UFW
Add rules
Add tcp on port 22 and only IPv4 (address specified)
ufw allow proto tcp to 0.0.0.0/0 port 22
List rules with number
ufw status numbered
Delete rule
sudo ufw delete 5
Add tcp on port 22 and only IPv4 (address specified)
ufw allow proto tcp to 0.0.0.0/0 port 22
ufw status numbered
sudo ufw delete 5