Unsure what a Linux distribution is? Read the Linux Distribution Guide
Alpine Linux is a community developed operating system designed for x86 routers, firewalls, vpns, voip boxes and servers. It uses grsecurity patched kernel by default and is based on uclibc/busybox.
ArchStrike is a Linux hacker distro based on Arch. It provides security professionals and hackers with powerful open-sourced tools for penetration testing and security auditing operations.
Astaro Security Linux
Astaro Security Linux offers an integrated software solution that provides performance in an all-in-one Firewall. Its hardened operating system, stateful packet inspection, content filtering (virus & surf protection), application proxies and IPsec based VPN provides a powerful solution to todays security issues.
A distribution based on RedHat that is aimed primarily at individual users who are less knowledgeable about security than experts would be. The Bastille Hardening program "locks down" an operating system, proactively configuring the system for increased security and decreasing its susceptibility to compromise. Bastille can also assess a system's current state of hardening, granularly reporting on each of the security settings with which it works.
Cryptux is a full featured Linux distribution that aims to bring full disk encryption to the common user. Cryptux is based on RedHat Linux with the inclusion of the PPDD crypto block driver by Allan Latham.
Darkfire Secure Linux
aims to be the be a fast, secure computing environment for both Server and Desktop. Darkfire uses 100% FSF/OSI licensesd tools so it will remain free and redistributable
Endian Firewall is a "turn-key" linux security distribution based on IPCop that turns every system into a full featured security appliance. The software has been designed with "usability in mind" and is very easy to install, use and mange, without loosing its flexibility.
EnGarde Secure Linux
EnGarde Secure Linux is a secure distribution of Linux that implements advanced security techniques. It can be used as a web, DNS, mail, database, e-commerce, and general Internet server.
Hardened Debian/Debian Hardened is a project that brings to Debian GNU/Linux high security & hardening features, hardened kernels, packages and enhanced toolchain, the DHKP kernel patches and other cryptography-related enhancements.
Hardened Linux is a hardened and minimalized Slackware Linux. It includes the grsec kernel patch and hardened versions of Slackware packages and hardening for /proc, configuration files and the filesystem.
The IPCop Firewall is a Linux firewall distro. It will be geared towards home and SOHO users. The difference with existing firewalls is that the IPCop interface will be very user-friendly and task-based.
NetSecL (previously known as ISlack) is a security-focused Linux distribution. It includes Grsecurity by default. Most of the numerous security-related software is suited for penetration testing of your network. There are also security tools for testing your local security and IDSs for monitoring. The configuration of NetSecL is hardened by default: (listening for connection) services are turned off, and incoming ports are closed.
A Linux distribution, originally based on Red Hat Linux, designed for servers and with emphasis on strong security. The installation program allows the user to choose from a selection of pre-defined server classes, depending on the server's purpose, with all unneeded services turned off by default. For those who intend to install and test drive OpenNA Linux, beware that it cannot be installed on a pre-selected partition - the OS takes over the entire first hard disk.
A security-enhanced server operating system with Linux and GNU software as its core. It includes a complete build environment capable of rebuilding the entire system from source, supports multiple architectures (x86 and SPARC), and offers some compatibility for packages developed for other major Linux distributions. Owl combines several approaches to reduce the number and/or impact of flaws in its software components and impact of flaws in third-party software that one might install on the system. The primary approach used is proactive source code review for several classes of software vulnerabilities. However, because of the large amount of code, there's a certain level of "importance" for a software component or a part thereof to be audited. Currently, only pieces of code which are typically run with privileges greater than those of a regular user and/or typically process data obtained over a network are audited before the corresponding software component is included.
REMnux is a lightweight Linux distribution for assisting malware analysts in reverse-engineering malicious software. The distribution is based on Ubuntu.
Santoku is dedicated to mobile forensics, analysis, and security, and packaged in an easy to use, Open Source platform.
Securepoint Firewall & VPN Server
A high end firewall and VPN solution for protecting your Internet gateway.
Security Enhanced Linux
Security-enhanced Linux is a research prototype of the Linux® kernel and a number of utilities with enhanced security functionality designed simply to demonstrate the value of mandatory access controls to the Linux community and how such controls could be added to Linux. The Security-enhanced Linux kernel contains new architectural components originally developed to improve the security of the Flask operating system. These architectural components provide general support for the enforcement of many kinds of mandatory access control policies, including those based on the concepts of Type Enforcement®, Role-based Access Control, and Multi-level Security.
Sentry Firewall CD-ROM
Sentry Firewall CD-ROM is a Linux-based bootable CDROM suitable for use as an inexpensive and easy to maintain firewall, server, or IDS(Intrusion Detection System) Node. The system is designed to be immediately configurable for a variety of different operating environments via a configuration file located on a floppy disk, a local hard drive, and/or a network via HTTP(S), FTP, SFTP, or SCP.
SmoothWall Express is an open source firewall distribution based on the GNU/Linux operating system. Linux is the ideal choice for security systems; it is well proven, secure, highly configurable and freely??? available as open source code. SmoothWall includes a hardened subset of the GNU/Linux operating system, so there is no separate OS to install. Designed for ease of use, SmoothWall is configured via a web-based GUI, and requires absolutely no knowledge of Linux to install or use. Read more
Subgraph OS is based on a foundation designed to be resistant to attacks against operating systems and the applications they run.
Tinfoil Hat Linux
Tinfoil Hat Linux started as a secure, single floppy, bootable Linux distribution for storing PGP keys and then encrypting, signing and wiping files.
An updated, secure desktop distribution of Linux intended for University of Buffalo students, faculty, and staff who want to install a secure version of Linux but may not have the expertise to do so. UBLinux includes most, if not all, of the software needed for academic work.