General Commands:

sudo ufw status
sudo ufw status verbose
sudo ufw app list
sudo ufw allow OpenSSH
sudo ufw allow ssh
sudo ufw show added
sudo ufw allow http
sudo ufw allow https
sudo ufw allow 'Nginx Full'
sudo ufw allow 'Nginx HTTP'
sudo ufw allow 'Nginx HTTPS'
sudo ufw enable
sudo ufw reload

sudo lsof -i :8888

sudo ufw allow from <ip-address> to any port 8888

Additional reference: https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-with-ufw-on-ubuntu