Ran into a bizarre issue with /.ssh/config the other day. Essentially the problem seems to be that when you add an “IdentityFile” entry you need to specify the full path (/.ssh/some_key will work) and not just the name of the file in the ~/.ssh directory. Now you may think that this is always required but either it does not work on OSX or it only works on Ubuntu. But it definitely work on Ubuntu. I have not had a chance to check it out on a third operating system yet.