[management,client] Make DNS ForwarderPort Configurable & Change Well Known Port (#4479)

makes the DNS forwarder port configurable in the management and client components, while changing the well-known port from 5454 to 22054. The change includes version-aware port assignment to ensure backward compatibility.

- Adds a configurable `ForwarderPort` field to the DNS configuration protocol
- Implements version-based port computation that returns the new port (22054) only when all peers support version 0.59.0 or newer
- Updates the client to dynamically restart the DNS forwarder when the port changes

client/internal/dnsfwd/manager.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"net"
+	"sync"
 
 	"github.com/hashicorp/go-multierror"
 	log "github.com/sirupsen/logrus"
@@ -11,14 +12,18 @@ import (
 	nberrors "github.com/netbirdio/netbird/client/errors"
 	firewall "github.com/netbirdio/netbird/client/firewall/manager"
 	"github.com/netbirdio/netbird/client/internal/peer"
-	"github.com/netbirdio/netbird/shared/management/domain"
 	"github.com/netbirdio/netbird/route"
+	"github.com/netbirdio/netbird/shared/management/domain"
+)
+
+var (
+	// ListenPort is the port that the DNS forwarder listens on. It has been used by the client peers also
+	listenPort   uint16 = 5353
+	listenPortMu sync.RWMutex
 )
 
 const (
-	// ListenPort is the port that the DNS forwarder listens on. It has been used by the client peers also
-	ListenPort = 5353
-	dnsTTL     = 60 //seconds
+	dnsTTL = 60 //seconds
 )
 
 // ForwarderEntry is a mapping from a domain to a resource ID and a hash of the parent domain list.
@@ -35,12 +40,20 @@ type Manager struct {
 	fwRules      []firewall.Rule
 	tcpRules     []firewall.Rule
 	dnsForwarder *DNSForwarder
+	port         uint16
 }
 
-func NewManager(fw firewall.Manager, statusRecorder *peer.Status) *Manager {
+func ListenPort() uint16 {
+	listenPortMu.RLock()
+	defer listenPortMu.RUnlock()
+	return listenPort
+}
+
+func NewManager(fw firewall.Manager, statusRecorder *peer.Status, port uint16) *Manager {
 	return &Manager{
 		firewall:       fw,
 		statusRecorder: statusRecorder,
+		port:           port,
 	}
 }
 
@@ -54,7 +67,13 @@ func (m *Manager) Start(fwdEntries []*ForwarderEntry) error {
 		return err
 	}
 
-	m.dnsForwarder = NewDNSForwarder(fmt.Sprintf(":%d", ListenPort), dnsTTL, m.firewall, m.statusRecorder)
+	if m.port > 0 {
+		listenPortMu.Lock()
+		listenPort = m.port
+		listenPortMu.Unlock()
+	}
+
+	m.dnsForwarder = NewDNSForwarder(fmt.Sprintf(":%d", ListenPort()), dnsTTL, m.firewall, m.statusRecorder)
 	go func() {
 		if err := m.dnsForwarder.Listen(fwdEntries); err != nil {
 			// todo handle close error if it is exists
@@ -94,7 +113,7 @@ func (m *Manager) Stop(ctx context.Context) error {
 func (m *Manager) allowDNSFirewall() error {
 	dport := &firewall.Port{
 		IsRange: false,
-		Values:  []uint16{ListenPort},
+		Values:  []uint16{ListenPort()},
 	}
 
 	if m.firewall == nil {

client/internal/engine.go

@@ -202,6 +202,9 @@ type Engine struct {
 	// WireGuard interface monitor
 	wgIfaceMonitor   *WGIfaceMonitor
 	wgIfaceMonitorWg sync.WaitGroup
+
+	// dns forwarder port
+	dnsFwdPort uint16
 }
 
 // Peer is an instance of the Connection Peer
@@ -244,6 +247,7 @@ func NewEngine(
 		statusRecorder: statusRecorder,
 		checks:         checks,
 		connSemaphore:  semaphoregroup.NewSemaphoreGroup(connInitLimit),
+		dnsFwdPort:     dnsfwd.ListenPort(),
 	}
 
 	sm := profilemanager.NewServiceManager("")
@@ -1080,7 +1084,7 @@ func (e *Engine) updateNetworkMap(networkMap *mgmProto.NetworkMap) error {
 	}
 
 	fwdEntries := toRouteDomains(e.config.WgPrivateKey.PublicKey().String(), routes)
-	e.updateDNSForwarder(dnsRouteFeatureFlag, fwdEntries)
+	e.updateDNSForwarder(dnsRouteFeatureFlag, fwdEntries, uint16(protoDNSConfig.ForwarderPort))
 
 	// Ingress forward rules
 	forwardingRules, err := e.updateForwardRules(networkMap.GetForwardingRules())
@@ -1839,6 +1843,7 @@ func (e *Engine) GetWgAddr() netip.Addr {
 func (e *Engine) updateDNSForwarder(
 	enabled bool,
 	fwdEntries []*dnsfwd.ForwarderEntry,
+	forwarderPort uint16,
 ) {
 	if e.config.DisableServerRoutes {
 		return
@@ -1855,16 +1860,20 @@ func (e *Engine) updateDNSForwarder(
 	}
 
 	if len(fwdEntries) > 0 {
-		if e.dnsForwardMgr == nil {
-			e.dnsForwardMgr = dnsfwd.NewManager(e.firewall, e.statusRecorder)
-
+		switch {
+		case e.dnsForwardMgr == nil:
+			e.dnsForwardMgr = dnsfwd.NewManager(e.firewall, e.statusRecorder, forwarderPort)
 			if err := e.dnsForwardMgr.Start(fwdEntries); err != nil {
 				log.Errorf("failed to start DNS forward: %v", err)
 				e.dnsForwardMgr = nil
 			}
-
 			log.Infof("started domain router service with %d entries", len(fwdEntries))
-		} else {
+		case e.dnsFwdPort != forwarderPort:
+			log.Infof("updating domain router service port from %d to %d", e.dnsFwdPort, forwarderPort)
+			e.restartDnsFwd(fwdEntries, forwarderPort)
+			e.dnsFwdPort = forwarderPort
+
+		default:
 			e.dnsForwardMgr.UpdateDomains(fwdEntries)
 		}
 	} else if e.dnsForwardMgr != nil {
@@ -1874,6 +1883,20 @@ func (e *Engine) updateDNSForwarder(
 		}
 		e.dnsForwardMgr = nil
 	}
+
+}
+
+func (e *Engine) restartDnsFwd(fwdEntries []*dnsfwd.ForwarderEntry, forwarderPort uint16) {
+	log.Infof("updating domain router service port from %d to %d", e.dnsFwdPort, forwarderPort)
+	// stop and start the forwarder to apply the new port
+	if err := e.dnsForwardMgr.Stop(context.Background()); err != nil {
+		log.Errorf("failed to stop DNS forward: %v", err)
+	}
+	e.dnsForwardMgr = dnsfwd.NewManager(e.firewall, e.statusRecorder, forwarderPort)
+	if err := e.dnsForwardMgr.Start(fwdEntries); err != nil {
+		log.Errorf("failed to start DNS forward: %v", err)
+		e.dnsForwardMgr = nil
+	}
 }
 
 func (e *Engine) GetNet() (*netstack.Net, error) {

client/internal/netflow/logger/logger.go

@@ -138,7 +138,7 @@ func (l *Logger) UpdateConfig(dnsCollection, exitNodeCollection bool) {
 
 func (l *Logger) shouldStore(event *types.EventFields, isExitNode bool) bool {
 	// check dns collection
-	if !l.dnsCollection.Load() && event.Protocol == types.UDP && (event.DestPort == 53 || event.DestPort == dnsfwd.ListenPort) {
+	if !l.dnsCollection.Load() && event.Protocol == types.UDP && (event.DestPort == 53 || event.DestPort == uint16(dnsfwd.ListenPort())) {
 		return false
 	}
 

client/internal/routemanager/dnsinterceptor/handler.go

@@ -24,8 +24,8 @@ import (
 	"github.com/netbirdio/netbird/client/internal/routemanager/common"
 	"github.com/netbirdio/netbird/client/internal/routemanager/fakeip"
 	"github.com/netbirdio/netbird/client/internal/routemanager/refcounter"
-	"github.com/netbirdio/netbird/shared/management/domain"
 	"github.com/netbirdio/netbird/route"
+	"github.com/netbirdio/netbird/shared/management/domain"
 )
 
 const dnsTimeout = 8 * time.Second
@@ -257,7 +257,7 @@ func (d *DnsInterceptor) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
 		r.MsgHdr.AuthenticatedData = true
 	}
 
-	upstream := fmt.Sprintf("%s:%d", upstreamIP.String(), dnsfwd.ListenPort)
+	upstream := fmt.Sprintf("%s:%d", upstreamIP.String(), dnsfwd.ListenPort())
 	ctx, cancel := context.WithTimeout(context.Background(), dnsTimeout)
 	defer cancel()