[Mediawiki-l] Securing images directory

[Sullivan, James (NIH/CIT) [C]]

I have set up a wiki where the LocalSettings is set to not allow
unauthenticated users access except to the Login and Help page via a
$wgWhiteListRead setting for those two pages.  This works just fine.

However, I can go directly to the images directory via the browser and
access all content stored there.  For example, if my wiki is stored in
the directory /var/www/html/wiki on a machine names wikis.example.com
and I have saved images, I can access those images by pointing my
browser to http://wikis.example.com/wiki/images.

I am presented with the directory tree and can access all files saved
under the images directory.  I cannot find anything in the archives
describing this and how to restrict access.  I plan to try .htaccess but
I was wondering if there is a better approach and whether other
directories are as unprotected as the images directory from being read
by non-logged in users.  Maybe a httpd.conf directive?  

Any help appreciated.

-Jim