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I would like to get Mobile-phone verification or something else besides the SSH-key verification.

How can you add defence to the SSH-keys?

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closed as unclear what you're asking by Grant, HopelessN00b, Scott Pack, Tom O'Connor Feb 10 '14 at 0:18

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question.If this question can be reworded to fit the rules in the help center, please edit the question.

What do you mean that someone is spoofing you? – Michael Hampton Feb 9 '14 at 7:54
up vote 5 down vote accepted

You can use Two Factor Authentication to improve the security of ssh keys (and other authentication methods). I use Duo's two factor authentication. It's free for a limited number of users and is relatively cheap beyond that. It can be installed in a wide variety of OS/Applications etc. There are other 2FA products available.

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I found that hardware two-factor tokens work well. I chose the yubikey, because it was reasonably inexpensive, had no licensing costs over and above the initial hardware purchase, required no specialist client-side software except a USB port, and I was entirely responsible for key management and distribution; I had to reposit my trust in noone except myself.

You can find a more detailed writeup here, if you want the technical nitty-gritty. (Disclaimer: I have no connection to yubico at all, save as a satisfied customer.)

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Maybe adding a one-time passcode authentication PAM (ex. to your system will give you some extra "layer of security".

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