+## It's not valid to have a multicast address as a packet source: multicast
+## routing is done away from the source, so a multicast address would make
+## this impossible to do. So discard these packets. Also discard class-E
+## IPv4 addresses, since they aren't assigned.
+run iptables -t mangle -A in-classify -g bad-source-address \
+ -s 224.0.0.0/3
+run ip6tables -t mangle -A in-classify -g bad-source-address \
+ -s ff00::/8
+