IPtables

Hey guys, I have just started using IP tables and was wondering if anyone could direct me to any good online resources as I am totally new to this. Thanks.

http://www.netfilter.org/documentation/HOWTO/netfilter-hacking-HOWTO.html

Good Books:
Linux Firewalls (New Riders Professional Library) by Ziegler, Robert L
Linux iptables Pocket Reference [ILLUSTRATED] by Gregor N. Purdy
Linux Firewalls (3rd Edition) (Novell Press) by Steve Suehring, Robert Ziegler