I saw an e-mail recently talking about how to do this with Google
Authenticator, though it's targeting Ubuntu specifically:

http://www.techradar.com/how-to/how-...-authenticator

The part that does the magic is available in the Open Build Service, and
can probably be built for any system elsewhere:

https://software.opensuse.org/packag..._authenticator

https://github.com/google/google-authenticator-libpam


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Good luck.

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