> Fair enough. I'd love to learn. What threats does the firewall even defend against? Many Debian/Ubuntu packages have a dependency on postfix. Even some trivi

> Fair enough. I'd love to learn. What threats does the firewall even defend against? Many Debian/Ubuntu packages have a dependency on postfix. Even some trivial ones. Installing these packages installs postfix (which at least asks you to configure it during install). Having a firewall active means that your grandmother won't have services you didn't realise she had running listening.