Even if you log out or reboot that client machine, you still won’t have to type your passphrase for SSH key authentication to that Ubuntu Server.

To set up SSH key authentication, you'll need at least two Linux machines, one you log in to and one you log in from. I'll demonstrate with Pop!_OS as my desktop and Ubuntu Server as my remote server.

Ubuntu terminal with nano open and showing how to add Google Authenticator to pam configuration. Ubuntu terminal showing Google Authenticator QR code for setting up 2FA.

So I am finally returning to linux after a bit of a hiatus. I have installed Ubuntu 7.10 on my laptop and I am absolutely AMAZED with how easy to set-up and use it is. Truly plug-and-play.Anyway ...