
+	}
+
+	// Try each port in the randomized order
+	for _, port := range portRange {
+		// Check if port is available
+		addr1 := &net.UDPAddr{
+			IP:   net.ParseIP("127.0.0.1"),
+			Port: int(port),
+		}
+		conn1, err1 := net.ListenUDP("udp", addr1)
+		if err1 != nil {
+			continue // Port is in use or there was an error, try next port
+		}
+
+		conn1.Close()
+		return port, nil
+	}
+
+	return 0, fmt.Errorf("no available consecutive UDP ports found in range %d-%d", minPort, maxPort)
+}
+
+func FixKey(key string) string {
+	// Remove any whitespace
+	key = strings.TrimSpace(key)
+
+	// Decode from base64
+	decoded, err := base64.StdEncoding.DecodeString(key)
+	if err != nil {
+		logger.Fatal("Error decoding base64: %v", err)
+	}
+
+	// Convert to hex
+	return hex.EncodeToString(decoded)
+}
+
+// this is the opposite of FixKey
+func UnfixKey(hexKey string) string {
+	// Decode from hex
+	decoded, err := hex.DecodeString(hexKey)
+	if err != nil {
+		logger.Fatal("Error decoding hex: %v", err)
+	}
+
+	// Convert to base64
+	return base64.StdEncoding.EncodeToString(decoded)
+}
+
+func MapToWireGuardLogLevel(level logger.LogLevel) int {
+	switch level {
+	case logger.DEBUG:
+		return device.LogLevelVerbose
+	// case logger.INFO:
+	// return device.LogLevel
+	case logger.WARN:
+		return device.LogLevelError
+	case logger.ERROR, logger.FATAL:
+		return device.LogLevelSilent
+	default:
+		return device.LogLevelSilent
+	}
+}
+
+// GetProtocol returns protocol number from IPv4 packet (fast path)
+func GetProtocol(packet []byte) (uint8, bool) {
+	if len(packet) < 20 {
+		return 0, false
+	}
+	version := packet[0] >> 4
+	if version == 4 {
+		return packet[9], true
+	} else if version == 6 {
+		if len(packet) < 40 {
+			return 0, false
+		}
+		return packet[6], true
+	}
+	return 0, false
+}
+
+// GetDestPort returns destination port from TCP/UDP packet (fast path)
+func GetDestPort(packet []byte) (uint16, bool) {
+	if len(packet) < 20 {
+		return 0, false
+	}
+
+	version := packet[0] >> 4
+	var headerLen int
+
+	if version == 4 {
+		ihl := packet[0] & 0x0F
+		headerLen = int(ihl) * 4
+		if len(packet) < headerLen+4 {
+			return 0, false
+		}
+	} else if version == 6 {
+		headerLen = 40
+		if len(packet) < headerLen+4 {
+			return 0, false
+		}
+	} else {
+		return 0, false
+	}
+
+	// Destination port is at bytes 2-3 of TCP/UDP header
+	port := binary.BigEndian.Uint16(packet[headerLen+2 : headerLen+4])
+	return port, true
+}

websocket/client.go

@@ -46,6 +46,7 @@ type Client struct {
 	metricsCtxMu      sync.RWMutex
 	metricsCtx        context.Context
 	configNeedsSave   bool // Flag to track if config needs to be saved
+	serverVersion     string
 }
 
 type ClientOption func(*Client)
@@ -149,6 +150,10 @@ func (c *Client) GetConfig() *Config {
 	return c.config
 }
 
+func (c *Client) GetServerVersion() string {
+	return c.serverVersion
+}
+
 // Connect establishes the WebSocket connection
 func (c *Client) Connect() error {
 	go c.connectWithRetry()
@@ -206,6 +211,26 @@ func (c *Client) SendMessage(messageType string, data interface{}) error {
 	return nil
 }
 
+// SendMessage sends a message through the WebSocket connection
+func (c *Client) SendMessageNoLog(messageType string, data interface{}) error {
+	if c.conn == nil {
+		return fmt.Errorf("not connected")
+	}
+
+	msg := WSMessage{
+		Type: messageType,
+		Data: data,
+	}
+
+	c.writeMux.Lock()
+	defer c.writeMux.Unlock()
+	if err := c.conn.WriteJSON(msg); err != nil {
+		return err
+	}
+	telemetry.IncWSMessage(c.metricsContext(), "out", "text")
+	return nil
+}
+
 func (c *Client) SendMessageInterval(messageType string, data interface{}, interval time.Duration) (stop func()) {
 	stopChan := make(chan struct{})
 	go func() {
@@ -331,9 +356,11 @@ func (c *Client) getToken() (string, error) {
 	}
 	defer resp.Body.Close()
 
+	body, _ := io.ReadAll(resp.Body)
+	logger.Debug("Token response body: %s", string(body))
+
 	if resp.StatusCode != http.StatusOK {
-		body, _ := io.ReadAll(resp.Body)
+		logger.Error("Failed to get token with status code: %d", resp.StatusCode)
-		logger.Error("Failed to get token with status code: %d, body: %s", resp.StatusCode, string(body))
 		telemetry.IncConnAttempt(ctx, "auth", "failure")
 		etype := "io_error"
 		if resp.StatusCode == http.StatusUnauthorized || resp.StatusCode == http.StatusForbidden {
@@ -348,7 +375,7 @@ func (c *Client) getToken() (string, error) {
 	}
 
 	var tokenResp TokenResponse
-	if err := json.NewDecoder(resp.Body).Decode(&tokenResp); err != nil {
+	if err := json.Unmarshal(body, &tokenResp); err != nil {
 		logger.Error("Failed to decode token response.")
 		return "", fmt.Errorf("failed to decode token response: %w", err)
 	}
@@ -361,6 +388,11 @@ func (c *Client) getToken() (string, error) {
 		return "", fmt.Errorf("received empty token from server")
 	}
 
+	// print server version
+	logger.Info("Server version: %s", tokenResp.Data.ServerVersion)
+
+	c.serverVersion = tokenResp.Data.ServerVersion
+
 	logger.Debug("Received token: %s", tokenResp.Data.Token)
 	telemetry.IncConnAttempt(ctx, "auth", "success")
 

websocket/types.go

@@ -9,7 +9,8 @@ type Config struct {
 
 type TokenResponse struct {
 	Data struct {
-		Token string `json:"token"`
+		Token         string `json:"token"`
+		ServerVersion string `json:"serverVersion"`
 	} `json:"data"`
 	Success bool   `json:"success"`
 	Message string `json:"message"`

wgtester/wgtester.go

@@ -3,12 +3,13 @@ package wgtester
 import (
 	"encoding/binary"
 	"fmt"
+	"io"
 	"net"
 	"sync"
 	"time"
 
 	"github.com/fosrl/newt/logger"
-	"golang.zx2c4.com/wireguard/tun/netstack"
+	"github.com/fosrl/newt/netstack2"
 	"gvisor.dev/gvisor/pkg/tcpip/adapters/gonet"
 )
 
@@ -39,7 +40,7 @@ type Server struct {
 	newtID       string
 	outputPrefix string
 	useNetstack  bool
-	tnet         interface{} // Will be *netstack.Net when using netstack
+	tnet         interface{} // Will be *netstack2.Net when using netstack
 }
 
 // NewServer creates a new connection test server using UDP
@@ -56,7 +57,7 @@ func NewServer(serverAddr string, serverPort uint16, newtID string) *Server {
 }
 
 // NewServerWithNetstack creates a new connection test server using WireGuard netstack
-func NewServerWithNetstack(serverAddr string, serverPort uint16, newtID string, tnet *netstack.Net) *Server {
+func NewServerWithNetstack(serverAddr string, serverPort uint16, newtID string, tnet *netstack2.Net) *Server {
 	return &Server{
 		serverAddr:   serverAddr,
 		serverPort:   serverPort + 1, // use the next port for the server
@@ -82,7 +83,7 @@ func (s *Server) Start() error {
 
 	if s.useNetstack && s.tnet != nil {
 		// Use WireGuard netstack
-		tnet := s.tnet.(*netstack.Net)
+		tnet := s.tnet.(*netstack2.Net)
 		udpAddr := &net.UDPAddr{Port: int(s.serverPort)}
 		netstackConn, err := tnet.ListenUDP(udpAddr)
 		if err != nil {
@@ -130,7 +131,7 @@ func (s *Server) Stop() {
 }
 
 // RestartWithNetstack stops the current server and restarts it with netstack
-func (s *Server) RestartWithNetstack(tnet *netstack.Net) error {
+func (s *Server) RestartWithNetstack(tnet *netstack2.Net) error {
 	s.Stop()
 
 	// Update configuration to use netstack
@@ -187,6 +188,10 @@ func (s *Server) handleConnections() {
 				case <-s.shutdownCh:
 					return // Don't log error if we're shutting down
 				default:
+					// Don't log EOF errors during shutdown - these are expected when connection is closed
+					if err == io.EOF {
+						return
+					}
 					logger.Error("%sError reading from UDP: %v", s.outputPrefix, err)
 				}
 				continue
@@ -219,7 +224,7 @@ func (s *Server) handleConnections() {
 			copy(responsePacket[5:13], buffer[5:13])
 
 			// Log response being sent for debugging
-			logger.Debug("%sSending response to %s", s.outputPrefix, addr.String())
+			// logger.Debug("%sSending response to %s", s.outputPrefix, addr.String())
 
 			// Send the response packet - handle both regular UDP and netstack UDP
 			if s.useNetstack {
@@ -235,7 +240,7 @@ func (s *Server) handleConnections() {
 			if err != nil {
 				logger.Error("%sError sending response: %v", s.outputPrefix, err)
 			} else {
-				logger.Debug("%sResponse sent successfully", s.outputPrefix)
+				// logger.Debug("%sResponse sent successfully", s.outputPrefix)
 			}
 		}
 	}