De man backintime
:
To prepare your user account for ssh-mode you have to add the user
to group 'fuse' by typing 'sudo adduser <USER> fuse' in terminal.
To apply changes you have to logout and login again.
Next you have to create a password-less login to the remote host
(for further information look at http://www.debian-administration.org/articles/152).
Type in terminal 'ssh-keygen -t rsa' hit enter for default path
and enter a passphrase for the private key.
Finally type 'ssh-copy-id -i ~/.ssh/id_rsa.pub <REMOTE_USER>@<HOST>'
and enter your password on remote host.