Secure a Linux VPS: UFW, fail2ban, SSH keys, disable root

A VPS exposed to the internet is constantly scanned. Without basic configuration, you risk SSH brute-force attempts, intrusions and compromised services. This guide lays the foundations for a hardened Debian/Ubuntu VPS in under 30 minutes.

⚙️ Prerequisites

A Lordhosting VPS (Debian 11/12 or Ubuntu 22.04/24.04 recommended)
An SSH client (Terminal on macOS/Linux, PowerShell or PuTTY on Windows)
Your root credentials received by email at delivery

⚙️ 1. Initial SSH connection

Connect one last time as root to prepare what follows:

ssh root@your_ip

⚙️ 2. Update the system

Always start by patching installed packages:

apt update && apt upgrade -y

⚙️ 3. Create a sudo user

Disabling root is dangerous without a replacement user. Create one with sudo privileges:

adduser lordadmin
usermod -aG sudo lordadmin

Replace lordadmin with the username of your choice.

⚙️ 4. Set up SSH key authentication

On your local machine, generate a key pair if you don't already have one:

ssh-keygen -t ed25519 -C "your_email@example.com"

Accept the default path (~/.ssh/id_ed25519) and choose a strong passphrase.

Then copy the public key to the VPS:

ssh-copy-id lordadmin@your_ip

If ssh-copy-id isn't available (Windows), manually copy the contents of ~/.ssh/id_ed25519.pub into /home/lordadmin/.ssh/authorized_keys on the VPS.

Test the key-based connection in a new window:

ssh lordadmin@your_ip

If it works without asking for a password, continue. Otherwise, don't touch anything and fix authentication first.

Still connected as lordadmin, open the SSH config:

sudo nano /etc/ssh/sshd_config

Modify or add the following lines:

PermitRootLogin no
PasswordAuthentication no
PubkeyAuthentication yes

Save (Ctrl+O, Enter, Ctrl+X) then reload SSH:

sudo systemctl restart ssh

⚠️ Don't close your active session until you've verified, in a new window, that you can reconnect as lordadmin with your key. If it doesn't work, you're still logged in and can roll back.

⚙️ 6. Install and configure UFW (firewall)

UFW (Uncomplicated Firewall) is a simple wrapper around iptables.

sudo apt install -y ufw
sudo ufw default deny incoming
sudo ufw default allow outgoing
sudo ufw allow OpenSSH
sudo ufw enable

Check the status:

sudo ufw status verbose

Remember to open the ports needed for your services. Some examples:

sudo ufw allow 80/tcp       # HTTP
sudo ufw allow 443/tcp      # HTTPS
sudo ufw allow 25565/tcp    # Minecraft Java
sudo ufw allow 19132/udp    # Minecraft Bedrock

⚙️ 7. Install and configure fail2ban

fail2ban automatically bans IPs that repeatedly fail login attempts:

sudo apt install -y fail2ban

Create a local config (don't edit jail.conf directly):

sudo nano /etc/fail2ban/jail.local

Paste this:

[DEFAULT]
bantime = 1h
findtime = 10m
maxretry = 5

[sshd]
enabled = true
port = ssh
logpath = %(sshd_log)s
backend = %(sshd_backend)s

Start the service:

sudo systemctl enable --now fail2ban

To see banned IPs in real time:

sudo fail2ban-client status sshd

⚙️ 8. Final check

✅ SSH connection by key only (no password)
✅ Root login disabled
✅ UFW active with minimal rules
✅ fail2ban monitoring SSH

You can now install your services (web, Pterodactyl, Discord bots, etc.) on a clean ground. To go further, enable automatic security updates with unattended-upgrades and set up regular backups of your VPS.