Chapter 10: Keeping Your System Hardened with SELinux

In this chapter, we are going to familiarize ourselves with SELinux. SELinux has been around for a while, but a lack of understanding regarding how it works leads many people to suggest disabling it.

This is not something we want, as it would be similar to telling a user to forego a password because it is hard to remember.

We will introduce the origins of SELinux, and what the default modes and policies are. Then, we will understand how SELinux applies to our files, folders, and processes, and how to restore them to the system defaults.

Additionally, we will explore how to fine-tune the policies using Booleans and troubleshoot common issues with the help of the following sections:

• SELinux usage in enforcing and permissive modes
• Reviewing the SELinux context for files and processes
• Tweaking the policy with semanage
• Restoring changed file contexts to the default policy
• Using SELinux Boolean settings...