diff --git a/common/net/refconn.go b/common/net/refconn.go
index 6d28a2bf..324e6474 100644
--- a/common/net/refconn.go
+++ b/common/net/refconn.go
@@ -51,6 +51,10 @@ func (c *refConn) SetWriteDeadline(t time.Time) error {
 	return c.conn.SetWriteDeadline(t)
 }
 
+func (c *refConn) Upstream() any {
+	return c.conn
+}
+
 func NewRefConn(conn net.Conn, ref any) net.Conn {
 	return &refConn{conn: conn, ref: ref}
 }
diff --git a/listener/sing/sing.go b/listener/sing/sing.go
index 2780e275..27a9d6ac 100644
--- a/listener/sing/sing.go
+++ b/listener/sing/sing.go
@@ -48,6 +48,10 @@ func (c *waitCloseConn) RemoteAddr() net.Addr {
 	return c.rAddr
 }
 
+func (c *waitCloseConn) Upstream() any {
+	return c.Conn
+}
+
 func (h *ListenerHandler) NewConnection(ctx context.Context, conn net.Conn, metadata M.Metadata) error {
 	additions := h.Additions
 	if ctxAdditions := getAdditions(ctx); len(ctxAdditions) > 0 {