dump_udp_multicast.py

import socket
import struct
import sys
import binascii

assert len(sys.argv) ==3
IP = sys.argv[1]
PORT = sys.argv[2]
print "Connecting to",IP, "on port", PORT

MCAST_GRP = IP
MCAST_PORT = int(PORT)
IS_ALL_GROUPS = True

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
if IS_ALL_GROUPS:
    # on this port, receives ALL multicast groups
    sock.bind(('', MCAST_PORT))
else:
    # on this port, listen ONLY to MCAST_GRP
    sock.bind((MCAST_GRP, MCAST_PORT))
mreq = struct.pack("4sl", socket.inet_aton(MCAST_GRP), socket.INADDR_ANY)

sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)

while True:
  # For Python 3, change next line to "print(sock.recv(10240))"
  print sock.recv(10240)

Usage:

dump_udp_multicast.py MULTICAST_IP_ADDRESS PORT