sniff.py

import collections
import socket
import threading


def worker(ipaddr):
    try:
        hostname = socket.gethostbyaddr(ipaddr)[0]
    except socket.herror:
        hostname = '--'
    hosts[hostname].append(ipaddr)


def wait(threads):
    for t in threads:
        t.join()


def main():
    threads = []
    for i in range(98, 105):
        for j in range(256):
            ipaddr = '172.16.%s.%s' % (i, j)
            t = threading.Thread(target=worker, args=(ipaddr,))
            threads.append(t)
            t.start()
    wait(threads)


if __name__ == '__main__':
    hosts = collections.defaultdict(list)
    main()
    hosts_w_mi = [
        (len(ipaddrs), hostname) for hostname, ipaddrs in hosts.items()
        if len(ipaddrs) != 1]
    print(*sorted(hosts_w_mi), sep='\n')