The following method shows how to setup SSH Automatic RSA Key login with two simple steps.
Create RSA key on LOCAL Host without a passphrase.
ssh-keygen -t rsa
Copy the RSA key to the REMOTE Host, while making sure the directory .ssh exists within the user’s home directory.
cat .ssh/id_rsa.pub | ssh username@REMOTE.Host 'cat >> .ssh/authorized_keys'
If you want to have this feature from both direction, you need to do the above tasks from both servers.