Firewall and NATer

[David.Pierce@peoplelink.com]

Hello, everyone.  I've been trying to wrap my brain around netfilter for
some time now, but I find I still lack some Deep Logic about how to put
together a proper Firewall/NAT box.  The scenario is a box sitting between
the Internet and a privately addressed network, with a few boxes inside
with valid Internet IPs that need DNAT'd and a bunch of others that need
just SNAT'd.  The DNAT'd boxes each have a few different (from each other)
ports they need to catch traffic on.  The other workstations need pretty
much unlimited access to the world outside, but should only receive
ESTABLISHED and RELATED traffic.  If someone has a script which vaguely
addresses these needs, I'd really appreciate seeing it--I must understand
this.  The various scripts I've found on the 'net and tried to use as
jumping-off points have only served to baffle me (one of these days I'm
going to stick to _just_ reading the man pages, and if the pages fail to
explain how the program operates, file a bug :P).

Much thanks to all for just reading this,
David Pierce