This HOWTO explains how to use the libiptc library included in the iptables package. This document can show you how to use short C or C++ programs to query the internal structure of the firewalling code, to check chains and rules, packet and byte counters, and in a second phase, if you are a little "brave", to modify them.
You can find the latest version of this document at Querying libiptc HOWTO.html.
If you have suggestions to help make this document better, please submit your ideas to me at the following address: firstname.lastname@example.org.
While I wrote this HOWTO, I developed a simple bandwith meter using user-defined chains to get the data to be measured. This idea was conceived looking at monitor.pl, a simple perl program for bandwith measurement, written by Stef Coene at http://www.docum.org. I recommend this site to people interested in bandwidth control and measurement.