First you’ll need to install OpenSSH Server on the remote system:
apt-get install openssh-server
Configure SSH for Passwordless Logins

You’ll need to configure passwordless logins between the two hosts you want to use, this is how rsync will pass the files back and forth. I’ve previously written a HOWTO on this topic, so we’ll crib from there.

First, generate a key:

ssh-keygen -t rsa

UPDATE: actually, it’s easier to do it this way

ssh-keygen -N ” -f ~/.ssh/id_dsa

(Enter)

You shouldn’t have a key stored there yet, but if you do it will prompt you now; make sure you overwrite it.

Enter passphrase (empty for no passphrase):

(Enter)

Enter same passphrase again:

(Enter)

We’re not using passphrases so logins can be automated, this should only be done for scripts or applications that need this functionality, it’s not for logging into servers lazily, and it should not be done as root!

Now, replace REMOTE_SERVER with the hostname or IP that you’re going to call when you SSH to it, and copy the key over to the server:

cat ~/.ssh/id_rsa.pub | ssh REMOTE_SERVER ‘cat – >> ~/.ssh/authorized_keys2’

UPDATE: now you can use ssh-copy-id for this instead (hat tip briealeida)

ssh-copy-id REMOTE_SERVER

Set the permissions to a sane level:

ssh REMOTE_SERVER ‘chmod 700 .ssh’

Lastly, give it a go to see if it worked:

ssh REMOTE_SERVER

You should be dropped to a prompt on the remote server. If not you may need to redo your .ssh directory, so on both servers:

`mv ~/.ssh ~/.ssh-old`

and goto 10