Most common commands

sudo ufw enable
sudo ufw disable
sudo ufw status numbered
sudo ufw delete 1
sudo systemctl status ufw.service

More commands

Rules

ufw default deny # deny incoming by default
ufw allow from 90.16.45.159 # allow all from IP

Troubleshoot

1. Disable it first and then add rule and enable it
2. sudo ufw reload

Issues

1. It does not block docker ports well

IPTable

Cheat sheet: https://andreafortuna.org/2019/05/08/iptables-a-simple-cheatsheet/