UFW Firewall Basics for Ubuntu

This guide is for learning. Run these commands only on your own lab or servers.

UFW is a simple front end for the Linux firewall. The idea is to deny all incoming traffic and then allow only the services you actually run.

1. Set the defaults

sudo ufw default deny incoming
sudo ufw default allow outgoing

2. Allow your services

sudo ufw allow OpenSSH
sudo ufw allow 80/tcp
sudo ufw allow 443/tcp

3. Enable and check

sudo ufw enable
sudo ufw status verbose

4. Remove a rule

sudo ufw status numbered
sudo ufw delete 3

Allow SSH before you enable UFW, otherwise you can lock yourself out of a remote server.