firewall

Hello, I'm running a website on Apache2 ubuntu 18.04 and I was wondering how to block all ip addresses except for my public ip address for ssh. Trying to lock the server down as much as I can.

I'm a new convert to Linux and very much like the usability. My main concern when switching over was security as I handle some sensitive information on my computer, and maybe have an all to healthy sense of paranoia. This is partly my reason for switching over. I have an account with CactusVPN...

I've been using untangle on a Dell r210 for the past few years - it's based on Debian and has been pretty solid. I've been thinking of switching to pfsense though to see what the differences are.