IPTables-tutorial is a tutorial which explains how to install and set up iptables and netfilters on Linux. It takes you through a usable example file step by step, and helps you understand its basic functionality. The tutorial currently contains 6 different example scripts that may be used freely under GPL licensing terms.
Statsnet is a small set of scripts that will generate graphical statistics for a specific device. The statistics contain among other things, transmitted/received packets as well as bytes. In addition, it shows amount of currently tracked connections in the conntrack engine of netfilter.