How does intellitamper work?

I just wonder how this tool works. If you try to view a directory and directory listings is off you cannot see whats in the folder. How does intellitamper give you a listing of the directory anyway? Is this because you are viewing through a web browser and intellitamper has more control over the type of request its sending? how is it possible to get a directory listing when directory listing seems to be disabled? i.e. when you try to access the directory it says denied or forbidden.

Couple related questions not worth creating threads over.

Is there anyway to type in a username/password to view a blocked directory or file?

what is .htaccess and .htpasswd?

Obviously, when a server is telling you 'denied', you can conclude something is there. Only a 404 would (most of the times) mean there is nothing there.

Your last two questions are related and incredibly easy to answer for yourself by visiting http://ddg.gg

Just to add to what spyware has said: it checks what response the server gives when it tries requesting files from a pre-made list.

IntelliTamper is able to scan a website for unlisted files and folders with a dictionary based scan.Source: http://www.softpedia.com/get/Internet/Other-Internet-Related/IntelliTamper.shtml (first result on DDG for intellitamper)

@ the intellitamper question:

My guess would be it creates a url to try against using a database of known files and directories.

use this url: http://www.website.com/

for each known directory
   new_url is url + guessed_dirname

   if new_url does not 404
      inform me of this

      for each known file
          new_url is new_url + / + guessed_filename

          if new_url does not 404
               inform me of this
          or if new_url does 404
               ignore it
          end if
      end for
   or if new_url does 404
      ignore it
   end if
end for