diff --git a/component/auth/auth.go b/component/auth/auth.go
index 176b21d7..11078a06 100644
--- a/component/auth/auth.go
+++ b/component/auth/auth.go
@@ -41,3 +41,11 @@ func NewAuthenticator(users []AuthUser) Authenticator {
 	}
 	return au
 }
+
+var AlwaysValid Authenticator = alwaysValid{}
+
+type alwaysValid struct{}
+
+func (alwaysValid) Verify(string, string) bool { return true }
+
+func (alwaysValid) Users() []string { return nil }
diff --git a/transport/socks5/socks5.go b/transport/socks5/socks5.go
index 5f699bb0..c71ef3f6 100644
--- a/transport/socks5/socks5.go
+++ b/transport/socks5/socks5.go
@@ -118,6 +118,10 @@ func ServerHandshake(rw net.Conn, authenticator auth.Authenticator) (addr Addr,
 		return
 	}
 
+	if nmethods == 1 && buf[0] == 0x02 /* will use password */ && authenticator == nil {
+		authenticator = auth.AlwaysValid
+	}
+
 	// write VER METHOD
 	if authenticator != nil {
 		if _, err = rw.Write([]byte{5, 2}); err != nil {