fix: 重构 ssh agent forwarding 转发代理并修复资源残留

- 将 agent forwarding 从长持有本地 agent 连接改为按 uth-agent@openssh.com channel 动态建桥
- 新增 ssh-agent 可用性探测流程，区分 forwarding 探测与实际转发注册
- 重构 forwarding 注册接口，按连接超时创建本地 agent bridge，不再复用单个长期占用的 agent 连接
- 新增 sshAgentForwardProxy 与 sshAgentForwardBridge，显式管理活跃 agent bridge 生命周期
- 在远端 channel 单侧 EOF、bridge 关闭和 proxy.Close() 路径上主动关闭本地 agent 连接与 SSH channel，避免 goroutine 和 agent 句柄残留
- 保留现有 denied / unavailable / close-race 语义，并继续保证自动 forwarding 的 best-effort 行为
- 扩充 agent forwarding 回归测试，覆盖单次启用、禁用、denied、unavailable、close race、单侧 EOF 释放以及 proxy Close 主动回收活跃 bridge 等关键场景

agent_forward.go

@@ -0,0 +1,355 @@
+package starssh
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"strings"
+	"sync"
+	"time"
+
+	"golang.org/x/crypto/ssh"
+	sshagent "golang.org/x/crypto/ssh/agent"
+)
+
+var requestSSHAgentForwarding = func(session *ssh.Session) error {
+	return sshagent.RequestAgentForwarding(session)
+}
+
+const sshAgentChannelType = "auth-agent@openssh.com"
+
+var routeSSHAgentForwarding = func(client *ssh.Client, timeout time.Duration) (io.Closer, error) {
+	return startSSHAgentForwardProxy(client, timeout)
+}
+
+var probeSSHAgentForwarding = func(timeout time.Duration) error {
+	conn, err := dialSSHAgent(timeout)
+	if err != nil {
+		return wrapSSHAgentForwardingUnavailable(err)
+	}
+	if conn == nil {
+		return wrapSSHAgentForwardingUnavailable(errors.New("empty agent connection"))
+	}
+	return conn.Close()
+}
+
+var errSSHAgentForwardingDenied = errors.New("ssh-agent forwarding request denied")
+var errSSHAgentForwardingUnavailable = errors.New("ssh-agent forwarding unavailable")
+
+type sshAgentForwardProxy struct {
+	stopOnce sync.Once
+	stopCh   chan struct{}
+
+	activeMu sync.Mutex
+	active   map[*sshAgentForwardBridge]struct{}
+}
+
+func (p *sshAgentForwardProxy) Close() error {
+	if p == nil {
+		return nil
+	}
+	p.stopOnce.Do(func() {
+		close(p.stopCh)
+	})
+	p.closeActive()
+	return nil
+}
+
+type sshAgentForwardBridge struct {
+	proxy   *sshAgentForwardProxy
+	channel ssh.Channel
+	conn    net.Conn
+
+	closeOnce sync.Once
+}
+
+func (s *StarSSH) RequestAgentForwarding(session *ssh.Session) error {
+	if s == nil {
+		return errors.New("ssh client is nil")
+	}
+	if session == nil {
+		return errors.New("ssh session is nil")
+	}
+	if err := s.ensureAgentForwarding(); err != nil {
+		return err
+	}
+	if err := requestSSHAgentForwarding(session); err != nil {
+		if isSSHAgentForwardingDeniedError(err) {
+			return fmt.Errorf("%w: %v", errSSHAgentForwardingDenied, err)
+		}
+		return err
+	}
+	return nil
+}
+
+func (s *StarSSH) maybeRequestAgentForwarding(session *ssh.Session) error {
+	if s == nil || !s.LoginInfo.ForwardSSHAgent {
+		return nil
+	}
+	err := s.RequestAgentForwarding(session)
+	if isSSHAgentForwardingDeniedError(err) || isSSHAgentForwardingUnavailableError(err) {
+		return nil
+	}
+	return err
+}
+
+func (s *StarSSH) ensureAgentForwarding() error {
+	if s == nil {
+		return errors.New("ssh client is nil")
+	}
+
+	s.agentForwardMu.Lock()
+	defer s.agentForwardMu.Unlock()
+
+	if s.agentForwarder != nil {
+		return nil
+	}
+
+	client, err := s.requireSSHClient()
+	if err != nil {
+		return err
+	}
+
+	timeout := effectiveDialTimeout(s.LoginInfo)
+	if err := probeSSHAgentForwarding(timeout); err != nil {
+		return wrapSSHAgentForwardingUnavailable(err)
+	}
+	if s.closing.Load() {
+		return errSSHClientClosing
+	}
+	closer, err := routeSSHAgentForwarding(client, timeout)
+	if err != nil {
+		return err
+	}
+	if !s.canAttachAgentForwarder(client) {
+		if closer != nil {
+			_ = closer.Close()
+		}
+		return errSSHClientClosing
+	}
+	s.agentForwarder = closer
+	return nil
+}
+
+func (s *StarSSH) takeAgentForwarder() io.Closer {
+	if s == nil {
+		return nil
+	}
+
+	s.agentForwardMu.Lock()
+	defer s.agentForwardMu.Unlock()
+
+	closer := s.agentForwarder
+	s.agentForwarder = nil
+	return closer
+}
+
+func isSSHAgentForwardingDeniedError(err error) bool {
+	if err == nil {
+		return false
+	}
+	if errors.Is(err, errSSHAgentForwardingDenied) {
+		return true
+	}
+	message := strings.ToLower(err.Error())
+	return strings.Contains(message, "forwarding request denied") ||
+		strings.Contains(message, "agent forwarding disabled")
+}
+
+func isSSHAgentForwardingUnavailableError(err error) bool {
+	if err == nil {
+		return false
+	}
+	if errors.Is(err, errSSHAgentForwardingUnavailable) {
+		return true
+	}
+	message := strings.ToLower(err.Error())
+	return strings.Contains(message, "ssh-agent forwarding unavailable") ||
+		strings.Contains(message, "ssh-agent unavailable")
+}
+
+func wrapSSHAgentForwardingUnavailable(err error) error {
+	if err == nil {
+		return nil
+	}
+	if errors.Is(err, errSSHAgentForwardingUnavailable) {
+		return err
+	}
+	if errors.Is(err, errSSHAgentUnavailable) {
+		return fmt.Errorf("%w: %w", errSSHAgentForwardingUnavailable, err)
+	}
+	return fmt.Errorf("%w: %v", errSSHAgentForwardingUnavailable, err)
+}
+
+func startSSHAgentForwardProxy(client *ssh.Client, timeout time.Duration) (io.Closer, error) {
+	if client == nil {
+		return nil, errors.New("ssh client is nil")
+	}
+	channels := client.HandleChannelOpen(sshAgentChannelType)
+	if channels == nil {
+		return nil, errors.New("agent: already have handler for " + sshAgentChannelType)
+	}
+
+	proxy := &sshAgentForwardProxy{
+		stopCh: make(chan struct{}),
+		active: make(map[*sshAgentForwardBridge]struct{}),
+	}
+	go func() {
+		for {
+			select {
+			case <-proxy.stopCh:
+				return
+			case ch, ok := <-channels:
+				if !ok {
+					return
+				}
+				go handleSSHAgentForwardChannel(proxy, ch, timeout)
+			}
+		}
+	}()
+	return proxy, nil
+}
+
+func handleSSHAgentForwardChannel(proxy *sshAgentForwardProxy, ch ssh.NewChannel, timeout time.Duration) {
+	if ch == nil {
+		return
+	}
+	conn, err := dialSSHAgent(timeout)
+	if err != nil {
+		_ = ch.Reject(ssh.ConnectionFailed, err.Error())
+		return
+	}
+	if conn == nil {
+		_ = ch.Reject(ssh.ConnectionFailed, "ssh-agent connection unavailable")
+		return
+	}
+
+	channel, reqs, err := ch.Accept()
+	if err != nil {
+		_ = conn.Close()
+		return
+	}
+	go ssh.DiscardRequests(reqs)
+
+	bridge := &sshAgentForwardBridge{
+		proxy:   proxy,
+		channel: channel,
+		conn:    conn,
+	}
+	if !proxy.registerBridge(bridge) {
+		bridge.close()
+		return
+	}
+	go bridge.run()
+}
+
+func proxySSHAgentChannel(channel ssh.Channel, conn net.Conn) {
+	bridge := &sshAgentForwardBridge{
+		channel: channel,
+		conn:    conn,
+	}
+	bridge.run()
+}
+
+func (b *sshAgentForwardBridge) run() {
+	if b == nil {
+		return
+	}
+	defer b.unregister()
+
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() {
+		defer wg.Done()
+		_, _ = io.Copy(b.channel, b.conn)
+		b.close()
+	}()
+	go func() {
+		defer wg.Done()
+		_, _ = io.Copy(b.conn, b.channel)
+		b.close()
+	}()
+	wg.Wait()
+}
+
+func (b *sshAgentForwardBridge) close() {
+	if b == nil {
+		return
+	}
+	b.closeOnce.Do(func() {
+		closeWriter(b.channel)
+		closeWriter(b.conn)
+		if b.channel != nil {
+			_ = b.channel.Close()
+		}
+		if b.conn != nil {
+			_ = b.conn.Close()
+		}
+	})
+}
+
+func (b *sshAgentForwardBridge) unregister() {
+	if b == nil || b.proxy == nil {
+		return
+	}
+	b.proxy.unregisterBridge(b)
+}
+
+func (p *sshAgentForwardProxy) registerBridge(bridge *sshAgentForwardBridge) bool {
+	if p == nil || bridge == nil {
+		return false
+	}
+
+	p.activeMu.Lock()
+	defer p.activeMu.Unlock()
+
+	select {
+	case <-p.stopCh:
+		return false
+	default:
+	}
+	if p.active == nil {
+		p.active = make(map[*sshAgentForwardBridge]struct{})
+	}
+	p.active[bridge] = struct{}{}
+	return true
+}
+
+func (p *sshAgentForwardProxy) unregisterBridge(bridge *sshAgentForwardBridge) {
+	if p == nil || bridge == nil {
+		return
+	}
+
+	p.activeMu.Lock()
+	defer p.activeMu.Unlock()
+
+	delete(p.active, bridge)
+}
+
+func (p *sshAgentForwardProxy) closeActive() {
+	if p == nil {
+		return
+	}
+
+	p.activeMu.Lock()
+	active := make([]*sshAgentForwardBridge, 0, len(p.active))
+	for bridge := range p.active {
+		active = append(active, bridge)
+	}
+	p.active = make(map[*sshAgentForwardBridge]struct{})
+	p.activeMu.Unlock()
+
+	for _, bridge := range active {
+		bridge.close()
+	}
+}
+
+func closeWriter(value any) {
+	type closeWriter interface {
+		CloseWrite() error
+	}
+	if cw, ok := value.(closeWriter); ok {
+		_ = cw.CloseWrite()
+	}
+}

agent_forward_test.go

@@ -0,0 +1,572 @@
+package starssh
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"net"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"golang.org/x/crypto/ssh"
+)
+
+type testCloser struct {
+	closed atomic.Int32
+}
+
+func (c *testCloser) Close() error {
+	c.closed.Add(1)
+	return nil
+}
+
+type trackedConn struct {
+	net.Conn
+	closed atomic.Int32
+}
+
+func (c *trackedConn) Close() error {
+	c.closed.Add(1)
+	if c.Conn == nil {
+		return nil
+	}
+	return c.Conn.Close()
+}
+
+type testSSHChannel struct {
+	readFunc func([]byte) (int, error)
+
+	stderr    bytes.Buffer
+	closed    atomic.Int32
+	closeOnce sync.Once
+	closeCh   chan struct{}
+}
+
+func newTestSSHChannel(readFunc func([]byte) (int, error)) *testSSHChannel {
+	return &testSSHChannel{
+		readFunc: readFunc,
+		closeCh:  make(chan struct{}),
+	}
+}
+
+func newBlockingTestSSHChannel() *testSSHChannel {
+	ch := newTestSSHChannel(nil)
+	ch.readFunc = func(p []byte) (int, error) {
+		<-ch.closeCh
+		return 0, io.EOF
+	}
+	return ch
+}
+
+func (c *testSSHChannel) Read(p []byte) (int, error) {
+	if c == nil {
+		return 0, io.EOF
+	}
+	if c.readFunc != nil {
+		return c.readFunc(p)
+	}
+	return 0, io.EOF
+}
+
+func (c *testSSHChannel) Write(p []byte) (int, error) {
+	return len(p), nil
+}
+
+func (c *testSSHChannel) Close() error {
+	if c == nil {
+		return nil
+	}
+	c.closeOnce.Do(func() {
+		c.closed.Add(1)
+		close(c.closeCh)
+	})
+	return nil
+}
+
+func (c *testSSHChannel) CloseWrite() error {
+	return nil
+}
+
+func (c *testSSHChannel) SendRequest(name string, wantReply bool, payload []byte) (bool, error) {
+	return false, nil
+}
+
+func (c *testSSHChannel) Stderr() io.ReadWriter {
+	return &c.stderr
+}
+
+func TestNewExecSessionEnablesAgentForwardingOnce(t *testing.T) {
+	oldNewSSHSession := newSSHSession
+	oldProbeSSHAgentForwarding := probeSSHAgentForwarding
+	oldRouteSSHAgentForwarding := routeSSHAgentForwarding
+	oldRequestSSHAgentForwarding := requestSSHAgentForwarding
+	oldCloseSSHClient := closeSSHClient
+	t.Cleanup(func() {
+		newSSHSession = oldNewSSHSession
+		probeSSHAgentForwarding = oldProbeSSHAgentForwarding
+		routeSSHAgentForwarding = oldRouteSSHAgentForwarding
+		requestSSHAgentForwarding = oldRequestSSHAgentForwarding
+		closeSSHClient = oldCloseSSHClient
+	})
+
+	baseClient := &ssh.Client{}
+	star := &StarSSH{
+		LoginInfo: LoginInput{
+			ForwardSSHAgent: true,
+			Timeout:         time.Second,
+		},
+	}
+	star.setTransport(baseClient, nil)
+
+	newSSHSession = func(client *ssh.Client) (*ssh.Session, error) {
+		if client != baseClient {
+			t.Fatalf("unexpected ssh client %p", client)
+		}
+		return &ssh.Session{}, nil
+	}
+
+	var probeCalls atomic.Int32
+	closer := &testCloser{}
+	probeSSHAgentForwarding = func(timeout time.Duration) error {
+		probeCalls.Add(1)
+		if timeout != time.Second {
+			t.Fatalf("unexpected forwarding timeout: %v", timeout)
+		}
+		return nil
+	}
+
+	var routeCalls atomic.Int32
+	routeSSHAgentForwarding = func(client *ssh.Client, timeout time.Duration) (io.Closer, error) {
+		routeCalls.Add(1)
+		if client != baseClient {
+			t.Fatalf("unexpected routed client %p", client)
+		}
+		if timeout != time.Second {
+			t.Fatalf("unexpected routed timeout: %v", timeout)
+		}
+		return closer, nil
+	}
+
+	var requestCalls atomic.Int32
+	requestSSHAgentForwarding = func(session *ssh.Session) error {
+		requestCalls.Add(1)
+		if session == nil {
+			t.Fatal("expected non-nil ssh session")
+		}
+		return nil
+	}
+
+	if _, err := star.NewExecSession(); err != nil {
+		t.Fatalf("first exec session: %v", err)
+	}
+	if _, err := star.NewExecSession(); err != nil {
+		t.Fatalf("second exec session: %v", err)
+	}
+
+	if probeCalls.Load() != 1 {
+		t.Fatalf("expected one agent probe, got %d", probeCalls.Load())
+	}
+	if routeCalls.Load() != 1 {
+		t.Fatalf("expected one agent route registration, got %d", routeCalls.Load())
+	}
+	if requestCalls.Load() != 2 {
+		t.Fatalf("expected agent forwarding request on each session, got %d", requestCalls.Load())
+	}
+
+	closeSSHClient = func(client sshClientRequester) error { return nil }
+	if err := star.Close(); err != nil {
+		t.Fatalf("close starssh: %v", err)
+	}
+	if closer.closed.Load() != 1 {
+		t.Fatalf("expected forwarded agent closer to run once, got %d", closer.closed.Load())
+	}
+}
+
+func TestNewPTYSessionEnablesAgentForwardingWhenConfigured(t *testing.T) {
+	oldNewSSHSession := newSSHSession
+	oldRequestSessionPTY := requestSessionPTY
+	oldProbeSSHAgentForwarding := probeSSHAgentForwarding
+	oldRouteSSHAgentForwarding := routeSSHAgentForwarding
+	oldRequestSSHAgentForwarding := requestSSHAgentForwarding
+	t.Cleanup(func() {
+		newSSHSession = oldNewSSHSession
+		requestSessionPTY = oldRequestSessionPTY
+		probeSSHAgentForwarding = oldProbeSSHAgentForwarding
+		routeSSHAgentForwarding = oldRouteSSHAgentForwarding
+		requestSSHAgentForwarding = oldRequestSSHAgentForwarding
+	})
+
+	star := &StarSSH{
+		LoginInfo: LoginInput{
+			ForwardSSHAgent: true,
+		},
+	}
+	star.setTransport(&ssh.Client{}, nil)
+
+	newSSHSession = func(client *ssh.Client) (*ssh.Session, error) {
+		return &ssh.Session{}, nil
+	}
+
+	var ptyCalls atomic.Int32
+	requestSessionPTY = func(session *ssh.Session, config TerminalConfig) error {
+		ptyCalls.Add(1)
+		return nil
+	}
+
+	probeSSHAgentForwarding = func(timeout time.Duration) error {
+		return nil
+	}
+	routeSSHAgentForwarding = func(client *ssh.Client, timeout time.Duration) (io.Closer, error) {
+		return &testCloser{}, nil
+	}
+
+	var requestCalls atomic.Int32
+	requestSSHAgentForwarding = func(session *ssh.Session) error {
+		requestCalls.Add(1)
+		return nil
+	}
+
+	if _, err := star.NewPTYSession(nil); err != nil {
+		t.Fatalf("new pty session: %v", err)
+	}
+	if ptyCalls.Load() != 1 {
+		t.Fatalf("expected one PTY request, got %d", ptyCalls.Load())
+	}
+	if requestCalls.Load() != 1 {
+		t.Fatalf("expected one agent forwarding request, got %d", requestCalls.Load())
+	}
+}
+
+func TestNewExecSessionSkipsAgentForwardingWhenDisabled(t *testing.T) {
+	oldNewSSHSession := newSSHSession
+	oldProbeSSHAgentForwarding := probeSSHAgentForwarding
+	oldRequestSSHAgentForwarding := requestSSHAgentForwarding
+	t.Cleanup(func() {
+		newSSHSession = oldNewSSHSession
+		probeSSHAgentForwarding = oldProbeSSHAgentForwarding
+		requestSSHAgentForwarding = oldRequestSSHAgentForwarding
+	})
+
+	star := &StarSSH{}
+	star.setTransport(&ssh.Client{}, nil)
+
+	newSSHSession = func(client *ssh.Client) (*ssh.Session, error) {
+		return &ssh.Session{}, nil
+	}
+	probeSSHAgentForwarding = func(timeout time.Duration) error {
+		t.Fatal("agent forwarding probe should not run when disabled")
+		return nil
+	}
+	requestSSHAgentForwarding = func(session *ssh.Session) error {
+		t.Fatal("agent forwarding should not be requested when disabled")
+		return nil
+	}
+
+	if _, err := star.NewExecSession(); err != nil {
+		t.Fatalf("new exec session without forwarding: %v", err)
+	}
+}
+
+func TestRequestAgentForwardingReturnsUnavailableError(t *testing.T) {
+	oldProbeSSHAgentForwarding := probeSSHAgentForwarding
+	oldRequestSSHAgentForwarding := requestSSHAgentForwarding
+	t.Cleanup(func() {
+		probeSSHAgentForwarding = oldProbeSSHAgentForwarding
+		requestSSHAgentForwarding = oldRequestSSHAgentForwarding
+	})
+
+	star := &StarSSH{}
+	star.setTransport(&ssh.Client{}, nil)
+
+	probeSSHAgentForwarding = func(timeout time.Duration) error {
+		return errors.New("ssh-agent forwarding unavailable: ssh-agent unavailable")
+	}
+	requestSSHAgentForwarding = func(session *ssh.Session) error {
+		t.Fatal("session request should not run when agent forwarder init fails")
+		return nil
+	}
+
+	err := star.RequestAgentForwarding(&ssh.Session{})
+	if err == nil {
+		t.Fatal("expected agent forwarding init error")
+	}
+}
+
+func TestRequestAgentForwardingWrapsSetupErrorAsUnavailable(t *testing.T) {
+	oldProbeSSHAgentForwarding := probeSSHAgentForwarding
+	t.Cleanup(func() {
+		probeSSHAgentForwarding = oldProbeSSHAgentForwarding
+	})
+
+	star := &StarSSH{}
+	star.setTransport(&ssh.Client{}, nil)
+
+	probeSSHAgentForwarding = func(timeout time.Duration) error {
+		return errors.New("dial unix /tmp/ssh-broken.sock: connect: permission denied")
+	}
+
+	err := star.RequestAgentForwarding(&ssh.Session{})
+	if !isSSHAgentForwardingUnavailableError(err) {
+		t.Fatalf("expected unavailable error, got %v", err)
+	}
+}
+
+func TestRequestAgentForwardingReturnsDeniedError(t *testing.T) {
+	oldProbeSSHAgentForwarding := probeSSHAgentForwarding
+	oldRouteSSHAgentForwarding := routeSSHAgentForwarding
+	oldRequestSSHAgentForwarding := requestSSHAgentForwarding
+	t.Cleanup(func() {
+		probeSSHAgentForwarding = oldProbeSSHAgentForwarding
+		routeSSHAgentForwarding = oldRouteSSHAgentForwarding
+		requestSSHAgentForwarding = oldRequestSSHAgentForwarding
+	})
+
+	star := &StarSSH{}
+	star.setTransport(&ssh.Client{}, nil)
+
+	probeSSHAgentForwarding = func(timeout time.Duration) error {
+		return nil
+	}
+	routeSSHAgentForwarding = func(client *ssh.Client, timeout time.Duration) (io.Closer, error) {
+		return &testCloser{}, nil
+	}
+	requestSSHAgentForwarding = func(session *ssh.Session) error {
+		return errors.New("forwarding request denied")
+	}
+
+	err := star.RequestAgentForwarding(&ssh.Session{})
+	if !isSSHAgentForwardingDeniedError(err) {
+		t.Fatalf("expected forwarding denied error, got %v", err)
+	}
+}
+
+func TestNewExecSessionIgnoresAgentForwardingDenied(t *testing.T) {
+	oldNewSSHSession := newSSHSession
+	oldProbeSSHAgentForwarding := probeSSHAgentForwarding
+	oldRouteSSHAgentForwarding := routeSSHAgentForwarding
+	oldRequestSSHAgentForwarding := requestSSHAgentForwarding
+	t.Cleanup(func() {
+		newSSHSession = oldNewSSHSession
+		probeSSHAgentForwarding = oldProbeSSHAgentForwarding
+		routeSSHAgentForwarding = oldRouteSSHAgentForwarding
+		requestSSHAgentForwarding = oldRequestSSHAgentForwarding
+	})
+
+	star := &StarSSH{
+		LoginInfo: LoginInput{
+			ForwardSSHAgent: true,
+		},
+	}
+	star.setTransport(&ssh.Client{}, nil)
+
+	newSSHSession = func(client *ssh.Client) (*ssh.Session, error) {
+		return &ssh.Session{}, nil
+	}
+	probeSSHAgentForwarding = func(timeout time.Duration) error {
+		return nil
+	}
+	routeSSHAgentForwarding = func(client *ssh.Client, timeout time.Duration) (io.Closer, error) {
+		return &testCloser{}, nil
+	}
+	requestSSHAgentForwarding = func(session *ssh.Session) error {
+		return errors.New("forwarding request denied")
+	}
+
+	if _, err := star.NewExecSession(); err != nil {
+		t.Fatalf("new exec session should ignore denied agent forwarding: %v", err)
+	}
+}
+
+func TestNewExecSessionIgnoresAgentForwardingUnavailable(t *testing.T) {
+	oldNewSSHSession := newSSHSession
+	oldProbeSSHAgentForwarding := probeSSHAgentForwarding
+	t.Cleanup(func() {
+		newSSHSession = oldNewSSHSession
+		probeSSHAgentForwarding = oldProbeSSHAgentForwarding
+	})
+
+	star := &StarSSH{
+		LoginInfo: LoginInput{
+			ForwardSSHAgent: true,
+		},
+	}
+	star.setTransport(&ssh.Client{}, nil)
+
+	newSSHSession = func(client *ssh.Client) (*ssh.Session, error) {
+		return &ssh.Session{}, nil
+	}
+	probeSSHAgentForwarding = func(timeout time.Duration) error {
+		return errors.New("ssh-agent forwarding unavailable: ssh-agent unavailable")
+	}
+
+	if _, err := star.NewExecSession(); err != nil {
+		t.Fatalf("new exec session should ignore unavailable agent forwarding: %v", err)
+	}
+}
+
+func TestNewExecSessionIgnoresAgentForwardingSetupError(t *testing.T) {
+	oldNewSSHSession := newSSHSession
+	oldProbeSSHAgentForwarding := probeSSHAgentForwarding
+	t.Cleanup(func() {
+		newSSHSession = oldNewSSHSession
+		probeSSHAgentForwarding = oldProbeSSHAgentForwarding
+	})
+
+	star := &StarSSH{
+		LoginInfo: LoginInput{
+			ForwardSSHAgent: true,
+		},
+	}
+	star.setTransport(&ssh.Client{}, nil)
+
+	newSSHSession = func(client *ssh.Client) (*ssh.Session, error) {
+		return &ssh.Session{}, nil
+	}
+	probeSSHAgentForwarding = func(timeout time.Duration) error {
+		return errors.New("dial unix /tmp/ssh-broken.sock: connect: connection refused")
+	}
+
+	if _, err := star.NewExecSession(); err != nil {
+		t.Fatalf("new exec session should ignore agent setup error: %v", err)
+	}
+}
+
+func TestEnsureAgentForwardingClosesNewForwarderWhenCloseStarts(t *testing.T) {
+	oldProbeSSHAgentForwarding := probeSSHAgentForwarding
+	oldRouteSSHAgentForwarding := routeSSHAgentForwarding
+	oldCloseSSHClient := closeSSHClient
+	t.Cleanup(func() {
+		probeSSHAgentForwarding = oldProbeSSHAgentForwarding
+		routeSSHAgentForwarding = oldRouteSSHAgentForwarding
+		closeSSHClient = oldCloseSSHClient
+	})
+
+	star := &StarSSH{
+		LoginInfo: LoginInput{
+			ForwardSSHAgent: true,
+		},
+	}
+	star.setTransport(&ssh.Client{}, nil)
+
+	started := make(chan struct{})
+	release := make(chan struct{})
+	closer := &testCloser{}
+	probeSSHAgentForwarding = func(timeout time.Duration) error {
+		return nil
+	}
+	routeSSHAgentForwarding = func(client *ssh.Client, timeout time.Duration) (io.Closer, error) {
+		close(started)
+		<-release
+		return closer, nil
+	}
+	closeSSHClient = func(client sshClientRequester) error { return nil }
+
+	errCh := make(chan error, 1)
+	go func() {
+		errCh <- star.ensureAgentForwarding()
+	}()
+
+	<-started
+	closeDone := make(chan struct{})
+	go func() {
+		_ = star.Close()
+		close(closeDone)
+	}()
+
+	deadline := time.Now().Add(time.Second)
+	for !star.closing.Load() {
+		if time.Now().After(deadline) {
+			t.Fatal("close did not enter closing state in time")
+		}
+		time.Sleep(time.Millisecond)
+	}
+
+	close(release)
+
+	err := <-errCh
+	if !errors.Is(err, errSSHClientClosing) {
+		t.Fatalf("expected closing error, got %v", err)
+	}
+	<-closeDone
+
+	if closer.closed.Load() != 1 {
+		t.Fatalf("expected new forwarder closer to be closed once, got %d", closer.closed.Load())
+	}
+	if got := star.takeAgentForwarder(); got != nil {
+		t.Fatal("expected no leaked agent forwarder after close race")
+	}
+}
+
+func TestProxySSHAgentChannelClosesBlockedAgentConnWhenRemoteChannelEnds(t *testing.T) {
+	agentConn, peerConn := net.Pipe()
+	defer peerConn.Close()
+
+	tracked := &trackedConn{Conn: agentConn}
+	channel := newTestSSHChannel(func(p []byte) (int, error) {
+		return 0, io.EOF
+	})
+
+	done := make(chan struct{})
+	go func() {
+		proxySSHAgentChannel(channel, tracked)
+		close(done)
+	}()
+
+	select {
+	case <-done:
+	case <-time.After(time.Second):
+		t.Fatal("proxySSHAgentChannel did not exit after remote EOF")
+	}
+
+	if tracked.closed.Load() == 0 {
+		t.Fatal("expected local agent connection to be closed")
+	}
+	if channel.closed.Load() == 0 {
+		t.Fatal("expected ssh channel to be closed")
+	}
+}
+
+func TestSSHAgentForwardProxyCloseClosesActiveBridges(t *testing.T) {
+	agentConn, peerConn := net.Pipe()
+	defer peerConn.Close()
+
+	tracked := &trackedConn{Conn: agentConn}
+	channel := newBlockingTestSSHChannel()
+	proxy := &sshAgentForwardProxy{
+		stopCh: make(chan struct{}),
+		active: make(map[*sshAgentForwardBridge]struct{}),
+	}
+	bridge := &sshAgentForwardBridge{
+		proxy:   proxy,
+		channel: channel,
+		conn:    tracked,
+	}
+	if !proxy.registerBridge(bridge) {
+		t.Fatal("expected bridge registration to succeed")
+	}
+
+	done := make(chan struct{})
+	go func() {
+		bridge.run()
+		close(done)
+	}()
+
+	if err := proxy.Close(); err != nil {
+		t.Fatalf("close proxy: %v", err)
+	}
+
+	select {
+	case <-done:
+	case <-time.After(time.Second):
+		t.Fatal("bridge did not exit after proxy close")
+	}
+
+	if tracked.closed.Load() == 0 {
+		t.Fatal("expected proxy close to close local agent connection")
+	}
+	if channel.closed.Load() == 0 {
+		t.Fatal("expected proxy close to close ssh channel")
+	}
+}

forward.go

@@ -3,21 +3,39 @@ package starssh
 import (
 	"context"
 	"errors"
+	"fmt"
 	"io"
 	"net"
+	"os"
 	"strconv"
 	"strings"
 	"sync"
+	"syscall"
+	"time"
 
 	"golang.org/x/crypto/ssh"
 )
 
 type ForwardRequest struct {
+	// Keep the exported shape compatible with older positional literals:
+	// ForwardRequest{listenAddr, targetAddr, dialContext}.
+	//
+	// Non-default networks can be encoded with an explicit scheme-like prefix:
+	// "tcp4://127.0.0.1:22", "tcp6://[::1]:22", "unix:///tmp/socket".
+	// Bare values default to the "tcp" network.
 	ListenAddr  string
 	TargetAddr  string
 	DialContext DialContextFunc
 }
 
+type normalizedForwardRequest struct {
+	ListenNetwork string
+	ListenAddr    string
+	TargetNetwork string
+	TargetAddr    string
+	DialContext   DialContextFunc
+}
+
 type DynamicForwardRequest struct {
 	ListenAddr string
 }
@@ -41,10 +59,16 @@ type PortForwarder struct {
 	cleanupFns  []func() error
 }
 
+const unixForwardProbeTimeout = 200 * time.Millisecond
+
 var dialSSHClient = func(ctx context.Context, client *ssh.Client, network, address string) (net.Conn, error) {
 	return client.Dial(network, address)
 }
 
+var listenSSHClient = func(client *ssh.Client, network, address string) (net.Listener, error) {
+	return client.Listen(network, address)
+}
+
 var newDetachedForwardClient = func(ctx context.Context, input LoginInput) (*StarSSH, error) {
 	if ctx == nil {
 		ctx = context.Background()
@@ -64,6 +88,90 @@ func (s *StarSSH) DialTCPContextCloseOnCancel(ctx context.Context, network strin
 	return s.dialTCPContext(ctx, network, address, s.Close)
 }
 
+func (s *StarSSH) StartLocalTCPForward(listenAddr string, targetAddr string) (*PortForwarder, error) {
+	return s.StartLocalForward(ForwardRequest{
+		ListenAddr: listenAddr,
+		TargetAddr: targetAddr,
+	})
+}
+
+func (s *StarSSH) StartLocalTCPForwardDetached(listenAddr string, targetAddr string) (*PortForwarder, error) {
+	return s.StartLocalForwardDetached(ForwardRequest{
+		ListenAddr: listenAddr,
+		TargetAddr: targetAddr,
+	})
+}
+
+func (s *StarSSH) StartLocalTCPToUnixForward(listenAddr string, targetPath string) (*PortForwarder, error) {
+	return s.StartLocalForward(ForwardRequest{
+		ListenAddr: listenAddr,
+		TargetAddr: forwardEndpoint("unix", targetPath),
+	})
+}
+
+func (s *StarSSH) StartLocalTCPToUnixForwardDetached(listenAddr string, targetPath string) (*PortForwarder, error) {
+	return s.StartLocalForwardDetached(ForwardRequest{
+		ListenAddr: listenAddr,
+		TargetAddr: forwardEndpoint("unix", targetPath),
+	})
+}
+
+func (s *StarSSH) StartLocalUnixForward(listenPath string, targetAddr string) (*PortForwarder, error) {
+	return s.StartLocalForward(ForwardRequest{
+		ListenAddr: forwardEndpoint("unix", listenPath),
+		TargetAddr: targetAddr,
+	})
+}
+
+func (s *StarSSH) StartLocalUnixForwardDetached(listenPath string, targetAddr string) (*PortForwarder, error) {
+	return s.StartLocalForwardDetached(ForwardRequest{
+		ListenAddr: forwardEndpoint("unix", listenPath),
+		TargetAddr: targetAddr,
+	})
+}
+
+func (s *StarSSH) StartLocalUnixToUnixForward(listenPath string, targetPath string) (*PortForwarder, error) {
+	return s.StartLocalForward(ForwardRequest{
+		ListenAddr: forwardEndpoint("unix", listenPath),
+		TargetAddr: forwardEndpoint("unix", targetPath),
+	})
+}
+
+func (s *StarSSH) StartLocalUnixToUnixForwardDetached(listenPath string, targetPath string) (*PortForwarder, error) {
+	return s.StartLocalForwardDetached(ForwardRequest{
+		ListenAddr: forwardEndpoint("unix", listenPath),
+		TargetAddr: forwardEndpoint("unix", targetPath),
+	})
+}
+
+func (s *StarSSH) StartRemoteTCPForward(listenAddr string, targetAddr string) (*PortForwarder, error) {
+	return s.StartRemoteForward(ForwardRequest{
+		ListenAddr: listenAddr,
+		TargetAddr: targetAddr,
+	})
+}
+
+func (s *StarSSH) StartRemoteTCPToUnixForward(listenAddr string, targetPath string) (*PortForwarder, error) {
+	return s.StartRemoteForward(ForwardRequest{
+		ListenAddr: listenAddr,
+		TargetAddr: forwardEndpoint("unix", targetPath),
+	})
+}
+
+func (s *StarSSH) StartRemoteUnixForward(listenPath string, targetAddr string) (*PortForwarder, error) {
+	return s.StartRemoteForward(ForwardRequest{
+		ListenAddr: forwardEndpoint("unix", listenPath),
+		TargetAddr: targetAddr,
+	})
+}
+
+func (s *StarSSH) StartRemoteUnixToUnixForward(listenPath string, targetPath string) (*PortForwarder, error) {
+	return s.StartRemoteForward(ForwardRequest{
+		ListenAddr: forwardEndpoint("unix", listenPath),
+		TargetAddr: forwardEndpoint("unix", targetPath),
+	})
+}
+
 func (s *StarSSH) dialTCPContext(ctx context.Context, network string, address string, onCancel func() error) (net.Conn, error) {
 	if ctx == nil {
 		ctx = context.Background()
@@ -136,21 +244,22 @@ func (s *StarSSH) StartLocalForward(req ForwardRequest) (*PortForwarder, error)
 	if _, err := s.requireSSHClient(); err != nil {
 		return nil, err
 	}
-	if strings.TrimSpace(req.ListenAddr) == "" {
+	normalizedReq, err := normalizeForwardRequest(req)
+	if err != nil {
+		return nil, err
+	}
+	if strings.TrimSpace(normalizedReq.ListenAddr) == "" {
 		return nil, errors.New("local forward listen address is empty")
 	}
-	if strings.TrimSpace(req.TargetAddr) == "" {
-		return nil, errors.New("local forward target address is empty")
-	}
-
-	listener, err := net.Listen("tcp", req.ListenAddr)
+	listener, cleanup, err := prepareLocalForwardListener(normalizedReq.ListenNetwork, normalizedReq.ListenAddr)
 	if err != nil {
 		return nil, err
 	}
 
 	forwarder := newPortForwarder(listener)
+	forwarder.addCleanup(cleanup)
 	forwarder.serve(func(ctx context.Context) (net.Conn, error) {
-		return s.DialTCPContext(ctx, "tcp", req.TargetAddr)
+		return s.DialTCPContext(ctx, normalizedReq.TargetNetwork, normalizedReq.TargetAddr)
 	})
 	return forwarder, nil
 }
@@ -159,14 +268,12 @@ func (s *StarSSH) StartLocalForwardDetached(req ForwardRequest) (*PortForwarder,
 	if _, err := s.requireSSHClient(); err != nil {
 		return nil, err
 	}
-	if strings.TrimSpace(req.ListenAddr) == "" {
-		return nil, errors.New("local forward listen address is empty")
-	}
-	if strings.TrimSpace(req.TargetAddr) == "" {
-		return nil, errors.New("local forward target address is empty")
+	normalizedReq, err := normalizeForwardRequest(req)
+	if err != nil {
+		return nil, err
 	}
 
-	listener, err := net.Listen("tcp", req.ListenAddr)
+	listener, cleanup, err := prepareLocalForwardListener(normalizedReq.ListenNetwork, normalizedReq.ListenAddr)
 	if err != nil {
 		return nil, err
 	}
@@ -174,15 +281,19 @@ func (s *StarSSH) StartLocalForwardDetached(req ForwardRequest) (*PortForwarder,
 	forwardClient, err := s.newForwardDialClient(context.Background())
 	if err != nil {
 		_ = listener.Close()
+		if cleanup != nil {
+			_ = cleanup()
+		}
 		return nil, err
 	}
 
 	forwarder := newPortForwarder(listener)
+	forwarder.addCleanup(cleanup)
 	forwarder.addCleanup(func() error {
 		return normalizeAlreadyClosedError(forwardClient.Close())
 	})
 	forwarder.serve(func(ctx context.Context) (net.Conn, error) {
-		return forwardClient.DialTCPContext(ctx, "tcp", req.TargetAddr)
+		return forwardClient.DialTCPContext(ctx, normalizedReq.TargetNetwork, normalizedReq.TargetAddr)
 	})
 	return forwarder, nil
 }
@@ -192,19 +303,17 @@ func (s *StarSSH) StartRemoteForward(req ForwardRequest) (*PortForwarder, error)
 	if err != nil {
 		return nil, err
 	}
-	if strings.TrimSpace(req.ListenAddr) == "" {
-		return nil, errors.New("remote forward listen address is empty")
-	}
-	if strings.TrimSpace(req.TargetAddr) == "" {
-		return nil, errors.New("remote forward target address is empty")
-	}
-
-	listener, err := client.Listen("tcp", req.ListenAddr)
+	normalizedReq, err := normalizeForwardRequest(req)
 	if err != nil {
 		return nil, err
 	}
 
-	dialContext := req.DialContext
+	listener, err := listenSSHClient(client, normalizedReq.ListenNetwork, normalizedReq.ListenAddr)
+	if err != nil {
+		return nil, err
+	}
+
+	dialContext := normalizedReq.DialContext
 	if dialContext == nil {
 		dialer := &net.Dialer{
 			Timeout: defaultLoginTimeout,
@@ -214,7 +323,7 @@ func (s *StarSSH) StartRemoteForward(req ForwardRequest) (*PortForwarder, error)
 
 	forwarder := newPortForwarder(listener)
 	forwarder.serve(func(ctx context.Context) (net.Conn, error) {
-		return dialContext(ctx, "tcp", req.TargetAddr)
+		return dialContext(ctx, normalizedReq.TargetNetwork, normalizedReq.TargetAddr)
 	})
 	return forwarder, nil
 }
@@ -239,6 +348,74 @@ func (s *StarSSH) StartDynamicForward(req DynamicForwardRequest) (*PortForwarder
 	return forwarder, nil
 }
 
+func normalizeForwardRequest(req ForwardRequest) (normalizedForwardRequest, error) {
+	normalized := normalizedForwardRequest{
+		DialContext: req.DialContext,
+	}
+
+	var err error
+	normalized.ListenNetwork, normalized.ListenAddr, err = parseForwardEndpoint(req.ListenAddr)
+	if err != nil {
+		return normalized, fmt.Errorf("normalize listen address: %w", err)
+	}
+	normalized.TargetNetwork, normalized.TargetAddr, err = parseForwardEndpoint(req.TargetAddr)
+	if err != nil {
+		return normalized, fmt.Errorf("normalize target address: %w", err)
+	}
+	if strings.TrimSpace(normalized.ListenAddr) == "" {
+		return normalized, errors.New("forward listen address is empty")
+	}
+	if strings.TrimSpace(normalized.TargetAddr) == "" {
+		return normalized, errors.New("forward target address is empty")
+	}
+	return normalized, nil
+}
+
+func normalizeForwardNetwork(network string) string {
+	network = strings.ToLower(strings.TrimSpace(network))
+	if network == "" {
+		return "tcp"
+	}
+	return network
+}
+
+func isSupportedForwardNetwork(network string) bool {
+	switch network {
+	case "tcp", "tcp4", "tcp6", "unix":
+		return true
+	default:
+		return false
+	}
+}
+
+func parseForwardEndpoint(value string) (network string, address string, err error) {
+	value = strings.TrimSpace(value)
+	if value == "" {
+		return "tcp", "", nil
+	}
+
+	lowerValue := strings.ToLower(value)
+	for _, prefix := range []string{"tcp4://", "tcp6://", "tcp://", "unix://"} {
+		if strings.HasPrefix(lowerValue, prefix) {
+			network = normalizeForwardNetwork(strings.TrimSuffix(prefix, "://"))
+			address = value[len(prefix):]
+			if !isSupportedForwardNetwork(network) {
+				return "", "", fmt.Errorf("unsupported forward network %q", network)
+			}
+			return network, address, nil
+		}
+	}
+	return "tcp", value, nil
+}
+
+func forwardEndpoint(network string, address string) string {
+	network = normalizeForwardNetwork(network)
+	if network == "tcp" {
+		return address
+	}
+	return network + "://" + address
+}
+
 func (s *StarSSH) StartDynamicForwardDetached(req DynamicForwardRequest) (*PortForwarder, error) {
 	if _, err := s.requireSSHClient(); err != nil {
 		return nil, err
@@ -344,6 +521,87 @@ func (f *PortForwarder) addCleanup(fn func() error) {
 	f.cleanupFns = append(f.cleanupFns, fn)
 }
 
+func prepareLocalForwardListener(network string, address string) (net.Listener, func() error, error) {
+	network = normalizeForwardNetwork(network)
+	if network != "unix" {
+		listener, err := net.Listen(network, address)
+		return listener, nil, err
+	}
+
+	if err := removeStaleUnixSocket(address); err != nil {
+		return nil, nil, err
+	}
+
+	listener, err := net.Listen(network, address)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	cleanup, err := makeUnixSocketCleanup(address)
+	if err != nil {
+		_ = listener.Close()
+		_ = removeUnixSocketPath(address)
+		return nil, nil, err
+	}
+	return listener, cleanup, nil
+}
+
+func removeStaleUnixSocket(path string) error {
+	info, err := os.Lstat(path)
+	if errors.Is(err, os.ErrNotExist) {
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+	if info.Mode()&os.ModeSocket == 0 {
+		return fmt.Errorf("local unix forward path %q already exists and is not a socket", path)
+	}
+
+	conn, err := net.DialTimeout("unix", path, unixForwardProbeTimeout)
+	if err == nil {
+		_ = conn.Close()
+		return fmt.Errorf("local unix forward path %q is already in use", path)
+	}
+	if !isStaleUnixSocketDialError(err) {
+		return fmt.Errorf("probe existing unix socket %q: %w", path, err)
+	}
+	return removeUnixSocketPath(path)
+}
+
+func isStaleUnixSocketDialError(err error) bool {
+	return errors.Is(err, syscall.ECONNREFUSED) || errors.Is(err, syscall.ENOENT)
+}
+
+func makeUnixSocketCleanup(path string) (func() error, error) {
+	info, err := os.Lstat(path)
+	if err != nil {
+		return nil, err
+	}
+
+	return func() error {
+		current, err := os.Lstat(path)
+		if errors.Is(err, os.ErrNotExist) {
+			return nil
+		}
+		if err != nil {
+			return err
+		}
+		if current.Mode()&os.ModeSocket == 0 || !os.SameFile(info, current) {
+			return nil
+		}
+		return removeUnixSocketPath(path)
+	}, nil
+}
+
+func removeUnixSocketPath(path string) error {
+	err := os.Remove(path)
+	if errors.Is(err, os.ErrNotExist) {
+		return nil
+	}
+	return err
+}
+
 func (f *PortForwarder) runCleanup() {
 	if f == nil {
 		return

forward_test.go

@@ -2,8 +2,13 @@ package starssh
 
 import (
 	"context"
+	"errors"
 	"io"
 	"net"
+	"os"
+	"path/filepath"
+	"runtime"
+	"sync"
 	"sync/atomic"
 	"testing"
 	"time"
@@ -11,6 +16,59 @@ import (
 	"golang.org/x/crypto/ssh"
 )
 
+type stubListener struct {
+	addr      net.Addr
+	acceptCh  chan net.Conn
+	closeCh   chan struct{}
+	closeOnce sync.Once
+}
+
+type dialRecord struct {
+	network string
+	addr    string
+}
+
+func newStubListener(addr net.Addr) *stubListener {
+	return &stubListener{
+		addr:     addr,
+		acceptCh: make(chan net.Conn, 1),
+		closeCh:  make(chan struct{}),
+	}
+}
+
+func (l *stubListener) Accept() (net.Conn, error) {
+	select {
+	case conn, ok := <-l.acceptCh:
+		if !ok {
+			return nil, io.EOF
+		}
+		return conn, nil
+	case <-l.closeCh:
+		return nil, net.ErrClosed
+	}
+}
+
+func (l *stubListener) Close() error {
+	l.closeOnce.Do(func() {
+		close(l.closeCh)
+		close(l.acceptCh)
+	})
+	return nil
+}
+
+func (l *stubListener) Addr() net.Addr {
+	return l.addr
+}
+
+func (l *stubListener) Push(conn net.Conn) error {
+	select {
+	case <-l.closeCh:
+		return net.ErrClosed
+	case l.acceptCh <- conn:
+		return nil
+	}
+}
+
 func TestStartLocalForwardUsesExistingConnectionByDefault(t *testing.T) {
 	oldDialSSHClient := dialSSHClient
 	oldNewDetachedForwardClient := newDetachedForwardClient
@@ -63,6 +121,64 @@ func TestStartLocalForwardUsesExistingConnectionByDefault(t *testing.T) {
 	}
 }
 
+func TestForwardRequestLegacyPositionalLiteralDefaultsToTCP(t *testing.T) {
+	dialer := func(ctx context.Context, network, address string) (net.Conn, error) {
+		return nil, nil
+	}
+
+	req, err := normalizeForwardRequest(ForwardRequest{
+		"127.0.0.1:10022",
+		"example.internal:22",
+		dialer,
+	})
+	if err != nil {
+		t.Fatalf("normalizeForwardRequest: %v", err)
+	}
+	if req.ListenNetwork != "tcp" {
+		t.Fatalf("ListenNetwork=%q want tcp", req.ListenNetwork)
+	}
+	if req.TargetNetwork != "tcp" {
+		t.Fatalf("TargetNetwork=%q want tcp", req.TargetNetwork)
+	}
+	if req.ListenAddr != "127.0.0.1:10022" || req.TargetAddr != "example.internal:22" {
+		t.Fatalf("unexpected normalized request: %+v", req)
+	}
+	if req.DialContext == nil {
+		t.Fatal("expected DialContext to be preserved")
+	}
+}
+
+func TestParseForwardEndpointTreatsTCPPrefixLikePlainAddress(t *testing.T) {
+	network, address, err := parseForwardEndpoint("tcp:22")
+	if err != nil {
+		t.Fatalf("parseForwardEndpoint: %v", err)
+	}
+	if network != "tcp" {
+		t.Fatalf("network=%q want tcp", network)
+	}
+	if address != "tcp:22" {
+		t.Fatalf("address=%q want tcp:22", address)
+	}
+}
+
+func TestParseForwardEndpointSupportsExplicitSchemes(t *testing.T) {
+	network, address, err := parseForwardEndpoint("unix:///tmp/test-forward.sock")
+	if err != nil {
+		t.Fatalf("parseForwardEndpoint unix: %v", err)
+	}
+	if network != "unix" || address != "/tmp/test-forward.sock" {
+		t.Fatalf("unexpected unix endpoint parse: network=%q address=%q", network, address)
+	}
+
+	network, address, err = parseForwardEndpoint("tcp6://[::1]:2222")
+	if err != nil {
+		t.Fatalf("parseForwardEndpoint tcp6: %v", err)
+	}
+	if network != "tcp6" || address != "[::1]:2222" {
+		t.Fatalf("unexpected tcp6 endpoint parse: network=%q address=%q", network, address)
+	}
+}
+
 func TestStartLocalForwardDetachedUsesSeparateConnection(t *testing.T) {
 	oldDialSSHClient := dialSSHClient
 	oldNewDetachedForwardClient := newDetachedForwardClient
@@ -132,6 +248,424 @@ func TestStartLocalForwardDetachedUsesSeparateConnection(t *testing.T) {
 	}
 }
 
+func TestStartRemoteForwardSupportsUnixListenAndTCPTarget(t *testing.T) {
+	oldListenSSHClient := listenSSHClient
+	t.Cleanup(func() {
+		listenSSHClient = oldListenSSHClient
+	})
+
+	baseClient := &ssh.Client{}
+	star := &StarSSH{}
+	star.setTransport(baseClient, nil)
+
+	listener := newStubListener(&net.UnixAddr{
+		Name: "/run/user/0/gnupg/S.gpg-agent",
+		Net:  "unix",
+	})
+
+	var listenedNetwork string
+	var listenedAddr string
+	listenSSHClient = func(client *ssh.Client, network, address string) (net.Listener, error) {
+		if client != baseClient {
+			t.Fatalf("unexpected ssh client %p", client)
+		}
+		listenedNetwork = network
+		listenedAddr = address
+		return listener, nil
+	}
+
+	var targetNetwork string
+	var targetAddr string
+	forwarder, err := star.StartRemoteForward(ForwardRequest{
+		ListenAddr: forwardEndpoint("unix", "/run/user/0/gnupg/S.gpg-agent"),
+		TargetAddr: "127.0.0.1:4321",
+		DialContext: func(ctx context.Context, network, address string) (net.Conn, error) {
+			targetNetwork = network
+			targetAddr = address
+			serverConn, clientConn := net.Pipe()
+			go echoForwardPipe(serverConn)
+			return clientConn, nil
+		},
+	})
+	if err != nil {
+		t.Fatalf("start remote unix forward: %v", err)
+	}
+	defer forwarder.Close()
+
+	srcPeer, forwardedConn := net.Pipe()
+	defer srcPeer.Close()
+	if err := listener.Push(forwardedConn); err != nil {
+		t.Fatalf("push forwarded connection: %v", err)
+	}
+
+	payload := []byte("unix-forward")
+	done := make(chan []byte, 1)
+	go func() {
+		reply := make([]byte, len(payload))
+		_, _ = io.ReadFull(srcPeer, reply)
+		done <- reply
+	}()
+
+	if _, err := srcPeer.Write(payload); err != nil {
+		t.Fatalf("write source payload: %v", err)
+	}
+
+	select {
+	case reply := <-done:
+		if string(reply) != string(payload) {
+			t.Fatalf("unexpected remote unix forward reply: %q", string(reply))
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("remote unix forward did not relay payload")
+	}
+
+	if listenedNetwork != "unix" || listenedAddr != "/run/user/0/gnupg/S.gpg-agent" {
+		t.Fatalf("unexpected remote listen request: network=%q addr=%q", listenedNetwork, listenedAddr)
+	}
+	if targetNetwork != "tcp" || targetAddr != "127.0.0.1:4321" {
+		t.Fatalf("unexpected local dial target: network=%q addr=%q", targetNetwork, targetAddr)
+	}
+}
+
+func TestStartLocalUnixForwardUsesUnixListenerAndTCPTarget(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("unix socket smoke test is exercised in WSL/Linux CI path")
+	}
+
+	oldDialSSHClient := dialSSHClient
+	t.Cleanup(func() {
+		dialSSHClient = oldDialSSHClient
+	})
+
+	baseClient := &ssh.Client{}
+	star := &StarSSH{}
+	star.setTransport(baseClient, nil)
+
+	var targetNetwork string
+	var targetAddr string
+	dialSSHClient = func(ctx context.Context, client *ssh.Client, network, address string) (net.Conn, error) {
+		if client != baseClient {
+			t.Fatalf("unexpected ssh client %p", client)
+		}
+		targetNetwork = network
+		targetAddr = address
+		serverConn, clientConn := net.Pipe()
+		go echoForwardPipe(serverConn)
+		return clientConn, nil
+	}
+
+	socketPath := filepath.Join(t.TempDir(), "forward.sock")
+	forwarder, err := star.StartLocalUnixForward(socketPath, "127.0.0.1:4321")
+	if err != nil {
+		t.Fatalf("start local unix forward: %v", err)
+	}
+	defer func() {
+		closeErr := forwarder.Close()
+		if closeErr != nil && !errors.Is(closeErr, net.ErrClosed) {
+			t.Fatalf("close local unix forward: %v", closeErr)
+		}
+	}()
+
+	conn, err := net.DialTimeout("unix", socketPath, time.Second)
+	if err != nil {
+		t.Fatalf("dial unix forward listener: %v", err)
+	}
+	defer conn.Close()
+	_ = conn.SetDeadline(time.Now().Add(2 * time.Second))
+
+	payload := []byte("unix-local-forward")
+	if _, err := conn.Write(payload); err != nil {
+		t.Fatalf("write unix forward payload: %v", err)
+	}
+	reply := make([]byte, len(payload))
+	if _, err := io.ReadFull(conn, reply); err != nil {
+		t.Fatalf("read unix forward reply: %v", err)
+	}
+	if string(reply) != string(payload) {
+		t.Fatalf("unexpected unix forward reply: %q", string(reply))
+	}
+	if targetNetwork != "tcp" || targetAddr != "127.0.0.1:4321" {
+		t.Fatalf("unexpected remote dial target: network=%q addr=%q", targetNetwork, targetAddr)
+	}
+}
+
+func TestStartLocalUnixForwardRemovesSocketOnClose(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("unix socket smoke test is exercised in WSL/Linux CI path")
+	}
+
+	oldDialSSHClient := dialSSHClient
+	t.Cleanup(func() {
+		dialSSHClient = oldDialSSHClient
+	})
+
+	baseClient := &ssh.Client{}
+	star := &StarSSH{}
+	star.setTransport(baseClient, nil)
+
+	dialSSHClient = func(ctx context.Context, client *ssh.Client, network, address string) (net.Conn, error) {
+		serverConn, clientConn := net.Pipe()
+		go echoForwardPipe(serverConn)
+		return clientConn, nil
+	}
+
+	socketPath := filepath.Join(t.TempDir(), "cleanup.sock")
+	forwarder, err := star.StartLocalUnixForward(socketPath, "127.0.0.1:4321")
+	if err != nil {
+		t.Fatalf("start local unix forward: %v", err)
+	}
+
+	if _, err := os.Lstat(socketPath); err != nil {
+		t.Fatalf("socket should exist while forward is running: %v", err)
+	}
+	if err := forwarder.Close(); err != nil && !errors.Is(err, net.ErrClosed) {
+		t.Fatalf("close local unix forward: %v", err)
+	}
+	if _, err := os.Lstat(socketPath); !errors.Is(err, os.ErrNotExist) {
+		t.Fatalf("socket path should be removed on close, got err=%v", err)
+	}
+}
+
+func TestStartLocalUnixForwardReusesStaleSocketPath(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("unix socket smoke test is exercised in WSL/Linux CI path")
+	}
+
+	oldDialSSHClient := dialSSHClient
+	t.Cleanup(func() {
+		dialSSHClient = oldDialSSHClient
+	})
+
+	baseClient := &ssh.Client{}
+	star := &StarSSH{}
+	star.setTransport(baseClient, nil)
+
+	dialSSHClient = func(ctx context.Context, client *ssh.Client, network, address string) (net.Conn, error) {
+		serverConn, clientConn := net.Pipe()
+		go echoForwardPipe(serverConn)
+		return clientConn, nil
+	}
+
+	socketPath := filepath.Join(t.TempDir(), "stale.sock")
+	staleListener, err := net.ListenUnix("unix", &net.UnixAddr{
+		Name: socketPath,
+		Net:  "unix",
+	})
+	if err != nil {
+		t.Fatalf("create stale unix socket: %v", err)
+	}
+	staleListener.SetUnlinkOnClose(false)
+	if err := staleListener.Close(); err != nil {
+		t.Fatalf("close stale unix socket listener: %v", err)
+	}
+	if _, err := os.Lstat(socketPath); err != nil {
+		t.Fatalf("expected stale unix socket path to remain after close: %v", err)
+	}
+
+	forwarder, err := star.StartLocalUnixForward(socketPath, "127.0.0.1:4321")
+	if err != nil {
+		t.Fatalf("start local unix forward on stale socket path: %v", err)
+	}
+	defer func() {
+		closeErr := forwarder.Close()
+		if closeErr != nil && !errors.Is(closeErr, net.ErrClosed) {
+			t.Fatalf("close local unix forward: %v", closeErr)
+		}
+	}()
+
+	reply := make([]byte, len("stale-reuse"))
+	conn, err := net.DialTimeout("unix", socketPath, time.Second)
+	if err != nil {
+		t.Fatalf("dial reused unix forward listener: %v", err)
+	}
+	defer conn.Close()
+	_ = conn.SetDeadline(time.Now().Add(2 * time.Second))
+	if _, err := conn.Write([]byte("stale-reuse")); err != nil {
+		t.Fatalf("write reused unix forward payload: %v", err)
+	}
+	if _, err := io.ReadFull(conn, reply); err != nil {
+		t.Fatalf("read reused unix forward reply: %v", err)
+	}
+	if string(reply) != "stale-reuse" {
+		t.Fatalf("unexpected reply on reused unix forward: %q", string(reply))
+	}
+}
+
+func TestStartLocalUnixToUnixForwardUsesUnixTarget(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("unix socket smoke test is exercised in WSL/Linux CI path")
+	}
+
+	oldDialSSHClient := dialSSHClient
+	t.Cleanup(func() {
+		dialSSHClient = oldDialSSHClient
+	})
+
+	baseClient := &ssh.Client{}
+	star := &StarSSH{}
+	star.setTransport(baseClient, nil)
+
+	targetSocketPath := filepath.Join(t.TempDir(), "target.sock")
+	targetListener, err := net.Listen("unix", targetSocketPath)
+	if err != nil {
+		t.Fatalf("listen target unix socket: %v", err)
+	}
+	defer targetListener.Close()
+
+	done := make(chan []byte, 1)
+	go func() {
+		conn, acceptErr := targetListener.Accept()
+		if acceptErr != nil {
+			done <- nil
+			return
+		}
+		defer conn.Close()
+		buf := make([]byte, 64)
+		n, _ := conn.Read(buf)
+		_, _ = conn.Write(buf[:n])
+		done <- buf[:n]
+	}()
+
+	dialRecordCh := make(chan dialRecord, 1)
+	dialSSHClient = func(ctx context.Context, client *ssh.Client, network, address string) (net.Conn, error) {
+		if client != baseClient {
+			t.Fatalf("unexpected ssh client %p", client)
+		}
+		dialRecordCh <- dialRecord{network: network, addr: address}
+		var dialer net.Dialer
+		return dialer.DialContext(ctx, network, address)
+	}
+
+	listenSocketPath := filepath.Join(t.TempDir(), "listen.sock")
+	forwarder, err := star.StartLocalUnixToUnixForward(listenSocketPath, targetSocketPath)
+	if err != nil {
+		t.Fatalf("start local unix-to-unix forward: %v", err)
+	}
+	defer func() {
+		closeErr := forwarder.Close()
+		if closeErr != nil && !errors.Is(closeErr, net.ErrClosed) {
+			t.Fatalf("close local unix-to-unix forward: %v", closeErr)
+		}
+	}()
+
+	conn, err := net.DialTimeout("unix", listenSocketPath, time.Second)
+	if err != nil {
+		t.Fatalf("dial unix-to-unix listener: %v", err)
+	}
+	defer conn.Close()
+	_ = conn.SetDeadline(time.Now().Add(2 * time.Second))
+
+	payload := []byte("unix-to-unix")
+	if _, err := conn.Write(payload); err != nil {
+		t.Fatalf("write unix-to-unix payload: %v", err)
+	}
+	reply := make([]byte, len(payload))
+	if _, err := io.ReadFull(conn, reply); err != nil {
+		t.Fatalf("read unix-to-unix reply: %v", err)
+	}
+	if string(reply) != string(payload) {
+		t.Fatalf("unexpected unix-to-unix reply: %q", string(reply))
+	}
+
+	select {
+	case got := <-done:
+		if string(got) != string(payload) {
+			t.Fatalf("unexpected payload seen by target unix socket: %q", string(got))
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("target unix socket did not receive forwarded payload")
+	}
+
+	select {
+	case got := <-dialRecordCh:
+		if got.network != "unix" || got.addr != targetSocketPath {
+			t.Fatalf("unexpected unix target dial: network=%q addr=%q", got.network, got.addr)
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("did not observe unix target dial")
+	}
+}
+
+func TestStartLocalTCPToUnixForwardUsesUnixTarget(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("unix socket smoke test is exercised in WSL/Linux CI path")
+	}
+
+	oldDialSSHClient := dialSSHClient
+	t.Cleanup(func() {
+		dialSSHClient = oldDialSSHClient
+	})
+
+	baseClient := &ssh.Client{}
+	star := &StarSSH{}
+	star.setTransport(baseClient, nil)
+
+	targetSocketPath := filepath.Join(t.TempDir(), "target-tcp-to-unix.sock")
+	targetListener, err := net.Listen("unix", targetSocketPath)
+	if err != nil {
+		t.Fatalf("listen target unix socket: %v", err)
+	}
+	defer targetListener.Close()
+
+	done := make(chan []byte, 1)
+	go func() {
+		conn, acceptErr := targetListener.Accept()
+		if acceptErr != nil {
+			done <- nil
+			return
+		}
+		defer conn.Close()
+		buf := make([]byte, 64)
+		n, _ := conn.Read(buf)
+		_, _ = conn.Write(buf[:n])
+		done <- buf[:n]
+	}()
+
+	dialRecordCh := make(chan dialRecord, 1)
+	dialSSHClient = func(ctx context.Context, client *ssh.Client, network, address string) (net.Conn, error) {
+		if client != baseClient {
+			t.Fatalf("unexpected ssh client %p", client)
+		}
+		dialRecordCh <- dialRecord{network: network, addr: address}
+		var dialer net.Dialer
+		return dialer.DialContext(ctx, network, address)
+	}
+
+	forwarder, err := star.StartLocalTCPToUnixForward("127.0.0.1:0", targetSocketPath)
+	if err != nil {
+		t.Fatalf("start local tcp-to-unix forward: %v", err)
+	}
+	defer func() {
+		closeErr := forwarder.Close()
+		if closeErr != nil && !errors.Is(closeErr, net.ErrClosed) {
+			t.Fatalf("close local tcp-to-unix forward: %v", closeErr)
+		}
+	}()
+
+	reply := exerciseForwarder(t, forwarder.Addr().String(), []byte("tcp-to-unix"))
+	if string(reply) != "tcp-to-unix" {
+		t.Fatalf("unexpected tcp-to-unix reply: %q", string(reply))
+	}
+
+	select {
+	case got := <-done:
+		if string(got) != "tcp-to-unix" {
+			t.Fatalf("unexpected payload seen by unix target: %q", string(got))
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("unix target did not receive forwarded tcp payload")
+	}
+
+	select {
+	case got := <-dialRecordCh:
+		if got.network != "unix" || got.addr != targetSocketPath {
+			t.Fatalf("unexpected unix target dial: network=%q addr=%q", got.network, got.addr)
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("did not observe unix target dial")
+	}
+}
+
 func echoForwardPipe(conn net.Conn) {
 	defer conn.Close()
 	buf := make([]byte, 4096)

login.go

@@ -16,6 +16,7 @@ import (
 
 var ErrHostKeyCallbackRequired = errors.New("host key callback is required; use DefaultAllowHostKeyCallback to explicitly allow any host key")
 var errSSHAgentUnavailable = errors.New("ssh-agent unavailable")
+var buildSSHAgentAuthMethodFunc = buildSSHAgentAuthMethod
 
 var defaultAuthOrder = []AuthMethodKind{
 	AuthMethodSSHAgent,
@@ -42,7 +43,8 @@ func loginWithContext(ctx context.Context, info LoginInput) (*StarSSH, error) {
 		return nil, ErrHostKeyCallbackRequired
 	}
 
-	loginCtx, cancel := contextWithLoginTimeout(ctx, info.Timeout)
+	authTimeout := effectiveLoginTimeout(info)
+	loginCtx, cancel := contextWithLoginTimeout(ctx, authTimeout)
 	defer cancel()
 
 	sshInfo := &StarSSH{
@@ -76,7 +78,7 @@ func loginWithContext(ctx context.Context, info LoginInput) (*StarSSH, error) {
 	clientConfig := &ssh.ClientConfig{
 		User:            info.User,
 		Auth:            auth,
-		Timeout:         info.Timeout,
+		Timeout:         authTimeout,
 		HostKeyCallback: hostKeyCallback,
 		BannerCallback:  bannerCallback,
 	}
@@ -93,7 +95,7 @@ func loginWithContext(ctx context.Context, info LoginInput) (*StarSSH, error) {
 	if err != nil {
 		return sshInfo, err
 	}
-	restoreDeadline := applyConnDeadline(rawConn, loginCtx, info.Timeout)
+	restoreDeadline := applyConnDeadline(rawConn, loginCtx, authTimeout)
 	defer restoreDeadline()
 
 	clientConn, chans, reqs, err := ssh.NewClientConn(rawConn, targetAddr, clientConfig)
@@ -130,6 +132,7 @@ func LoginSimple(host string, user string, passwd string, prikeyPath string, por
 		Addr:            host,
 		Port:            port,
 		Timeout:         timeout,
+		DialTimeout:     timeout,
 		User:            user,
 		HostKeyCallback: DefaultAllowHostKeyCallback,
 	}
@@ -154,12 +157,29 @@ func normalizeLoginInput(info LoginInput) LoginInput {
 	if info.Port <= 0 {
 		info.Port = defaultSSHPort
 	}
-	if info.Timeout <= 0 {
-		info.Timeout = defaultLoginTimeout
-	}
 	return info
 }
 
+func effectiveLoginTimeout(info LoginInput) time.Duration {
+	if info.Timeout <= 0 {
+		return 0
+	}
+	return info.Timeout
+}
+
+func effectiveDialTimeout(info LoginInput) time.Duration {
+	switch {
+	case info.DialTimeout < 0:
+		return 0
+	case info.DialTimeout > 0:
+		return info.DialTimeout
+	case info.Timeout > 0:
+		return info.Timeout
+	default:
+		return defaultLoginTimeout
+	}
+}
+
 func buildAuthMethods(info LoginInput) ([]ssh.AuthMethod, func(), error) {
 	order, err := normalizeAuthOrder(info.AuthOrder)
 	if err != nil {
@@ -194,7 +214,7 @@ func buildAuthMethods(info LoginInput) ([]ssh.AuthMethod, func(), error) {
 			if info.DisableSSHAgent {
 				continue
 			}
-			agentMethod, cleanup, err := buildSSHAgentAuthMethod(info.Timeout)
+			agentMethod, cleanup, err := buildSSHAgentAuthMethodFunc(effectiveDialTimeout(info))
 			if err != nil {
 				agentErr = err
 				continue

login_timeout_test.go

@@ -0,0 +1,99 @@
+package starssh
+
+import (
+	"testing"
+	"time"
+
+	"golang.org/x/crypto/ssh"
+)
+
+func TestNormalizeLoginInputKeepsZeroAuthTimeout(t *testing.T) {
+	info := normalizeLoginInput(LoginInput{})
+	if info.Port != defaultSSHPort {
+		t.Fatalf("Port=%d want %d", info.Port, defaultSSHPort)
+	}
+	if info.Timeout != 0 {
+		t.Fatalf("Timeout=%v want 0", info.Timeout)
+	}
+	if info.DialTimeout != 0 {
+		t.Fatalf("DialTimeout=%v want 0", info.DialTimeout)
+	}
+}
+
+func TestEffectiveLoginTimeout(t *testing.T) {
+	if got := effectiveLoginTimeout(LoginInput{}); got != 0 {
+		t.Fatalf("zero login timeout should stay zero, got %v", got)
+	}
+	if got := effectiveLoginTimeout(LoginInput{Timeout: 7 * time.Second}); got != 7*time.Second {
+		t.Fatalf("expected explicit login timeout, got %v", got)
+	}
+}
+
+func TestEffectiveDialTimeout(t *testing.T) {
+	tests := []struct {
+		name string
+		info LoginInput
+		want time.Duration
+	}{
+		{
+			name: "default fallback",
+			info: LoginInput{},
+			want: defaultLoginTimeout,
+		},
+		{
+			name: "reuse timeout when dial timeout omitted",
+			info: LoginInput{Timeout: 9 * time.Second},
+			want: 9 * time.Second,
+		},
+		{
+			name: "explicit dial timeout wins",
+			info: LoginInput{Timeout: 9 * time.Second, DialTimeout: 3 * time.Second},
+			want: 3 * time.Second,
+		},
+		{
+			name: "negative dial timeout disables default dial deadline",
+			info: LoginInput{Timeout: 9 * time.Second, DialTimeout: -1},
+			want: 0,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := effectiveDialTimeout(tc.info); got != tc.want {
+				t.Fatalf("effectiveDialTimeout(%+v)=%v want %v", tc.info, got, tc.want)
+			}
+		})
+	}
+}
+
+func TestBuildAuthMethodsUsesDialTimeoutInsteadOfAuthTimeout(t *testing.T) {
+	oldBuilder := buildSSHAgentAuthMethodFunc
+	t.Cleanup(func() {
+		buildSSHAgentAuthMethodFunc = oldBuilder
+	})
+
+	captured := time.Duration(-2)
+	buildSSHAgentAuthMethodFunc = func(timeout time.Duration) (ssh.AuthMethod, func(), error) {
+		captured = timeout
+		return ssh.Password("agent"), nil, nil
+	}
+
+	info := LoginInput{
+		Timeout:     0,
+		DialTimeout: 11 * time.Second,
+		AuthOrder:   []AuthMethodKind{AuthMethodSSHAgent},
+	}
+	auth, cleanup, err := buildAuthMethods(info)
+	if err != nil {
+		t.Fatalf("buildAuthMethods: %v", err)
+	}
+	if cleanup != nil {
+		cleanup()
+	}
+	if len(auth) != 1 {
+		t.Fatalf("expected one auth method, got %d", len(auth))
+	}
+	if captured != 11*time.Second {
+		t.Fatalf("agent auth builder timeout=%v want %v", captured, 11*time.Second)
+	}
+}

session.go

@@ -9,6 +9,14 @@ import (
 	"golang.org/x/crypto/ssh"
 )
 
+var newSSHSession = func(client *ssh.Client) (*ssh.Session, error) {
+	return client.NewSession()
+}
+
+var requestSessionPTY = func(session *ssh.Session, config TerminalConfig) error {
+	return session.RequestPty(config.Term, config.Rows, config.Columns, config.Modes)
+}
+
 func (s *StarSSH) Close() error {
 	return s.closeTransport(true)
 }
@@ -22,7 +30,15 @@ func (s *StarSSH) NewExecSession() (*ssh.Session, error) {
 	if err != nil {
 		return nil, err
 	}
-	return NewExecSession(client)
+	session, err := NewExecSession(client)
+	if err != nil {
+		return nil, err
+	}
+	if err := s.maybeRequestAgentForwarding(session); err != nil {
+		_ = session.Close()
+		return nil, err
+	}
+	return session, nil
 }
 
 func (s *StarSSH) NewPTYSession(config *TerminalConfig) (*ssh.Session, error) {
@@ -30,7 +46,15 @@ func (s *StarSSH) NewPTYSession(config *TerminalConfig) (*ssh.Session, error) {
 	if err != nil {
 		return nil, err
 	}
-	return NewPTYSession(client, config)
+	session, err := NewPTYSession(client, config)
+	if err != nil {
+		return nil, err
+	}
+	if err := s.maybeRequestAgentForwarding(session); err != nil {
+		_ = session.Close()
+		return nil, err
+	}
+	return session, nil
 }
 
 func NewTransferSession(client *ssh.Client) (*ssh.Session, error) {
@@ -41,7 +65,7 @@ func NewExecSession(client *ssh.Client) (*ssh.Session, error) {
 	if client == nil {
 		return nil, errors.New("ssh client is nil")
 	}
-	return client.NewSession()
+	return newSSHSession(client)
 }
 
 func NewSession(client *ssh.Client) (*ssh.Session, error) {
@@ -53,13 +77,13 @@ func NewPTYSession(client *ssh.Client, config *TerminalConfig) (*ssh.Session, er
 		return nil, errors.New("ssh client is nil")
 	}
 
-	session, err := client.NewSession()
+	session, err := newSSHSession(client)
 	if err != nil {
 		return nil, err
 	}
 
 	cfg := normalizeTerminalConfig(config)
-	if err := session.RequestPty(cfg.Term, cfg.Rows, cfg.Columns, cfg.Modes); err != nil {
+	if err := requestSessionPTY(session, cfg); err != nil {
 		_ = session.Close()
 		return nil, err
 	}

state.go

@@ -6,6 +6,8 @@ import (
 	"golang.org/x/crypto/ssh"
 )
 
+var errSSHClientClosing = errors.New("ssh client is closing")
+
 type sshClientRequester interface {
 	SendRequest(name string, wantReply bool, payload []byte) (bool, []byte, error)
 	Close() error
@@ -29,10 +31,19 @@ func (s *StarSSH) snapshotSSHClient() *ssh.Client {
 }
 
 func (s *StarSSH) requireSSHClient() (*ssh.Client, error) {
+	if s == nil {
+		return nil, errors.New("ssh client is nil")
+	}
+	if s.closing.Load() {
+		return nil, errSSHClientClosing
+	}
 	client := s.snapshotSSHClient()
 	if client == nil {
 		return nil, errors.New("ssh client is nil")
 	}
+	if s.closing.Load() {
+		return nil, errSSHClientClosing
+	}
 	return client, nil
 }
 
@@ -46,6 +57,7 @@ func (s *StarSSH) setTransport(client *ssh.Client, upstream *StarSSH) {
 	s.Client = client
 	s.upstream = upstream
 	s.online = client != nil
+	s.closing.Store(false)
 }
 
 func (s *StarSSH) detachTransport() (*ssh.Client, *StarSSH) {
@@ -84,7 +96,9 @@ func (s *StarSSH) closeTransport(waitKeepalive bool) error {
 		return nil
 	}
 
+	s.closing.Store(true)
 	_ = s.closeReusableSFTPClient()
+	agentForwarder := s.takeAgentForwarder()
 
 	client, upstream := s.detachTransport()
 	stop, done := s.takeKeepaliveHandles()
@@ -93,8 +107,13 @@ func (s *StarSSH) closeTransport(waitKeepalive bool) error {
 	}
 
 	var closeErr error
+	if agentForwarder != nil {
+		closeErr = normalizeAlreadyClosedError(agentForwarder.Close())
+	}
 	if client != nil {
-		closeErr = normalizeAlreadyClosedError(closeSSHClient(client))
+		if err := normalizeAlreadyClosedError(closeSSHClient(client)); closeErr == nil {
+			closeErr = err
+		}
 	}
 	if waitKeepalive && done != nil {
 		<-done
@@ -104,3 +123,13 @@ func (s *StarSSH) closeTransport(waitKeepalive bool) error {
 	}
 	return closeErr
 }
+
+func (s *StarSSH) canAttachAgentForwarder(client *ssh.Client) bool {
+	if s == nil || client == nil || s.closing.Load() {
+		return false
+	}
+
+	s.stateMu.RLock()
+	defer s.stateMu.RUnlock()
+	return !s.closing.Load() && s.Client == client
+}

transport.go

@@ -32,7 +32,7 @@ func resolveDialContext(info LoginInput) DialContextFunc {
 	}
 
 	dialer := &net.Dialer{
-		Timeout: info.Timeout,
+		Timeout: effectiveDialTimeout(info),
 	}
 	return dialer.DialContext
 }
@@ -44,7 +44,7 @@ func dialTargetConn(ctx context.Context, info LoginInput) (net.Conn, *StarSSH, e
 	}
 
 	dialContext := resolveDialContext(info)
-	proxyConfig := normalizeProxyConfig(info.Proxy, info.Timeout)
+	proxyConfig := normalizeProxyConfig(info.Proxy, effectiveDialTimeout(info))
 	if proxyConfig != nil {
 		return dialViaProxy(ctx, dialContext, *proxyConfig, targetAddr)
 	}

types.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"net"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/pkg/sftp"
@@ -70,9 +71,12 @@ type StarSSH struct {
 	upstream       *StarSSH
 	sftpClient     *sftp.Client
 	sftpMu         sync.Mutex
+	agentForwardMu sync.Mutex
+	agentForwarder io.Closer
 	keepaliveMu    sync.Mutex
 	keepaliveStop  chan struct{}
 	keepaliveDone  chan struct{}
+	closing        atomic.Bool
 }
 
 type LoginInput struct {
@@ -86,10 +90,17 @@ type LoginInput struct {
 	Prikey                      string
 	PrikeyPwd                   string
 	DisableSSHAgent             bool
+	ForwardSSHAgent             bool
 	AuthOrder                   []AuthMethodKind
 	Addr                        string
 	Port                        int
+	// Timeout limits the SSH handshake/authentication phase after a TCP connection has
+	// already been established. Zero means no authentication timeout.
 	Timeout time.Duration
+	// DialTimeout limits outbound dial steps such as TCP connect, proxy connect, and
+	// local ssh-agent socket connect. Zero falls back to Timeout when set, otherwise
+	// uses the package default dial timeout. Negative disables the default dial timeout.
+	DialTimeout       time.Duration
 	DialContext       DialContextFunc
 	Proxy             *ProxyConfig
 	Jump              *LoginInput