INSERT (the Inside Security Rescue Toolkit) aims to be a multi-functional, multi-purpose disaster recovery and network analysis system. It boots from a credit card-sized CD-ROM and is basically a stripped-down version of Knoppix. It features good hardware detection, fluxbox, emelfm, links-hacked, ssh, tcpdump, nmap, chntpwd, and much more. It provides full read-write support for NTFS partitions (using ntfs-3g), and the ClamAV virus scanner (including a fairly recent signature database and a GUI). It provides partition handling with gParted and also has a network boot facility.
TrinityOS is a step-by-step, example-driven HOWTO on building a very functional Linux box with strong security in mind. TrinityOS is well known for its strong packet firewall ruleset, Chrooted and Split DNS (v9 and v8), secured Sendmail (8.x), Linux PPTP, Serial consoles and Reverse TELNET, DHCPd, SSHd, UPSes, system performance tuning, the automated TrinityOS-Security implementation scripts, and much more.
/etc/net represents a new approach to Linux network configuration tasks. Inspired by the limitations of traditional network configuration subsystems, /etc/net provides built-in support for configuration profiles, interface name management, removable devices, full iproute2 command set, interface dependencies resolution, QoS, and firewall configuration frameworks. /etc/net provides support for the following interface types: ethernet, WiFi (WEP), IPv4/IPv6 tunnels, PSK IPSec tunnels, VLAN, PLIP, ethernet bonding and bridging, traffic equalizer, Pent@NET, Pent@VALUE, SkyStar-2, TUN/TAP, OpenVPN TUN/TAP, usbnet, and PPP. Due to its modular structure, support for new interface types can be added without overall design changes.
The Auditor security collection is a live-system based on KNOPPIX. It provides tools for analyzing the security of a system. It features a menu structure that reflects the stages of a security check: foot-printing, analysis, scanning, wireless, brute-forcing, cracking. In addition to about 300 security tools, the collection includes background information regarding standard configuration and passwords, truly extensive word lists, and more mundane productivity tools.
Finnix is a small, self-contained, bootable Linux CD distribution ("LiveCD") for system administrators, based on Debian testing. You can use it to mount and manipulate hard drives and partitions, monitor networks, rebuild boot records, install other operating systems, and much more.
SoL (Server optimized Linux) is a Linux distribution completely independent from other Linux distributions. It was built from the original source packages and is optimized for heavy-duty server work. It contains all common server applications, and features XML boot and script technology that makes it easy to configure and make the server work.
eCos (Embedded Configurable OS) is an open source, configurable, portable, and royalty-free embedded Real Time Operating System. It is written in C++, provides all the usual OS things. You configure the OS so that the parts you don't need aren't loaded to the embedded system. eCos is released under a modified GPL that allows for its use in embedded systems without having to GPL the embedded application.