I just want to block Internet access in my kids' accounts.
This is possible with
iptables (see question: https://unix.stackexchange.com/questions/21650/how-to-restrict-internet-access-for-a-particular-user-on-the-lan-using-iptables?noredirect=1&lq=1).
But, Ubuntu 18.04 uses
netplan. I've been looking, looking, looking and I can't seem find a way to do something similar on
netplan. Perhaps there is no such way, and the answer is to disable