SELinuxin

SELinuxin is a term sometimes used to denote the Security-Enhanced Linux (SELinux) security framework and its integration in Linux systems. SELinux provides a mandatory access control mechanism intended to confine processes and limit the damage from security vulnerabilities.

At its core, SELinux is implemented as a security module in the Linux kernel. Policies written in the SELinux policy language define domains (types) for subjects such as processes and objects such as files, sockets, and IPC resources, and specify permitted interactions. Key concepts include Type Enforcement, roles, booleans, and, in some configurations, multi-level or multi-category security.

SELinux supports several modes: enforcing, permissive, and disabled. A policy can be targeted, offering strong protection for important services while remaining easier to manage than a full MLS policy. In practice, many deployments use targeted policies that confine a subset of services.

Management tasks include checking status with sestatus, switching modes with setenforce, and administering policy modules with semanage, semodule, and sepolicy. File labeling is performed with restorecon and chcon, and policy development involves writing .te files, compiling them, and loading the resulting modules.

Deployment considerations include that many major distributions ship with SELinux support and labeled policies. SELinux can improve security when properly configured but adds administrative complexity and potential troubleshooting overhead. In container environments, SELinux remains a key confinement mechanism, though compatibility and policy tuning are important.

See also: Security-Enhanced Linux; Linux Security Modules; Mandatory access control.