HostKeyAliases


Situation: Sometimes there are multiple SSH servers on different ports on the same host:
Multiple SSH servers on one machine.
Firewall that forwards to multiple private servers by port.

Problem: The known_hosts file only has host/ip granularity.

    xahria$ ssh firewall "hostname"
    daycare-firewall
    xahria$ ssh firewall -p 9999 "hostname"
    @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
    @    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
    @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
    IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
    Someone could be eavesdropping on you right now (MITM attack)!
    It is also possible that the RSA host key has just been
    changed.  The fingerprint for the RSA key sent by the
    remote host is ce:0b:9d:e4:ea:1c:3c:82:91:b8:83:4a:3b:09:f7:09.
    Please contact your system administrator.