{ "buffer", required_argument, 0, 'b' },
{ "rcvbuf", required_argument, 0, 'R' },
{ "multicast", required_argument, 0, 'M' },
{ "buffer", required_argument, 0, 'b' },
{ "rcvbuf", required_argument, 0, 'R' },
{ "multicast", required_argument, 0, 'M' },