[cllient] Don't track ebpf traffic in conntrack (#5166)

client/firewall/iptables/manager_linux.go

@@ -83,6 +83,10 @@ func (m *Manager) Init(stateManager *statemanager.Manager) error {
 		return fmt.Errorf("acl manager init: %w", err)
 	}
 
+	if err := m.initNoTrackChain(); err != nil {
+		return fmt.Errorf("init notrack chain: %w", err)
+	}
+
 	// persist early to ensure cleanup of chains
 	go func() {
 		if err := stateManager.PersistState(context.Background()); err != nil {
@@ -177,6 +181,10 @@ func (m *Manager) Close(stateManager *statemanager.Manager) error {
 
 	var merr *multierror.Error
 
+	if err := m.cleanupNoTrackChain(); err != nil {
+		merr = multierror.Append(merr, fmt.Errorf("cleanup notrack chain: %w", err))
+	}
+
 	if err := m.aclMgr.Reset(); err != nil {
 		merr = multierror.Append(merr, fmt.Errorf("reset acl manager: %w", err))
 	}
@@ -277,6 +285,125 @@ func (m *Manager) RemoveInboundDNAT(localAddr netip.Addr, protocol firewall.Prot
 	return m.router.RemoveInboundDNAT(localAddr, protocol, sourcePort, targetPort)
 }
 
+const (
+	chainNameRaw = "NETBIRD-RAW"
+	chainOUTPUT  = "OUTPUT"
+	tableRaw     = "raw"
+)
+
+// SetupEBPFProxyNoTrack creates notrack rules for eBPF proxy loopback traffic.
+// This prevents conntrack from tracking WireGuard proxy traffic on loopback, which
+// can interfere with MASQUERADE rules (e.g., from container runtimes like Podman/netavark).
+//
+// Traffic flows that need NOTRACK:
+//
+//  1. Egress: WireGuard -> fake endpoint (before eBPF rewrite)
+//     src=127.0.0.1:wgPort -> dst=127.0.0.1:fakePort
+//     Matched by: sport=wgPort
+//
+//  2. Egress: Proxy -> WireGuard (via raw socket)
+//     src=127.0.0.1:fakePort -> dst=127.0.0.1:wgPort
+//     Matched by: dport=wgPort
+//
+//  3. Ingress: Packets to WireGuard
+//     dst=127.0.0.1:wgPort
+//     Matched by: dport=wgPort
+//
+//  4. Ingress: Packets to proxy (after eBPF rewrite)
+//     dst=127.0.0.1:proxyPort
+//     Matched by: dport=proxyPort
+//
+// Rules are cleaned up when the firewall manager is closed.
+func (m *Manager) SetupEBPFProxyNoTrack(proxyPort, wgPort uint16) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	wgPortStr := fmt.Sprintf("%d", wgPort)
+	proxyPortStr := fmt.Sprintf("%d", proxyPort)
+
+	// Egress rules: match outgoing loopback UDP packets
+	outputRuleSport := []string{"-o", "lo", "-s", "127.0.0.1", "-d", "127.0.0.1", "-p", "udp", "--sport", wgPortStr, "-j", "NOTRACK"}
+	if err := m.ipv4Client.AppendUnique(tableRaw, chainNameRaw, outputRuleSport...); err != nil {
+		return fmt.Errorf("add output sport notrack rule: %w", err)
+	}
+
+	outputRuleDport := []string{"-o", "lo", "-s", "127.0.0.1", "-d", "127.0.0.1", "-p", "udp", "--dport", wgPortStr, "-j", "NOTRACK"}
+	if err := m.ipv4Client.AppendUnique(tableRaw, chainNameRaw, outputRuleDport...); err != nil {
+		return fmt.Errorf("add output dport notrack rule: %w", err)
+	}
+
+	// Ingress rules: match incoming loopback UDP packets
+	preroutingRuleWg := []string{"-i", "lo", "-s", "127.0.0.1", "-d", "127.0.0.1", "-p", "udp", "--dport", wgPortStr, "-j", "NOTRACK"}
+	if err := m.ipv4Client.AppendUnique(tableRaw, chainNameRaw, preroutingRuleWg...); err != nil {
+		return fmt.Errorf("add prerouting wg notrack rule: %w", err)
+	}
+
+	preroutingRuleProxy := []string{"-i", "lo", "-s", "127.0.0.1", "-d", "127.0.0.1", "-p", "udp", "--dport", proxyPortStr, "-j", "NOTRACK"}
+	if err := m.ipv4Client.AppendUnique(tableRaw, chainNameRaw, preroutingRuleProxy...); err != nil {
+		return fmt.Errorf("add prerouting proxy notrack rule: %w", err)
+	}
+
+	log.Debugf("set up ebpf proxy notrack rules for ports %d,%d", proxyPort, wgPort)
+	return nil
+}
+
+func (m *Manager) initNoTrackChain() error {
+	if err := m.cleanupNoTrackChain(); err != nil {
+		log.Debugf("cleanup notrack chain: %v", err)
+	}
+
+	if err := m.ipv4Client.NewChain(tableRaw, chainNameRaw); err != nil {
+		return fmt.Errorf("create chain: %w", err)
+	}
+
+	jumpRule := []string{"-j", chainNameRaw}
+
+	if err := m.ipv4Client.InsertUnique(tableRaw, chainOUTPUT, 1, jumpRule...); err != nil {
+		if delErr := m.ipv4Client.DeleteChain(tableRaw, chainNameRaw); delErr != nil {
+			log.Debugf("delete orphan chain: %v", delErr)
+		}
+		return fmt.Errorf("add output jump rule: %w", err)
+	}
+
+	if err := m.ipv4Client.InsertUnique(tableRaw, chainPREROUTING, 1, jumpRule...); err != nil {
+		if delErr := m.ipv4Client.DeleteIfExists(tableRaw, chainOUTPUT, jumpRule...); delErr != nil {
+			log.Debugf("delete output jump rule: %v", delErr)
+		}
+		if delErr := m.ipv4Client.DeleteChain(tableRaw, chainNameRaw); delErr != nil {
+			log.Debugf("delete orphan chain: %v", delErr)
+		}
+		return fmt.Errorf("add prerouting jump rule: %w", err)
+	}
+
+	return nil
+}
+
+func (m *Manager) cleanupNoTrackChain() error {
+	exists, err := m.ipv4Client.ChainExists(tableRaw, chainNameRaw)
+	if err != nil {
+		return fmt.Errorf("check chain exists: %w", err)
+	}
+	if !exists {
+		return nil
+	}
+
+	jumpRule := []string{"-j", chainNameRaw}
+
+	if err := m.ipv4Client.DeleteIfExists(tableRaw, chainOUTPUT, jumpRule...); err != nil {
+		return fmt.Errorf("remove output jump rule: %w", err)
+	}
+
+	if err := m.ipv4Client.DeleteIfExists(tableRaw, chainPREROUTING, jumpRule...); err != nil {
+		return fmt.Errorf("remove prerouting jump rule: %w", err)
+	}
+
+	if err := m.ipv4Client.ClearAndDeleteChain(tableRaw, chainNameRaw); err != nil {
+		return fmt.Errorf("clear and delete chain: %w", err)
+	}
+
+	return nil
+}
+
 func getConntrackEstablished() []string {
 	return []string{"-m", "conntrack", "--ctstate", "RELATED,ESTABLISHED", "-j", "ACCEPT"}
 }

client/firewall/manager/firewall.go

@@ -168,6 +168,10 @@ type Manager interface {
 
 	// RemoveInboundDNAT removes inbound DNAT rule
 	RemoveInboundDNAT(localAddr netip.Addr, protocol Protocol, sourcePort, targetPort uint16) error
+
+	// SetupEBPFProxyNoTrack creates static notrack rules for eBPF proxy loopback traffic.
+	// This prevents conntrack from interfering with WireGuard proxy communication.
+	SetupEBPFProxyNoTrack(proxyPort, wgPort uint16) error
 }
 
 func GenKey(format string, pair RouterPair) string {

client/firewall/nftables/manager_linux.go

@@ -12,6 +12,7 @@ import (
 	"github.com/google/nftables/binaryutil"
 	"github.com/google/nftables/expr"
 	log "github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
 
 	firewall "github.com/netbirdio/netbird/client/firewall/manager"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
@@ -48,8 +49,10 @@ type Manager struct {
 	rConn   *nftables.Conn
 	wgIface iFaceMapper
 
-	router     *router
-	aclManager *AclManager
+	router                 *router
+	aclManager             *AclManager
+	notrackOutputChain     *nftables.Chain
+	notrackPreroutingChain *nftables.Chain
 }
 
 // Create nftables firewall manager
@@ -91,6 +94,10 @@ func (m *Manager) Init(stateManager *statemanager.Manager) error {
 		return fmt.Errorf("acl manager init: %w", err)
 	}
 
+	if err := m.initNoTrackChains(workTable); err != nil {
+		return fmt.Errorf("init notrack chains: %w", err)
+	}
+
 	stateManager.RegisterState(&ShutdownState{})
 
 	// We only need to record minimal interface state for potential recreation.
@@ -288,7 +295,15 @@ func (m *Manager) Flush() error {
 	m.mutex.Lock()
 	defer m.mutex.Unlock()
 
-	return m.aclManager.Flush()
+	if err := m.aclManager.Flush(); err != nil {
+		return err
+	}
+
+	if err := m.refreshNoTrackChains(); err != nil {
+		log.Errorf("failed to refresh notrack chains: %v", err)
+	}
+
+	return nil
 }
 
 // AddDNATRule adds a DNAT rule
@@ -331,6 +346,176 @@ func (m *Manager) RemoveInboundDNAT(localAddr netip.Addr, protocol firewall.Prot
 	return m.router.RemoveInboundDNAT(localAddr, protocol, sourcePort, targetPort)
 }
 
+const (
+	chainNameRawOutput     = "netbird-raw-out"
+	chainNameRawPrerouting = "netbird-raw-pre"
+)
+
+// SetupEBPFProxyNoTrack creates notrack rules for eBPF proxy loopback traffic.
+// This prevents conntrack from tracking WireGuard proxy traffic on loopback, which
+// can interfere with MASQUERADE rules (e.g., from container runtimes like Podman/netavark).
+//
+// Traffic flows that need NOTRACK:
+//
+//  1. Egress: WireGuard -> fake endpoint (before eBPF rewrite)
+//     src=127.0.0.1:wgPort -> dst=127.0.0.1:fakePort
+//     Matched by: sport=wgPort
+//
+//  2. Egress: Proxy -> WireGuard (via raw socket)
+//     src=127.0.0.1:fakePort -> dst=127.0.0.1:wgPort
+//     Matched by: dport=wgPort
+//
+//  3. Ingress: Packets to WireGuard
+//     dst=127.0.0.1:wgPort
+//     Matched by: dport=wgPort
+//
+//  4. Ingress: Packets to proxy (after eBPF rewrite)
+//     dst=127.0.0.1:proxyPort
+//     Matched by: dport=proxyPort
+//
+// Rules are cleaned up when the firewall manager is closed.
+func (m *Manager) SetupEBPFProxyNoTrack(proxyPort, wgPort uint16) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	if m.notrackOutputChain == nil || m.notrackPreroutingChain == nil {
+		return fmt.Errorf("notrack chains not initialized")
+	}
+
+	proxyPortBytes := binaryutil.BigEndian.PutUint16(proxyPort)
+	wgPortBytes := binaryutil.BigEndian.PutUint16(wgPort)
+	loopback := []byte{127, 0, 0, 1}
+
+	// Egress rules: match outgoing loopback UDP packets
+	m.rConn.AddRule(&nftables.Rule{
+		Table: m.notrackOutputChain.Table,
+		Chain: m.notrackOutputChain,
+		Exprs: []expr.Any{
+			&expr.Meta{Key: expr.MetaKeyOIFNAME, Register: 1},
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: ifname("lo")},
+			&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 12, Len: 4}, // saddr
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
+			&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 16, Len: 4}, // daddr
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
+			&expr.Meta{Key: expr.MetaKeyL4PROTO, Register: 1},
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: []byte{unix.IPPROTO_UDP}},
+			&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseTransportHeader, Offset: 0, Len: 2},
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: wgPortBytes}, // sport=wgPort
+			&expr.Counter{},
+			&expr.Notrack{},
+		},
+	})
+	m.rConn.AddRule(&nftables.Rule{
+		Table: m.notrackOutputChain.Table,
+		Chain: m.notrackOutputChain,
+		Exprs: []expr.Any{
+			&expr.Meta{Key: expr.MetaKeyOIFNAME, Register: 1},
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: ifname("lo")},
+			&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 12, Len: 4}, // saddr
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
+			&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 16, Len: 4}, // daddr
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
+			&expr.Meta{Key: expr.MetaKeyL4PROTO, Register: 1},
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: []byte{unix.IPPROTO_UDP}},
+			&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseTransportHeader, Offset: 2, Len: 2},
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: wgPortBytes}, // dport=wgPort
+			&expr.Counter{},
+			&expr.Notrack{},
+		},
+	})
+
+	// Ingress rules: match incoming loopback UDP packets
+	m.rConn.AddRule(&nftables.Rule{
+		Table: m.notrackPreroutingChain.Table,
+		Chain: m.notrackPreroutingChain,
+		Exprs: []expr.Any{
+			&expr.Meta{Key: expr.MetaKeyIIFNAME, Register: 1},
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: ifname("lo")},
+			&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 12, Len: 4}, // saddr
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
+			&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 16, Len: 4}, // daddr
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
+			&expr.Meta{Key: expr.MetaKeyL4PROTO, Register: 1},
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: []byte{unix.IPPROTO_UDP}},
+			&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseTransportHeader, Offset: 2, Len: 2},
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: wgPortBytes}, // dport=wgPort
+			&expr.Counter{},
+			&expr.Notrack{},
+		},
+	})
+	m.rConn.AddRule(&nftables.Rule{
+		Table: m.notrackPreroutingChain.Table,
+		Chain: m.notrackPreroutingChain,
+		Exprs: []expr.Any{
+			&expr.Meta{Key: expr.MetaKeyIIFNAME, Register: 1},
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: ifname("lo")},
+			&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 12, Len: 4}, // saddr
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
+			&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 16, Len: 4}, // daddr
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
+			&expr.Meta{Key: expr.MetaKeyL4PROTO, Register: 1},
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: []byte{unix.IPPROTO_UDP}},
+			&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseTransportHeader, Offset: 2, Len: 2},
+			&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: proxyPortBytes}, // dport=proxyPort
+			&expr.Counter{},
+			&expr.Notrack{},
+		},
+	})
+
+	if err := m.rConn.Flush(); err != nil {
+		return fmt.Errorf("flush notrack rules: %w", err)
+	}
+
+	log.Debugf("set up ebpf proxy notrack rules for ports %d,%d", proxyPort, wgPort)
+	return nil
+}
+
+func (m *Manager) initNoTrackChains(table *nftables.Table) error {
+	m.notrackOutputChain = m.rConn.AddChain(&nftables.Chain{
+		Name:     chainNameRawOutput,
+		Table:    table,
+		Type:     nftables.ChainTypeFilter,
+		Hooknum:  nftables.ChainHookOutput,
+		Priority: nftables.ChainPriorityRaw,
+	})
+
+	m.notrackPreroutingChain = m.rConn.AddChain(&nftables.Chain{
+		Name:     chainNameRawPrerouting,
+		Table:    table,
+		Type:     nftables.ChainTypeFilter,
+		Hooknum:  nftables.ChainHookPrerouting,
+		Priority: nftables.ChainPriorityRaw,
+	})
+
+	if err := m.rConn.Flush(); err != nil {
+		return fmt.Errorf("flush chain creation: %w", err)
+	}
+
+	return nil
+}
+
+func (m *Manager) refreshNoTrackChains() error {
+	chains, err := m.rConn.ListChainsOfTableFamily(nftables.TableFamilyIPv4)
+	if err != nil {
+		return fmt.Errorf("list chains: %w", err)
+	}
+
+	tableName := getTableName()
+	for _, c := range chains {
+		if c.Table.Name != tableName {
+			continue
+		}
+		switch c.Name {
+		case chainNameRawOutput:
+			m.notrackOutputChain = c
+		case chainNameRawPrerouting:
+			m.notrackPreroutingChain = c
+		}
+	}
+
+	return nil
+}
+
 func (m *Manager) createWorkTable() (*nftables.Table, error) {
 	tables, err := m.rConn.ListTablesOfFamily(nftables.TableFamilyIPv4)
 	if err != nil {

client/firewall/uspfilter/filter.go

@@ -570,6 +570,14 @@ func (m *Manager) SetLegacyManagement(isLegacy bool) error {
 // Flush doesn't need to be implemented for this manager
 func (m *Manager) Flush() error { return nil }
 
+// SetupEBPFProxyNoTrack creates notrack rules for eBPF proxy loopback traffic.
+func (m *Manager) SetupEBPFProxyNoTrack(proxyPort, wgPort uint16) error {
+	if m.nativeFirewall == nil {
+		return nil
+	}
+	return m.nativeFirewall.SetupEBPFProxyNoTrack(proxyPort, wgPort)
+}
+
 // UpdateSet updates the rule destinations associated with the given set
 // by merging the existing prefixes with the new ones, then deduplicating.
 func (m *Manager) UpdateSet(set firewall.Set, prefixes []netip.Prefix) error {

client/iface/iface.go

@@ -50,6 +50,7 @@ func ValidateMTU(mtu uint16) error {
 
 type wgProxyFactory interface {
 	GetProxy() wgproxy.Proxy
+	GetProxyPort() uint16
 	Free() error
 }
 
@@ -80,6 +81,12 @@ func (w *WGIface) GetProxy() wgproxy.Proxy {
 	return w.wgProxyFactory.GetProxy()
 }
 
+// GetProxyPort returns the proxy port used by the WireGuard proxy.
+// Returns 0 if no proxy port is used (e.g., for userspace WireGuard).
+func (w *WGIface) GetProxyPort() uint16 {
+	return w.wgProxyFactory.GetProxyPort()
+}
+
 // GetBind returns the EndpointManager userspace bind mode.
 func (w *WGIface) GetBind() device.EndpointManager {
 	w.mu.Lock()

client/iface/wgproxy/ebpf/proxy.go

@@ -39,6 +39,7 @@ var (
 // WGEBPFProxy definition for proxy with EBPF support
 type WGEBPFProxy struct {
 	localWGListenPort int
+	proxyPort         int
 	mtu               uint16
 
 	ebpfManager   ebpfMgr.Manager
@@ -69,10 +70,11 @@ func NewWGEBPFProxy(wgPort int, mtu uint16) *WGEBPFProxy {
 // Listen load ebpf program and listen the proxy
 func (p *WGEBPFProxy) Listen() error {
 	pl := portLookup{}
-	wgPorxyPort, err := pl.searchFreePort()
+	proxyPort, err := pl.searchFreePort()
 	if err != nil {
 		return err
 	}
+	p.proxyPort = proxyPort
 
 	// Prepare IPv4 raw socket (required)
 	p.rawConnIPv4, err = rawsocket.PrepareSenderRawSocketIPv4()
@@ -86,7 +88,7 @@ func (p *WGEBPFProxy) Listen() error {
 		log.Warnf("failed to prepare IPv6 raw socket, continuing with IPv4 only: %v", err)
 	}
 
-	err = p.ebpfManager.LoadWgProxy(wgPorxyPort, p.localWGListenPort)
+	err = p.ebpfManager.LoadWgProxy(proxyPort, p.localWGListenPort)
 	if err != nil {
 		if closeErr := p.rawConnIPv4.Close(); closeErr != nil {
 			log.Warnf("failed to close IPv4 raw socket: %v", closeErr)
@@ -100,7 +102,7 @@ func (p *WGEBPFProxy) Listen() error {
 	}
 
 	addr := net.UDPAddr{
-		Port: wgPorxyPort,
+		Port: proxyPort,
 		IP:   net.ParseIP(loopbackAddr),
 	}
 
@@ -116,7 +118,7 @@ func (p *WGEBPFProxy) Listen() error {
 	p.conn = conn
 
 	go p.proxyToRemote()
-	log.Infof("local wg proxy listening on: %d", wgPorxyPort)
+	log.Infof("local wg proxy listening on: %d", proxyPort)
 	return nil
 }
 
@@ -171,6 +173,11 @@ func (p *WGEBPFProxy) Free() error {
 	return nberrors.FormatErrorOrNil(result)
 }
 
+// GetProxyPort returns the proxy listening port.
+func (p *WGEBPFProxy) GetProxyPort() uint16 {
+	return uint16(p.proxyPort)
+}
+
 // proxyToRemote read messages from local WireGuard interface and forward it to remote conn
 // From this go routine has only one instance.
 func (p *WGEBPFProxy) proxyToRemote() {

client/iface/wgproxy/factory_kernel.go

@@ -54,6 +54,14 @@ func (w *KernelFactory) GetProxy() Proxy {
 	return ebpf.NewProxyWrapper(w.ebpfProxy)
 }
 
+// GetProxyPort returns the eBPF proxy port, or 0 if eBPF is not active.
+func (w *KernelFactory) GetProxyPort() uint16 {
+	if w.ebpfProxy == nil {
+		return 0
+	}
+	return w.ebpfProxy.GetProxyPort()
+}
+
 func (w *KernelFactory) Free() error {
 	if w.ebpfProxy == nil {
 		return nil

client/iface/wgproxy/factory_usp.go

@@ -24,6 +24,11 @@ func (w *USPFactory) GetProxy() Proxy {
 	return proxyBind.NewProxyBind(w.bind, w.mtu)
 }
 
+// GetProxyPort returns 0 as userspace WireGuard doesn't use a separate proxy port.
+func (w *USPFactory) GetProxyPort() uint16 {
+	return 0
+}
+
 func (w *USPFactory) Free() error {
 	return nil
 }

client/internal/engine.go

@@ -505,6 +505,10 @@ func (e *Engine) Start(netbirdConfig *mgmProto.NetbirdConfig, mgmtURL *url.URL)
 		return fmt.Errorf("up wg interface: %w", err)
 	}
 
+	// Set up notrack rules immediately after proxy is listening to prevent
+	// conntrack entries from being created before the rules are in place
+	e.setupWGProxyNoTrack()
+
 	// Set the WireGuard interface for rosenpass after interface is up
 	if e.rpManager != nil {
 		e.rpManager.SetInterface(e.wgInterface)
@@ -617,6 +621,23 @@ func (e *Engine) initFirewall() error {
 	return nil
 }
 
+// setupWGProxyNoTrack configures connection tracking exclusion for WireGuard proxy traffic.
+// This prevents conntrack/MASQUERADE from affecting loopback traffic between WireGuard and the eBPF proxy.
+func (e *Engine) setupWGProxyNoTrack() {
+	if e.firewall == nil {
+		return
+	}
+
+	proxyPort := e.wgInterface.GetProxyPort()
+	if proxyPort == 0 {
+		return
+	}
+
+	if err := e.firewall.SetupEBPFProxyNoTrack(proxyPort, uint16(e.config.WgPort)); err != nil {
+		log.Warnf("failed to setup ebpf proxy notrack: %v", err)
+	}
+}
+
 func (e *Engine) blockLanAccess() {
 	if e.config.BlockInbound {
 		// no need to set up extra deny rules if inbound is already blocked in general
@@ -1644,6 +1665,7 @@ func (e *Engine) parseNATExternalIPMappings() []string {
 
 func (e *Engine) close() {
 	log.Debugf("removing Netbird interface %s", e.config.WgIfaceName)
+
 	if e.wgInterface != nil {
 		if err := e.wgInterface.Close(); err != nil {
 			log.Errorf("failed closing Netbird interface %s %v", e.config.WgIfaceName, err)

client/internal/engine_test.go

@@ -107,6 +107,7 @@ type MockWGIface struct {
 	GetStatsFunc               func() (map[string]configurer.WGStats, error)
 	GetInterfaceGUIDStringFunc func() (string, error)
 	GetProxyFunc               func() wgproxy.Proxy
+	GetProxyPortFunc           func() uint16
 	GetNetFunc                 func() *netstack.Net
 	LastActivitiesFunc         func() map[string]monotime.Time
 }
@@ -203,6 +204,13 @@ func (m *MockWGIface) GetProxy() wgproxy.Proxy {
 	return m.GetProxyFunc()
 }
 
+func (m *MockWGIface) GetProxyPort() uint16 {
+	if m.GetProxyPortFunc != nil {
+		return m.GetProxyPortFunc()
+	}
+	return 0
+}
+
 func (m *MockWGIface) GetNet() *netstack.Net {
 	return m.GetNetFunc()
 }

client/internal/iface_common.go

@@ -28,6 +28,7 @@ type wgIfaceBase interface {
 	Up() (*udpmux.UniversalUDPMuxDefault, error)
 	UpdateAddr(newAddr string) error
 	GetProxy() wgproxy.Proxy
+	GetProxyPort() uint16
 	UpdatePeer(peerKey string, allowedIps []netip.Prefix, keepAlive time.Duration, endpoint *net.UDPAddr, preSharedKey *wgtypes.Key) error
 	RemoveEndpointAddress(key string) error
 	RemovePeer(peerKey string) error