blocking icmp protocol

[Cameron Simpson]

If, as suggested by another poster, there is an earlier rule permitting
icmp access, try "inserting" the rule instead of "appending it. So
instead of:

  iptables -A INPUT -p icmp ...

say:

  iptables -I INPUT -p icmp ...

Because the first rule to match applies, your blocking rule needs to
appear before something that lets icmp through.
-- 
Cameron Simpson <cs at zip.com.au> DoD#743
http://www.cskk.ezoshosting.com/cs/

Always code as if the guy who ends up maintaining your code will be a violent
psychopath who knows where you live.
        - Martin Golding, DoD #0236, martin at plaza.ds.adp.com