From f4848352920cb053b9681453979784af024693c2 Mon Sep 17 00:00:00 2001
From: Viktor Liu <17948409+lixmal@users.noreply.github.com>
Date: Fri, 10 Apr 2026 09:10:57 +0800
Subject: [PATCH] Use net.JoinHostPort and net.SplitHostPort for IPv6-safe
 host:port handling (#5836)

---
 client/anonymize/anonymize.go                 |  4 +-
 client/anonymize/anonymize_test.go            | 10 ++++
 client/cmd/ssh.go                             |  2 +-
 .../uspfilter/conntrack/common_test.go        | 48 +++++++++++++++++++
 client/firewall/uspfilter/conntrack/icmp.go   |  5 +-
 .../firewall/uspfilter/conntrack/icmp_test.go | 36 ++++++++++++++
 client/firewall/uspfilter/tracer.go           |  4 +-
 client/internal/profilemanager/config.go      |  4 +-
 client/internal/relay/relay.go                |  3 +-
 client/internal/rosenpass/manager.go          |  7 ++-
 client/internal/rosenpass/manager_test.go     | 14 ++++++
 client/ssh/proxy/proxy.go                     |  2 +-
 client/ssh/server/port_forwarding.go          | 29 +++++------
 client/ssh/server/server.go                   | 10 ++--
 combined/cmd/config.go                        |  2 +-
 .../reverseproxy/service/manager/manager.go   |  3 +-
 .../http/handlers/dns/nameservers_handler.go  |  5 +-
 .../handlers/dns/nameservers_handler_test.go  | 34 +++++++++++++
 relay/test/benchmark_test.go                  |  2 +-
 relay/testec2/turn_allocator.go               |  2 +-
 upload-server/server/s3_test.go               |  3 +-
 21 files changed, 193 insertions(+), 36 deletions(-)
 create mode 100644 client/internal/rosenpass/manager_test.go

diff --git a/client/anonymize/anonymize.go b/client/anonymize/anonymize.go
index b7b6a20dd..629966dcc 100644
--- a/client/anonymize/anonymize.go
+++ b/client/anonymize/anonymize.go
@@ -157,7 +157,7 @@ func (a *Anonymizer) AnonymizeURI(uri string) string {
 	if u.Opaque != "" {
 		host, port, err := net.SplitHostPort(u.Opaque)
 		if err == nil {
-			anonymizedHost = fmt.Sprintf("%s:%s", a.AnonymizeDomain(host), port)
+			anonymizedHost = net.JoinHostPort(a.AnonymizeDomain(host), port)
 		} else {
 			anonymizedHost = a.AnonymizeDomain(u.Opaque)
 		}
@@ -165,7 +165,7 @@ func (a *Anonymizer) AnonymizeURI(uri string) string {
 	} else if u.Host != "" {
 		host, port, err := net.SplitHostPort(u.Host)
 		if err == nil {
-			anonymizedHost = fmt.Sprintf("%s:%s", a.AnonymizeDomain(host), port)
+			anonymizedHost = net.JoinHostPort(a.AnonymizeDomain(host), port)
 		} else {
 			anonymizedHost = a.AnonymizeDomain(u.Host)
 		}
diff --git a/client/anonymize/anonymize_test.go b/client/anonymize/anonymize_test.go
index 45e205834..852315fa1 100644
--- a/client/anonymize/anonymize_test.go
+++ b/client/anonymize/anonymize_test.go
@@ -286,6 +286,16 @@ func TestAnonymizeString_IPAddresses(t *testing.T) {
 			input:  "IPv4: 142.108.0.1 and IPv6: 2001:db8::ff00:43",
 			expect: "IPv4: 198.51.100.1 and IPv6: 2001:db8:ffff::1",
 		},
+		{
+			name:   "STUN URI with IPv6",
+			input:  "Connecting to stun:[2001:db8::ff00:42]:3478",
+			expect: "Connecting to stun:[2001:db8:ffff::]:3478",
+		},
+		{
+			name:   "HTTPS URI with IPv6",
+			input:  "Visit https://[2001:db8::ff00:42]:443/path",
+			expect: "Visit https://[2001:db8:ffff::]:443/path",
+		},
 	}
 
 	for _, tc := range tests {
diff --git a/client/cmd/ssh.go b/client/cmd/ssh.go
index de5150b1f..d6e052e08 100644
--- a/client/cmd/ssh.go
+++ b/client/cmd/ssh.go
@@ -523,7 +523,7 @@ func parseHostnameAndCommand(args []string) error {
 }
 
 func runSSH(ctx context.Context, addr string, cmd *cobra.Command) error {
-	target := fmt.Sprintf("%s:%d", addr, port)
+	target := net.JoinHostPort(strings.Trim(addr, "[]"), strconv.Itoa(port))
 	c, err := sshclient.Dial(ctx, target, username, sshclient.DialOptions{
 		KnownHostsFile:     knownHostsFile,
 		IdentityFile:       identityFile,
diff --git a/client/firewall/uspfilter/conntrack/common_test.go b/client/firewall/uspfilter/conntrack/common_test.go
index d868dd1fb..7e67b98fa 100644
--- a/client/firewall/uspfilter/conntrack/common_test.go
+++ b/client/firewall/uspfilter/conntrack/common_test.go
@@ -13,6 +13,54 @@ import (
 var logger = log.NewFromLogrus(logrus.StandardLogger())
 var flowLogger = netflow.NewManager(nil, []byte{}, nil).GetLogger()
 
+func TestConnKey_String(t *testing.T) {
+	tests := []struct {
+		name   string
+		key    ConnKey
+		expect string
+	}{
+		{
+			name: "IPv4",
+			key: ConnKey{
+				SrcIP:   netip.MustParseAddr("192.168.1.1"),
+				DstIP:   netip.MustParseAddr("10.0.0.1"),
+				SrcPort: 12345,
+				DstPort: 80,
+			},
+			expect: "192.168.1.1:12345 → 10.0.0.1:80",
+		},
+		{
+			name: "IPv6",
+			key: ConnKey{
+				SrcIP:   netip.MustParseAddr("2001:db8::1"),
+				DstIP:   netip.MustParseAddr("2001:db8::2"),
+				SrcPort: 54321,
+				DstPort: 443,
+			},
+			expect: "[2001:db8::1]:54321 → [2001:db8::2]:443",
+		},
+		{
+			name: "IPv4-mapped IPv6 unmaps",
+			key: ConnKey{
+				SrcIP:   netip.MustParseAddr("::ffff:10.0.0.1"),
+				DstIP:   netip.MustParseAddr("::ffff:10.0.0.2"),
+				SrcPort: 1000,
+				DstPort: 2000,
+			},
+			expect: "10.0.0.1:1000 → 10.0.0.2:2000",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got := tc.key.String()
+			if got != tc.expect {
+				t.Errorf("got %q, want %q", got, tc.expect)
+			}
+		})
+	}
+}
+
 // Memory pressure tests
 func BenchmarkMemoryPressure(b *testing.B) {
 	b.Run("TCPHighLoad", func(b *testing.B) {
diff --git a/client/firewall/uspfilter/conntrack/icmp.go b/client/firewall/uspfilter/conntrack/icmp.go
index 85b6f13be..5f7d78b56 100644
--- a/client/firewall/uspfilter/conntrack/icmp.go
+++ b/client/firewall/uspfilter/conntrack/icmp.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net"
 	"net/netip"
+	"strconv"
 	"sync"
 	"time"
 
@@ -137,12 +138,12 @@ func (info ICMPInfo) parseOriginalPacket() string {
 	case nftypes.TCP:
 		srcPort := uint16(transportData[0])<<8 | uint16(transportData[1])
 		dstPort := uint16(transportData[2])<<8 | uint16(transportData[3])
-		return fmt.Sprintf("TCP %s:%d → %s:%d", srcIP, srcPort, dstIP, dstPort)
+		return "TCP " + net.JoinHostPort(srcIP.String(), strconv.Itoa(int(srcPort))) + " → " + net.JoinHostPort(dstIP.String(), strconv.Itoa(int(dstPort)))
 
 	case nftypes.UDP:
 		srcPort := uint16(transportData[0])<<8 | uint16(transportData[1])
 		dstPort := uint16(transportData[2])<<8 | uint16(transportData[3])
-		return fmt.Sprintf("UDP %s:%d → %s:%d", srcIP, srcPort, dstIP, dstPort)
+		return "UDP " + net.JoinHostPort(srcIP.String(), strconv.Itoa(int(srcPort))) + " → " + net.JoinHostPort(dstIP.String(), strconv.Itoa(int(dstPort)))
 
 	case nftypes.ICMP:
 		icmpType := transportData[0]
diff --git a/client/firewall/uspfilter/conntrack/icmp_test.go b/client/firewall/uspfilter/conntrack/icmp_test.go
index b15b42cf0..6d1f87162 100644
--- a/client/firewall/uspfilter/conntrack/icmp_test.go
+++ b/client/firewall/uspfilter/conntrack/icmp_test.go
@@ -5,6 +5,42 @@ import (
 	"testing"
 )
 
+func TestICMPConnKey_String(t *testing.T) {
+	tests := []struct {
+		name   string
+		key    ICMPConnKey
+		expect string
+	}{
+		{
+			name: "IPv4",
+			key: ICMPConnKey{
+				SrcIP: netip.MustParseAddr("192.168.1.1"),
+				DstIP: netip.MustParseAddr("10.0.0.1"),
+				ID:    1234,
+			},
+			expect: "192.168.1.1 → 10.0.0.1 (id 1234)",
+		},
+		{
+			name: "IPv6",
+			key: ICMPConnKey{
+				SrcIP: netip.MustParseAddr("2001:db8::1"),
+				DstIP: netip.MustParseAddr("2001:db8::2"),
+				ID:    5678,
+			},
+			expect: "2001:db8::1 → 2001:db8::2 (id 5678)",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got := tc.key.String()
+			if got != tc.expect {
+				t.Errorf("got %q, want %q", got, tc.expect)
+			}
+		})
+	}
+}
+
 func BenchmarkICMPTracker(b *testing.B) {
 	b.Run("TrackOutbound", func(b *testing.B) {
 		tracker := NewICMPTracker(DefaultICMPTimeout, logger, flowLogger)
diff --git a/client/firewall/uspfilter/tracer.go b/client/firewall/uspfilter/tracer.go
index 3b066c160..696489e95 100644
--- a/client/firewall/uspfilter/tracer.go
+++ b/client/firewall/uspfilter/tracer.go
@@ -2,7 +2,9 @@ package uspfilter
 
 import (
 	"fmt"
+	"net"
 	"net/netip"
+	"strconv"
 	"time"
 
 	"github.com/google/gopacket"
@@ -443,7 +445,7 @@ func (m *Manager) handleRouteACLs(trace *PacketTrace, d *decoder, srcIP, dstIP n
 	trace.AddResult(StageRouteACL, msg, allowed)
 
 	if allowed && m.forwarder.Load() != nil {
-		m.addForwardingResult(trace, "proxy-remote", fmt.Sprintf("%s:%d", dstIP, dstPort), true)
+		m.addForwardingResult(trace, "proxy-remote", net.JoinHostPort(dstIP.String(), strconv.Itoa(int(dstPort))), true)
 	}
 
 	trace.AddResult(StageCompleted, msgProcessingCompleted, allowed)
diff --git a/client/internal/profilemanager/config.go b/client/internal/profilemanager/config.go
index 2f21a03cb..cd5bc0680 100644
--- a/client/internal/profilemanager/config.go
+++ b/client/internal/profilemanager/config.go
@@ -5,6 +5,7 @@ import (
 	"crypto/tls"
 	"encoding/json"
 	"fmt"
+	"net"
 	"net/url"
 	"os"
 	"os/user"
@@ -759,8 +760,7 @@ func UpdateOldManagementURL(ctx context.Context, config *Config, configPath stri
 		return config, nil
 	}
 
-	newURL, err := parseURL("Management URL", fmt.Sprintf("%s://%s:%d",
-		config.ManagementURL.Scheme, defaultManagementURL.Hostname(), 443))
+	newURL, err := parseURL("Management URL", fmt.Sprintf("%s://%s", config.ManagementURL.Scheme, net.JoinHostPort(defaultManagementURL.Hostname(), "443")))
 	if err != nil {
 		return nil, err
 	}
diff --git a/client/internal/relay/relay.go b/client/internal/relay/relay.go
index 59be5b0a7..f00a8d93a 100644
--- a/client/internal/relay/relay.go
+++ b/client/internal/relay/relay.go
@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"net"
+	"strconv"
 	"sync"
 	"time"
 
@@ -257,7 +258,7 @@ func (p *StunTurnProbe) probeTURN(ctx context.Context, uri *stun.URI) (addr stri
 		}
 	}()
 
-	turnServerAddr := fmt.Sprintf("%s:%d", uri.Host, uri.Port)
+	turnServerAddr := net.JoinHostPort(uri.Host, strconv.Itoa(uri.Port))
 
 	var conn net.PacketConn
 	switch uri.Proto {
diff --git a/client/internal/rosenpass/manager.go b/client/internal/rosenpass/manager.go
index c69ea9a6c..11cda8dbc 100644
--- a/client/internal/rosenpass/manager.go
+++ b/client/internal/rosenpass/manager.go
@@ -259,6 +259,9 @@ func findRandomAvailableUDPPort() (int, error) {
 	}
 	defer conn.Close()
 
-	splitAddress := strings.Split(conn.LocalAddr().String(), ":")
-	return strconv.Atoi(splitAddress[len(splitAddress)-1])
+	_, portStr, err := net.SplitHostPort(conn.LocalAddr().String())
+	if err != nil {
+		return 0, fmt.Errorf("parse local address %s: %w", conn.LocalAddr(), err)
+	}
+	return strconv.Atoi(portStr)
 }
diff --git a/client/internal/rosenpass/manager_test.go b/client/internal/rosenpass/manager_test.go
new file mode 100644
index 000000000..90bbdda59
--- /dev/null
+++ b/client/internal/rosenpass/manager_test.go
@@ -0,0 +1,14 @@
+package rosenpass
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFindRandomAvailableUDPPort(t *testing.T) {
+	port, err := findRandomAvailableUDPPort()
+	require.NoError(t, err)
+	require.Greater(t, port, 0)
+	require.LessOrEqual(t, port, 65535)
+}
diff --git a/client/ssh/proxy/proxy.go b/client/ssh/proxy/proxy.go
index 59007f75c..eb659fe21 100644
--- a/client/ssh/proxy/proxy.go
+++ b/client/ssh/proxy/proxy.go
@@ -321,7 +321,7 @@ func (p *SSHProxy) directTCPIPHandler(_ *ssh.Server, _ *cryptossh.ServerConn, ne
 		return
 	}
 
-	dest := fmt.Sprintf("%s:%d", payload.DestAddr, payload.DestPort)
+	dest := net.JoinHostPort(payload.DestAddr, strconv.Itoa(int(payload.DestPort)))
 	log.Debugf("local port forwarding: %s", dest)
 
 	backendClient, err := p.getOrCreateBackendClient(sshCtx, sshCtx.User())
diff --git a/client/ssh/server/port_forwarding.go b/client/ssh/server/port_forwarding.go
index e16ff5d46..f5ac66fca 100644
--- a/client/ssh/server/port_forwarding.go
+++ b/client/ssh/server/port_forwarding.go
@@ -56,12 +56,12 @@ func (s *Server) configurePortForwarding(server *ssh.Server) {
 	server.LocalPortForwardingCallback = func(ctx ssh.Context, dstHost string, dstPort uint32) bool {
 		logger := s.getRequestLogger(ctx)
 		if !allowLocal {
-			logger.Warnf("local port forwarding denied for %s:%d: disabled", dstHost, dstPort)
+			logger.Warnf("local port forwarding denied for %s: disabled", net.JoinHostPort(dstHost, strconv.Itoa(int(dstPort))))
 			return false
 		}
 
 		if err := s.checkPortForwardingPrivileges(ctx, "local", dstPort); err != nil {
-			logger.Warnf("local port forwarding denied for %s:%d: %v", dstHost, dstPort, err)
+			logger.Warnf("local port forwarding denied for %s: %v", net.JoinHostPort(dstHost, strconv.Itoa(int(dstPort))), err)
 			return false
 		}
 
@@ -71,12 +71,12 @@ func (s *Server) configurePortForwarding(server *ssh.Server) {
 	server.ReversePortForwardingCallback = func(ctx ssh.Context, bindHost string, bindPort uint32) bool {
 		logger := s.getRequestLogger(ctx)
 		if !allowRemote {
-			logger.Warnf("remote port forwarding denied for %s:%d: disabled", bindHost, bindPort)
+			logger.Warnf("remote port forwarding denied for %s: disabled", net.JoinHostPort(bindHost, strconv.Itoa(int(bindPort))))
 			return false
 		}
 
 		if err := s.checkPortForwardingPrivileges(ctx, "remote", bindPort); err != nil {
-			logger.Warnf("remote port forwarding denied for %s:%d: %v", bindHost, bindPort, err)
+			logger.Warnf("remote port forwarding denied for %s: %v", net.JoinHostPort(bindHost, strconv.Itoa(int(bindPort))), err)
 			return false
 		}
 
@@ -183,15 +183,16 @@ func (s *Server) cancelTcpipForwardHandler(ctx ssh.Context, _ *ssh.Server, req *
 		return false, nil
 	}
 
-	key := forwardKey(fmt.Sprintf("%s:%d", payload.Host, payload.Port))
+	hostPort := net.JoinHostPort(payload.Host, strconv.Itoa(int(payload.Port)))
+	key := forwardKey(hostPort)
 	if s.removeRemoteForwardListener(key) {
-		forwardAddr := fmt.Sprintf("-R %s:%d", payload.Host, payload.Port)
+		forwardAddr := "-R " + hostPort
 		s.removeConnectionPortForward(ctx.RemoteAddr(), forwardAddr)
-		logger.Infof("remote port forwarding cancelled: %s:%d", payload.Host, payload.Port)
+		logger.Infof("remote port forwarding cancelled: %s", hostPort)
 		return true, nil
 	}
 
-	logger.Warnf("cancel-tcpip-forward failed: no listener found for %s:%d", payload.Host, payload.Port)
+	logger.Warnf("cancel-tcpip-forward failed: no listener found for %s", net.JoinHostPort(payload.Host, strconv.Itoa(int(payload.Port))))
 	return false, nil
 }
 
@@ -201,7 +202,7 @@ func (s *Server) handleRemoteForwardListener(ctx ssh.Context, ln net.Listener, h
 
 	defer func() {
 		if err := ln.Close(); err != nil {
-			logger.Debugf("remote forward listener close error for %s:%d: %v", host, port, err)
+			logger.Debugf("remote forward listener close error for %s: %v", net.JoinHostPort(host, strconv.Itoa(int(port))), err)
 		}
 	}()
 
@@ -230,7 +231,7 @@ func (s *Server) handleRemoteForwardListener(ctx ssh.Context, ln net.Listener, h
 			}
 			go s.handleRemoteForwardConnection(ctx, result.conn, host, port)
 		case <-ctx.Done():
-			logger.Debugf("remote forward listener shutting down for %s:%d", host, port)
+			logger.Debugf("remote forward listener shutting down for %s", net.JoinHostPort(host, strconv.Itoa(int(port))))
 			return
 		}
 	}
@@ -311,17 +312,17 @@ func (s *Server) setupDirectForward(ctx ssh.Context, logger *log.Entry, sshConn
 		logger.Debugf("tcpip-forward allocated port %d for %s", actualPort, payload.Host)
 	}
 
-	key := forwardKey(fmt.Sprintf("%s:%d", payload.Host, payload.Port))
+	key := forwardKey(net.JoinHostPort(payload.Host, strconv.Itoa(int(payload.Port))))
 	s.storeRemoteForwardListener(key, ln)
 
-	forwardAddr := fmt.Sprintf("-R %s:%d", payload.Host, actualPort)
+	forwardAddr := "-R " + net.JoinHostPort(payload.Host, strconv.Itoa(int(actualPort)))
 	s.addConnectionPortForward(ctx.User(), ctx.RemoteAddr(), forwardAddr)
 	go s.handleRemoteForwardListener(ctx, ln, payload.Host, actualPort)
 
 	response := make([]byte, 4)
 	binary.BigEndian.PutUint32(response, actualPort)
 
-	logger.Infof("remote port forwarding established: %s:%d", payload.Host, actualPort)
+	logger.Infof("remote port forwarding established: %s", net.JoinHostPort(payload.Host, strconv.Itoa(int(actualPort))))
 	return true, response
 }
 
@@ -351,7 +352,7 @@ func (s *Server) handleRemoteForwardConnection(ctx ssh.Context, conn net.Conn, h
 
 	channel, err := s.openForwardChannel(sshConn, host, port, remoteAddr)
 	if err != nil {
-		logger.Debugf("open forward channel for %s:%d: %v", host, port, err)
+		logger.Debugf("open forward channel for %s: %v", net.JoinHostPort(host, strconv.Itoa(int(port))), err)
 		_ = conn.Close()
 		return
 	}
diff --git a/client/ssh/server/server.go b/client/ssh/server/server.go
index 020ba149e..fbf3346bb 100644
--- a/client/ssh/server/server.go
+++ b/client/ssh/server/server.go
@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"strconv"
 	"net/netip"
 	"slices"
 	"strings"
@@ -918,20 +919,21 @@ func (s *Server) directTCPIPHandler(srv *ssh.Server, conn *cryptossh.ServerConn,
 	s.mu.RUnlock()
 
 	if !allowLocal {
-		logger.Warnf("local port forwarding denied for %s:%d: disabled", payload.Host, payload.Port)
+		logger.Warnf("local port forwarding denied for %s: disabled", net.JoinHostPort(payload.Host, strconv.Itoa(int(payload.Port))))
 		_ = newChan.Reject(cryptossh.Prohibited, "local port forwarding disabled")
 		return
 	}
 
 	if err := s.checkPortForwardingPrivileges(ctx, "local", payload.Port); err != nil {
-		logger.Warnf("local port forwarding denied for %s:%d: %v", payload.Host, payload.Port, err)
+		logger.Warnf("local port forwarding denied for %s: %v", net.JoinHostPort(payload.Host, strconv.Itoa(int(payload.Port))), err)
 		_ = newChan.Reject(cryptossh.Prohibited, "insufficient privileges")
 		return
 	}
 
-	forwardAddr := fmt.Sprintf("-L %s:%d", payload.Host, payload.Port)
+	hostPort := net.JoinHostPort(payload.Host, strconv.Itoa(int(payload.Port)))
+	forwardAddr := "-L " + hostPort
 	s.addConnectionPortForward(ctx.User(), ctx.RemoteAddr(), forwardAddr)
-	logger.Infof("local port forwarding: %s:%d", payload.Host, payload.Port)
+	logger.Infof("local port forwarding: %s", hostPort)
 
 	ssh.DirectTCPIPHandler(srv, conn, newChan, ctx)
 }
diff --git a/combined/cmd/config.go b/combined/cmd/config.go
index 85664d0d2..28340ee37 100644
--- a/combined/cmd/config.go
+++ b/combined/cmd/config.go
@@ -378,7 +378,7 @@ func (c *CombinedConfig) autoConfigureClientSettings(exposedProto, exposedHost,
 		// Auto-configure local STUN servers for all ports
 		for _, port := range c.Server.StunPorts {
 			c.Management.Stuns = append(c.Management.Stuns, HostConfig{
-				URI: fmt.Sprintf("stun:%s:%d", exposedHost, port),
+				URI: "stun:" + net.JoinHostPort(strings.Trim(exposedHost, "[]"), fmt.Sprintf("%d", port)),
 			})
 		}
 	}
diff --git a/management/internals/modules/reverseproxy/service/manager/manager.go b/management/internals/modules/reverseproxy/service/manager/manager.go
index 2b24063d6..a2df99db0 100644
--- a/management/internals/modules/reverseproxy/service/manager/manager.go
+++ b/management/internals/modules/reverseproxy/service/manager/manager.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"math/rand/v2"
+	"net"
 	"net/http"
 	"os"
 	"slices"
@@ -1102,7 +1103,7 @@ func (m *Manager) CreateServiceFromPeer(ctx context.Context, accountID, peerID s
 
 	serviceURL := "https://" + svc.Domain
 	if service.IsL4Protocol(svc.Mode) {
-		serviceURL = fmt.Sprintf("%s://%s:%d", svc.Mode, svc.Domain, svc.ListenPort)
+		serviceURL = fmt.Sprintf("%s://%s", svc.Mode, net.JoinHostPort(svc.Domain, strconv.Itoa(int(svc.ListenPort))))
 	}
 
 	return &service.ExposeServiceResponse{
diff --git a/management/server/http/handlers/dns/nameservers_handler.go b/management/server/http/handlers/dns/nameservers_handler.go
index bce1c4b78..5dbe09323 100644
--- a/management/server/http/handlers/dns/nameservers_handler.go
+++ b/management/server/http/handlers/dns/nameservers_handler.go
@@ -3,7 +3,10 @@ package dns
 import (
 	"encoding/json"
 	"fmt"
+	"net"
 	"net/http"
+	"strconv"
+	"strings"
 
 	"github.com/gorilla/mux"
 	log "github.com/sirupsen/logrus"
@@ -201,7 +204,7 @@ func (h *nameserversHandler) getNameserverGroup(w http.ResponseWriter, r *http.R
 func toServerNSList(apiNSList []api.Nameserver) ([]nbdns.NameServer, error) {
 	var nsList []nbdns.NameServer
 	for _, apiNS := range apiNSList {
-		parsed, err := nbdns.ParseNameServerURL(fmt.Sprintf("%s://%s:%d", apiNS.NsType, apiNS.Ip, apiNS.Port))
+		parsed, err := nbdns.ParseNameServerURL(fmt.Sprintf("%s://%s", apiNS.NsType, net.JoinHostPort(strings.Trim(apiNS.Ip, "[]"), strconv.Itoa(apiNS.Port))))
 		if err != nil {
 			return nil, err
 		}
diff --git a/management/server/http/handlers/dns/nameservers_handler_test.go b/management/server/http/handlers/dns/nameservers_handler_test.go
index 4716782f3..a165f009b 100644
--- a/management/server/http/handlers/dns/nameservers_handler_test.go
+++ b/management/server/http/handlers/dns/nameservers_handler_test.go
@@ -233,3 +233,37 @@ func TestNameserversHandlers(t *testing.T) {
 		})
 	}
 }
+
+func TestToServerNSList_IPv6(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    []api.Nameserver
+		expectIP netip.Addr
+	}{
+		{
+			name: "IPv4",
+			input: []api.Nameserver{
+				{Ip: "1.1.1.1", NsType: "udp", Port: 53},
+			},
+			expectIP: netip.MustParseAddr("1.1.1.1"),
+		},
+		{
+			name: "IPv6",
+			input: []api.Nameserver{
+				{Ip: "2001:4860:4860::8888", NsType: "udp", Port: 53},
+			},
+			expectIP: netip.MustParseAddr("2001:4860:4860::8888"),
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			result, err := toServerNSList(tc.input)
+			assert.NoError(t, err)
+			if assert.Len(t, result, 1) {
+				assert.Equal(t, tc.expectIP, result[0].IP)
+				assert.Equal(t, 53, result[0].Port)
+			}
+		})
+	}
+}
diff --git a/relay/test/benchmark_test.go b/relay/test/benchmark_test.go
index 4dfea6da1..6b1131f1e 100644
--- a/relay/test/benchmark_test.go
+++ b/relay/test/benchmark_test.go
@@ -337,7 +337,7 @@ func runTurnDataTransfer(t *testing.T, testData []byte) time.Duration {
 func getTurnClient(t *testing.T, address string, conn net.Conn) (*turn.Client, error) {
 	t.Helper()
 	// Dial TURN Server
-	addrStr := fmt.Sprintf("%s:%d", address, 443)
+	addrStr := net.JoinHostPort(address, "443")
 
 	fac := logging.NewDefaultLoggerFactory()
 	//fac.DefaultLogLevel = logging.LogLevelTrace
diff --git a/relay/testec2/turn_allocator.go b/relay/testec2/turn_allocator.go
index fd86208df..440f6222a 100644
--- a/relay/testec2/turn_allocator.go
+++ b/relay/testec2/turn_allocator.go
@@ -52,7 +52,7 @@ func AllocateTurnClient(serverAddr string) *TurnConn {
 
 func getTurnClient(address string, conn net.Conn) (*turn.Client, error) {
 	// Dial TURN Server
-	addrStr := fmt.Sprintf("%s:%d", address, 443)
+	addrStr := net.JoinHostPort(address, "443")
 
 	fac := logging.NewDefaultLoggerFactory()
 	//fac.DefaultLogLevel = logging.LogLevelTrace
diff --git a/upload-server/server/s3_test.go b/upload-server/server/s3_test.go
index 7ab1bb379..a72356409 100644
--- a/upload-server/server/s3_test.go
+++ b/upload-server/server/s3_test.go
@@ -3,6 +3,7 @@ package server
 import (
 	"context"
 	"encoding/json"
+	"net"
 	"net/http"
 	"net/http/httptest"
 	"runtime"
@@ -52,7 +53,7 @@ func Test_S3HandlerGetUploadURL(t *testing.T) {
 	hostIP, err := c.Host(ctx)
 	require.NoError(t, err)
 
-	awsEndpoint := "http://" + hostIP + ":" + mappedPort.Port()
+	awsEndpoint := "http://" + net.JoinHostPort(hostIP, mappedPort.Port())
 
 	t.Setenv("AWS_REGION", awsRegion)
 	t.Setenv("AWS_ENDPOINT_URL", awsEndpoint)