Some Things that Shorewall Cannot Do Tom Eastep 2003 Thomas M Eastep 2003-10-07
Shorewall Cannot: Be used to filter traffic through a Layer 2 Bridge Act as a "Personal Firewall" that allows internet access by application. Be used with an Operating System other than Linux (version >= 2.4.0) Do content filtering: HTTP - better to use Squid for that. Email -- Install something like Postfix on your firewall and integrate it with SpamAssassin and Amavisd-new.
In Addition: Shorewall does not contain any support for Netfilter Patch-O-Matic features -- Shorewall only supports features from released kernels.