An evolving how-to guide for securing a Linux server that, hopefully, also teaches you a little about security and why it matters. Table of Contents: - Introduction - Guide Objective - Why Secure Your Server - Why Yet Another Guide - Other Guides - To Do / To Add - Guide Overview - About This Guide - My Use-Case - Editing Configuration Files - For The Lazy - Contributing - Before You Start - Identify Your Principles - Picking A Linux Distribution - Installing Linux Pre/Post Installation Requirements - Other Important Notes - Using Ansible Playbooks to secure your Linux Server - The SSH Server - Important Note Before You Make SSH Changes - SSH Public/Private Keys - Create SSH Group For AllowGroups - Secure /etc/ssh/sshd_config - Remove Short Diffie-Hellman Keys - 2FA/MFA for SSH - The Basics - Limit Who Can Use sudo - Limit Who Can Use su - Run applications in a sandbox with FireJail - NTP Client - Securing /proc - Force Accounts To Use Secure Passwords - Automatic Security Updates and Alerts - More Secure Random Entropy Pool (WIP) - Add Panic/Secondary/Fake password Login Security System - The Network Firewall With UFW (Uncomplicated Firewall) - iptables - Intrusion Detection And Prevention with PSAD - Application Intrusion Detection