# $Id: README,v 1.5 2004/04/11 23:31:50 lars Exp $

* What's this?

pf4lin is a port of the OpenBSD packetfilter (pf), see 
http://www.benzedrine.cx/pf.html, to Linux. At the moment  
the port is done from the first sources of pf that were 
checked in to the OpenBSD source tree back in June 2001.
It is implemented as a kernel module so no patching of 
the kernel is necessary to give it a go.


* Why?

Because!


* Does it work?

Well, I'm not sure if it works perfectly but it seems
to work ok. If you find things that doesn't work please
email me, or, better yet, send me a patch!

The only things that I know doesn't work is the send_reset()
for tcp.

I have only tested it with the 2.6.3 kernel but I think it
should work in 2.4 if the Makefile is changed.


* How do I compile pf4lin?

$ make && make pfctl


* How do I run pf4lin?

$ ./load.sh

This scripts loads the module which is assigned a dynamic
major number. The script then parses /proc/devices to
find the assigned major number. Finally a device file
called /dev/pf4lin is created with the major number.

Now pfctl can be used to load rules, start/stop etc.

One nifty command is
$ ./pfctl td 
which toggles debug mode (it is off to begin with).
This will create more debug messages in /var/log/messages

To unload the module simply:
$ ./unload.sh


* Where can I find a manual for pf4lin and pfctl?

Use the source Luke :-) Some examples of filter 
rules and nat stuff can be found in the files
pf.conf and nat.conf. You can also see an old
pf manual at http://www.inebriated.demon.nl/pf-howto/


* Future plans:

Try and port more modern versions of pf. The ultimate
goal is to follow the -current tree. I also plan to
write a script that will make porting easier by substituting
different structure names like ip to iphdr and variable
names like ip_sum to check etc. 


* Known problems:

Alpha: code segfaults (reported on a dec alpha ds10 machine running debian)

* Tested With:

I386 and X86_64

* Other resources:

OpenBSD: http://www.openbsd.org
pf: http://www.benzedrine.cx/pf.html 


* Thanks:

Big thanks to the OpenBSD guys people for writing great
software and especially Daniel Hartmeier for all the help.


* Who's behind this thingy?

Lars Olsson 
lo@abstractvoid.se 
L.A.Olsson@herts.ac.uk

Ido Sebastiaan van Oostveen
v dot oostveen at gmail dot com