diff --git a/src/pingtunnel/client.go b/src/pingtunnel/client.go
index 11bdf56..1c2db53 100644
--- a/src/pingtunnel/client.go
+++ b/src/pingtunnel/client.go
@@ -1,17 +1,15 @@
 package pingtunnel
 
 import (
-	"encoding/json"
 	"fmt"
 	"golang.org/x/net/icmp"
-	"golang.org/x/net/ipv4"
 	"net"
-	"syscall"
+	"time"
 )
 
 func NewClient(addr string, target string) (*Client, error) {
 
-	ipaddr, err := net.ResolveTCPAddr("tcp", addr)
+	ipaddr, err := net.ResolveUDPAddr("udp", addr)
 	if err != nil {
 		return nil, err
 	}
@@ -30,21 +28,24 @@ func NewClient(addr string, target string) (*Client, error) {
 }
 
 type Client struct {
-	ipaddr *net.TCPAddr
+	ipaddr *net.UDPAddr
 	addr   string
 
 	ipaddrTarget *net.IPAddr
 	addrTarget   string
 
 	conn       *icmp.PacketConn
-	listenConn *net.TCPListener
+	listenConn *net.UDPConn
+
+	localConnToIdMap map[string]uint32
+	localIdToConnMap map[uint32]*net.UDPAddr
 }
 
 func (p *Client) Addr() string {
 	return p.addr
 }
 
-func (p *Client) IPAddr() *net.TCPAddr {
+func (p *Client) IPAddr() *net.UDPAddr {
 	return p.ipaddr
 }
 
@@ -66,81 +67,78 @@ func (p *Client) Run() {
 	defer conn.Close()
 	p.conn = conn
 
-	listener, err := net.ListenTCP("tcp", p.ipaddr)
+	listener, err := net.ListenUDP("udp", p.ipaddr)
 	if err != nil {
-		fmt.Printf("Error listening for tcp packets: %s\n", err.Error())
+		fmt.Printf("Error listening for udp packets: %s\n", err.Error())
 		return
 	}
-
+	defer listener.Close()
 	p.listenConn = listener
 
-	p.Accept()
+	p.localConnToIdMap = make(map[string]uint32)
+	p.localIdToConnMap = make(map[uint32]*net.UDPAddr)
+
+	go p.Accept()
+
+	recv := make(chan *Packet, 1000)
+	go recvICMP(*p.conn, recv)
+
+	for {
+		select {
+		case r := <-recv:
+			p.processPacket(r)
+		}
+	}
 }
 
 func (p *Client) Accept() error {
 
 	fmt.Println("client waiting local accept")
 
+	bytes := make([]byte, 10240)
+
 	for {
-		localConn, err := p.listenConn.AcceptTCP()
+		p.conn.SetReadDeadline(time.Now().Add(time.Millisecond * 100))
+		n, srcaddr, err := p.listenConn.ReadFromUDP(bytes)
 		if err != nil {
-			fmt.Println(err)
-			continue
-		}
-
-		localConn.SetLinger(0)
-		go p.handleConn(*localConn)
-	}
-}
-
-func (p *Client) handleConn(conn net.TCPConn) {
-	defer conn.Close()
-
-	uuid := UniqueId()
-
-	fmt.Printf("client new conn %s %s", conn.RemoteAddr().String(), uuid)
-
-	data, err := json.Marshal(RegisterData{localaddr: conn.RemoteAddr().String()})
-	if err != nil {
-		fmt.Printf("Unable to marshal data %s\n", err)
-		return
-	}
-
-	for {
-		p.sendICMP(uuid, REGISTER, data)
-	}
-}
-
-func (p *Client) sendICMP(connId string, msgType MSGID, data []byte) error {
-
-	body := &Msg{
-		ID:   connId,
-		TYPE: (int)(msgType),
-		Data: data,
-	}
-
-	msg := &icmp.Message{
-		Type: ipv4.ICMPTypeExtendedEchoRequest,
-		Code: 0,
-		Body: body,
-	}
-
-	bytes, err := msg.Marshal(nil)
-	if err != nil {
-		return err
-	}
-
-	for {
-		if _, err := (*p.conn).WriteTo(bytes, p.ipaddrTarget); err != nil {
 			if neterr, ok := err.(*net.OpError); ok {
-				if neterr.Err == syscall.ENOBUFS {
+				if neterr.Timeout() {
+					// Read timeout
+					continue
+				} else {
+					fmt.Printf("Error read udp %s\n", err)
 					continue
 				}
 			}
-			fmt.Printf("sendICMP error %s %s\n", p.ipaddrTarget.String(), err)
 		}
-		break
+
+		uuid := p.localConnToIdMap[srcaddr.String()]
+		if uuid == 0 {
+			uuid = UniqueId()
+			p.localConnToIdMap[srcaddr.String()] = uuid
+			p.localIdToConnMap[uuid] = srcaddr
+			fmt.Printf("client accept new local %d %s\n", uuid, srcaddr.String())
+		}
+
+		sendICMP(*p.conn, p.ipaddrTarget, uuid, (uint32)(DATA), bytes[:n])
+	}
+}
+
+func (p *Client) processPacket(packet *Packet) {
+
+	fmt.Printf("processPacket %d %s %d\n", packet.id, packet.src.String(), len(packet.data))
+
+	addr := p.localIdToConnMap[packet.id]
+	if addr == nil {
+		fmt.Printf("processPacket no conn %d \n", packet.id)
+		return
 	}
 
-	return nil
+	_, err := p.listenConn.WriteToUDP(packet.data, addr)
+	if err != nil {
+		fmt.Printf("WriteToUDP Error read udp %s\n", err)
+		p.localConnToIdMap[addr.String()] = 0
+		p.localIdToConnMap[packet.id] = nil
+		return
+	}
 }
diff --git a/src/pingtunnel/pingtunnel.go b/src/pingtunnel/pingtunnel.go
index e4d144b..56d5a94 100644
--- a/src/pingtunnel/pingtunnel.go
+++ b/src/pingtunnel/pingtunnel.go
@@ -1,60 +1,135 @@
 package pingtunnel
 
 import (
-	"crypto/md5"
-	"crypto/rand"
-	"encoding/base64"
 	"encoding/binary"
-	"encoding/hex"
-	"io"
+	"fmt"
+	"golang.org/x/net/icmp"
+	"golang.org/x/net/ipv4"
+	"net"
+	"sync/atomic"
+	"syscall"
+	"time"
 )
 
 type MSGID int
 
 const (
-	REGISTER         MSGID = 1
+	DATA MSGID = 0xDEADBEEF
 )
 
 const (
-	protocolICMP     = 1
+	protocolICMP = 1
 )
 
-type Msg struct {
-	TYPE int
-	ID   string // identifier
-	Data []byte // data
+// An Echo represents an ICMP echo request or reply message body.
+type MyMsg struct {
+	ID   uint32
+	TYPE uint32
+	Data []byte
 }
 
-func (p *Msg) Len(proto int) int {
+// Len implements the Len method of MessageBody interface.
+func (p *MyMsg) Len(proto int) int {
 	if p == nil {
 		return 0
 	}
-	return 4 + 32 + len(p.Data)
+	return 8 + len(p.Data)
 }
 
-func (p *Msg) Marshal(proto int) ([]byte, error) {
+// Marshal implements the Marshal method of MessageBody interface.
+func (p *MyMsg) Marshal(proto int) ([]byte, error) {
 	b := make([]byte, p.Len(proto))
-	binary.BigEndian.PutUint32(b, uint32(p.TYPE))
-	copy(b[4:], p.ID)
-	copy(b[4+32:], p.Data)
+	binary.BigEndian.PutUint32(b[:4], uint32(p.ID))
+	binary.BigEndian.PutUint32(b[4:8], uint32(p.TYPE))
+	copy(b[8:], p.Data)
 	return b, nil
 }
 
-func UniqueId() string {
-	b := make([]byte, 48)
+// Marshal implements the Marshal method of MessageBody interface.
+func (p *MyMsg) Unmarshal(b []byte) error {
+	p.ID = binary.BigEndian.Uint32(b[:4])
+	p.TYPE = binary.BigEndian.Uint32(b[4:8])
+	p.Data = make([]byte, len(b[8:]))
+	copy(p.Data, b[8:])
+	return nil
+}
 
-	if _, err := io.ReadFull(rand.Reader, b); err != nil {
-		return ""
+var uuid uint32
+
+func UniqueId() uint32 {
+	newValue := atomic.AddUint32(&uuid, 1)
+	return (uint32)(newValue)
+}
+
+func sendICMP(conn icmp.PacketConn, target *net.IPAddr, connId uint32, msgType uint32, data []byte) {
+
+	m := &MyMsg{
+		ID:   connId,
+		TYPE: msgType,
+		Data: data,
 	}
-	return GetMd5String(base64.URLEncoding.EncodeToString(b))
+
+	msg := &icmp.Message{
+		Type: ipv4.ICMPTypeExtendedEchoRequest,
+		Code: 0,
+		Body: m,
+	}
+
+	bytes, err := msg.Marshal(nil)
+	if err != nil {
+		fmt.Printf("sendICMP Marshal error %s %s\n", target.String(), err)
+		return
+	}
+
+	for {
+		if _, err := conn.WriteTo(bytes, target); err != nil {
+			if neterr, ok := err.(*net.OpError); ok {
+				if neterr.Err == syscall.ENOBUFS {
+					continue
+				}
+			}
+			fmt.Printf("sendICMP WriteTo error %s %s\n", target.String(), err)
+		}
+		break
+	}
+
+	return
 }
 
-func GetMd5String(s string) string {
-	h := md5.New()
-	h.Write([]byte(s))
-	return hex.EncodeToString(h.Sum(nil))
+func recvICMP(conn icmp.PacketConn, recv chan<- *Packet) {
+
+	bytes := make([]byte, 10240)
+	for {
+		conn.SetReadDeadline(time.Now().Add(time.Millisecond * 100))
+		n, srcaddr, err := conn.ReadFrom(bytes)
+
+		if err != nil {
+			if neterr, ok := err.(*net.OpError); ok {
+				if neterr.Timeout() {
+					// Read timeout
+					continue
+				} else {
+					fmt.Printf("Error read icmp message %s\n", err)
+					continue
+				}
+			}
+		}
+
+		my := &MyMsg{
+		}
+		my.Unmarshal(bytes[4:n])
+
+		if my.TYPE != (uint32)(DATA) {
+			fmt.Printf("processPacket diff type %d \n", my.TYPE)
+			continue
+		}
+
+		recv <- &Packet{data: my.Data, id: my.ID, src: srcaddr.(*net.IPAddr)}
+	}
 }
 
-type RegisterData struct {
-	localaddr string
+type Packet struct {
+	data []byte
+	id   uint32
+	src  *net.IPAddr
 }
diff --git a/src/pingtunnel/server.go b/src/pingtunnel/server.go
index f149dd2..7afc986 100644
--- a/src/pingtunnel/server.go
+++ b/src/pingtunnel/server.go
@@ -9,7 +9,7 @@ import (
 
 func NewServer(target string) (*Server, error) {
 
-	ipaddrTarget, err := net.ResolveTCPAddr("tcp", target)
+	ipaddrTarget, err := net.ResolveUDPAddr("udp", target)
 	if err != nil {
 		return nil, err
 	}
@@ -21,17 +21,19 @@ func NewServer(target string) (*Server, error) {
 }
 
 type Server struct {
-	ipaddrTarget *net.TCPAddr
+	ipaddrTarget *net.UDPAddr
 	addrTarget   string
 
-	conn net.PacketConn
+	conn *icmp.PacketConn
+
+	localConnMap map[uint32]*net.UDPConn
 }
 
 func (p *Server) TargetAddr() string {
 	return p.addrTarget
 }
 
-func (p *Server) TargetIPAddr() *net.TCPAddr {
+func (p *Server) TargetIPAddr() *net.UDPAddr {
 	return p.ipaddrTarget
 }
 
@@ -44,43 +46,66 @@ func (p *Server) Run() {
 	}
 	p.conn = conn
 
-	p.Recv()
-}
+	p.localConnMap = make(map[uint32]*net.UDPConn)
 
-func (p *Server) Recv() error {
+	recv := make(chan *Packet, 1000)
+	go recvICMP(*p.conn, recv)
 
 	for {
-		bytes := make([]byte, 512)
-		p.conn.SetReadDeadline(time.Now().Add(time.Millisecond * 100))
-		n, srcaddr, err := p.conn.ReadFrom(bytes)
+		select {
+		case r := <-recv:
+			p.processPacket(r)
+		}
+	}
+}
 
+func (p *Server) processPacket(packet *Packet) {
+
+	fmt.Printf("processPacket %d %s %d\n", packet.id, packet.src.String(), len(packet.data))
+
+	id := packet.id
+	udpConn := p.localConnMap[id]
+	if udpConn == nil {
+		targetConn, err := net.ListenUDP("udp", p.ipaddrTarget)
+		if err != nil {
+			fmt.Printf("Error listening for udp packets: %s\n", err.Error())
+			return
+		}
+		udpConn = targetConn
+		p.localConnMap[id] = udpConn
+		go p.Recv(udpConn, id, packet.src)
+	}
+
+	_, err := udpConn.WriteToUDP(packet.data, p.ipaddrTarget)
+	if err != nil {
+		fmt.Printf("WriteToUDP Error read udp %s\n", err)
+		p.localConnMap[id] = nil
+		return
+	}
+}
+
+func (p *Server) Recv(conn *net.UDPConn, id uint32, src *net.IPAddr) {
+
+	fmt.Println("server waiting target response")
+
+	bytes := make([]byte, 10240)
+
+	for {
+		p.conn.SetReadDeadline(time.Now().Add(time.Millisecond * 100))
+		n, _, err := conn.ReadFromUDP(bytes)
 		if err != nil {
 			if neterr, ok := err.(*net.OpError); ok {
 				if neterr.Timeout() {
 					// Read timeout
 					continue
 				} else {
-					return err
+					fmt.Printf("ReadFromUDP Error read udp %s\n", err)
+					p.localConnMap[id] = nil
+					return
 				}
 			}
 		}
 
-		var m *icmp.Message
-		if m, err = icmp.ParseMessage(protocolICMP, bytes[:n]); err != nil {
-			fmt.Println("Error parsing icmp message")
-			return err
-		}
-
-		fmt.Printf("%d %d %d %s \n", m.Type, m.Code, n, srcaddr)
+		sendICMP(*p.conn, src, id, (uint32)(DATA), bytes[:n])
 	}
 }
-
-func (p *Server) listen(netProto string, source string) *icmp.PacketConn {
-
-	conn, err := icmp.ListenPacket(netProto, source)
-	if err != nil {
-		fmt.Printf("Error listening for ICMP packets: %s\n", err.Error())
-		return nil
-	}
-	return conn
-}