Linux System Hardening

Linux System Hardening Guide

Complete beginner-friendly guide to system hardening on Linux, covering Arch Linux, CachyOS, and other distributions including security best practices, system lockdown, and security tools.

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Table of Contents

1. Security Best Practices
2. Firewall Configuration
3. Kernel Hardening
4. Security Tools
5. Troubleshooting

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Security Best Practices

User Management

Secure users:

# Disable root login
sudo passwd -l root

# Use sudo
sudo visudo
# Ensure: %wheel ALL=(ALL) ALL

Service Management

Disable unnecessary:

# List services
systemctl list-unit-files --type=service

# Disable service
sudo systemctl disable service-name

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Firewall Configuration

UFW

Configure UFW:

# Install UFW
sudo pacman -S ufw

# Enable firewall
sudo ufw enable

# Default deny
sudo ufw default deny incoming
sudo ufw default allow outgoing

firewalld

Configure firewalld:

# Install firewalld
sudo pacman -S firewalld

# Enable
sudo systemctl enable --now firewalld

# Configure zones
sudo firewall-cmd --set-default-zone public

See Security Configuration for detailed guide.

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Kernel Hardening

Kernel Parameters

Harden kernel:

# Edit GRUB
sudo vim /etc/default/grub

Add:

GRUB_CMDLINE_LINUX_DEFAULT="... apparmor=1 security=apparmor"

Regenerate:

sudo grub-mkconfig -o /boot/grub/grub.cfg

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Security Tools

fail2ban

Install fail2ban:

# Install fail2ban
sudo pacman -S fail2ban

# Enable
sudo systemctl enable fail2ban
sudo systemctl start fail2ban

rkhunter

Install rkhunter:

# Install rkhunter
sudo pacman -S rkhunter

# Update database
sudo rkhunter --update

# Check system
sudo rkhunter --check

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Troubleshooting

Security Issues

Check security:

# Check firewall
sudo ufw status

# Check services
systemctl list-unit-files --type=service

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Summary

This guide covered system hardening for Arch Linux, CachyOS, and other distributions, including security practices, firewall, and security tools.

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Next Steps

• Security Configuration - Security setup
• SELinux and AppArmor - MAC setup
• SSH Configuration - SSH security
• ArchWiki Security: https://wiki.archlinux.org/title/Security

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This guide covers Arch Linux, CachyOS, and other Linux distributions. For distribution-specific details, refer to your distribution's documentation.