ssh-keygen for creating your own SSH key

Creates a new ssh key, using the provided email as a label

$ ssh-keygen -t rsa -C "your_email@example.com"

...

$ clip < ~/.ssh/id_rsa.pub

you can add this key to GitHub or Bitbucket, then you can through ssh tunnel authenticate Git repo without password.

Reference
http://linux.vbird.org/linux_server/0310telnetssh.php
https://help.github.com/articles/generating-ssh-keys