ssh_config bad configuration options

Problem

After an upgrade to macOS Sierra, High Sierra, or Mojave, you may see the following error when you try "vagrant ssh":

/etc/ssh/ssh_config: terminating, 1 bad configuration options


Solution

You may have old config options that are no longer supported.  You can edit these options as follows:

sudo vi /etc/ssh/ssh_config

If you have an old machine set up by MIT, you would need to comment out "GSSAPIDelegateCredentials" and "GSSAPIKeyExchange" as follows:

# System-wide defaults set by MIT Kerberos Extras
Host *
GSSAPIAuthentication yes
# GSSAPIDelegateCredentials yes
# GSSAPIKeyExchange yes


For more details, please visit this MIT KB article.