Automatic directory listing/indexing is a web server function that lists all of the files within a requested directory if the normal base file (index.html / home.html / default.htm) is not present. When a user requests the main page of a web site, they normally type in a URL such as: http://www.example – using the domain name and excluding a specific file. The web server processes this request and searches the document root directory for the default file name and sends this page to the client. If this page is not present, the web server will issue a directory listing and send the output to the client. Essentially, this is equivalent to issuing an “ls” (Unix) or “dir” (Windows) command within this directory and showing the results in HTML form. From an attack and countermeasure perspective, it is important to realize that unintended directory listings may be possible due to software vulnerabilities (discussed in the example section below) combined with a specific web request.