Generating RSA Key on Mac

Here are the steps to create a new RSA key on an Apple Mac.

Open the Terminal application

Execute the following command

ssh-keygen -t rsa

Go through the questions and answer.  Most of the time the defaults are fine.

This will generate two files.  The first one, or private key, will not have an extension.  The second, or public key, with have a .pub extension.  Send ONLY the .pub file to your system administrator so that it can be added to your user account.

Once the public key has been added, then just use the following command in your Terminal application to access the server.

ssh -p 22 -i [path to private key file] [username]@[hostname]

Source: http://jeffreifman.com/2016/10/01/fix-macos-sierra-upgrade-breaking-ssh-keys/