I wrote some filtering code for Phil Karn's KA9Q package. This
program can use up to 4 packet drivers. Most versions have built-in
SLIP and CSLIP, and some versions have PPP.
There are at least 3 places to get it with my filtering code:
The KA9Q available by anonymous FTP from biochemistry.cwru.edu
includes my packet filtering and logging code, plus lots of other
Demon Internet Services has incorporated a version of my packet
filtering code in their version available from
The code I released in March '93 for packet filtering and logging
is available from ftp.demon.co.uk:/pub/ibmpc/dm930319/.
I have some not-quite-finished code to implement transparent proxy
routing on KA9Q. This code is intended to allow selective incoming
access and transparent outgoing access for a TCP/IP LAN while only
using one externally visible IP address. It works pretty well for me,
but I know the FTP kludges are not bulletproof. This program also
includes the earlier filtering code. If enough people are interested
I will put it up for anonymous FTP somewhere (hint - offer your site
if you want it).