Error ssh-ing to Athena - ssh_dispatch_run_fatal

You may get an error ssh_dispatch_run_fatal when ssh'ing to MIT Athena computers:

$ ssh username@athena.dialup.mit.edu

ssh_dispatch_run_fatal: Connection to 18.9.64.18: unexpected internal error

Context

• This has been seen on Macs running OSX 10.11 ("El Capitan")

Answer

Try disabling the GSSAPIKeyExchange SSH option.

• One way to do this is to add "-o GSSAPIKeyExchange=no" to the ssh command:

  $ ssh -o GSSAPIKeyExchange=no _username_@athena.dialup.mit.edu
  

• Another way to do it is to add the setting to your ~/.ssh/config file:

  # For each parameter, the first-obtained value will be used.
  Host *.mit.edu
   GSSAPIKeyExchange = no
  

• Some versions of OSX may object to the presence of the GSSAPIKeyExchange variable in your ~/.ssh/config file, and will report an error that includes 'Bad configuration option: GSSAPIKeyExchange' in which case you should try removing that line entirely.

For more information about the ssh config file see its man page.

Commentary

GSSAPIKeyExchange is reportedly broken in the openssh client that ships with Mac OS 10.11

GSSAPIKeyExchange isn't required for GSSAPIAuthentication to work, but lacking GSSAPIKeyExchange means you might have to wrangle host keys.