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I have installed NAS sever which is accessible from Internet by SFTP with certificate authentication. but I have a challenge:

I want to control who is using my server but If I send a certificate+username+server to a specific user, the receiver or user can share this information with everyone without us knowing, so we can not control who is using our server. is there any solution for it? if I can not exactly figure out who is using, at least I want to block sharing the username+password+certificate and use better solution than simple username and password. (should I use VPN? or hardware authenticators? software authenticators? using mac address?)

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What are you using for a NAS server? Have you checked the documentation to find out if there are other authentication methods? – Taegost Jul 25 '13 at 13:27
sorry I don't understand what you mean by your question: what are you using for a NAS server? Do you mean which protocol I use? – user240710 Jul 26 '13 at 8:16
You said you installed a NAS server... What are you using? Is it dedicated NAS hardware? An actual server? A workstation that you call a NAS? What's the model... Based on your response to my question, the answer would be that you hadn't checked the documentaiton... – Taegost Jul 29 '13 at 14:09
My NAS server is a dedicated NAS hardware (Diskstation) – user240710 Jul 30 '13 at 12:13
You still haven't fully answered my questions. Did you check the documentation? and what is the model? – Taegost Jul 30 '13 at 13:41


In the end, if you can't trust the users of your system, they will find a way to thwart whatever security mechanism you put in place. It's just that simple.

As the saying goes, loose lips sink ships.

On that note, you can make it harder for them to do so. Based on what you have described the only thing I can think of at the moment that would be feasible for you is some kind of one-time authentication system or maybe even smart card authentication. However, even these solutions are probably overkill for protecting a "NAS". That and the chances of the NAS software/firmware supporting these features is unlikely.


If the device supports it you could setup an IP address whitelist, though this isn't completely full proof. It would still allow anyone behind a given address access to your server. It does prevent everyone else though.

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Thank you for your comment. Yes, Apparently there is no solution to recognize who exactly connect to server. Do you know any solution for blocking users to share their username and password to someone else... I mean I am looking for a solution better than username and password... – user240710 Jul 26 '13 at 8:20
Actually my question is: My question is: I have a NAS server which I put all my files in it and I want to let some specific users to connect to my NAS server with SFTP protocol and upload or download files from my server.... so I am looking for the best security solution for Authenticate them (not just simple username and password) and encryption.... do you have any solution? – user240710 Jul 26 '13 at 8:30
@user240710 See updated answer – dtmland Jul 26 '13 at 14:48

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