funny you mention reverse proxy, i was day dreaming earlier about a way to break down some concepts for you and what analogies exist in audio engineering. The only i devised was that a proxy is kinda like a patchbay.

Anyways in terms of security top pf the charts, fail2ban is a classic banger found on most machines. It monitors login attempts on ssh, nginx or whatever and after a set amount of failures, it bans the IP of the purp! Check it out!