4
Send/receive UDP multicast packets.
5
Requires that your OS kernel supports IP multicast.
8
mcast -s (sender, IPv4)
9
mcast -s -6 (sender, IPv6)
10
mcast (receivers, IPv4)
11
mcast -6 (receivers, IPv6)
15
MYGROUP_4 = '225.0.0.250'
16
MYGROUP_6 = 'ff15:7079:7468:6f6e:6465:6d6f:6d63:6173'
17
MYTTL = 1 # Increase to reach other networks
25
group = MYGROUP_6 if "-6" in sys.argv[1:] else MYGROUP_4
27
if "-s" in sys.argv[1:]:
34
addrinfo = socket.getaddrinfo(group, None)[0]
36
s = socket.socket(addrinfo[0], socket.SOCK_DGRAM)
38
# Set Time-to-live (optional)
39
ttl_bin = struct.pack('@i', MYTTL)
40
if addrinfo[0] == socket.AF_INET: # IPv4
41
s.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, ttl_bin)
43
s.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_MULTICAST_HOPS, ttl_bin)
46
data = repr(time.time()).encode('utf-8') + b'\0'
47
s.sendto(data, (addrinfo[4][0], MYPORT))
52
# Look up multicast group address in name server and find out IP version
53
addrinfo = socket.getaddrinfo(group, None)[0]
56
s = socket.socket(addrinfo[0], socket.SOCK_DGRAM)
58
# Allow multiple copies of this program on one machine
59
# (not strictly needed)
60
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
65
group_bin = socket.inet_pton(addrinfo[0], addrinfo[4][0])
67
if addrinfo[0] == socket.AF_INET: # IPv4
68
mreq = group_bin + struct.pack('=I', socket.INADDR_ANY)
69
s.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)
71
mreq = group_bin + struct.pack('@I', 0)
72
s.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_JOIN_GROUP, mreq)
74
# Loop, printing any data we receive
76
data, sender = s.recvfrom(1500)
77
while data[-1:] == '\0': data = data[:-1] # Strip trailing \0's
78
print(str(sender) + ' ' + repr(data))
81
if __name__ == '__main__':