The Practical Linux Hardening Guide is a comprehensive resource that provides step-by-step instructions for securing GNU/Linux systems. The guide covers hardening techniques based on established industry standards including CIS (Center for Internet Security), STIG (Security Technical Implementation Guides), NIST (National Institute of Standards and Technology), PCI-DSS (Payment Card Industry Data Security Standard), and SCAP (Security Content Automation Protocol). It offers practical guidance for building hardened systems and services, addressing both internal and external security threats. The resource presents security configurations and hardening procedures in a straightforward manner, making it accessible for system administrators and security professionals working with Linux environments. The guide focuses on implementing security controls and configurations that align with recognized cybersecurity frameworks and compliance requirements.