[Zope] AUTHENTICATED_USER?

[Guy Davis]

I am trying to disallow anonymous access for all but a handful of
domains.  This is easy to do with Apache, but how can it be done with
Zope?

The only thing I could think of was to have the following in the
standard_html_header.

<dtml-if "AUTHENTICATED_USER == 'Anonymous User'" >
    {if remote address is acceptable}
	{show the true page}
    {else show an error message}
<dtml-else>
    {show the true page}
</dtml-if>

However the above expression never evaluates to true even when
<dtml-var AUTHENTICATED_USER> shows 'Anonymous User' on the same page. 
If I try to use string.find(), Zope complains that AUTHENTICATED_USER is
a bad arguement.  

Is there someway to salvage what I'm doing, or better yet is there a
simpler mechanism to achieve this goal?  Thanks.
-- 
       Guy Davis    mailto:davis@arc.ab.ca
  (403) 210-5334    Alberta Research Council