Hi,
Does anyone have a good solution on this issue? I have a couple of companies who wants to block IM totally on the firewall. Since some IM applications (like MSN messenger) is designed to bypass simple port-range blocks, I'm looking for another solution; possibly something like a list of blacklisted IP numbers that the firewall can update from time to time from a central server. The firewalls in question use Linux and netfilter.
Jarle