When i try to ssh into a computer i control there's a familiar message

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@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
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IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
[...].
Please contact your system administrator.
Add correct host key in /home/sward/.ssh/known_hosts to get rid of this message.
Offending RSA key in /home/sward/.ssh/known_hosts:86
RSA host key for [...] has changed and you have requested strict checking.
Host key verification failed.

I indeed did change the key And I read a few dozen postings saying that the way to resolve this problem is by deleting the old key from the known_hosts file.

But what i'd like is to have ssh accept both the new key and the old key The language in the error message (" Add correct host key ") suggests that there should be some way to add the correct host key without removing the old one.

I've not been able to find out how to add the new host key without removing the old one

Why is the error message so misleading?

Best Answer


  1. get the rsa key of your server, where server_ip is your server's IP address, such as 192.168.2.1:

    $ ssh-keyscan -t rsa server_ip

    Sample response.

    # server_ip SSH-2.0-OpenSSH_4.3
server_ip ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAwH5EXZG...

  2. and on the client, copy the entire response line server_ip ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAwH5EXZG..., and add this key to the bottom of your ~/.ssh/known_hosts file:

    server_ip ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAqx9m529...(the offending key, and/or the very bottom of the `known_hosts` file)
server_ip ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAwH5EXZG... (line you're adding, copied and pasted from above)