Painless Docker - 2nd Edition

Use SELinux

While most security systems act like a bouncer at a club (checking your ID at the door and then letting you run wild inside), SELinux acts like a high-security prison warden who follows a rulebook that never changes.

The story starts at the NSA. In the late '90s, they realized that the standard way Linux handled security was fundamentally flawed. If a hacker tricked a "root" program, they became "root" themselves - giving them the keys to the entire system.

The NSA wanted a system where identity didn't matter. They wanted a world where, even if you were the King, you still couldn't walk into the Treasury unless the rulebook specifically said: "The King is allowed to enter the Treasury on Tuesdays." They gifted this "Mandatory Access Control" to the world in 2000, and it changed the DNA of Linux security.

Imagine every single thing in your computer - every file, every folder, every mouse click, and every running app - has a sticky note attached to it.

• A text file might have a label that says: SECRET_DOCUMENT.