It means that the tool is trying to use multicast but the network interface
doesn't support it There are two likely causes:
Your machine doesn't have multicast support enabled. For example, on Linux
and FreeBSD it is possible to compile a kernel which doesn't support multicast.
You don't have a route for multicast traffic. Some systems don't add this
by default, and you need to run. route add -net 224.0.0.0 netmask 224.0.0.0 eth0
(or similar). If you wish to use RAT in unicast mode only, it is possible
to add the multicast route on the loopback interface.
