title: svnserve: Unable to restrict access to specific directories
body: <p>I have a SVN repository set up which is provided access through svnserve and ssh. 
  The command in authorized_keys is set up (only relevant part shown) as:</p>
  
  <pre><code>  svnserve -t --tunnel-user="${SSH_CLIENT%% *}" -r "/home/myDir" ...
  </code></pre>
  
  <p>I am trying to use authz to restrict access to different users. 
  svn log provides users by IP addresses which is understandable because of the way I have set up tunnel-user. When I try to restrict access to some user as in:</p>
  
  <pre><code>      [someRepo:/dir1/dir2]
        192.168.1.55 = 
  </code></pre>
  
  <p>It does not work. The full access to the entire repository is granted anyway to this IP.
  How do I restrict access to certain folders to some users only? </p>
  
  <p>Is there any way to pass some other Id to be logged in svn, other than IP address to identify user thru svnserve/ssh? I mean how to set tunnel-user to something other than IP address?</p>