This repo is a practical, hands-on Linux hardening lab built around the widely-respected CIS Benchmarks for Ubuntu 22.04 and RHEL 9. Instead of just documenting the benchmarks, the author bundles Bash automation scripts that apply hardening controls, then uses Lynis (a well-known auditing tool) to produce before/after comparisons so you can actually measure the impact of each change.

What makes it interesting:

• Two-distro coverage. Most hardening repos target a single distro. Covering both Debian-family (Ubuntu 22.04) and RHEL-family (RHEL 9) systems means the scripts have to grapple with the real differences between apt/dpkg vs dnf/rpm, AppArmor vs SELinux, and different default service sets.
• Measurable outcomes. The Lynis before/after workflow gives learners a concrete feedback loop: run the audit, apply the script, re-run the audit, see the hardening index climb. That's genuinely useful pedagogy compared to the more common "here is a wall of sysctl settings, good luck."
• CIS-aligned. The CIS Benchmarks are the de-facto baseline that auditors, compliance teams, and cloud security posture tools reference. Learning to implement them by hand demystifies what tools like OpenSCAP or Chef InSpec profiles are actually checking under the hood.

Who would benefit: Sysadmins studying for the RHCSA/RHCE or Linux+ exams, security engineers standing up a new baseline image, students in a blue-team or SOC track who want a repeatable lab environment, and homelabbers who want to lock down their self-hosted boxes without wading through 400-page PDFs. Also useful as a reference for anyone writing Ansible/Puppet hardening roles — you can crib the individual checks and translate them into idempotent config management resources.

The Roff language tag suggests the docs are being rendered as man pages, which is a nice touch for a hardening toolkit meant to live on the boxes it protects.