hi Victor,
YMMV but one thing you might want to try is to set your rules so
that it logs everything in and out from the icmp then just look at your logs
for the error. then tweak away till you get your icmp-echo-reply correct..
there is a url with a good ruleset somewhere on the OBSD site that covers
that component.. which might help. good luck.
Best Regards,
dreamwvr@dreamwvr.com