Permissions & Security (Chmod/Chown/ACLs/SELinux/AppArmor)

Stop your custom web app from failing when SELinux goes rogue

🧩 The Challenge

You finally pushed your new Python app to production, but it’s throwing permission denied errors even though your file ownership looks perfect. I’ve wasted entire afternoons hunting for a bug in my code only to realize the security kernel was blocking me the whole time.

💡 The Fix

Instead of just turning the whole security module off like a caveman, use the audit logs to generate a custom policy module that tells the kernel specifically what your app is allowed to touch.

ausearch -m AVC -ts recent | audit2allow -M my_custom_app
semodule -i my_custom_app.pp

⚙️ Why It Works

Running these commands identifies exactly which blocked syscalls your process is trying to make and compiles a small policy patch that whitelists only those operations. It keeps the system secure while letting your app actually function as intended.

🚀 Pro-Tip: If you just want to test if it’s SELinux, run setenforce 0, but never leave it like that in production.

Linux Tips & Tricks | © ngelinux.com | 7/27/2026