iptables script in main

[David Collett]

Hi all,
Is there a basic iptables based firewall in Ubuntu main?
I'm imagining a very basic package (just an init script and config,
eg. in /etc/defaults) where I set a few variables saying what I wish
to allow, and it blocks and/or logs the rest.

I just read a iptables tutorial and wrote something suitable myself,
but I'm sure theres plenty of little tricks I've missed, hence a
supported Ubuntu script would be prefered.

Any sugestions welcome!
Thanks,
Dave