Google authenticator

google authenticator is a 2 factor authentication program.
You can use it on linux, both for 2FA PAM logins - I don't believe you can use it as a source of 2FA.

Tutorials

Arch Wiki

https://wiki.archlinux.org/index.php/Google_Authenticator

Install

pacman -S libpam-google-authenticator

Usage

google-authenticator  # setup configuration