This script listens for ARP request packets using scapy to learn the IP and Mac Address of LAN hosts. Learn more about this script at https://jcutrer.com/python/scapy-arp-listener

scapy-arp-listener.py

#!/usr/bin/env python3
"""scapy-arp-listener.py

Listen for arp packets using scapy to learn the IP and Mac Address of LAN hosts

Copyright (C) 2018 Jonathan Cutrer

License Dual MIT, 0BSD

"""

from __future__ import print_function
from scapy.all import *
import time

__version__ = "0.0.1"

def handle_arp_packet(packet):

    # Match ARP requests
    if packet[ARP].op == ARP.who_has:
        print('New ARP Request')
        print(packet.summary())
        #print(ls(packet))
        print(packet[Ether].src, "has IP", packet[ARP].psrc)

    # Match ARP replies
    if packet[ARP].op == ARP.is_at:
        print('New ARP Reply')
        print(packet.summary())
        #print(ls(packet))

    return

if __name__ == "__main__":
    sniff(filter="arp", prn=handle_arp_packet)

 

Nice! Thank you! I had to make a small tweak and define the corresponding values for the OpCode field in the ARP packet:

who_has = 1;
is_at = 2;

# ...

if packet[ARP].op == who_has
if packet[ARP].op == is_at