I installed from a git build.  It might have some shortcomings or bugs with modern rsync.  I'm not sure.  Here are some work-arounds I needed:
<ul>
  <li>Use no-password ssh key for root in /root/.ssh/id_rsa.  I could not get an -i option to work with remote rsync</li>
  <li>Lock down your sshd to only allow root to connect from trusted host using rsync key, and only for rsync</li>
</ul>

I have lines like :
<PRE>
    PermitRootLogin no
    PubkeyAuthentication yes
    ...
    Match User root Address 192.168.1.37
         PermitRootLogin without-password
</PRE>
in /etc/ssh/sshd_config on my remote machine.
<br>
It appears that rssh has been depricated also.  It might be unnecessary.  I implemented the desired functionality with a little command on sshd.
<P>
On my remote machine, I have this entry in /root/.ssh/authorized_keys
<PRE>
  command="/usr/local/bin/sshCmdFilter.sh" ssh-rsa AAAA...gctDM= rsyncKey
</PRE>

<br>
The little shell only allows rsync commands to be run.  I could do some more detailed checking here, but my sh-fu is weak:<br>
<br>
sshCmdFilter.sh:
<pre>
     #!/bin/sh

     fLog="/var/log/filtered-ssh-command/$USER.log"
     /bin/echo '*****************' `/bin/date` &gt;&gt; $fLog
     env | grep -vi color     &gt;&gt; $fLog

     if  [ -n "$SSH_ORIGINAL_COMMAND" ] ; then
         case $SSH_ORIGINAL_COMMAND in
            rsync*)
                exec $SSH_ORIGINAL_COMMAND
            *)
                echo $SSH_ORIGINAL_COMMAND not supported
                echo "ERROR: SSH_ORIGINAL_COMMAND not supported" &gt;&gt; $fLog
         esac
     else
         echo "SSH_ORIGINAL_COMMAND not defined"
     fi
</pre>

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