Redirect dns forwarder port 5353 to new listening port 22054

Author: lixmal

client/firewall/iptables/manager_linux.go

@@ -260,6 +260,22 @@ func (m *Manager) UpdateSet(set firewall.Set, prefixes []netip.Prefix) error {
 	return m.router.UpdateSet(set, prefixes)
 }
 
+// AddInboundDNAT adds an inbound DNAT rule redirecting traffic from NetBird peers to local services
+func (m *Manager) AddInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	return m.router.AddInboundDNAT(localAddr, protocol, sourcePort, targetPort)
+}
+
+// RemoveInboundDNAT removes inbound DNAT rule
+func (m *Manager) RemoveInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	return m.router.RemoveInboundDNAT(localAddr, protocol, sourcePort, targetPort)
+}
+
 func getConntrackEstablished() []string {
 	return []string{"-m", "conntrack", "--ctstate", "RELATED,ESTABLISHED", "-j", "ACCEPT"}
 }

client/firewall/iptables/router_linux.go

@@ -880,6 +880,54 @@ func (r *router) UpdateSet(set firewall.Set, prefixes []netip.Prefix) error {
 	return nberrors.FormatErrorOrNil(merr)
 }
 
+// AddInboundDNAT adds an inbound DNAT rule redirecting traffic from NetBird peers to local services
+func (r *router) AddInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	ruleID := fmt.Sprintf("inbound-dnat-%s-%s-%d-%d", localAddr.String(), protocol, sourcePort, targetPort)
+
+	if _, exists := r.rules[ruleID]; exists {
+		return nil
+	}
+
+	dnatRule := []string{
+		"-i", r.wgIface.Name(),
+		"-p", strings.ToLower(string(protocol)),
+		"--dport", strconv.Itoa(int(sourcePort)),
+		"-d", localAddr.String(),
+		"-m", "addrtype", "--dst-type", "LOCAL",
+		"-j", "DNAT",
+		"--to-destination", ":" + strconv.Itoa(int(targetPort)),
+	}
+
+	ruleInfo := ruleInfo{
+		table: tableNat,
+		chain: chainRTRDR,
+		rule:  dnatRule,
+	}
+
+	if err := r.iptablesClient.Append(ruleInfo.table, ruleInfo.chain, ruleInfo.rule...); err != nil {
+		return fmt.Errorf("add inbound DNAT rule: %w", err)
+	}
+	r.rules[ruleID] = ruleInfo.rule
+
+	r.updateState()
+	return nil
+}
+
+// RemoveInboundDNAT removes inbound DNAT rule
+func (r *router) RemoveInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	ruleID := fmt.Sprintf("inbound-dnat-%s-%s-%d-%d", localAddr.String(), protocol, sourcePort, targetPort)
+
+	if dnatRule, exists := r.rules[ruleID]; exists {
+		if err := r.iptablesClient.Delete(tableNat, chainRTRDR, dnatRule...); err != nil {
+			return fmt.Errorf("delete inbound DNAT rule: %w", err)
+		}
+		delete(r.rules, ruleID)
+	}
+
+	r.updateState()
+	return nil
+}
+
 func applyPort(flag string, port *firewall.Port) []string {
 	if port == nil {
 		return nil

client/firewall/manager/firewall.go

@@ -151,14 +151,20 @@ type Manager interface {
 
 	DisableRouting() error
 
-	// AddDNATRule adds a DNAT rule
+	// AddDNATRule adds outbound DNAT rule for forwarding external traffic to the NetBird network.
 	AddDNATRule(ForwardRule) (Rule, error)
 
-	// DeleteDNATRule deletes a DNAT rule
+	// DeleteDNATRule deletes the outbound DNAT rule.
 	DeleteDNATRule(Rule) error
 
 	// UpdateSet updates the set with the given prefixes
 	UpdateSet(hash Set, prefixes []netip.Prefix) error
+
+	// AddInboundDNAT adds an inbound DNAT rule redirecting traffic from NetBird peers to local services
+	AddInboundDNAT(localAddr netip.Addr, protocol Protocol, sourcePort, targetPort uint16) error
+
+	// RemoveInboundDNAT removes inbound DNAT rule
+	RemoveInboundDNAT(localAddr netip.Addr, protocol Protocol, sourcePort, targetPort uint16) error
 }
 
 func GenKey(format string, pair RouterPair) string {

client/firewall/nftables/manager_linux.go

@@ -376,6 +376,22 @@ func (m *Manager) UpdateSet(set firewall.Set, prefixes []netip.Prefix) error {
 	return m.router.UpdateSet(set, prefixes)
 }
 
+// AddInboundDNAT adds an inbound DNAT rule redirecting traffic from NetBird peers to local services
+func (m *Manager) AddInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	return m.router.AddInboundDNAT(localAddr, protocol, sourcePort, targetPort)
+}
+
+// RemoveInboundDNAT removes inbound DNAT rule
+func (m *Manager) RemoveInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	return m.router.RemoveInboundDNAT(localAddr, protocol, sourcePort, targetPort)
+}
+
 func (m *Manager) createWorkTable() (*nftables.Table, error) {
 	tables, err := m.rConn.ListTablesOfFamily(nftables.TableFamilyIPv4)
 	if err != nil {

client/firewall/nftables/router_linux.go

@@ -1350,6 +1350,103 @@ func (r *router) UpdateSet(set firewall.Set, prefixes []netip.Prefix) error {
 	return nil
 }
 
+// AddInboundDNAT adds an inbound DNAT rule redirecting traffic from NetBird peers to local services
+func (r *router) AddInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	ruleID := fmt.Sprintf("inbound-dnat-%s-%s-%d-%d", localAddr.String(), protocol, sourcePort, targetPort)
+
+	if _, exists := r.rules[ruleID]; exists {
+		return nil
+	}
+
+	protoNum, err := protoToInt(protocol)
+	if err != nil {
+		return fmt.Errorf("convert protocol to number: %w", err)
+	}
+
+	exprs := []expr.Any{
+		&expr.Meta{Key: expr.MetaKeyIIFNAME, Register: 1},
+		&expr.Cmp{
+			Op:       expr.CmpOpEq,
+			Register: 1,
+			Data:     ifname(r.wgIface.Name()),
+		},
+		&expr.Meta{Key: expr.MetaKeyL4PROTO, Register: 2},
+		&expr.Cmp{
+			Op:       expr.CmpOpEq,
+			Register: 2,
+			Data:     []byte{protoNum},
+		},
+		&expr.Payload{
+			DestRegister: 3,
+			Base:         expr.PayloadBaseTransportHeader,
+			Offset:       2,
+			Len:          2,
+		},
+		&expr.Cmp{
+			Op:       expr.CmpOpEq,
+			Register: 3,
+			Data:     binaryutil.BigEndian.PutUint16(sourcePort),
+		},
+	}
+
+	exprs = append(exprs, applyPrefix(netip.PrefixFrom(localAddr, 32), false)...)
+
+	exprs = append(exprs,
+		&expr.Immediate{
+			Register: 1,
+			Data:     localAddr.AsSlice(),
+		},
+		&expr.Immediate{
+			Register: 2,
+			Data:     binaryutil.BigEndian.PutUint16(targetPort),
+		},
+		&expr.NAT{
+			Type:        expr.NATTypeDestNAT,
+			Family:      uint32(nftables.TableFamilyIPv4),
+			RegAddrMin:  1,
+			RegProtoMin: 2,
+			RegProtoMax: 0,
+		},
+	)
+
+	dnatRule := &nftables.Rule{
+		Table:    r.workTable,
+		Chain:    r.chains[chainNameRoutingRdr],
+		Exprs:    exprs,
+		UserData: []byte(ruleID),
+	}
+	r.conn.AddRule(dnatRule)
+
+	if err := r.conn.Flush(); err != nil {
+		return fmt.Errorf("add inbound DNAT rule: %w", err)
+	}
+
+	r.rules[ruleID] = dnatRule
+
+	return nil
+}
+
+// RemoveInboundDNAT removes inbound DNAT rule
+func (r *router) RemoveInboundDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error {
+	if err := r.refreshRulesMap(); err != nil {
+		return fmt.Errorf(refreshRulesMapError, err)
+	}
+
+	ruleID := fmt.Sprintf("inbound-dnat-%s-%s-%d-%d", localAddr.String(), protocol, sourcePort, targetPort)
+
+	if rule, exists := r.rules[ruleID]; exists {
+		if err := r.conn.DelRule(rule); err != nil {
+			return fmt.Errorf("delete inbound DNAT rule %s: %w", ruleID, err)
+		}
+		if err := r.conn.Flush(); err != nil {
+			return fmt.Errorf("flush delete inbound DNAT rule: %w", err)
+		}
+		delete(r.rules, ruleID)
+	}
+
+	return nil
+}
+
 // applyNetwork generates nftables expressions for networks (CIDR) or sets
 func (r *router) applyNetwork(
 	network firewall.Network,

client/firewall/uspfilter/filter.go

@@ -109,6 +109,12 @@ type Manager struct {
 	dnatMappings map[netip.Addr]netip.Addr
 	dnatMutex    sync.RWMutex
 	dnatBiMap    *biDNATMap
+
+	// Port-specific DNAT for SSH redirection
+	portDNATEnabled atomic.Bool
+	portDNATMap     *portDNATMap
+	portDNATMutex   sync.RWMutex
+	portNATTracker  *portNATTracker
 }
 
 // decoder for packages
@@ -196,6 +202,8 @@ func create(iface common.IFaceMapper, nativeFirewall firewall.Manager, disableSe
 		netstack:            netstack.IsEnabled(),
 		localForwarding:     enableLocalForwarding,
 		dnatMappings:        make(map[netip.Addr]netip.Addr),
+		portDNATMap:         &portDNATMap{rules: []portDNATRule{}},
+		portNATTracker:      newPortNATTracker(),
 	}
 	m.routingEnabled.Store(false)
 
@@ -632,6 +640,7 @@ func (m *Manager) filterOutbound(packetData []byte, size int) bool {
 
 	m.trackOutbound(d, srcIP, dstIP, size)
 	m.translateOutboundDNAT(packetData, d)
+	m.translateOutboundPortReverse(packetData, d)
 
 	return false
 }
@@ -759,6 +768,15 @@ func (m *Manager) filterInbound(packetData []byte, size int) bool {
 		return false
 	}
 
+	if translated := m.translateInboundPortDNAT(packetData, d); translated {
+		// Re-decode after port DNAT translation to update port information
+		if err := d.parser.DecodeLayers(packetData, &d.decoded); err != nil {
+			m.logger.Error1("Failed to re-decode packet after port DNAT: %v", err)
+			return true
+		}
+		srcIP, dstIP = m.extractIPs(d)
+	}
+
 	if translated := m.translateInboundReverse(packetData, d); translated {
 		// Re-decode after translation to get original addresses
 		if err := d.parser.DecodeLayers(packetData, &d.decoded); err != nil {

client/firewall/uspfilter/log/log.go

@@ -50,6 +50,8 @@ type logMessage struct {
 	arg4   any
 	arg5   any
 	arg6   any
+	arg7   any
+	arg8   any
 }
 
 // Logger is a high-performance, non-blocking logger
@@ -94,7 +96,6 @@ func (l *Logger) SetLevel(level Level) {
 	log.Debugf("Set uspfilter logger loglevel to %v", levelStrings[level])
 }
 
-
 func (l *Logger) Error(format string) {
 	if l.level.Load() >= uint32(LevelError) {
 		select {
@@ -185,6 +186,15 @@ func (l *Logger) Debug2(format string, arg1, arg2 any) {
 	}
 }
 
+func (l *Logger) Debug3(format string, arg1, arg2, arg3 any) {
+	if l.level.Load() >= uint32(LevelDebug) {
+		select {
+		case l.msgChannel <- logMessage{level: LevelDebug, format: format, arg1: arg1, arg2: arg2, arg3: arg3}:
+		default:
+		}
+	}
+}
+
 func (l *Logger) Trace1(format string, arg1 any) {
 	if l.level.Load() >= uint32(LevelTrace) {
 		select {
@@ -239,6 +249,16 @@ func (l *Logger) Trace6(format string, arg1, arg2, arg3, arg4, arg5, arg6 any) {
 	}
 }
 
+// Trace8 logs a trace message with 8 arguments (8 placeholder in format string)
+func (l *Logger) Trace8(format string, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8 any) {
+	if l.level.Load() >= uint32(LevelTrace) {
+		select {
+		case l.msgChannel <- logMessage{level: LevelTrace, format: format, arg1: arg1, arg2: arg2, arg3: arg3, arg4: arg4, arg5: arg5, arg6: arg6, arg7: arg7, arg8: arg8}:
+		default:
+		}
+	}
+}
+
 func (l *Logger) formatMessage(buf *[]byte, msg logMessage) {
 	*buf = (*buf)[:0]
 	*buf = time.Now().AppendFormat(*buf, "2006-01-02T15:04:05-07:00")
@@ -260,6 +280,12 @@ func (l *Logger) formatMessage(buf *[]byte, msg logMessage) {
 						argCount++
 						if msg.arg6 != nil {
 							argCount++
+							if msg.arg7 != nil {
+								argCount++
+								if msg.arg8 != nil {
+									argCount++
+								}
+							}
 						}
 					}
 				}
@@ -283,6 +309,10 @@ func (l *Logger) formatMessage(buf *[]byte, msg logMessage) {
 		formatted = fmt.Sprintf(msg.format, msg.arg1, msg.arg2, msg.arg3, msg.arg4, msg.arg5)
 	case 6:
 		formatted = fmt.Sprintf(msg.format, msg.arg1, msg.arg2, msg.arg3, msg.arg4, msg.arg5, msg.arg6)
+	case 7:
+		formatted = fmt.Sprintf(msg.format, msg.arg1, msg.arg2, msg.arg3, msg.arg4, msg.arg5, msg.arg6, msg.arg7)
+	case 8:
+		formatted = fmt.Sprintf(msg.format, msg.arg1, msg.arg2, msg.arg3, msg.arg4, msg.arg5, msg.arg6, msg.arg7, msg.arg8)
 	}
 
 	*buf = append(*buf, formatted...)
@@ -390,4 +420,4 @@ func (l *Logger) Stop(ctx context.Context) error {
 	case <-done:
 		return nil
 	}
-}
+}