add ssh tunnel

pkg/dialer/forward/ssh/dialer.go

@@ -15,10 +15,6 @@ import (
 	"golang.org/x/crypto/ssh"
 )
 
-var (
-	ErrSessionDead = errors.New("ssh: session is dead")
-)
-
 func init() {
 	registry.RegisterDialer("sshd", NewDialer)
 }
@@ -126,7 +122,7 @@ func (d *forwardDialer) Handshake(ctx context.Context, conn net.Conn, options ..
 	}
 	if session.IsClosed() {
 		delete(d.sessions, opts.Addr)
-		return nil, ErrSessionDead
+		return nil, ssh_util.ErrSessionDead
 	}
 
 	return ssh_util.NewClientConn(session.conn, session.client), nil