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When I try to ssh to my server from a linux computer with debian, I just get

Host key verification failed.

The only help I found online was deleting the key from ~/.ssh/known_hosts... well I did not only that, I deleted the whole ~/.ssh just to be sure, and it didn't help either, I still have Host key verification failed. error.

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up vote 5 down vote accepted

OK, answered.

When I run ssh with -v option, it showed me the actual error.

It was caused by mistakenly setting wrong access rights to /dev/tty, whatever that is, and ssh somehow didn't like it. sudo chmod 777 /dev/tty seemed to fix it.

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Make it 666. There's no point giving execution permission to that device. – Stéphane Chazelas Sep 23 '12 at 7:56
OK, if you say so :) – Karel Bílek Sep 23 '12 at 12:50
I have similar problem (debug1: read_passphrase: can't open /dev/tty: No such device or address) but chmod 666 /dev/tty does not help. It works with my user, but after I switched to another user with su it fails. – dma_k Mar 28 '13 at 20:31

So the poster's problem has been resolved. But in case others come to this question by searching and their symptoms are not coming from the same cause:

Deleting ~/.ssh/known_hosts (or just the offending line in it) will purge the cached host key. However, there is also a system-wide cache, which will be stored someplace like /etc/ssh/ssh_known_hosts. Host keys won't be cached there unless that's specifically requested. But if you're having host key verification issues, have a look in both of these files.

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