The ufw (uncomplicated firewall) represents a serious simplification to iptables and, in the years that it’s been available, has become the default firewall on systems such as Ubuntu and Debian. And, yes, ufw is surprisingly uncomplicated – a boon for newer admins who might otherwise have to invest a lot of time to get up to speed on firewall management.
GUIs are available for ufw (like gufw), but ufw commands are generally issued on the command line. This post examines some commands for using ufw and looks into how it works.
Thanks to Sandra Henry-Stocker (see source)