socks5

This is a Golang implementation of the Socks5 protocol library.
To see in this SOCKS Protocol Version 5.
This library is also compatible with Socks4 and Socks4a.

Contents

• Features
• Install
• Examples
  • Server example
    • simple (no authentication)
    • username/password authentication in memory
    • custom transporter to transmit data between client and remote
  • Client example
    • CONNECT usage
    • UDP_ASSOCIATE usage
    • BIND usage
• FAQ

Features

• socks5:
  • command: CONNECT, UDP ASSOCIATE, BIND.
  • auth methods:
    • Username/Password authentication.
    • No Authentication Required.
• socks4:
  • command: CONNECT, BIND.
  • auth: (no support).
• sock4a: same as socks4.
• Custom client and server authenticator.
• Easy to read source code.
• Similar to the Golang standard library experience.

Installation

$ go get "github.com/haochen233/socks5"`

Examples

Server example

simple (no authentication):

package main

import (
	"log"
	"github.com/haochen233/socks5"
)

func main() {
	// create socks server.
	srv := &socks5.Server{
		// socks server listen address.
		Addr: "127.0.0.1:1080",
		// UDP assocaite and bind command listen ip.
		// Don't need port, the port will automatically chosen.
		BindIP: "127.0.0.1",
		// if nil server will provide no authentication required method.
		Authenticators: nil,
	}

	// start listen
	err := srv.ListenAndServe()
	if err != nil {
		log.Fatal(err)
	}
}

username/password authentication in memory:

package main

import (
	"crypto/md5"
	"log"

	"github.com/haochen233/socks5"
)

func main() {
	// create a username/password store in memory.
	var userStorage socks5.UserPwdStore = socks5.NewMemeryStore(md5.New(), "secret")
	// set a pair of username/password.
	userStorage.Set("admin", "123456")

	srv := &socks5.Server{
		Addr:   "127.0.0.1:1080",
		BindIP: "127.0.0.1",
		// enable username/password method and authenticator.
		Authenticators: map[socks5.METHOD]socks5.Authenticator{
			socks5.USERNAME_PASSWORD: socks5.UserPwdAuth{UserPwdStore: userStorage},
			// There is already an authentication method.
			// If want enable no authentication required method.
			// you should enable it explicit.
			socks5.NO_AUTHENTICATION_REQUIRED: socks5.NoAuth{},
		},
	}

	err := srv.ListenAndServe()
	if err != nil {
		log.Fatal(err)
	}
}

custom transporter to transmit data between client and remote.

package main

import (
	"log"
	"net"

	"github.com/haochen233/socks5"
)

// simulate to impl socks5.Transporter interface.
// transport encrypted data.
type cryptTransport struct {
}

func (c *cryptTransport) TransportTCP(client *net.TCPConn, remote *net.TCPConn) <-chan error {
	//encrypt data and send to remote
	//decrypt data and send to client
	return nil
}

func (c *cryptTransport) TransportUDP(server *socks5.UDPConn, request *socks5.Request) error {
	panic("implement me")
	return nil
}

func main() {
	server := &socks5.Server{
		Addr:   "127.0.0.1:1080",
		BindIP: "127.0.0.1",
		// replace default Transporter interface
		Transporter: &cryptTransport{},
	}

	err := server.ListenAndServe()
	if err != nil {
		log.Fatal(err)
	}
}

Client example

CONNECT usage:

package main

import (
	"log"

	"github.com/haochen233/socks5"
)

func main() {
	// create socks client
	clnt := socks5.Client{
		ProxyAddr: "127.0.0.1:1080",
		// Authenticator supported by the client.
		// It must not be nil.
		Auth: map[socks5.METHOD]socks5.Authenticator{
			// If client want send NO_AUTHENTICATION_REQUIRED method to server, must
			// add socks5.NoAuth authenticator explicitly
			socks5.NO_AUTHENTICATION_REQUIRED: &socks5.NoAuth{},
		},
	}

	// client send CONNECT command and get a tcp connection.
	// and use this connection transit data between you and www.google.com:80.
	conn, err := clnt.Connect(socks5.Version5, "www.baidu.com:80")
	if err != nil {
		log.Fatal(err)
	}

	// close connection.
	conn.Close()
}

UDP_ASSOCIATE usage:

package main

import (
	"fmt"
	"log"

	"github.com/haochen233/socks5"
)

func main() {
	clnt := socks5.Client{
		ProxyAddr: "127.0.0.1:1080",
		// client provide USERNAME_PASSWORD method and 
		// NO_AUTHENTICATION_REQUIRED.
		Auth: map[socks5.METHOD]socks5.Authenticator{
			socks5.NO_AUTHENTICATION_REQUIRED: &socks5.NoAuth{},
			socks5.USERNAME_PASSWORD:          &socks5.UserPasswd{Username: "admin", Password: "123456"},
		},
	}

	// client send UDP_ASSOCIATE command and get a udp connection.
	// Empty local addr string a local address (127.0.0.1:port) is automatically chosen.
	// you can specific a address to tell socks server which client address will
	// send udp data. Such as clnt.UDPForward("127.0.0.1:9999").
	conn, err := clnt.UDPForward("")
	if err != nil {
		log.Fatal(err)
	}
	defer conn.Close()

	// send every datagram should add UDP request header.
	someData := []byte("some data")
	// dest addr where are you send to.
	destAddr, _ := socks5.ParseAddress("127.0.0.1:9190")
	// packing socks5 UDP data with dest addr.
	pakcedData, err := socks5.PackUDPData(destAddr, someData)
	// final send you data
	conn.Write(pakcedData)

	// on the contrary.
	// you should unpacked the packet, after received  every packedData.
	buf := make([]byte, 65507)
	conn.Read(buf)

	// unpacking data.
	destAddr, unpackedData, err := socks5.UnpackUDPData(buf)
	// operate your udp data. 
	fmt.Println(unpackedData)
}

BIND usage:

package main

import (
	"encoding/binary"
	"github.com/haochen233/socks5"
	"log"
)

func main() {
	c := socks5.Client{
		ProxyAddr: "172.16.1.28:1080",
		Auth: map[socks5.METHOD]socks5.Authenticator{
			socks5.USERNAME_PASSWORD:          &socks5.UserPasswd{"admin", "123456"},
			socks5.NO_AUTHENTICATION_REQUIRED: &socks5.NoAuth{},
		},
	}

	// connect
	conn1, err := c.Connect(5, "127.0.0.1:9000")
	if err != nil {
		log.Fatal(err)
	}

	dest := "127.0.0.1:9001"
	// bind
	bindAddr, errors, conn2, err := c.Bind(4, dest)
	if err != nil {
		log.Fatal(err)
	}

	// An example tell dest about socks server bind address 
	// via CONNECT proxy connection.
	port := make([]byte, 2)
	binary.BigEndian.PutUint16(port, bindAddr.Port)
	conn1.Write(append(bindAddr.Addr, port...))

	// wait the second reply. if nil the dest already
	// established with socks server.
	err = <-errors
	if err != nil {
		log.Fatal(err)
		return
	}

	// bind success
	_, err = conn2.Write([]byte("hello"))
	if err != nil {
		return
		log.Fatal(err)
	}
}

FAQ:

• Server default enable socks4. How to disable socks4 support?
  when you initialize a socks5 server, you should spefic this flag to disable explicitly.

  server := &socks5.Server{
      DisableSocks4: true,
  }