Security Hardening for Linux Hosts

What this arc covers

Security is framed as layered decisions with tradeoffs, not buzzword bingo. You will walk through minimal privilege models, sane firewall baselines, and auditd rules that remain readable six months later. Labs include misconfigured hosts you must harden without locking yourself out. We discuss quality standards expectations in enterprise markets without pretending a single course replaces dedicated security teams.

Feature stack

• SSH posture matrix covering keys, jump hosts, and bastion patterns
• AppArmor and SELinux introductions with failure triage flows
• Host firewall recipes with explicit allow lists
• Kernel parameter labs with documented rollback paths
• Audit rule authoring that survives upgrades
• Service account hygiene for daemons and cron
• Evidence bundles suitable for external reviewers walkthroughs

Outcomes you can demonstrate

• Produce a host hardening sheet with rationale per control
• Demonstrate a safe lockout recovery using out-of-band access
• Prioritize findings using severity, exploitability, and blast radius