alexwestside / go-stun

stun protocol and NAT Behaviour Discovery

go-stun

Go implementation of STUN

stun

stun client

   package main

   import (
   	"github.com/bhpike65/go-stun/stun"
   	"fmt"
   	"os"
   )

   func main() {
        req := stun.NewBindRequest(nil)
        req.SetChangeIP(true)
        req.SetChangePort(true)
        resp, localAddr, err := req.Request("192.168.1.3"", "stun.l.google.com:19302")
        if err != nil {
            fmt.Println("Failed to build STUN PP request:", err)
            os.Exit(1)
        }
        fmt.Println("mapping address: ", resp.Addr.String())
   }

stun server

   package main

   import (
   	"github.com/bhpike65/go-stun/stun"
   	"fmt"
   )

   func main() {
        addr, _ := net.ResolveUDPAddr("udp", "1.1.1.1:3478")
        conn, _ := net.ListenUDP("udp", addr)
        buf := make([]byte, 1500)
        for {
            n, remote, err := conn.ReadFromUDP(buf)

            var req stun.StunMessageReq
            if err = req.Unmarshal(buf[:n]); err != nil {
                continue
            }
            if err = req.RespondTo(conn, remote, other); err != nil {
                continue
            }
        }
   }

NAT Behaviour Discovery

package main

import (
	"flag"
	"fmt"
	"os"
	"github.com/bhpike65/go-stun/nat"
	"net"
)

func main() {
	res, err := nat.Discovery("192.168.1.1:0", "stun.l.google.com:19302", "")
	if err != nil {
		fmt.Println("nat discovery error: ", err.Error())
		os.Exit(-1)
	}

	fmt.Printf("nat discovery result:\n%s", res)
	return
}

it will output:

localAddress:192.168.1.3:56010, mappingAddress:1.1.1.1:15168
NAT mapping type: Endpoint-Independent Mapping NAT
NAT filtering type: Endpoint-Independent Filtering NAT
NAT Hairpinning Support: YES

Example Usage

server

go run ./server.go -primary-addr 1.1.1.1 -primary-port 3478  -alt-address 2.2.2.2 -alt-port 3479

or you can let the program auto select the public IP from the interface

go run ./server.go -public

slave server

if you don't have two public IP address in one machine, instead, you can use two machine and specify one as slave server.

1. start slave server

go run server.go -slave -slaveserver 1.1.1.1:12345 -primary-addr 2.2.2.2 -primary-port 3478 -alt-port 3479

then it will start a tcp server listen on 1.1.1.1:12345, and waits request from master server. you should add iptables rules to filter the packet which doesn't come from master server.

2. start master server

go run server.go -slaveserver 1.1.1.1:12345 -primary-addr 1.1.1.1 -primary-port 3478  -alt-port 3479

if master don't have alt-addr public IP, and the ChangeIP Bit in Bonding Request is set, then it will let slaveserver to reply to it. slaveserver and master server should have the same primary-port and alt-port

client

go run client.go -server 1.1.1.1:3478 -alt-server 2.2.2.2:3479

and get the NAT behaviour test result:

localAddress:192.168.1.3:49191, mappingAddress:3.3.3.3:37408
Address and Port-Dependent Mapping NAT
Endpoint-Independent Filtering NAT
NAT Hairpinning Support: YES

Spec

• RFC 4787: NAT
• RFC 5389: STUN
• RFC 5780: NAT Behaviour Discovery