ufw

Uncomplicated firewall.
ufw allow <port_number>
ufw deny <port_number>

Examples:
ufw allow https
ufw allow http
ufw allow tcp/22
ufw allow ssh

Allow IPs
ufw allow from <IP address>

Deny IPs
ufw deny from <IP address>

Allow IPs for a specific port
ufw allow from <IP address> to any port <PORT NUMBER

Deny IPs from a specific port
ufw deny from <IP ADDRESS> to any port <PORT NUMBER>

Reset UFW
ufw reset

Enable reset
ufw enable

View Rules
ufw status

View Numbered rules
ufw status numbered

Verbose rules
ufw status verbose

Delete a rule
ufw delete <RULE NUMBER>

Find default ufw file
cat /etc/deafult/ufw