I found a few related topic around this issue, all referring to the fact that (and
Assuming your firewall rules are set up appropriately to allow this traffic, the
reason is because they are duplicate or last packets of a session. This is
explained as follows by the IPFilter howto.
However, I find that some connections do not start at all and get blocked. This is
mainly http traffic and or exchange protocol (sorry, we can't implement a decent
mailserver ;-) ).
Any thought on this ???