I am using the following simple iptables rule that accepts related packets:
-A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
I am letting ICMP echo-requests pass with this other rule:
-A INPUT -p icmp --icmp-type echo-request -j ACCEPT
Should I explicitly add anything to receive "useful" ICMP messages like
parameter-problem, or the
RELATED clause will already accept them?