"The first part of this article has given an overview of DSL,
how it works with NetBSD and how you can set it up. Now after
you have installed and setup your shiny new DSL connection, some
considerations should be made about being online and utilizing the
connection while preparing for the less friendly side of "The Net".
This part of the article gives an overview of ways to use your DSL
machine as gateway for your home or office network, and goes
through the basic steps to setup and maintain security to machines
connected directly to the Internet."
"... Setting up NAT allows several computers to share one
network connection, multiplexed via a NATing gateway. One other
thing you will want to setup after NAT is a caching proxy, to only
fetch any web pages (and images, etc.) if they haven't been fetched
by someone from your internal network recently. ..."