Absolutely. As long as SSH can go thru the firewall, you can:
1. Set up rsa keys using ssh-keygen.
2. Copy the public key to the remote host's /root/.ssh/authorized_keys file.
3. Setup a cron job to run the rsync command. I use:
rsync -auv --delete -e "ssh -1" root@remoteHostIP:/path/to/remote/ibay/ /path/to local/ target/directory