ssh_reverse_port_forwarder.go

package main

// Reverse ssh port forwarder
// http://stackoverflow.com/questions/21417223/simple-ssh-port-forward-in-golang
// https://godoc.org/code.google.com/p/go.crypto/ssh#example-Client-Listen

import (
    "code.google.com/p/go.crypto/ssh"
    "io"
    "log"
    "net"
)

var (
    username          = "root"
    password          = "password"
    remoteSSHServer   = "192.168.1.100:22"
    remoteListnerAddr = "127.0.0.1:2222"
    localDialAddr     = "127.0.0.1:22"
)

func main() {
    config := &ssh.ClientConfig{
        User: username,
        Auth: []ssh.AuthMethod{
            ssh.Password(password),
        },
    }

    // Dial to remote ssh server.
    conn, err := ssh.Dial("tcp", remoteSSHServer, config)
    if err != nil {
        log.Fatalf("unable to connect: %s", err)
    }
    defer conn.Close()

    // Request the remote side to open port
    remoteListener, err := conn.Listen("tcp", remoteListnerAddr)
    if err != nil {
        log.Fatalf("unable to register tcp forward: %v", err)
    }
    defer remoteListener.Close()

    for {
        // Listen for remote connection
        r, err := remoteListener.Accept()
        if err != nil {
            log.Fatalf("listen.Accept failed: %v", err)
        }
        go func() {
            // Connect to local port
            l, err := net.Dial("tcp", localDialAddr)
            if err != nil {
                log.Fatalf("unable to register tcp forward: %v", err)
            }

            //copy local writer to remote reader
            go func() {
                _, err = io.Copy(l, r)
                if err != nil {
                    log.Fatalf("io.Copy failed: %v", err)
                }
            }()

            //copy remote writer to local reader
            go func() {
                _, err = io.Copy(r, l)
                if err != nil {
                    log.Fatalf("io.Copy failed: %v", err)
                }
            }()
        }()
    }
}