I had an interesting little issue the other day where connecting to some servers was taking aroudn 15 seconds before showing a login prompt. Everything after that was speedy so I knew it wasnt going to be a connection time issue.
I ran the following to get verbose connection info: ssh -v servername
and saw this error: debug1: Authentications that can continue: publickey,gssapi-with-mic,password debug1: Next authentication method: gssapi-with-mic debug1: An invalid name was supplied Cannot determine realm for numeric host address
It turns out that ssh is trying to use Kerberos (GSS-API). To turn this off we can simply edit our ssh config file.
# open up ~/.ssh/config # add the following line GSSAPIAuthentication no
And that fixes it!