diff --git a/README.md b/README.md
index c082f37..21329bf 100755
--- a/README.md
+++ b/README.md
@@ -3,6 +3,7 @@ socks-go
 
 A socks server implemented by golang, support socks4/4a, socks5.
 
+Only support connect command now.
 
 usage
 ====
diff --git a/socks4.go b/socks4.go
index 4abbca6..0eeda0d 100644
--- a/socks4.go
+++ b/socks4.go
@@ -8,6 +8,29 @@ import (
 	"net"
 )
 
+/*
+socks4 protocol
+
+request
+byte | 0  | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | ...  |
+     |0x04|cmd| port  |     ip        |  user\0  |
+
+reply
+byte | 0  |  1   | 2 | 3 | 4 | 5 | 6 | 7|
+     |0x00|status|       |              |
+
+
+socks4a protocol
+
+request
+byte | 0  | 1 | 2 | 3 |4 | 5 | 6 | 7 | 8 | ... |...     |
+     |0x04|cmd| port  |  0.0.0.x     |  user\0 |domain\0|
+
+reply
+byte | 0  |  1  | 2 | 3 | 4 | 5 | 6| 7 |
+	 |0x00|staus| port  |    ip        |
+
+*/
 type socks4Conn struct {
 	serverConn net.Conn
 	clientConn net.Conn
diff --git a/socks5.go b/socks5.go
index cb1b858..d624a4d 100644
--- a/socks5.go
+++ b/socks5.go
@@ -9,6 +9,31 @@ import (
 	"encoding/binary"
 )
 
+/*
+socks5 protocol
+
+initial
+
+byte | 0  |   1    | 2 | ...... | n |
+     |0x05|num auth|  auth methods  |
+
+
+reply
+
+byte | 0  |  1  |
+     |0x05| auth|
+
+
+request
+
+byte | 0  | 1 | 2  |   3    | 4 | .. | n-2 | n-1| n |
+     |0x05|cmd|0x00|addrtype|      addr    |  port  |
+
+response
+byte |0   |  1   | 2  |   3    | 4 | .. | n-2 | n-1 | n |
+     |0x05|status|0x00|addrtype|     addr     |  port   |
+
+*/
 type socks5Conn struct {
 	//addr        string
 	clientConn net.Conn