egress_listener.py

#!/usr/bin/python

import argparse
import subprocess
import sys
import netifaces as ni

def run():
        try:
                print("Listening on all TCP ports")
                subprocess.Popen("iptables -A PREROUTING -t nat -i "+args.interface+" -p tcp --dport 1:65535 -j DNAT --to-destination "+ args.address+":"+args.port,shell=True).wait()
                subprocess.Popen("ncat -lkp "+args.port,shell=True).wait()
        except KeyboardInterrupt:
                print("\nKilling listener and removing iptables rule")
                subprocess.Popen("iptables -D PREROUTING -t nat -i "+args.interface+" -p tcp --dport 1:65535 -j DNAT --to-destination "+ args.address+":"+args.port,shell=True).wait()
                sys.exit()
        except Exception, e:
                print("Error: "+str(e))

def getIP(interface):
        ni.ifaddresses(interface)
        ip = ni.ifaddresses(interface)[2][0]['addr']
        return ip

if __name__ == "__main__" :
        parser = argparse.ArgumentParser()
        parser.add_argument("-i","--interface",help="Specify interface (Default eth0)")
        parser.add_argument("-a","--address",help="Specify IP address")
        parser.add_argument("-p","--port",help="Specify port to redirect traffic (Default: 9999)")
        args = parser.parse_args()
        if (args.interface is None):
                args.interface="eth0"
        if (args.port is None):
                args.port = "9999"
        if (args.address is None):
                try:
                        args.address = getIP(args.interface)
                except KeyError:
                        print("Interface "+args.interface+" is without IP address")
                        sys.exit()

        run()