This is a list of operating systems specifically focused on security. Similar concepts include security-evaluated operating systems that have achieved certification from an auditing organization, and trusted operating systems that provide sufficient support for multilevel security and evidence of correctness to meet a particular set of requirements.
A Linux distribution is an operating system made from a software collection that includes the Linux kernel, and often a package management system. Linux users usually obtain their operating system by downloading one of the Linux distributions, which are available for a wide variety of systems ranging from embedded devices and personal computers to powerful supercomputers.
Free and Open source Software Developers' European Meeting (FOSDEM) is a non-commercial, volunteer-organized European event centered on free and open-source software development. It is aimed at developers and anyone interested in the free and open-source software movement. It aims to enable developers to meet and to promote the awareness and use of free and open-source software.
Technical variations of Linux distributions include support for different hardware devices and systems or software package configurations. Organizational differences may be motivated by historical reasons. Other criteria include security, including how quickly security upgrades are available; ease of package management; and number of packages available.
Kernel-based Virtual Machine (KVM) is a free and open-source virtualization module in the Linux kernel that allows the kernel to function as a hypervisor. It was merged into the mainline Linux kernel in version 2.6.20, which was released on February 5, 2007. KVM requires a processor with hardware virtualization extensions, such as Intel VT or AMD-V. KVM has also been ported to other operating systems such as FreeBSD and illumos in the form of loadable kernel modules.
Fedora Linux is a Linux distribution developed by the Fedora Project. It was originally developed in 2003 as a continuation of the Red Hat Linux project. It contains software distributed under various free and open-source licenses and aims to be on the leading edge of open-source technologies. It is now the upstream source for CentOS Stream and Red Hat Enterprise Linux.
Alpine Linux is a Linux distribution designed to be small, simple, and secure. It uses musl, BusyBox, and OpenRC instead of the more commonly used glibc, GNU Core Utilities, and systemd.
Tails, or "The Amnesic Incognito Live System," is a security-focused Debian-based Linux distribution aimed at preserving privacy and anonymity. It connects to the Internet exclusively through the anonymity network Tor. The system is designed to be booted as a live DVD or live USB and never writes to the hard drive or SSD, leaving no digital footprint on the machine unless explicitly told to do so. It can also be run as a virtual machine, with some additional security risks. The Tor Project provided financial support for its development in the beginnings of the project, and continues to do so alongside numerous corporate and anonymous sponsors.
BackBox is a penetration test and security assessment oriented Ubuntu-based Linux distribution providing a network and informatic systems analysis toolkit. It includes a complete set of tools required for ethical hacking and security testing.
Qubes OS is a security-focused desktop operating system that aims to provide security through isolation. Isolation is provided through the use of virtualization technology. This allows the segmentation of applications into secure virtual machines called qubes. Virtualization services in Qubes OS are provided by the Xen hypervisor.
Kali Linux is a Debian-derived Linux distribution designed for digital forensics and penetration testing. It is maintained and funded by Offensive Security.
Whonix is a Kicksecure-based security hardened Linux distribution. Its main goals are to provide strong privacy and anonymity on the Internet. The operating system consists of two virtual machines, a workstation and a Tor gateway running Debian. All communications are forced through Tor.
Besides the Linux distributions designed for general-purpose use on desktops and servers, distributions may be specialized for different purposes including computer architecture support, embedded systems, stability, security, localization to a specific region or language, targeting of specific user groups, support for real-time applications, or commitment to a given desktop environment. Furthermore, some distributions deliberately include only free software. As of 2015, over four hundred Linux distributions are actively developed, with about a dozen distributions being most popular for general-purpose use.
Parrot OS is a Linux distribution based on Debian with a focus on security, privacy, and development.
Subgraph OS was a Debian-based project designed to be resistant to surveillance and interference by sophisticated adversaries over the Internet. It has been mentioned by Edward Snowden as showing future potential.
Container Linux is a discontinued open-source lightweight operating system based on the Linux kernel and designed for providing infrastructure for clustered deployments while focusing on automation, ease of application deployment, security, reliability, and scalability. As an operating system, Container Linux provided only the minimal functionality required for deploying applications inside software containers, together with built-in mechanisms for service discovery and configuration sharing.
CalyxOS is an operating system for smartphones based on Android with mostly free and open-source software. It is produced by the Calyx Institute as part of its mission to "defend online privacy, security and accessibility."