diff --git a/peerprotocol/extension.go b/peerprotocol/extension.go
index 7ab53ff..02eb9e3 100644
--- a/peerprotocol/extension.go
+++ b/peerprotocol/extension.go
@@ -17,6 +17,7 @@ package peerprotocol
 import (
 	"bytes"
 	"errors"
+	"log"
 	"net"
 
 	"github.com/xgfone/bt/bencode"
@@ -43,39 +44,58 @@ const (
 )
 
 // CompactIP is used to handle the compact ipv4 or ipv6.
+//type CompactIPBytes []byte //net.IP
+
 type CompactIP net.IP
 
+func NewCompactIP(b []byte) (CompactIP, error) {
+	if len(b) == net.IPv4len {
+		return CompactIP(b), nil
+	}
+	if len(b) == net.IPv6len {
+		return CompactIP(b), nil
+	}
+	return nil, errInvalidIP
+}
+
 func (ci CompactIP) String() string {
-	return net.IP(ci).String()
+	return string(ci) //net.IP(ci).String()
 }
 
 // MarshalBencode implements the interface bencode.Marshaler.
-func (ci CompactIP) MarshalBencode() ([]byte, error) {
-	ip := net.IP(ci)
-	if ipv4 := ip.To4(); len(ipv4) != 0 {
-		ip = ipv4
+func (ci *CompactIP) MarshalBencode() ([]byte, error) {
+	ip := *ci
+	log.Println("Marshal IP,", ip, ",", len(ip), ",", ip.String(), ",", net.IPv4len)
+	log.Println("Marshal IP,", ci, ",", ",", ci.String(), ",", net.IPv4len)
+	if len(ip) == net.IPv4len {
+		ip = ip
 	}
 	return bencode.EncodeBytes(ip[:])
 }
 
 // UnmarshalBencode implements the interface bencode.Unmarshaler.
 func (ci *CompactIP) UnmarshalBencode(b []byte) (err error) {
-	var ip net.IP
+	var ip []byte
 	if err = bencode.DecodeBytes(b, &ip); err != nil {
 		return
 	}
+	log.Println("Unmarshal IP,", ip, ",", len(ip), ",", string(ip), ",", net.IPv4len)
 
 	switch len(ip) {
 	case net.IPv4len, net.IPv6len:
 	default:
-		return errInvalidIP
+		if len(ip) < net.IPv6len {
+			return errInvalidIP
+		}
 	}
 
-	if ipv4 := ip.To4(); len(ipv4) != 0 {
-		ip = ipv4
+	if len(ip) == net.IPv4len {
+		ip = []byte(ip)
 	}
+	//ip = ip
 
 	*ci = CompactIP(ip)
+	log.Println("Unmarshal IP,", ci, ",", ",", ci.String(), ",", net.IPv4len)
 	return
 }
 
@@ -90,8 +110,9 @@ type ExtendedHandshakeMsg struct {
 
 	// Port is the local client port, which is redundant and no need
 	// for the receiving side of the connection to send this.
-	Port   uint16    `bencode:"p,omitempty"`      // BEP 10
-	IPv6   net.IP    `bencode:"ipv6,omitempty"`   // BEP 10
+	Port uint16 `bencode:"p,omitempty"`    // BEP 10
+	IPv6 net.IP `bencode:"ipv6,omitempty"` // BEP 10
+	//IPv6   []byte    `bencode:"ipv6,omitempty"`   // BEP 10
 	IPv4   CompactIP `bencode:"ipv4,omitempty"`   // BEP 10
 	YourIP CompactIP `bencode:"yourip,omitempty"` // BEP 10