For Mac OS X and Linux

1. In Terminal, type
   ssh-keygen -t dsa
2. Accept the defaults when it queries you.
3. Enter the following command, replacing 'username' with your username, and 'ip.add.ress.here' with your server's IP address.
   rsync -av -e "ssh" ~/.ssh/id_dsa.pub
   username@ip.add.ress.here:.ssh/authorized_keys
4. Enter your root password.
5. Now you will need to SSH into your server to confirm the key was uploaded.
   ssh username@yourdomain.com
   
6. Enter the following commands:
   chmod 700 ~/.ssh
   chmod 600 ~/.ssh/authorized_keys
   chown username. ~/.ssh/authorized_keys
   

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