"Over the years I have learned how to roll my own firewall script and call it from /etc directory. Of course, my firewall is only INPUT based, instead of INPUT and OUTPUT based, but I find that building an INPUT/OUTPUT based firewall is tremendously difficult and not really all that necessary if you use good download practices on your Linux server or PC and/or if you're already behind a NAT router (such as a home-based DSL or cable router or wireless router) or other firewall.
"If you're scratching your head on what I mean by INPUT and OUTPUT, then just think about you being inside a house that has a front door (INPUT), and a backdoor (OUTPUT). When you surf the web, you first start sending packets of data out your backdoor (OUTPUT)..."
