sshd proxy...

sshd.go

package main

import (
	"errors"
	"flag"
	"fmt"
	"io"
	"log"
	"net"
	"strings"
)

var (
	sshdServerPorts = []int{3222, 9222}
	errConnRefuse   = errors.New("ssh: Connection refused ")
)

func main() {
	var laddr string
	flag.StringVar(&laddr, "l", ":9222", "")
	flag.Parse()
	l, err := net.Listen("tcp", laddr)
	if err != nil {
		log.Fatalln(err)
	}
	for {
		c, err := l.Accept()
		if err != nil {
			log.Fatalln(err)
		}
		go proxy(c)
	}
}

func proxy(c net.Conn) {
	raddr := c.RemoteAddr().String()
	raddr = raddr[:strings.Index(raddr, ":")]
	log.Println("recieve from:", raddr)
	rconn, err := tryConn(raddr, sshdServerPorts)
	if err != nil {
		c.Write([]byte(errConnRefuse.Error()))
		c.Close()
		return
	}
	go io.Copy(c, rconn)
	go io.Copy(rconn, c)
}

func tryConn(raddr string, ports []int) (rconn net.Conn, err error) {
	for _, port := range ports {
		rconn, err = net.Dial("tcp", fmt.Sprintf("%s:%d", raddr, port))
		if err == nil {
			return rconn, nil
		}
	}
	log.Println(err)
	return nil, err
}