IP Masquerade Resource page Will have all the current information for setting up IP Masquerade on 2.0.x, 2.2.x, and even old 1.2 kernels!
Juan Jose Ciarlante's WWW site (mirror) who is one of the current Linux IP Masquerade maintainers.
IP Masquerade mailing list Archives contains the recent messages sent to the mailing lists.
David Ranch's Linux page including the TrinityOS Linux document and current versions of the IP-MASQ-HOWTO.. Topics such as IP MASQ, strong IPFWADM/IPCHAINS rulesets, PPP, Diald, Cablemodems, DNS, Sendmail, Samba, NFS, Security, etc. are covered.
The IP Masquerading Applications page: A comprehensive list of applications that work or can be tuned to work through a Linux IP masquerading server.
For users setting up IP Masq on MkLinux, email Taro Fukunaga at firstname.lastname@example.org for a copy of his short MkLinux version of this HOWTO.
IP masquerade FAQ has some general information
Paul Russel's http://www.netfilter.org/ipchains/ doc and its possibly older backup at Linux IPCHAINS HOWTO. This HOWTO has lots of information for IPCHAINS usage, as well as source and binaries for the ipchains tool.
X/OS Ipfwadm page contains sources, binaries, documentation, and other information about the ipfwadm package
Check out the GreatCircle's Firewall mailing list for a great resource about strong firewall rulesets.
The LDP Network Administrator's Guide is a MUST for the beginner Linux administrator trying to set up a network.
The Linux NET HOWTO is also another comprehensive document on how to setup and configure Linux networking.
Linux Ethernet-Howto is a good source of information about setting up a LAN running over Ethernet.
You may also be interested in Linux Firewalling and Proxy Server HOWTO
Linux Kernel HOWTO will guide you through the kernel compilation process
Other Linux HOWTOs such as Kernel HOWTO
Posting to the USENET newsgroup: comp.os.linux.networking