SSH keys allow authentication between two hosts without the need of a password. SSH key authentication uses two keys, a private key and a public key.

To generate the keys, from a terminal prompt enter:

ssh-keygen -t dsa

This will generate the keys using the Digital Signature Algorithm (DSA) method. During the process you will be prompted for a password. Simply hit Enter when prompted to create the key.

By default the public key is saved in the file ~/.ssh/id_dsa.pub, while ~/.ssh/id_dsa is the private key. Now copy the id_dsa.pub file to the remote host and append it to ~/.ssh/authorized_keys by entering:

ssh-copy-id username@remotehost

Finally, double check the permissions on the authorized_keys file, only the authenticated user should have read and write permissions. If the permissions are not correct change them by:

chmod 600 .ssh/authorized_keys

You should now be able to SSH to the host without being prompted for a password.