Linux Server Hardening (Ubuntu)

A practical project to harden an Ubuntu server using security best practices.

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Table of Contents

• Project Overview
• Threat Model & Security Goals
• Baseline & Preparation
• User & Access Management
• SSH Hardening
• Firewall & Network Hardening
• System Updates & Patch Management
• Intrusion Prevention (Fail2ban)
• Kernel & Runtime Hardening
• Logging, Monitoring & Auditing
• Backup & Recovery
• Set password and auth policies (PAM)
• Operations & Maintenance
• Troubleshooting
• Future Improvements
• Appendix A: Command Reference
• Appendix B: Configuration Backup
• Validation and Security Checklist

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Scope

This project focuses on:

• Initial server baseline and inventory
• SSH hardening with key-based authentication
• Firewall and network controls
• Brute-force mitigation (Fail2ban)
• Automatic security updates
• Logging and auditing basics
• Backup and recovery readiness
• Validation checklist and ongoing maintenance

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Quick Start

1. Read Project Overview
2. Follow the guides in order (00 → 13)
3. Execute commands carefully and test access after each critical change
4. Complete Validation & Security Checklist
5. Check out the Project Demonstration on Youtube

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Safety Notes

• Always keep one active root/console session while hardening SSH and firewall settings.
• Test new SSH config in a second session before disconnecting your original session.
• Back up config files before changes (see Appendix B).
• Do not disable password auth until SSH keys are verified.