diff --git a/io/jsonvconfigmarshaller.go b/io/jsonvconfigmarshaller.go
index 1d80b9b6..4261845e 100644
--- a/io/jsonvconfigmarshaller.go
+++ b/io/jsonvconfigmarshaller.go
@@ -12,7 +12,6 @@ type JsonVUser struct {
 }
 
 type JsonVConfig struct {
-	RunAs    string      `json:"runas"`
 	Port     uint8       `json:"port"`
 	Clients  []JsonVUser `json:"users"`
 	Protocol string      `json:"protocol"`
@@ -32,6 +31,5 @@ func (*JsonVConfigUnmarshaller) Unmarshall(data []byte) (*core.VConfig, error) {
 		return nil, err
 	}
 	var vconfig = new(core.VConfig)
-	vconfig.RunAs = core.VUser{}
 	return vconfig, nil
 }
diff --git a/io/socks/socks.go b/io/socks/socks.go
new file mode 100644
index 00000000..347b67ea
--- /dev/null
+++ b/io/socks/socks.go
@@ -0,0 +1,66 @@
+// Package socks contains protocol definition and io lib for SOCKS5 protocol
+package socks
+
+import (
+  "fmt"
+  "io"
+)
+
+const (
+  socksVersion = uint8(5)
+)
+
+// Authentication request header of Socks5 protocol
+type Socks5AuthenticationRequest struct {
+  version byte
+  authMethods [256]byte
+}
+
+func ReadAuthentication(reader io.Reader) (auth Socks5AuthenticationRequest, err error) {
+  buffer := make([]byte, 2)
+  nBytes, err := reader.Read(buffer)
+  if err != nil {
+    return
+  }
+  if nBytes < 2 {
+    err = fmt.Errorf("Expected 2 bytes read, but actaully %d bytes read", nBytes)
+    return
+  }
+  
+  auth.version = buffer[0]
+  if auth.version != socksVersion {
+    err = fmt.Errorf("Unknown SOCKS version %d", auth.version)
+    return
+  }
+  
+  nMethods := buffer[1]
+  if nMethods <= 0 {
+    err = fmt.Errorf("Zero length of authentication methods")
+    return
+  }
+  
+  buffer = make([]byte, nMethods)
+  nBytes, err = reader.Read(buffer)
+  copy(auth.authMethods[:nBytes], buffer)
+  return
+}
+
+type Socks5AuthenticationResponse struct {
+  version byte
+  authMethod byte
+}
+
+func (r *Socks5AuthenticationResponse) ToBytes() []byte {
+  buffer := make([]byte, 2 /* size of Socks5AuthenticationResponse */)
+  buffer[0] = r.version
+  buffer[1] = r.authMethod
+  return buffer
+}
+
+func WriteAuthentication(writer io.Writer, response Socks5AuthenticationResponse) error {
+  _, err := writer.Write(response.ToBytes())
+  if err != nil {
+    return err
+  }
+  return nil
+}
diff --git a/io/vmessreader.go b/io/vmess/vmess.go
similarity index 90%
rename from io/vmessreader.go
rename to io/vmess/vmess.go
index 957eeae9..622aed3c 100644
--- a/io/vmessreader.go
+++ b/io/vmess/vmess.go
@@ -1,4 +1,5 @@
-package io
+// Package vmess contains protocol definition, io lib for VMess.
+package vmess
 
 import (
 	"net"