Seeking help - how to calculate fingerprints

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I often get this too familiar message, and want to know how to calculate
fingerprint. I do a lot of port forwarding, so I believe I have multiple
"localhost" keys that actually come from remote hosts. So I need to decide if
this fingerprint (allegedly "changed") is really changed, or is just due to
another host whose port was forwarded.

The fingerprint for the RSA key sent by the remote host is

I tried md5sum on entries for localhost in ssh_known_hosts file, but I fail to
get the same fingerprint that ssh gives me.

I would appreciate a pointer to a command, function or library that will do the
job. If possible I'd like to know one for windows platform (other than cygwin)
and one for unix platform (including cygwin).


Re: Seeking help - how to calculate fingerprints

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If you're port-forwarding ssh itself and using OpenSSH, you can use
HostKeyAlias to store the key with the appropriate name associated with
it, eg

Host hosta
    Hostname localhost
    HostKeyAlias hosta
    Port 2222

Host hostb
    Hostname localhost
    HostKeyAlias hostb
    Port 2223

Darren Tucker (dtucker at
GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
    Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.

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