What Does Security-Enhanced Linux Mean?
Security-Enhanced Linux (SELinux) is a security module specifically made for the Linux kernel, which enables features that support security policies for access control, including mandatory access control (MAC).
Released in January 1998, it is written in the C programming language and has been a part of the Linux mainline since 2003, when version 2.6 which was released.
Techopedia Explains Security-Enhanced Linux
SELinux is a compilation suite of various kernel modifications and user-level tools that can be incorporated into many Linux distributions. It is designed to separate security decision and policy enforcement and streamline security policy enhancement-enabled software.
SELinux is the result of several projects undertaken by the National Security Agency (NSA) as part of its Information Assurance Mission, which is geared toward separating information based on its confidentiality and integrity requirements for the purpose of providing security for whole systems.
SELinux provides administrators with more power over access control schemes. For example, access can be limited by using variables, such as user/application permission levels for resources like files and other types of data.
In the normal Linux environment, users and applications can change file modes (read, write, modify), but SELinux access controls are determined by preloaded policies that cannot be touched by careless users and misbehaving applications.
SELinux offers fine controls to access, not just specifying who can write, read or execute files. It also can specify who can unlink, move, or append specific files. This control extends to other computing resources, such as networking and inter-process communication (IPC).