Linux Firewall howto

http://www.iptables.org/

Like documentation, Tutorials...,

the last two/three years there were no big changes to the netfilter/iptables architecture,
about 2.6.17/18 some new internal achitecture showed up, iptables & the concept
are the same.

basicly documents regarding iptables/netfilter are still valid.

About hardening the box:
http://www.ecst.csuchico.edu/~dranch/LINUX/TrinityOS/cHTML/TrinityOS-c.html

automatic firewall rules generator for your SLackware 10.1:
http://www.slackware.com/~alien/efg/

Thanks folks, so far so good. I've retrieved and built iptables 1.3.7. I'm now going through noci's link for newbies. I'm been programming Unices for 18 yrs, but I'm a newbie at this. I got stuck on the "newbie" instructions. The link says, "Next you must 'emerge iptables' to get the userland tools for configuring iptables." Huh? What's newbier than newbie -- I must be that. I don't know what it means to 'emerge iptables'. There is no 'emerge' command on my system. How do I do this and what exactly am I doing? What are 'userland' tools and where do I get them? Why do I need them? The "newbie" link appears to assume I know all these things. Meanwhile, I'll keep reading ...

THX

if there is no emerge command on your system, that might mean that you are not using Gentoo linux, what distribution are you using?

btw, emerge is the gentoo package manager.
The gentoo link can be read as a guide to steps taken.

emerge iptables                  #-- is mutatis mutandis
rpm -i iptables-{verserion}.rpm  #on Redhat, CentOS etc.

So don't take it too literal, it just describes the steps to take
in a fairly detailed manner.