Linux Security Hardening

Acknowledgement: Shared by Peter Bamuhigire, techguypeter.com, +256 784 464178.

Use When

• Use when hardening a Debian/Ubuntu server — user/group/sudo hardening, file permission audits, PAM password policy + MFA, AppArmor mandatory access control, auditd system call logging, kernel sysctl hardening, file integrity monitoring (AIDE), rootkit detection (rkhunter/chkrootkit), unattended security patching, GRUB + UEFI + LUKS boot security, and CIS benchmark compliance.
• The task needs reusable judgment, domain constraints, or a proven workflow rather than ad hoc advice.

Do Not Use When

• The task is unrelated to linux-security-hardening or would be better handled by a more specific companion skill.
• The request only needs a trivial answer and none of this skill's constraints or references materially help.

Required Inputs

• Gather relevant project context, constraints, and the concrete problem to solve; load references only as needed.
• Confirm the desired deliverable: design, code, review, migration plan, audit, or documentation.