If your kernel version is before 2.1.102; you need the ipfwchains
patch to the 2.1.x or 2.0.x kernel series.

You need to be running a kernel compiled with CONFIG_IP_FIREWALL (for
2.1.102 and above) or CONFIG_IP_FIREWALL_CHAINS set to `y'.  You can
tell that your current kernel is compiled with this by looking for
`/proc/net/ip_fwchains' - if it exists, then your kernel is ready for
the ipchains utility.

See the HOWTO (available in plain text here, or from the web page in
other formats) for details.  There is also an excellent quick
reference card by Scott Bronson, in A4 and US Letter sizes (best
printed double-side).  This was written in Word Perfect 7 on Linux;
ask bronson@soda.berkeley.edu if you want it in that format.

The concept and chunks of the implementation were grabbed from ipfwadm
2.3; the name has been changed to avoid confusion, as `ipfwadm' will
NOT work with kernels with the new firewall code.  Also, I took the
opportunity to rationalize the command line parameters, making it
perhaps more difficult for ipfwadm users (not necessarily a bad thing,
as it highlights the differences) but hopefully making things more
sane in the long run.

In recognition of the fantastic work done by Jos Vos, without whom I
would have had no code or concepts to guide me, here is the original
copyright notice from many of the files.  (Do NOT contact Jos with
problems in these utilities; they are almost certainly things I
wrecked, and complaining to him would be unfair and unrewarding).

================
	Copyright (c) 1995,1996 by X/OS Experts in Open Systems BV.
	All rights reserved.

	Author: Jos Vos <jos@xos.nl>

		X/OS Experts in Open Systems BV
		Kruislaan 419
		1098 VA  Amsterdam
		The Netherlands

		E-mail: info@xos.nl
		WWW:    http://www.xos.nl/
================

Paul ``Rusty'' Russell,
Paul.Russell@rustcorp.com.au.
&
Michael Neuling,
mneuling@radlogic.com.au