Edit File: mcast.py
#! /usr/bin/python2.7 # # Send/receive UDP multicast packets. # Requires that your OS kernel supports IP multicast. # # Usage: # mcast -s (sender, IPv4) # mcast -s -6 (sender, IPv6) # mcast (receivers, IPv4) # mcast -6 (receivers, IPv6) MYPORT = 8123 MYGROUP_4 = '225.0.0.250' MYGROUP_6 = 'ff15:7079:7468:6f6e:6465:6d6f:6d63:6173' MYTTL = 1 # Increase to reach other networks import time import struct import socket import sys def main(): group = MYGROUP_6 if "-6" in sys.argv[1:] else MYGROUP_4 if "-s" in sys.argv[1:]: sender(group) else: receiver(group) def sender(group): addrinfo = socket.getaddrinfo(group, None)[0] s = socket.socket(addrinfo[0], socket.SOCK_DGRAM) # Set Time-to-live (optional) ttl_bin = struct.pack('@i', MYTTL) if addrinfo[0] == socket.AF_INET: # IPv4 s.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, ttl_bin) else: s.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_MULTICAST_HOPS, ttl_bin) while True: data = repr(time.time()) s.sendto(data + '\0', (addrinfo[4][0], MYPORT)) time.sleep(1) def receiver(group): # Look up multicast group address in name server and find out IP version addrinfo = socket.getaddrinfo(group, None)[0] # Create a socket s = socket.socket(addrinfo[0], socket.SOCK_DGRAM) # Allow multiple copies of this program on one machine # (not strictly needed) s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) # Bind it to the port s.bind(('', MYPORT)) group_bin = socket.inet_pton(addrinfo[0], addrinfo[4][0]) # Join group if addrinfo[0] == socket.AF_INET: # IPv4 mreq = group_bin + struct.pack('=I', socket.INADDR_ANY) s.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq) else: mreq = group_bin + struct.pack('@I', 0) s.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_JOIN_GROUP, mreq) # Loop, printing any data we receive while True: data, sender = s.recvfrom(1500) while data[-1:] == '\0': data = data[:-1] # Strip trailing \0's print (str(sender) + ' ' + repr(data)) if __name__ == '__main__': main()