Do work iptables across all users at the same time?

Question

I'm running Lubuntu 17.10 and I have two accounts; lightning and scholar. When logged into the desktop as scholar I want to block traffic to-and-from https://www.facebook.com/ on scholar, even while logged in via terminal as lightning (i.e: using su lightning and launching firefox under lightning)

Answer 1

As it turns out, according to waltinator, that iptables affects every user on the system at once.

For those of you looking for a GUI, I recommend going here.