Linux firewalls
Thursday, October 16th, 2008Linux firewalls : attack detection and response with iptables, psad, and fwsnort / by Michael Rash, No Starch Press, 2007
Here is a good introduction to iptables and related tools, with script examples. Make good use of this book, and there is a good chance you and your company will never get hacked.
get it from OPL