This week I've been playing around with two factor authentication & thought it might be nice to share with the team incase you fancy setting it up yourself.
It's also worth noting that with this method, if you are using SSH keys from this guide then it'll skip the two factor steps.
This means two factor only really becomes an issue when you're logging in with a username & password (when you're probaby going to want it most).
I found a fantastic tutorial on Digital Ocean talking you through exactly what to do.
How To Protect SSH With Two-Factor Authentication
Remember when you're playing with ssh - if it's your only way of controlling the computer, open an ssh window & minimise it - the connection will stay open if you restart the ssh service & lock yourself out.