Security-focused operating system

This is a list of operating systems with a sharp security focus. Here, "security-focused" means that the project is devoted to increasing the security as a major goal. As such, something may be secure without being "security-focused." For example, almost all of the operating systems mentioned here are faced with security bug fixes in their lifetime; however, they all strive consistently to approach all generic security flaws inherent in their design with new ideas in an attempt to create a secure computing environment. Security-focused does not mean security-evaluated operating system, which refers to operating systems that have achieved certification from an external security-auditing organization. An operating system that provides sufficient support for multilevel security and evidence of correctness to meet a particular set of government requirements is called a "trusted operating system".

The list is alphabetical and does not imply a ranking.

The Linux kernel provides among other security features, the Linux Security Module (LSM), officially integrated with the mainline Linux kernel since 2003. However, there have been specialized distributions and projects that attempt to make Linux more secure in general or for particular scenarios.

openSUSE is a stateful network packet filter (also known as firewall inside the SUSE communities). A YaST Firewall configuration module is provided.

The "Securing Debian Manual" contains information for Debian administrators. Debian includes support for SELinux since version 5.0, as well as AppArmor and Tomoyo. See also Debian Security information and policy.

Kali Linux is a Debian-derived Linux distribution designed for digital forensics and penetration testing, formerly known as Backtrack.

Tails is a security-focused Debian-based Linux distribution aimed at preserving privacy and anonymity.

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