Simple tester to send multicast packets between two hosts.

Build:
 make

Execute the sender:
 bin/mcast send 224.0.0.1/12345   to send a message to port 12345 in multicast
 group 224.0.0.1

Execute the receiver:
 bin/mcast receive 224.0.0.1/12345  to join the multicast group 224.0.0.1 and
 receive messages on port 12345.

IPv6 and IPv4 are supported.