On my linux box I've 2NICS:
br0 192.168.1.0/24 (192.168.1.1 server) eth1 192.168.2.0/24 lan1 eth2 192.168.3.0/24 lan [...]
there's a routing from eth1 to br0 and also from eth2 to br0
I droppped icmp requests on eth1:
iptables -A INPUT -i eth1 -p icmp --icmp-type echo-request -j DROP
but I also want block icmp requests ONLY from 192.168.2.0/24 network on 192.168.1.1.