I'm trying to configure iptables rules on a router that allows ICMP (PMTU-D, ping, traceroute, etc.) to function.
1) Allow all ICMP outbound traffic initiated from the router and internal clients.
2) Allow ICMP inbound traffic only for replies to router and client initiated connections.
3) Drop all other ICMP inbound traffic from the WAN.
1) Are the icmp-types below reply messages to client and router initiated requests ?
0/0 3 14
2) Are icmp-types 5 and 9-12 reply messages ?