Make the next change safer.

Learn to protect the machine, the workload, and the path to production. Practical hardening guides with commands, evidence to check, and a way back.

Start here · 35 min

Servers & SSH

Keep a way back in while you tighten SSH, review exposed ports, and plan security updates.

Build on the basics · 30 min

Linux services

Move from shell permissions to service isolation, useful logs, and a recovery plan.

Container basics needed · 25 min

Docker

Run a small container with a non-root user, fewer privileges, and limited writes. Inspect the result rather than trusting the flags.

Cluster basics needed · 40 min

Kubernetes

Review access, introduce Pod Security carefully, and test network isolation in a dedicated namespace.

Repository basics needed · 25–35 min per platform

CI/CD & supply chain

Choose GitHub Actions or Azure DevOps. Review pipeline permissions, protect credentials, and put approval boundaries around delivery.

A useful habit for every layer

Inspect
Know what runs, who needs access, and what must keep working.
Change
Apply one control in a disposable environment first.
Verify
Test both the behavior you allow and the behavior you intend to block.
Recover
Keep the previous state and practice restoring it.

Original OpsRung walkthroughs informed by Ubuntu, Docker, Kubernetes, systemd, GNU, GitHub, and Microsoft documentation. Official references are linked beside each control. Reviewed 31 October 2026.