I'm using yubico-pam (https://github.com/Yubico/yubico-pam https://github.com/Yubico/yubico-pam) module for a bit over a year now on our controlling servers as

I'm using yubico-pam (https://github.com/Yubico/yubico-pam https://github.com/Yubico/yubico-pam) module for a bit over a year now on our controlling servers as well as my own, so that we can use Yubikeys for authentication. Works extremely well so far.