diff --git a/client.go b/client.go
index e629010..439d27c 100644
--- a/client.go
+++ b/client.go
@@ -7,7 +7,7 @@ import (
 	"time"
 )
 
-func NewClient(addr string, server string, target string, timeout int) (*Client, error) {
+func NewClient(addr string, server string, target string, timeout int, proto int) (*Client, error) {
 
 	ipaddr, err := net.ResolveUDPAddr("udp", addr)
 	if err != nil {
@@ -26,11 +26,13 @@ func NewClient(addr string, server string, target string, timeout int) (*Client,
 		addrServer:   server,
 		targetAddr:   target,
 		timeout:      timeout,
+		proto:        proto,
 	}, nil
 }
 
 type Client struct {
 	timeout int
+	proto   int
 
 	ipaddr *net.UDPAddr
 	addr   string
@@ -145,7 +147,7 @@ func (p *Client) Accept() error {
 		}
 
 		clientConn.activeTime = now
-		sendICMP(*p.conn, p.ipaddrServer, p.targetAddr, clientConn.id, (uint32)(DATA), bytes[:n])
+		sendICMP(*p.conn, p.ipaddrServer, p.targetAddr, clientConn.id, (uint32)(DATA), bytes[:n], p.proto)
 	}
 }
 
diff --git a/cmd/main.go b/cmd/main.go
index 0801647..007e56f 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -28,8 +28,11 @@ Usage:
     -t        远端服务器转发的目的地址，流量将转发到这个地址
               Destination address forwarded by the remote server, traffic will be forwarded to this address
 
-    -timeout  本地记录连接超时的时间，单位是秒
-              The time when the local record connection timed out, in seconds
+    -timeout  本地记录连接超时的时间，单位是秒，默认60s
+              The time when the local record connection timed out, in seconds, 60 seconds by default
+
+    -proto    ping的协议，默认是42
+              Ping protocol, the default is 42
 `
 
 func main() {
@@ -39,6 +42,7 @@ func main() {
 	target := flag.String("t", "", "target addr")
 	server := flag.String("s", "", "server addr")
 	timeout := flag.Int("timeout", 60, "conn timeout")
+	proto := flag.Int("proto", 2, "ping proto")
 	flag.Usage = func() {
 		fmt.Printf(usage)
 	}
@@ -53,7 +57,7 @@ func main() {
 	fmt.Println("start...")
 
 	if *t == "server" {
-		s, err := pingtunnel.NewServer(*timeout)
+		s, err := pingtunnel.NewServer(*timeout, *proto)
 		if err != nil {
 			fmt.Printf("ERROR: %s\n", err.Error())
 			return
@@ -68,7 +72,7 @@ func main() {
 		fmt.Printf("server %s\n", *server)
 		fmt.Printf("target %s\n", *target)
 
-		c, err := pingtunnel.NewClient(*listen, *server, *target, *timeout)
+		c, err := pingtunnel.NewClient(*listen, *server, *target, *timeout, *proto)
 		if err != nil {
 			fmt.Printf("ERROR: %s\n", err.Error())
 			return
diff --git a/pingtunnel.go b/pingtunnel.go
index 090f6a0..f4f5061 100644
--- a/pingtunnel.go
+++ b/pingtunnel.go
@@ -89,7 +89,7 @@ func (p *MyMsg) UnmarshalString(b []byte) string {
 	return string(data)
 }
 
-func sendICMP(conn icmp.PacketConn, server *net.IPAddr, target string, connId string, msgType uint32, data []byte) {
+func sendICMP(conn icmp.PacketConn, server *net.IPAddr, target string, connId string, msgType uint32, data []byte, proto int) {
 
 	m := &MyMsg{
 		ID:     connId,
@@ -99,7 +99,7 @@ func sendICMP(conn icmp.PacketConn, server *net.IPAddr, target string, connId st
 	}
 
 	msg := &icmp.Message{
-		Type: ipv4.ICMPTypeExtendedEchoRequest,
+		Type: (ipv4.ICMPType)(proto),
 		Code: 0,
 		Body: m,
 	}
diff --git a/server.go b/server.go
index ee2ab94..d00e2fb 100644
--- a/server.go
+++ b/server.go
@@ -7,14 +7,16 @@ import (
 	"time"
 )
 
-func NewServer(timeout int) (*Server, error) {
+func NewServer(timeout int, proto int) (*Server, error) {
 	return &Server{
 		timeout: timeout,
+		proto:   proto,
 	}, nil
 }
 
 type Server struct {
 	timeout int
+	proto   int
 
 	conn *icmp.PacketConn
 
@@ -118,7 +120,7 @@ func (p *Server) Recv(conn *ServerConn, id string, src *net.IPAddr) {
 		now := time.Now()
 		conn.activeTime = now
 
-		sendICMP(*p.conn, src, "", id, (uint32)(DATA), bytes[:n])
+		sendICMP(*p.conn, src, "", id, (uint32)(DATA), bytes[:n], p.proto)
 	}
 }