Educational Resource

Endpoint Security

How-To-Secure-A-Linux-Server

by imthenachoman

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1.2Kforks

335watchers

Updated 7 months ago

About

A comprehensive, evolving guide that teaches how to secure a Linux server through practical endpoint protection, intrusion detection, and security automation techniques.

An evolving how-to guide for securing a Linux server.

Primary Use Case

This guide is designed for system administrators and Linux users who want to harden their Linux servers against attacks by implementing best security practices. It provides step-by-step instructions and automation tips to secure SSH, configure firewalls, enable intrusion detection, and audit system integrity, making it ideal for those setting up or maintaining secure Linux server environments.

Key Features

Step-by-step SSH hardening including key management and 2FA/MFA
Firewall configuration using UFW and iptables with PSAD intrusion detection
Application-level intrusion prevention with Fail2Ban and CrowdSec
Security auditing with tools like Lynis, OSSEC, and logwatch
File integrity monitoring with AIDE (work in progress)
Rootkit detection using Rkhunter and chrootkit (work in progress)
Automated security updates and alerting
Sandboxing applications with FireJail

Installation

Choose and install a suitable Linux distribution for your server
Follow pre/post installation requirements outlined in the guide
Configure SSH server securely by editing /etc/ssh/sshd_config
Set up SSH public/private keys and create SSH groups for access control
Install and configure UFW firewall and iptables with PSAD
Install Fail2Ban and CrowdSec for application intrusion prevention
Set up auditing tools like Lynis, OSSEC, and logwatch
Optionally install AIDE, ClamAV, Rkhunter, and chrootkit for enhanced auditing
Configure automatic security updates and alerting mechanisms
Use provided Ansible playbooks to automate security configurations

Usage

>_ ufw enable

Enable the Uncomplicated Firewall to start filtering network traffic

>_ psad -H

Start PSAD for iptables intrusion detection and prevention

>_ fail2ban-client status

Check the status of Fail2Ban to monitor banned IPs and jails

>_ crowdsec-cli decisions list

List current decisions made by CrowdSec for intrusion prevention

>_ lynis audit system

Run a full security audit of the Linux system using Lynis

>_ ossec-control start

Start the OSSEC host intrusion detection system

>_ aide --check

Perform a file integrity check using AIDE (work in progress)

>_ rkhunter --check

Run rootkit detection scan with Rkhunter

>_ chrootkit

Execute chrootkit rootkit detection tool

>_ firejail <application>

Run an application inside a sandbox environment using FireJail

Security Frameworks

Initial Access

Defense Evasion

Credential Access

Discovery

Protect

Usage Insights

Integrate the guide's automation scripts with configuration management tools like Ansible or Puppet for scalable deployment.
Use the step-by-step SSH hardening and 2FA setup to reduce attack surface from credential theft and brute force.
Leverage the intrusion detection and prevention setups (Fail2Ban, CrowdSec, PSAD) for real-time alerting and automated response.
Incorporate file integrity monitoring and rootkit detection tools into continuous monitoring pipelines for early compromise detection.
Use the guide as a training baseline for blue and purple teams to understand Linux server hardening and detection capabilities.

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Security Profile

Red Team80%

Blue Team70%

Purple Team60%

Details

LicenseCreative Commons Attribution Share Alike 4.0 International

Open Issues75

Topics

linux

hardening

hardening-steps