limiting root login for rsync

ssh Rsync Security
Set "PermitRootLogin forced-commands-only" in /etc/ssh/sshd_config and,
command="rsync --server -vulogDtpre.iLsf --delete . /backup",no-pty,no-agent-forwarding,no-port-forwarding ssh-rsa ssh-rsa xxxxx
in ~root/.ssh/authorized_keys.