FrazierWall Linux is a single floppy distribution Linux firewall that is based on the Linux Router Project. It is designed for use with ethernet base internet connections (such as cable modems or xDSL lines). It allows you to share such a connection with several other computers on a LAN. It is easy to setup and maintain, and is available in a Linux configurable software version.
CD Linux Server is an embedded Linux system on a bootable live CD. It can be used to set up mail, Web, file, FTP, proxy, DHCP, DNS, MySQL, LDAP, and other services very quickly. The mail server includes antivirus, antispam, and mail recorder features. It can be used for free for up to 10 accounts, while the advanced version is licensed for an unlimited number of users. There is not any restriction against the time.
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.
/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.
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.