diff --git a/proxy/socks/tcp.go b/proxy/socks/tcp.go
index 573d08b..6490f31 100644
--- a/proxy/socks/tcp.go
+++ b/proxy/socks/tcp.go
@@ -42,6 +42,9 @@ func (h *tcpHandler) relay(localConn, remoteConn net.Conn) {
 		})
 	}
 
+	// Close
+	defer closeOnce()
+
 	// WaitGroup
 	var wg sync.WaitGroup
 	wg.Add(1)
@@ -56,7 +59,6 @@ func (h *tcpHandler) relay(localConn, remoteConn net.Conn) {
 	// Down Link
 	io.Copy(localConn, remoteConn)
 	tcpCloseRead(localConn)
-	defer closeOnce()
 
 	wg.Wait() // Wait for Up Link done
 
@@ -120,17 +122,3 @@ func (h *tcpHandler) Handle(localConn net.Conn, target *net.TCPAddr) error {
 	log.Access(process, "proxy", target.Network(), localConn.LocalAddr().String(), targetAddr)
 	return nil
 }
-
-func tcpKeepAlive(conn net.Conn) {
-	if tcp, ok := conn.(*net.TCPConn); ok {
-		tcp.SetKeepAlive(true)
-		tcp.SetKeepAlivePeriod(30 * time.Second)
-	}
-}
-
-func tcpCloseRead(conn net.Conn) {
-	if c, ok := conn.(interface{ CloseRead() error }); ok {
-		log.Warnf("ok!")
-		c.CloseRead()
-	}
-}
diff --git a/proxy/socks/utils.go b/proxy/socks/utils.go
new file mode 100644
index 0000000..38ee5ec
--- /dev/null
+++ b/proxy/socks/utils.go
@@ -0,0 +1,28 @@
+package socks
+
+import (
+	"net"
+	"time"
+
+	"github.com/xjasonlyu/tun2socks/common/log"
+)
+
+type duplexConn interface {
+	net.Conn
+	CloseRead() error
+	CloseWrite() error
+}
+
+func tcpCloseRead(conn net.Conn) {
+	if c, ok := conn.(duplexConn); ok {
+		log.Warnf("ok!----")
+		c.CloseRead()
+	}
+}
+
+func tcpKeepAlive(conn net.Conn) {
+	if tcp, ok := conn.(*net.TCPConn); ok {
+		tcp.SetKeepAlive(true)
+		tcp.SetKeepAlivePeriod(30 * time.Second)
+	}
+}