What is SELinux?
Security-Enhanced Linux (SELinux) is a built-in security system for Linux that adds an extra layer of protection by controlling what programs and users are allowed to do on the system.
Let's break it down
- Security-Enhanced: stronger than the usual Linux security.
- Linux: the operating system that runs on many servers, phones, and computers.
- Security system: a set of rules that decide who can read, write, or run things.
- Controls what programs and users can do: instead of trusting every program, SELinux checks each action against its rules and blocks anything not allowed.
Why does it matter?
Because it can stop malware, bugs, or a compromised program from damaging the whole system, keeping data safe and reducing the risk of a security breach.
Where is it used?
- Web servers that host public websites, to prevent a hacked site from taking over the whole server.
- Cloud platforms (e.g., AWS, OpenStack) where many virtual machines share the same hardware.
- Enterprise workstations that need strict data-access policies.
- Embedded devices like routers or IoT gadgets that run a Linux base.
Good things about it
- Provides fine-grained, mandatory access control that even root can’t easily bypass.
- Helps contain attacks, limiting damage to a single process or service.
- Integrated into major Linux distributions, so it’s readily available and regularly updated.
- Offers predefined policy templates that simplify initial setup.
- Auditing logs make it easier to see why something was blocked.
Not-so-good things
- Can be complex to configure; a small mistake may break legitimate functionality.
- Learning curve is steep for beginners unfamiliar with Linux security concepts.
- Some applications may need custom policies, adding extra maintenance work.
- Performance overhead is usually low but can be noticeable on very low-resource devices.