Join a multicast group in python and receive data

joingroup.py

#!/usr/bin/env python3

import socket
import sys


def main(argv):
    multicast_group = argv[1]
    multicast_port = int(argv[2])
    interface_ip = argv[3]

    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
    sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 32)
    sock.bind(('', multicast_port))
    sock.setsockopt(socket.SOL_IP, socket.IP_ADD_MEMBERSHIP,
                    socket.inet_aton(multicast_group) + socket.inet_aton(interface_ip))

    while True:
        received = sock.recv(1500)
        print('Received packet of {0} bytes'.format(len(received)))


if __name__ == '__main__':
    if len(sys.argv) != 4:
        print("Usage: {0} <group address> <port> <interface ip>".format(sys.argv[0]))
        sys.exit(1)
    main(sys.argv)

very neat! can I just ask, what is the interface ip and how does it differ from the multicast group argument? thanks!

The interface IP is the address of your local interface.
0.0.0.0 may work but this may be system dependent. Using 0.0.0.0 while having a route to 224.0.0.0/4 may work too.

oh cheers, brilliant!