os-hardening

What problem does it solve?

This Skill reduces the attack surface of a Linux system by disabling what is unnecessary, tightening permissions, and enforcing safer defaults that mitigate common intrusion paths.

Core Features & Use Cases

• SSH and authentication hardening: disables root login, enforces key-only SSH, and applies safer access policies for users and service accounts.
• Network exposure reduction: removes unnecessary listening services, applies default-deny firewall rules, and restricts internal services to localhost.
• Filesystem and update hardening: locks down sensitive files, restricts execution in risky mount points like /tmp, and ensures security patching with safe reboot practices.
• Audit and monitoring: enables auditing, logs privileged actions, and supports integrity monitoring to detect unexpected changes.
• Use Case: When onboarding a new server before internet exposure or responding to a security scan finding, apply the checklist to bring the system in line with baseline hardening practices.

Quick Start

Use the os-hardening skill to produce a hardened baseline plan for a new Ubuntu/Debian server by applying SSH, firewall, filesystem, patching, and auditing recommendations.