Filterrules is a program which allows you to determine the rules of a firewall in a very reliable way. It is made up of two parts: a "master", in charge of forging several IP packets, and a "slave", which listens on the other side of the firewall, and which tells to the master which packets passed through. At the end of the test, the firewall rules are displayed in the ipfw format.
This product was designed by HSC and coded by Renaud Deraison (firstname.lastname@example.org), author of the Nessus software. It is available for free under GNU license.
www.hsc.fr / cvs.nessus.org