Knocker is a simple and easy to use TCP security port scanner written in C to analyze hosts and all of the different services started on them. It is available for Linux, FreeBSD, HP-UX, and Windows9x/2000/NT and it is licensed under the GPL.
With knocker it is possible to limit port scan by a single port [...]

From Bastille Man page:

Bastille Linux is a security hardening program for Mandrake, Red Hat, and Debian GNU/Linux. If run in the preferred Interactive mode (using InteractiveBastille), it can teach you a good deal about security while enhancing your system’s protection against attacks. If run in the quicker Automated mode (using AutomatedBastille), it can quickly tighten [...]

Electronic Frontier Foundation (EFF) released a step by step guide to figure out if your ISP is logging your internet activity. Due to the recent complains by many Comcast users that their online activity is abruptly cut-off because of their heavy use of torrent downloading.
EFF, with the help of whireshark shows you how to verify [...]

This utility checks or sets the status of a network interface’s Media Independent Interface (MII) unit. Most fast ethernet adapters use an MII to autonegotiate link speed and duplex setting.
Most intelligent network devices use an autonegotiation protocol to communicate what media technologies they support, and then select the fastest mutually supported media technology. The -A [...]