Security Best Practices

Introduction

Linux is inherently secure by design, but a poorly configured server is an easy target for attackers. Following security best practices ensures that your system remains robust against unauthorized access, malware, and data breaches.

1. Keep the System Updated

The most common way servers are breached is through known vulnerabilities in outdated software. Always keep your system packages updated.

# On Debian/Ubuntu systems
sudo apt update && sudo apt upgrade -y

Consider configuring unattended-upgrades to automatically install critical security patches without manual intervention.

2. Disable Root SSH Login

The root account has ultimate power. Attackers constantly run automated scripts to brute-force the password for the root account over SSH.

You should absolutely prevent the root user from logging in remotely.

1. Open the SSH config file: sudo nano /etc/ssh/sshd_config
2. Find the line: PermitRootLogin yes
3. Change it to: PermitRootLogin no
4. Restart the SSH service: sudo systemctl restart sshd

Users must now log in as a standard user and use sudo for administrative tasks.

3. Use a Firewall (UFW)

A firewall blocks unwanted incoming network traffic. The Uncomplicated Firewall (UFW) is the easiest way to manage iptables on Ubuntu.

# Deny all incoming traffic by default
sudo ufw default deny incoming

# Allow all outgoing traffic
sudo ufw default allow outgoing

# Explicitly allow SSH (Port 22) and HTTP (Port 80)
sudo ufw allow ssh
sudo ufw allow http

# Enable the firewall
sudo ufw enable

Warning: Always ensure you allow SSH before enabling the firewall, otherwise you will lock yourself out of your remote server!

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