[client] Fix/pkg loss (#3338)

The Relayed connection setup is optimistic. It does not have any confirmation of an established end-to-end connection. Peers start sending WireGuard handshake packets immediately after the successful offer-answer handshake.
Meanwhile, for successful P2P connection negotiation, we change the WireGuard endpoint address, but this change does not trigger new handshake initiation. Because the peer switched from Relayed connection to P2P, the packets from the Relay server are dropped and must wait for the next WireGuard handshake via P2P.

To avoid this scenario, the relayed WireGuard proxy no longer drops the packets. Instead, it rewrites the source address to the new P2P endpoint and continues forwarding the packets.

We still have one corner case: if the Relayed server negotiation chooses a server that has not been used before. In this case, one side of the peer connection will be slower to reach the Relay server, and the Relay server will drop the handshake packet.

If everything goes well we should see exactly 5 seconds improvements between the WireGuard configuration time and the handshake time.

client/iface/bind/endpoint.go

@@ -1,5 +1,17 @@
 package bind
 
-import wgConn "golang.zx2c4.com/wireguard/conn"
+import (
+	"net"
+
+	wgConn "golang.zx2c4.com/wireguard/conn"
+)
 
 type Endpoint = wgConn.StdNetEndpoint
+
+func EndpointToUDPAddr(e Endpoint) *net.UDPAddr {
+	return &net.UDPAddr{
+		IP:   e.Addr().AsSlice(),
+		Port: int(e.Port()),
+		Zone: e.Addr().Zone(),
+	}
+}

client/iface/bind/ice_bind.go

@@ -1,6 +1,7 @@
 package bind
 
 import (
+	"context"
 	"encoding/binary"
 	"fmt"
 	"net"
@@ -42,7 +43,7 @@ func (rc receiverCreator) CreateIPv4ReceiverFn(pc *ipv4.PacketConn, conn *net.UD
 // use the port because in the Send function the wgConn.Endpoint the port info is not exported.
 type ICEBind struct {
 	*wgConn.StdNetBind
-	RecvChan chan RecvMessage
+	recvChan chan RecvMessage
 
 	transportNet transport.Net
 	filterFn     udpmux.FilterFn
@@ -65,7 +66,7 @@ func NewICEBind(transportNet transport.Net, filterFn udpmux.FilterFn, address wg
 	b, _ := wgConn.NewStdNetBind().(*wgConn.StdNetBind)
 	ib := &ICEBind{
 		StdNetBind:       b,
-		RecvChan:         make(chan RecvMessage, 1),
+		recvChan:         make(chan RecvMessage, 1),
 		transportNet:     transportNet,
 		filterFn:         filterFn,
 		endpoints:        make(map[netip.Addr]net.Conn),
@@ -155,6 +156,14 @@ func (b *ICEBind) Send(bufs [][]byte, ep wgConn.Endpoint) error {
 	return nil
 }
 
+func (b *ICEBind) Recv(ctx context.Context, msg RecvMessage) {
+	select {
+	case <-ctx.Done():
+		return
+	case b.recvChan <- msg:
+	}
+}
+
 func (s *ICEBind) createIPv4ReceiverFn(pc *ipv4.PacketConn, conn *net.UDPConn, rxOffload bool, msgsPool *sync.Pool) wgConn.ReceiveFunc {
 	s.muUDPMux.Lock()
 	defer s.muUDPMux.Unlock()
@@ -271,7 +280,7 @@ func (c *ICEBind) receiveRelayed(buffs [][]byte, sizes []int, eps []wgConn.Endpo
 	select {
 	case <-c.closedChan:
 		return 0, net.ErrClosed
-	case msg, ok := <-c.RecvChan:
+	case msg, ok := <-c.recvChan:
 		if !ok {
 			return 0, net.ErrClosed
 		}

client/iface/iface_new_freebsd.go

@@ -0,0 +1,41 @@
+//go:build freebsd
+
+package iface
+
+import (
+	"fmt"
+
+	"github.com/netbirdio/netbird/client/iface/bind"
+	"github.com/netbirdio/netbird/client/iface/device"
+	"github.com/netbirdio/netbird/client/iface/netstack"
+	"github.com/netbirdio/netbird/client/iface/wgaddr"
+	"github.com/netbirdio/netbird/client/iface/wgproxy"
+)
+
+// NewWGIFace Creates a new WireGuard interface instance
+func NewWGIFace(opts WGIFaceOpts) (*WGIface, error) {
+	wgAddress, err := wgaddr.ParseWGAddress(opts.Address)
+	if err != nil {
+		return nil, err
+	}
+
+	wgIFace := &WGIface{}
+
+	if netstack.IsEnabled() {
+		iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress, opts.MTU)
+		wgIFace.tun = device.NewNetstackDevice(opts.IFaceName, wgAddress, opts.WGPort, opts.WGPrivKey, opts.MTU, iceBind, netstack.ListenAddr())
+		wgIFace.userspaceBind = true
+		wgIFace.wgProxyFactory = wgproxy.NewUSPFactory(iceBind)
+		return wgIFace, nil
+	}
+
+	if device.ModuleTunIsLoaded() {
+		iceBind := bind.NewICEBind(opts.TransportNet, opts.FilterFn, wgAddress, opts.MTU)
+		wgIFace.tun = device.NewUSPDevice(opts.IFaceName, wgAddress, opts.WGPort, opts.WGPrivKey, opts.MTU, iceBind)
+		wgIFace.userspaceBind = true
+		wgIFace.wgProxyFactory = wgproxy.NewUSPFactory(iceBind)
+		return wgIFace, nil
+	}
+
+	return nil, fmt.Errorf("couldn't check or load tun module")
+}

client/iface/iface_new_linux.go

@@ -1,4 +1,4 @@
-//go:build (linux && !android) || freebsd
+//go:build linux && !android
 
 package iface
 

client/iface/wgproxy/bind/proxy.go

@@ -16,28 +16,37 @@ import (
 	"github.com/netbirdio/netbird/client/iface/wgproxy/listener"
 )
 
+type IceBind interface {
+	SetEndpoint(fakeIP netip.Addr, conn net.Conn)
+	RemoveEndpoint(fakeIP netip.Addr)
+	Recv(ctx context.Context, msg bind.RecvMessage)
+	MTU() uint16
+}
+
 type ProxyBind struct {
-	Bind *bind.ICEBind
+	bind IceBind
 
-	fakeNetIP      *netip.AddrPort
-	wgBindEndpoint *bind.Endpoint
-	remoteConn     net.Conn
-	ctx            context.Context
-	cancel         context.CancelFunc
-	closeMu        sync.Mutex
-	closed         bool
+	// wgRelayedEndpoint is a fake address that generated by the Bind.SetEndpoint based on the remote NetBird peer address
+	wgRelayedEndpoint *bind.Endpoint
+	wgCurrentUsed     *bind.Endpoint
+	remoteConn        net.Conn
+	ctx               context.Context
+	cancel            context.CancelFunc
+	closeMu           sync.Mutex
+	closed            bool
 
-	pausedMu  sync.Mutex
-	paused    bool
-	isStarted bool
+	paused     bool
+	pausedCond *sync.Cond
+	isStarted  bool
 
 	closeListener *listener.CloseListener
 }
 
-func NewProxyBind(bind *bind.ICEBind) *ProxyBind {
+func NewProxyBind(bind IceBind) *ProxyBind {
 	p := &ProxyBind{
-		Bind:          bind,
+		bind:          bind,
 		closeListener: listener.NewCloseListener(),
+		pausedCond:    sync.NewCond(&sync.Mutex{}),
 	}
 
 	return p
@@ -46,25 +55,25 @@ func NewProxyBind(bind *bind.ICEBind) *ProxyBind {
 // AddTurnConn adds a new connection to the bind.
 // endpoint is the NetBird address of the remote peer. The SetEndpoint return with the address what will be used in the
 // WireGuard configuration.
+//
+// Parameters:
+//   - ctx: Context is used for proxyToLocal to avoid unnecessary error messages
+//   - nbAddr: The NetBird UDP address of the remote peer, it required to generate fake address
+//   - remoteConn: The established TURN connection to the remote peer
 func (p *ProxyBind) AddTurnConn(ctx context.Context, nbAddr *net.UDPAddr, remoteConn net.Conn) error {
 	fakeNetIP, err := fakeAddress(nbAddr)
 	if err != nil {
 		return err
 	}
-
-	p.fakeNetIP = fakeNetIP
-	p.wgBindEndpoint = &bind.Endpoint{AddrPort: *fakeNetIP}
+	p.wgRelayedEndpoint = &bind.Endpoint{AddrPort: *fakeNetIP}
 	p.remoteConn = remoteConn
 	p.ctx, p.cancel = context.WithCancel(ctx)
 	return nil
 
 }
+
 func (p *ProxyBind) EndpointAddr() *net.UDPAddr {
-	return &net.UDPAddr{
-		IP:   p.fakeNetIP.Addr().AsSlice(),
-		Port: int(p.fakeNetIP.Port()),
-		Zone: p.fakeNetIP.Addr().Zone(),
-	}
+	return bind.EndpointToUDPAddr(*p.wgRelayedEndpoint)
 }
 
 func (p *ProxyBind) SetDisconnectListener(disconnected func()) {
@@ -76,17 +85,21 @@ func (p *ProxyBind) Work() {
 		return
 	}
 
-	p.Bind.SetEndpoint(p.fakeNetIP.Addr(), p.remoteConn)
+	p.bind.SetEndpoint(p.wgRelayedEndpoint.Addr(), p.remoteConn)
 
-	p.pausedMu.Lock()
+	p.pausedCond.L.Lock()
 	p.paused = false
-	p.pausedMu.Unlock()
+
+	p.wgCurrentUsed = p.wgRelayedEndpoint
 
 	// Start the proxy only once
 	if !p.isStarted {
 		p.isStarted = true
 		go p.proxyToLocal(p.ctx)
 	}
+
+	p.pausedCond.Signal()
+	p.pausedCond.L.Unlock()
 }
 
 func (p *ProxyBind) Pause() {
@@ -94,9 +107,25 @@ func (p *ProxyBind) Pause() {
 		return
 	}
 
-	p.pausedMu.Lock()
+	p.pausedCond.L.Lock()
 	p.paused = true
-	p.pausedMu.Unlock()
+	p.pausedCond.L.Unlock()
+}
+
+func (p *ProxyBind) RedirectAs(endpoint *net.UDPAddr) {
+	p.pausedCond.L.Lock()
+	p.paused = false
+
+	p.wgCurrentUsed = addrToEndpoint(endpoint)
+
+	p.pausedCond.Signal()
+	p.pausedCond.L.Unlock()
+}
+
+func addrToEndpoint(addr *net.UDPAddr) *bind.Endpoint {
+	ip, _ := netip.AddrFromSlice(addr.IP.To4())
+	addrPort := netip.AddrPortFrom(ip, uint16(addr.Port))
+	return &bind.Endpoint{AddrPort: addrPort}
 }
 
 func (p *ProxyBind) CloseConn() error {
@@ -107,6 +136,10 @@ func (p *ProxyBind) CloseConn() error {
 }
 
 func (p *ProxyBind) close() error {
+	if p.remoteConn == nil {
+		return nil
+	}
+
 	p.closeMu.Lock()
 	defer p.closeMu.Unlock()
 
@@ -120,7 +153,12 @@ func (p *ProxyBind) close() error {
 
 	p.cancel()
 
-	p.Bind.RemoveEndpoint(p.fakeNetIP.Addr())
+	p.pausedCond.L.Lock()
+	p.paused = false
+	p.pausedCond.Signal()
+	p.pausedCond.L.Unlock()
+
+	p.bind.RemoveEndpoint(p.wgRelayedEndpoint.Addr())
 
 	if rErr := p.remoteConn.Close(); rErr != nil && !errors.Is(rErr, net.ErrClosed) {
 		return rErr
@@ -136,7 +174,7 @@ func (p *ProxyBind) proxyToLocal(ctx context.Context) {
 	}()
 
 	for {
-		buf := make([]byte, p.Bind.MTU()+bufsize.WGBufferOverhead)
+		buf := make([]byte, p.bind.MTU()+bufsize.WGBufferOverhead)
 		n, err := p.remoteConn.Read(buf)
 		if err != nil {
 			if ctx.Err() != nil {
@@ -147,18 +185,17 @@ func (p *ProxyBind) proxyToLocal(ctx context.Context) {
 			return
 		}
 
-		p.pausedMu.Lock()
-		if p.paused {
-			p.pausedMu.Unlock()
-			continue
+		p.pausedCond.L.Lock()
+		for p.paused {
+			p.pausedCond.Wait()
 		}
 
 		msg := bind.RecvMessage{
-			Endpoint: p.wgBindEndpoint,
+			Endpoint: p.wgCurrentUsed,
 			Buffer:   buf[:n],
 		}
-		p.Bind.RecvChan <- msg
-		p.pausedMu.Unlock()
+		p.bind.Recv(ctx, msg)
+		p.pausedCond.L.Unlock()
 	}
 }
 

client/iface/wgproxy/ebpf/proxy.go

@@ -6,9 +6,7 @@ import (
 	"context"
 	"fmt"
 	"net"
-	"os"
 	"sync"
-	"syscall"
 
 	"github.com/google/gopacket"
 	"github.com/google/gopacket/layers"
@@ -18,6 +16,7 @@ import (
 
 	nberrors "github.com/netbirdio/netbird/client/errors"
 	"github.com/netbirdio/netbird/client/iface/bufsize"
+	"github.com/netbirdio/netbird/client/iface/wgproxy/rawsocket"
 	"github.com/netbirdio/netbird/client/internal/ebpf"
 	ebpfMgr "github.com/netbirdio/netbird/client/internal/ebpf/manager"
 	nbnet "github.com/netbirdio/netbird/client/net"
@@ -27,6 +26,10 @@ const (
 	loopbackAddr = "127.0.0.1"
 )
 
+var (
+	localHostNetIP = net.ParseIP("127.0.0.1")
+)
+
 // WGEBPFProxy definition for proxy with EBPF support
 type WGEBPFProxy struct {
 	localWGListenPort int
@@ -64,7 +67,7 @@ func (p *WGEBPFProxy) Listen() error {
 		return err
 	}
 
-	p.rawConn, err = p.prepareSenderRawSocket()
+	p.rawConn, err = rawsocket.PrepareSenderRawSocket()
 	if err != nil {
 		return err
 	}
@@ -214,57 +217,17 @@ generatePort:
 	return p.lastUsedPort, nil
 }
 
-func (p *WGEBPFProxy) prepareSenderRawSocket() (net.PacketConn, error) {
-	// Create a raw socket.
-	fd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_RAW, syscall.IPPROTO_RAW)
-	if err != nil {
-		return nil, fmt.Errorf("creating raw socket failed: %w", err)
-	}
-
-	// Set the IP_HDRINCL option on the socket to tell the kernel that headers are included in the packet.
-	err = syscall.SetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_HDRINCL, 1)
-	if err != nil {
-		return nil, fmt.Errorf("setting IP_HDRINCL failed: %w", err)
-	}
-
-	// Bind the socket to the "lo" interface.
-	err = syscall.SetsockoptString(fd, syscall.SOL_SOCKET, syscall.SO_BINDTODEVICE, "lo")
-	if err != nil {
-		return nil, fmt.Errorf("binding to lo interface failed: %w", err)
-	}
-
-	// Set the fwmark on the socket.
-	err = nbnet.SetSocketOpt(fd)
-	if err != nil {
-		return nil, fmt.Errorf("setting fwmark failed: %w", err)
-	}
-
-	// Convert the file descriptor to a PacketConn.
-	file := os.NewFile(uintptr(fd), fmt.Sprintf("fd %d", fd))
-	if file == nil {
-		return nil, fmt.Errorf("converting fd to file failed")
-	}
-	packetConn, err := net.FilePacketConn(file)
-	if err != nil {
-		return nil, fmt.Errorf("converting file to packet conn failed: %w", err)
-	}
-
-	return packetConn, nil
-}
-
-func (p *WGEBPFProxy) sendPkg(data []byte, port int) error {
-	localhost := net.ParseIP("127.0.0.1")
-
+func (p *WGEBPFProxy) sendPkg(data []byte, endpointAddr *net.UDPAddr) error {
 	payload := gopacket.Payload(data)
 	ipH := &layers.IPv4{
-		DstIP:    localhost,
-		SrcIP:    localhost,
+		DstIP:    localHostNetIP,
+		SrcIP:    endpointAddr.IP,
 		Version:  4,
 		TTL:      64,
 		Protocol: layers.IPProtocolUDP,
 	}
 	udpH := &layers.UDP{
-		SrcPort: layers.UDPPort(port),
+		SrcPort: layers.UDPPort(endpointAddr.Port),
 		DstPort: layers.UDPPort(p.localWGListenPort),
 	}
 
@@ -279,7 +242,7 @@ func (p *WGEBPFProxy) sendPkg(data []byte, port int) error {
 	if err != nil {
 		return fmt.Errorf("serialize layers: %w", err)
 	}
-	if _, err = p.rawConn.WriteTo(layerBuffer.Bytes(), &net.IPAddr{IP: localhost}); err != nil {
+	if _, err = p.rawConn.WriteTo(layerBuffer.Bytes(), &net.IPAddr{IP: localHostNetIP}); err != nil {
 		return fmt.Errorf("write to raw conn: %w", err)
 	}
 	return nil

client/iface/wgproxy/ebpf/wrapper.go

@@ -18,41 +18,42 @@ import (
 
 // ProxyWrapper help to keep the remoteConn instance for net.Conn.Close function call
 type ProxyWrapper struct {
-	WgeBPFProxy *WGEBPFProxy
+	wgeBPFProxy *WGEBPFProxy
 
 	remoteConn net.Conn
 	ctx        context.Context
 	cancel     context.CancelFunc
 
-	wgEndpointAddr *net.UDPAddr
+	wgRelayedEndpointAddr     *net.UDPAddr
+	wgEndpointCurrentUsedAddr *net.UDPAddr
 
-	pausedMu  sync.Mutex
-	paused    bool
-	isStarted bool
+	paused     bool
+	pausedCond *sync.Cond
+	isStarted  bool
 
 	closeListener *listener.CloseListener
 }
 
-func NewProxyWrapper(WgeBPFProxy *WGEBPFProxy) *ProxyWrapper {
+func NewProxyWrapper(proxy *WGEBPFProxy) *ProxyWrapper {
 	return &ProxyWrapper{
-		WgeBPFProxy:   WgeBPFProxy,
+		wgeBPFProxy:   proxy,
+		pausedCond:    sync.NewCond(&sync.Mutex{}),
 		closeListener: listener.NewCloseListener(),
 	}
 }
-
 func (p *ProxyWrapper) AddTurnConn(ctx context.Context, endpoint *net.UDPAddr, remoteConn net.Conn) error {
-	addr, err := p.WgeBPFProxy.AddTurnConn(remoteConn)
+	addr, err := p.wgeBPFProxy.AddTurnConn(remoteConn)
 	if err != nil {
 		return fmt.Errorf("add turn conn: %w", err)
 	}
 	p.remoteConn = remoteConn
 	p.ctx, p.cancel = context.WithCancel(ctx)
-	p.wgEndpointAddr = addr
+	p.wgRelayedEndpointAddr = addr
 	return err
 }
 
 func (p *ProxyWrapper) EndpointAddr() *net.UDPAddr {
-	return p.wgEndpointAddr
+	return p.wgRelayedEndpointAddr
 }
 
 func (p *ProxyWrapper) SetDisconnectListener(disconnected func()) {
@@ -64,14 +65,18 @@ func (p *ProxyWrapper) Work() {
 		return
 	}
 
-	p.pausedMu.Lock()
+	p.pausedCond.L.Lock()
 	p.paused = false
-	p.pausedMu.Unlock()
+
+	p.wgEndpointCurrentUsedAddr = p.wgRelayedEndpointAddr
 
 	if !p.isStarted {
 		p.isStarted = true
 		go p.proxyToLocal(p.ctx)
 	}
+
+	p.pausedCond.Signal()
+	p.pausedCond.L.Unlock()
 }
 
 func (p *ProxyWrapper) Pause() {
@@ -80,45 +85,59 @@ func (p *ProxyWrapper) Pause() {
 	}
 
 	log.Tracef("pause proxy reading from: %s", p.remoteConn.RemoteAddr())
-	p.pausedMu.Lock()
+	p.pausedCond.L.Lock()
 	p.paused = true
-	p.pausedMu.Unlock()
+	p.pausedCond.L.Unlock()
+}
+
+func (p *ProxyWrapper) RedirectAs(endpoint *net.UDPAddr) {
+	p.pausedCond.L.Lock()
+	p.paused = false
+
+	p.wgEndpointCurrentUsedAddr = endpoint
+
+	p.pausedCond.Signal()
+	p.pausedCond.L.Unlock()
 }
 
 // CloseConn close the remoteConn and automatically remove the conn instance from the map
-func (e *ProxyWrapper) CloseConn() error {
-	if e.cancel == nil {
+func (p *ProxyWrapper) CloseConn() error {
+	if p.cancel == nil {
 		return fmt.Errorf("proxy not started")
 	}
 
-	e.cancel()
+	p.cancel()
 
-	e.closeListener.SetCloseListener(nil)
+	p.closeListener.SetCloseListener(nil)
 
-	if err := e.remoteConn.Close(); err != nil && !errors.Is(err, net.ErrClosed) {
-		return fmt.Errorf("close remote conn: %w", err)
+	p.pausedCond.L.Lock()
+	p.paused = false
+	p.pausedCond.Signal()
+	p.pausedCond.L.Unlock()
+
+	if err := p.remoteConn.Close(); err != nil && !errors.Is(err, net.ErrClosed) {
+		return fmt.Errorf("failed to close remote conn: %w", err)
 	}
 	return nil
 }
 
 func (p *ProxyWrapper) proxyToLocal(ctx context.Context) {
-	defer p.WgeBPFProxy.removeTurnConn(uint16(p.wgEndpointAddr.Port))
+	defer p.wgeBPFProxy.removeTurnConn(uint16(p.wgRelayedEndpointAddr.Port))
 
-	buf := make([]byte, p.WgeBPFProxy.mtu+bufsize.WGBufferOverhead)
+	buf := make([]byte, p.wgeBPFProxy.mtu+bufsize.WGBufferOverhead)
 	for {
 		n, err := p.readFromRemote(ctx, buf)
 		if err != nil {
 			return
 		}
 
-		p.pausedMu.Lock()
-		if p.paused {
-			p.pausedMu.Unlock()
-			continue
+		p.pausedCond.L.Lock()
+		for p.paused {
+			p.pausedCond.Wait()
 		}
 
-		err = p.WgeBPFProxy.sendPkg(buf[:n], p.wgEndpointAddr.Port)
-		p.pausedMu.Unlock()
+		err = p.wgeBPFProxy.sendPkg(buf[:n], p.wgEndpointCurrentUsedAddr)
+		p.pausedCond.L.Unlock()
 
 		if err != nil {
 			if ctx.Err() != nil {
@@ -137,7 +156,7 @@ func (p *ProxyWrapper) readFromRemote(ctx context.Context, buf []byte) (int, err
 		}
 		p.closeListener.Notify()
 		if !errors.Is(err, io.EOF) {
-			log.Errorf("failed to read from turn conn (endpoint: :%d): %s", p.wgEndpointAddr.Port, err)
+			log.Errorf("failed to read from turn conn (endpoint: :%d): %s", p.wgRelayedEndpointAddr.Port, err)
 		}
 		return 0, err
 	}

client/iface/wgproxy/factory_kernel.go

@@ -39,7 +39,6 @@ func (w *KernelFactory) GetProxy() Proxy {
 	}
 
 	return ebpf.NewProxyWrapper(w.ebpfProxy)
-
 }
 
 func (w *KernelFactory) Free() error {

client/iface/wgproxy/factory_kernel_freebsd.go

@@ -1,31 +0,0 @@
-package wgproxy
-
-import (
-	log "github.com/sirupsen/logrus"
-
-	udpProxy "github.com/netbirdio/netbird/client/iface/wgproxy/udp"
-)
-
-// KernelFactory todo: check eBPF support on FreeBSD
-type KernelFactory struct {
-	wgPort int
-	mtu    uint16
-}
-
-func NewKernelFactory(wgPort int, mtu uint16) *KernelFactory {
-	log.Infof("WireGuard Proxy Factory will produce UDP proxy")
-	f := &KernelFactory{
-		wgPort: wgPort,
-		mtu:    mtu,
-	}
-
-	return f
-}
-
-func (w *KernelFactory) GetProxy() Proxy {
-	return udpProxy.NewWGUDPProxy(w.wgPort, w.mtu)
-}
-
-func (w *KernelFactory) Free() error {
-	return nil
-}

client/iface/wgproxy/proxy.go

@@ -11,6 +11,11 @@ type Proxy interface {
 	EndpointAddr() *net.UDPAddr // EndpointAddr returns the address of the WireGuard peer endpoint
 	Work()                      // Work start or resume the proxy
 	Pause()                     // Pause to forward the packages from remote connection to WireGuard. The opposite way still works.
+
+	//RedirectAs resume the forwarding the packages from relayed connection to WireGuard interface if it was paused
+	//and rewrite the src address to the endpoint address.
+	//With this logic can avoid the package loss from relayed connections.
+	RedirectAs(endpoint *net.UDPAddr)
 	CloseConn() error
 	SetDisconnectListener(disconnected func())
 }

client/iface/wgproxy/proxy_linux_test.go

@@ -3,54 +3,82 @@
 package wgproxy
 
 import (
-	"context"
-	"os"
-	"testing"
+	"fmt"
+	"net"
 
+	"github.com/netbirdio/netbird/client/iface/bind"
+	"github.com/netbirdio/netbird/client/iface/wgaddr"
+	bindproxy "github.com/netbirdio/netbird/client/iface/wgproxy/bind"
 	"github.com/netbirdio/netbird/client/iface/wgproxy/ebpf"
+	"github.com/netbirdio/netbird/client/iface/wgproxy/udp"
 )
 
-func TestProxyCloseByRemoteConnEBPF(t *testing.T) {
-	if os.Getenv("GITHUB_ACTIONS") != "true" {
-		t.Skip("Skipping test as it requires root privileges")
-	}
-	ctx := context.Background()
+func seedProxies() ([]proxyInstance, error) {
+	pl := make([]proxyInstance, 0)
 
 	ebpfProxy := ebpf.NewWGEBPFProxy(51831, 1280)
 	if err := ebpfProxy.Listen(); err != nil {
-		t.Fatalf("failed to initialize ebpf proxy: %s", err)
+		return nil, fmt.Errorf("failed to initialize ebpf proxy: %s", err)
 	}
 
-	defer func() {
-		if err := ebpfProxy.Free(); err != nil {
-			t.Errorf("failed to free ebpf proxy: %s", err)
-		}
-	}()
-
-	tests := []struct {
-		name  string
-		proxy Proxy
-	}{
-		{
-			name: "ebpf proxy",
-			proxy: &ebpf.ProxyWrapper{
-				WgeBPFProxy: ebpfProxy,
-			},
-		},
+	pEbpf := proxyInstance{
+		name:    "ebpf kernel proxy",
+		proxy:   ebpf.NewProxyWrapper(ebpfProxy),
+		wgPort:  51831,
+		closeFn: ebpfProxy.Free,
 	}
+	pl = append(pl, pEbpf)
 
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			relayedConn := newMockConn()
-			err := tt.proxy.AddTurnConn(ctx, nil, relayedConn)
-			if err != nil {
-				t.Errorf("error: %v", err)
-			}
-
-			_ = relayedConn.Close()
-			if err := tt.proxy.CloseConn(); err != nil {
-				t.Errorf("error: %v", err)
-			}
-		})
+	pUDP := proxyInstance{
+		name:    "udp kernel proxy",
+		proxy:   udp.NewWGUDPProxy(51832, 1280),
+		wgPort:  51832,
+		closeFn: func() error { return nil },
 	}
+	pl = append(pl, pUDP)
+	return pl, nil
+}
+
+func seedProxyForProxyCloseByRemoteConn() ([]proxyInstance, error) {
+	pl := make([]proxyInstance, 0)
+
+	ebpfProxy := ebpf.NewWGEBPFProxy(51831, 1280)
+	if err := ebpfProxy.Listen(); err != nil {
+		return nil, fmt.Errorf("failed to initialize ebpf proxy: %s", err)
+	}
+
+	pEbpf := proxyInstance{
+		name:    "ebpf kernel proxy",
+		proxy:   ebpf.NewProxyWrapper(ebpfProxy),
+		wgPort:  51831,
+		closeFn: ebpfProxy.Free,
+	}
+	pl = append(pl, pEbpf)
+
+	pUDP := proxyInstance{
+		name:    "udp kernel proxy",
+		proxy:   udp.NewWGUDPProxy(51832, 1280),
+		wgPort:  51832,
+		closeFn: func() error { return nil },
+	}
+	pl = append(pl, pUDP)
+	wgAddress, err := wgaddr.ParseWGAddress("10.0.0.1/32")
+	if err != nil {
+		return nil, err
+	}
+	iceBind := bind.NewICEBind(nil, nil, wgAddress, 1280)
+	endpointAddress := &net.UDPAddr{
+		IP:   net.IPv4(10, 0, 0, 1),
+		Port: 1234,
+	}
+
+	pBind := proxyInstance{
+		name:         "bind proxy",
+		proxy:        bindproxy.NewProxyBind(iceBind),
+		endpointAddr: endpointAddress,
+		closeFn:      func() error { return nil },
+	}
+	pl = append(pl, pBind)
+
+	return pl, nil
 }

client/iface/wgproxy/proxy_seed_test.go

@@ -0,0 +1,39 @@
+//go:build !linux
+
+package wgproxy
+
+import (
+	"net"
+
+	"github.com/netbirdio/netbird/client/iface/bind"
+	"github.com/netbirdio/netbird/client/iface/wgaddr"
+	bindproxy "github.com/netbirdio/netbird/client/iface/wgproxy/bind"
+)
+
+func seedProxies() ([]proxyInstance, error) {
+	// todo extend with Bind proxy
+	pl := make([]proxyInstance, 0)
+	return pl, nil
+}
+
+func seedProxyForProxyCloseByRemoteConn() ([]proxyInstance, error) {
+	pl := make([]proxyInstance, 0)
+	wgAddress, err := wgaddr.ParseWGAddress("10.0.0.1/32")
+	if err != nil {
+		return nil, err
+	}
+	iceBind := bind.NewICEBind(nil, nil, wgAddress, 1280)
+	endpointAddress := &net.UDPAddr{
+		IP:   net.IPv4(10, 0, 0, 1),
+		Port: 1234,
+	}
+
+	pBind := proxyInstance{
+		name:         "bind proxy",
+		proxy:        bindproxy.NewProxyBind(iceBind),
+		endpointAddr: endpointAddress,
+		closeFn:      func() error { return nil },
+	}
+	pl = append(pl, pBind)
+	return pl, nil
+}

client/iface/wgproxy/proxy_test.go

@@ -1,5 +1,3 @@
-//go:build linux
-
 package wgproxy
 
 import (
@@ -7,12 +5,9 @@ import (
 	"io"
 	"net"
 	"os"
-	"runtime"
 	"testing"
 	"time"
 
-	"github.com/netbirdio/netbird/client/iface/wgproxy/ebpf"
-	udpProxy "github.com/netbirdio/netbird/client/iface/wgproxy/udp"
 	"github.com/netbirdio/netbird/util"
 )
 
@@ -22,6 +17,14 @@ func TestMain(m *testing.M) {
 	os.Exit(code)
 }
 
+type proxyInstance struct {
+	name         string
+	proxy        Proxy
+	wgPort       int
+	endpointAddr *net.UDPAddr
+	closeFn      func() error
+}
+
 type mocConn struct {
 	closeChan chan struct{}
 	closed    bool
@@ -78,41 +81,21 @@ func (m *mocConn) SetWriteDeadline(t time.Time) error {
 func TestProxyCloseByRemoteConn(t *testing.T) {
 	ctx := context.Background()
 
-	tests := []struct {
-		name  string
-		proxy Proxy
-	}{
-		{
-			name:  "userspace proxy",
-			proxy: udpProxy.NewWGUDPProxy(51830, 1280),
-		},
+	tests, err := seedProxyForProxyCloseByRemoteConn()
+	if err != nil {
+		t.Fatalf("error: %v", err)
 	}
 
-	if runtime.GOOS == "linux" && os.Getenv("GITHUB_ACTIONS") != "true" {
-		ebpfProxy := ebpf.NewWGEBPFProxy(51831, 1280)
-		if err := ebpfProxy.Listen(); err != nil {
-			t.Fatalf("failed to initialize ebpf proxy: %s", err)
-		}
-		defer func() {
-			if err := ebpfProxy.Free(); err != nil {
-				t.Errorf("failed to free ebpf proxy: %s", err)
-			}
-		}()
-		proxyWrapper := ebpf.NewProxyWrapper(ebpfProxy)
-
-		tests = append(tests, struct {
-			name  string
-			proxy Proxy
-		}{
-			name:  "ebpf proxy",
-			proxy: proxyWrapper,
-		})
-	}
+	relayedConn, _ := net.Dial("udp", "127.0.0.1:1234")
+	defer func() {
+		_ = relayedConn.Close()
+	}()
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			addr, _ := net.ResolveUDPAddr("udp", "100.108.135.221:51892")
 			relayedConn := newMockConn()
-			err := tt.proxy.AddTurnConn(ctx, nil, relayedConn)
+			err := tt.proxy.AddTurnConn(ctx, addr, relayedConn)
 			if err != nil {
 				t.Errorf("error: %v", err)
 			}
@@ -124,3 +107,104 @@ func TestProxyCloseByRemoteConn(t *testing.T) {
 		})
 	}
 }
+
+// TestProxyRedirect todo extend the proxies with Bind proxy
+func TestProxyRedirect(t *testing.T) {
+	tests, err := seedProxies()
+	if err != nil {
+		t.Fatalf("error: %v", err)
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			redirectTraffic(t, tt.proxy, tt.wgPort, tt.endpointAddr)
+			if err := tt.closeFn(); err != nil {
+				t.Errorf("error: %v", err)
+			}
+		})
+	}
+}
+
+func redirectTraffic(t *testing.T, proxy Proxy, wgPort int, endPointAddr *net.UDPAddr) {
+	t.Helper()
+
+	msgHelloFromRelay := []byte("hello from relay")
+	msgRedirected := [][]byte{
+		[]byte("hello 1. to p2p"),
+		[]byte("hello 2. to p2p"),
+		[]byte("hello 3. to p2p"),
+	}
+
+	dummyWgListener, err := net.ListenUDP("udp", &net.UDPAddr{
+		IP:   net.IPv4(127, 0, 0, 1),
+		Port: wgPort})
+	if err != nil {
+		t.Fatalf("failed to listen on udp port: %s", err)
+	}
+
+	relayedServer, _ := net.ListenUDP("udp",
+		&net.UDPAddr{
+			IP:   net.IPv4(127, 0, 0, 1),
+			Port: 1234,
+		},
+	)
+
+	relayedConn, _ := net.Dial("udp", "127.0.0.1:1234")
+
+	defer func() {
+		_ = dummyWgListener.Close()
+		_ = relayedConn.Close()
+		_ = relayedServer.Close()
+	}()
+
+	if err := proxy.AddTurnConn(context.Background(), endPointAddr, relayedConn); err != nil {
+		t.Errorf("error: %v", err)
+	}
+	defer func() {
+		if err := proxy.CloseConn(); err != nil {
+			t.Errorf("error: %v", err)
+		}
+	}()
+
+	proxy.Work()
+
+	if _, err := relayedServer.WriteTo(msgHelloFromRelay, relayedConn.LocalAddr()); err != nil {
+		t.Errorf("error relayedServer.Write(msgHelloFromRelay): %v", err)
+	}
+
+	n, err := dummyWgListener.Read(make([]byte, 1024))
+	if err != nil {
+		t.Errorf("error: %v", err)
+	}
+
+	if n != len(msgHelloFromRelay) {
+		t.Errorf("expected %d bytes, got %d", len(msgHelloFromRelay), n)
+	}
+
+	p2pEndpointAddr := &net.UDPAddr{
+		IP:   net.IPv4(192, 168, 0, 56),
+		Port: 1234,
+	}
+	proxy.RedirectAs(p2pEndpointAddr)
+
+	for _, msg := range msgRedirected {
+		if _, err := relayedServer.WriteTo(msg, relayedConn.LocalAddr()); err != nil {
+			t.Errorf("error: %v", err)
+		}
+	}
+
+	for i := 0; i < len(msgRedirected); i++ {
+		buf := make([]byte, 1024)
+		n, rAddr, err := dummyWgListener.ReadFrom(buf)
+		if err != nil {
+			t.Errorf("error: %v", err)
+		}
+
+		if rAddr.String() != p2pEndpointAddr.String() {
+			t.Errorf("expected %s, got %s", p2pEndpointAddr.String(), rAddr.String())
+		}
+		if string(buf[:n]) != string(msgRedirected[i]) {
+			t.Errorf("expected %s, got %s", string(msgRedirected[i]), string(buf[:n]))
+		}
+	}
+}

client/iface/wgproxy/rawsocket/rawsocket.go

@@ -0,0 +1,50 @@
+//go:build linux && !android
+
+package rawsocket
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"syscall"
+
+	nbnet "github.com/netbirdio/netbird/client/net"
+)
+
+func PrepareSenderRawSocket() (net.PacketConn, error) {
+	// Create a raw socket.
+	fd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_RAW, syscall.IPPROTO_RAW)
+	if err != nil {
+		return nil, fmt.Errorf("creating raw socket failed: %w", err)
+	}
+
+	// Set the IP_HDRINCL option on the socket to tell the kernel that headers are included in the packet.
+	err = syscall.SetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_HDRINCL, 1)
+	if err != nil {
+		return nil, fmt.Errorf("setting IP_HDRINCL failed: %w", err)
+	}
+
+	// Bind the socket to the "lo" interface.
+	err = syscall.SetsockoptString(fd, syscall.SOL_SOCKET, syscall.SO_BINDTODEVICE, "lo")
+	if err != nil {
+		return nil, fmt.Errorf("binding to lo interface failed: %w", err)
+	}
+
+	// Set the fwmark on the socket.
+	err = nbnet.SetSocketOpt(fd)
+	if err != nil {
+		return nil, fmt.Errorf("setting fwmark failed: %w", err)
+	}
+
+	// Convert the file descriptor to a PacketConn.
+	file := os.NewFile(uintptr(fd), fmt.Sprintf("fd %d", fd))
+	if file == nil {
+		return nil, fmt.Errorf("converting fd to file failed")
+	}
+	packetConn, err := net.FilePacketConn(file)
+	if err != nil {
+		return nil, fmt.Errorf("converting file to packet conn failed: %w", err)
+	}
+
+	return packetConn, nil
+}

client/iface/wgproxy/udp/proxy.go

@@ -1,3 +1,5 @@
+//go:build linux && !android
+
 package udp
 
 import (
@@ -21,16 +23,18 @@ type WGUDPProxy struct {
 	localWGListenPort int
 	mtu               uint16
 
-	remoteConn net.Conn
-	localConn  net.Conn
-	ctx        context.Context
-	cancel     context.CancelFunc
-	closeMu    sync.Mutex
-	closed     bool
+	remoteConn   net.Conn
+	localConn    net.Conn
+	srcFakerConn *SrcFaker
+	sendPkg      func(data []byte) (int, error)
+	ctx          context.Context
+	cancel       context.CancelFunc
+	closeMu      sync.Mutex
+	closed       bool
 
-	pausedMu  sync.Mutex
-	paused    bool
-	isStarted bool
+	paused     bool
+	pausedCond *sync.Cond
+	isStarted  bool
 
 	closeListener *listener.CloseListener
 }
@@ -41,6 +45,7 @@ func NewWGUDPProxy(wgPort int, mtu uint16) *WGUDPProxy {
 	p := &WGUDPProxy{
 		localWGListenPort: wgPort,
 		mtu:               mtu,
+		pausedCond:        sync.NewCond(&sync.Mutex{}),
 		closeListener:     listener.NewCloseListener(),
 	}
 	return p
@@ -61,6 +66,7 @@ func (p *WGUDPProxy) AddTurnConn(ctx context.Context, endpoint *net.UDPAddr, rem
 
 	p.ctx, p.cancel = context.WithCancel(ctx)
 	p.localConn = localConn
+	p.sendPkg = p.localConn.Write
 	p.remoteConn = remoteConn
 
 	return err
@@ -84,15 +90,24 @@ func (p *WGUDPProxy) Work() {
 		return
 	}
 
-	p.pausedMu.Lock()
+	p.pausedCond.L.Lock()
 	p.paused = false
-	p.pausedMu.Unlock()
+	p.sendPkg = p.localConn.Write
+
+	if p.srcFakerConn != nil {
+		if err := p.srcFakerConn.Close(); err != nil {
+			log.Errorf("failed to close src faker conn: %s", err)
+		}
+		p.srcFakerConn = nil
+	}
 
 	if !p.isStarted {
 		p.isStarted = true
 		go p.proxyToRemote(p.ctx)
 		go p.proxyToLocal(p.ctx)
 	}
+	p.pausedCond.Signal()
+	p.pausedCond.L.Unlock()
 }
 
 // Pause pauses the proxy from receiving data from the remote peer
@@ -101,9 +116,35 @@ func (p *WGUDPProxy) Pause() {
 		return
 	}
 
-	p.pausedMu.Lock()
+	p.pausedCond.L.Lock()
 	p.paused = true
-	p.pausedMu.Unlock()
+	p.pausedCond.L.Unlock()
+}
+
+// RedirectAs start to use the fake sourced raw socket as package sender
+func (p *WGUDPProxy) RedirectAs(endpoint *net.UDPAddr) {
+	p.pausedCond.L.Lock()
+	defer func() {
+		p.pausedCond.Signal()
+		p.pausedCond.L.Unlock()
+	}()
+
+	p.paused = false
+	if p.srcFakerConn != nil {
+		if err := p.srcFakerConn.Close(); err != nil {
+			log.Errorf("failed to close src faker conn: %s", err)
+		}
+		p.srcFakerConn = nil
+	}
+	srcFakerConn, err := NewSrcFaker(p.localWGListenPort, endpoint)
+	if err != nil {
+		log.Errorf("failed to create src faker conn: %s", err)
+		// fallback to continue without redirecting
+		p.paused = true
+		return
+	}
+	p.srcFakerConn = srcFakerConn
+	p.sendPkg = p.srcFakerConn.SendPkg
 }
 
 // CloseConn close the localConn
@@ -115,6 +156,8 @@ func (p *WGUDPProxy) CloseConn() error {
 }
 
 func (p *WGUDPProxy) close() error {
+	var result *multierror.Error
+
 	p.closeMu.Lock()
 	defer p.closeMu.Unlock()
 
@@ -128,7 +171,11 @@ func (p *WGUDPProxy) close() error {
 
 	p.cancel()
 
-	var result *multierror.Error
+	p.pausedCond.L.Lock()
+	p.paused = false
+	p.pausedCond.Signal()
+	p.pausedCond.L.Unlock()
+
 	if err := p.remoteConn.Close(); err != nil && !errors.Is(err, net.ErrClosed) {
 		result = multierror.Append(result, fmt.Errorf("remote conn: %s", err))
 	}
@@ -136,6 +183,13 @@ func (p *WGUDPProxy) close() error {
 	if err := p.localConn.Close(); err != nil {
 		result = multierror.Append(result, fmt.Errorf("local conn: %s", err))
 	}
+
+	if p.srcFakerConn != nil {
+		if err := p.srcFakerConn.Close(); err != nil {
+			result = multierror.Append(result, fmt.Errorf("src faker raw conn: %s", err))
+		}
+	}
+
 	return cerrors.FormatErrorOrNil(result)
 }
 
@@ -194,14 +248,12 @@ func (p *WGUDPProxy) proxyToLocal(ctx context.Context) {
 			return
 		}
 
-		p.pausedMu.Lock()
-		if p.paused {
-			p.pausedMu.Unlock()
-			continue
+		p.pausedCond.L.Lock()
+		for p.paused {
+			p.pausedCond.Wait()
 		}
-
-		_, err = p.localConn.Write(buf[:n])
-		p.pausedMu.Unlock()
+		_, err = p.sendPkg(buf[:n])
+		p.pausedCond.L.Unlock()
 
 		if err != nil {
 			if ctx.Err() != nil {

client/iface/wgproxy/udp/rawsocket.go

@@ -0,0 +1,101 @@
+//go:build linux && !android
+
+package udp
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/google/gopacket"
+	"github.com/google/gopacket/layers"
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/client/iface/wgproxy/rawsocket"
+)
+
+var (
+	serializeOpts = gopacket.SerializeOptions{
+		ComputeChecksums: true,
+		FixLengths:       true,
+	}
+
+	localHostNetIPAddr = &net.IPAddr{
+		IP: net.ParseIP("127.0.0.1"),
+	}
+)
+
+type SrcFaker struct {
+	srcAddr *net.UDPAddr
+
+	rawSocket   net.PacketConn
+	ipH         gopacket.SerializableLayer
+	udpH        gopacket.SerializableLayer
+	layerBuffer gopacket.SerializeBuffer
+}
+
+func NewSrcFaker(dstPort int, srcAddr *net.UDPAddr) (*SrcFaker, error) {
+	rawSocket, err := rawsocket.PrepareSenderRawSocket()
+	if err != nil {
+		return nil, err
+	}
+
+	ipH, udpH, err := prepareHeaders(dstPort, srcAddr)
+	if err != nil {
+		return nil, err
+	}
+
+	f := &SrcFaker{
+		srcAddr:     srcAddr,
+		rawSocket:   rawSocket,
+		ipH:         ipH,
+		udpH:        udpH,
+		layerBuffer: gopacket.NewSerializeBuffer(),
+	}
+
+	return f, nil
+}
+
+func (f *SrcFaker) Close() error {
+	return f.rawSocket.Close()
+}
+
+func (f *SrcFaker) SendPkg(data []byte) (int, error) {
+	defer func() {
+		if err := f.layerBuffer.Clear(); err != nil {
+			log.Errorf("failed to clear layer buffer: %s", err)
+		}
+	}()
+
+	payload := gopacket.Payload(data)
+
+	err := gopacket.SerializeLayers(f.layerBuffer, serializeOpts, f.ipH, f.udpH, payload)
+	if err != nil {
+		return 0, fmt.Errorf("serialize layers: %w", err)
+	}
+	n, err := f.rawSocket.WriteTo(f.layerBuffer.Bytes(), localHostNetIPAddr)
+	if err != nil {
+		return 0, fmt.Errorf("write to raw conn: %w", err)
+	}
+	return n, nil
+}
+
+func prepareHeaders(dstPort int, srcAddr *net.UDPAddr) (gopacket.SerializableLayer, gopacket.SerializableLayer, error) {
+	ipH := &layers.IPv4{
+		DstIP:    net.ParseIP("127.0.0.1"),
+		SrcIP:    srcAddr.IP,
+		Version:  4,
+		TTL:      64,
+		Protocol: layers.IPProtocolUDP,
+	}
+	udpH := &layers.UDP{
+		SrcPort: layers.UDPPort(srcAddr.Port),
+		DstPort: layers.UDPPort(dstPort), // dst is the localhost WireGuard port
+	}
+
+	err := udpH.SetNetworkLayerForChecksum(ipH)
+	if err != nil {
+		return nil, nil, fmt.Errorf("set network layer for checksum: %w", err)
+	}
+
+	return ipH, udpH, nil
+}

client/internal/peer/conn.go

@@ -28,10 +28,6 @@ import (
 	semaphoregroup "github.com/netbirdio/netbird/util/semaphore-group"
 )
 
-const (
-	defaultWgKeepAlive = 25 * time.Second
-)
-
 type ServiceDependencies struct {
 	StatusRecorder     *Status
 	Signaler           *Signaler
@@ -117,6 +113,8 @@ type Conn struct {
 
 	// debug purpose
 	dumpState *stateDump
+
+	endpointUpdater *EndpointUpdater
 }
 
 // NewConn creates a new not opened Conn to the remote peer.
@@ -129,17 +127,18 @@ func NewConn(config ConnConfig, services ServiceDependencies) (*Conn, error) {
 	connLog := log.WithField("peer", config.Key)
 
 	var conn = &Conn{
-		Log:            connLog,
-		config:         config,
-		statusRecorder: services.StatusRecorder,
-		signaler:       services.Signaler,
-		iFaceDiscover:  services.IFaceDiscover,
-		relayManager:   services.RelayManager,
-		srWatcher:      services.SrWatcher,
-		semaphore:      services.Semaphore,
-		statusRelay:    worker.NewAtomicStatus(),
-		statusICE:      worker.NewAtomicStatus(),
-		dumpState:      newStateDump(config.Key, connLog, services.StatusRecorder),
+		Log:             connLog,
+		config:          config,
+		statusRecorder:  services.StatusRecorder,
+		signaler:        services.Signaler,
+		iFaceDiscover:   services.IFaceDiscover,
+		relayManager:    services.RelayManager,
+		srWatcher:       services.SrWatcher,
+		semaphore:       services.Semaphore,
+		statusRelay:     worker.NewAtomicStatus(),
+		statusICE:       worker.NewAtomicStatus(),
+		dumpState:       newStateDump(config.Key, connLog, services.StatusRecorder),
+		endpointUpdater: NewEndpointUpdater(connLog, config.WgConfig, isController(config)),
 	}
 
 	return conn, nil
@@ -249,7 +248,7 @@ func (conn *Conn) Close(signalToRemote bool) {
 		conn.wgProxyICE = nil
 	}
 
-	if err := conn.removeWgPeer(); err != nil {
+	if err := conn.endpointUpdater.RemoveWgPeer(); err != nil {
 		conn.Log.Errorf("failed to remove wg endpoint: %v", err)
 	}
 
@@ -375,12 +374,19 @@ func (conn *Conn) onICEConnectionIsReady(priority conntype.ConnPriority, iceConn
 		wgProxy.Work()
 	}
 
-	if err = conn.configureWGEndpoint(ep, iceConnInfo.RosenpassPubKey); err != nil {
+	conn.Log.Infof("configure WireGuard endpoint to: %s", ep.String())
+	presharedKey := conn.presharedKey(iceConnInfo.RosenpassPubKey)
+	if err = conn.endpointUpdater.ConfigureWGEndpoint(ep, presharedKey); err != nil {
 		conn.handleConfigurationFailure(err, wgProxy)
 		return
 	}
 	wgConfigWorkaround()
 
+	if conn.wgProxyRelay != nil {
+		conn.Log.Debugf("redirect packets from relayed conn to WireGuard")
+		conn.wgProxyRelay.RedirectAs(ep)
+	}
+
 	conn.currentConnPriority = priority
 	conn.statusICE.SetConnected()
 	conn.updateIceState(iceConnInfo)
@@ -409,7 +415,8 @@ func (conn *Conn) onICEStateDisconnected() {
 		conn.dumpState.SwitchToRelay()
 		conn.wgProxyRelay.Work()
 
-		if err := conn.configureWGEndpoint(conn.wgProxyRelay.EndpointAddr(), conn.rosenpassRemoteKey); err != nil {
+		presharedKey := conn.presharedKey(conn.rosenpassRemoteKey)
+		if err := conn.endpointUpdater.ConfigureWGEndpoint(conn.wgProxyRelay.EndpointAddr(), presharedKey); err != nil {
 			conn.Log.Errorf("failed to switch to relay conn: %v", err)
 		}
 
@@ -418,6 +425,7 @@ func (conn *Conn) onICEStateDisconnected() {
 			defer conn.wgWatcherWg.Done()
 			conn.workerRelay.EnableWgWatcher(conn.ctx)
 		}()
+		conn.wgProxyRelay.Work()
 		conn.currentConnPriority = conntype.Relay
 	} else {
 		conn.Log.Infof("ICE disconnected, do not switch to Relay. Reset priority to: %s", conntype.None.String())
@@ -477,7 +485,8 @@ func (conn *Conn) onRelayConnectionIsReady(rci RelayConnInfo) {
 	}
 
 	wgProxy.Work()
-	if err := conn.configureWGEndpoint(wgProxy.EndpointAddr(), rci.rosenpassPubKey); err != nil {
+	presharedKey := conn.presharedKey(rci.rosenpassPubKey)
+	if err := conn.endpointUpdater.ConfigureWGEndpoint(wgProxy.EndpointAddr(), presharedKey); err != nil {
 		if err := wgProxy.CloseConn(); err != nil {
 			conn.Log.Warnf("Failed to close relay connection: %v", err)
 		}
@@ -545,17 +554,6 @@ func (conn *Conn) onGuardEvent() {
 	}
 }
 
-func (conn *Conn) configureWGEndpoint(addr *net.UDPAddr, remoteRPKey []byte) error {
-	presharedKey := conn.presharedKey(remoteRPKey)
-	return conn.config.WgConfig.WgInterface.UpdatePeer(
-		conn.config.WgConfig.RemoteKey,
-		conn.config.WgConfig.AllowedIps,
-		defaultWgKeepAlive,
-		addr,
-		presharedKey,
-	)
-}
-
 func (conn *Conn) updateRelayStatus(relayServerAddr string, rosenpassPubKey []byte) {
 	peerState := State{
 		PubKey:             conn.config.Key,
@@ -698,10 +696,6 @@ func (conn *Conn) isICEActive() bool {
 	return (conn.currentConnPriority == conntype.ICEP2P || conn.currentConnPriority == conntype.ICETurn) && conn.statusICE.Get() == worker.StatusConnected
 }
 
-func (conn *Conn) removeWgPeer() error {
-	return conn.config.WgConfig.WgInterface.RemovePeer(conn.config.WgConfig.RemoteKey)
-}
-
 func (conn *Conn) handleConfigurationFailure(err error, wgProxy wgproxy.Proxy) {
 	conn.Log.Warnf("Failed to update wg peer configuration: %v", err)
 	if wgProxy != nil {

client/internal/peer/endpoint.go

@@ -0,0 +1,105 @@
+package peer
+
+import (
+	"context"
+	"net"
+	"sync"
+	"time"
+
+	"github.com/sirupsen/logrus"
+	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
+)
+
+const (
+	defaultWgKeepAlive = 25 * time.Second
+	fallbackDelay      = 5 * time.Second
+)
+
+type EndpointUpdater struct {
+	log       *logrus.Entry
+	wgConfig  WgConfig
+	initiator bool
+
+	// mu protects updateWireGuardPeer and cancelFunc
+	mu         sync.Mutex
+	cancelFunc func()
+	updateWg   sync.WaitGroup
+}
+
+func NewEndpointUpdater(log *logrus.Entry, wgConfig WgConfig, initiator bool) *EndpointUpdater {
+	return &EndpointUpdater{
+		log:       log,
+		wgConfig:  wgConfig,
+		initiator: initiator,
+	}
+}
+
+// ConfigureWGEndpoint sets up the WireGuard endpoint configuration.
+// The initiator immediately configures the endpoint, while the non-initiator
+// waits for a fallback period before configuring to avoid handshake congestion.
+func (e *EndpointUpdater) ConfigureWGEndpoint(addr *net.UDPAddr, presharedKey *wgtypes.Key) error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	if e.initiator {
+		e.log.Debugf("configure up WireGuard as initiatr")
+		return e.updateWireGuardPeer(addr, presharedKey)
+	}
+
+	// prevent to run new update while cancel the previous update
+	e.waitForCloseTheDelayedUpdate()
+
+	var ctx context.Context
+	ctx, e.cancelFunc = context.WithCancel(context.Background())
+	e.updateWg.Add(1)
+	go e.scheduleDelayedUpdate(ctx, addr, presharedKey)
+
+	e.log.Debugf("configure up WireGuard and wait for handshake")
+	return e.updateWireGuardPeer(nil, presharedKey)
+}
+
+func (e *EndpointUpdater) RemoveWgPeer() error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	e.waitForCloseTheDelayedUpdate()
+	return e.wgConfig.WgInterface.RemovePeer(e.wgConfig.RemoteKey)
+}
+
+func (e *EndpointUpdater) waitForCloseTheDelayedUpdate() {
+	if e.cancelFunc == nil {
+		return
+	}
+
+	e.cancelFunc()
+	e.cancelFunc = nil
+	e.updateWg.Wait()
+}
+
+// scheduleDelayedUpdate waits for the fallback period before updating the endpoint
+func (e *EndpointUpdater) scheduleDelayedUpdate(ctx context.Context, addr *net.UDPAddr, presharedKey *wgtypes.Key) {
+	defer e.updateWg.Done()
+	t := time.NewTimer(fallbackDelay)
+	defer t.Stop()
+
+	select {
+	case <-ctx.Done():
+		return
+	case <-t.C:
+		e.mu.Lock()
+		if err := e.updateWireGuardPeer(addr, presharedKey); err != nil {
+			e.log.Errorf("failed to update WireGuard peer, address: %s, error: %v", addr, err)
+		}
+		e.mu.Unlock()
+	}
+}
+
+func (e *EndpointUpdater) updateWireGuardPeer(endpoint *net.UDPAddr, presharedKey *wgtypes.Key) error {
+	return e.wgConfig.WgInterface.UpdatePeer(
+		e.wgConfig.RemoteKey,
+		e.wgConfig.AllowedIps,
+		defaultWgKeepAlive,
+		endpoint,
+		presharedKey,
+	)
+}