Linux Server Hardening Checklist is a practical, no-nonsense reference for system administrators, students, developers, DevOps engineers, and anyone responsible for running a Linux server.Instead of overwhelming you with security theory, this book breaks Linux server hardening into 100 practical, numbered steps that you can use during a server build, security review, or routine maintenance.You'll learn how to:Harden SSH and user access controlsReduce unnecessary network exposure and configure firewallsKeep Ubuntu, RHEL, and CentOS Stream systems properly patched and updatedStrengthen file permissions and filesystem securityIdentify and lock down unnecessary services and daemonsConfigure and understand logging and auditingImprove monitoring and endpoint securityPrepare reliable backups and recovery proceduresReview important security settings using a 100-point checklistQuickly find commonly used commands in the Quick Command ReferenceThe book explains not only what to change, but also why the change matters, helping you understand the security risk behind each recommendation.Commands and configuration examples are presented with the differences between Ubuntu/Debian-based systems and RHEL/CentOS Stream systems clearly identified where applicable.Whether you're hardening a single home-lab server, managing production infrastructure, studying for a Linux or security certification, or simply trying to build safer Linux systems, this checklist gives you a structured starting point.Practical. Repeatable. Focused on the settings that matter.2026 Edition