Stopping bandwidth leeching may seem to be a daunting task, but you will see that it is not. All you need to do is to find a way to identify where the requests to your website's contents are coming from. If the Http Referrer isn't the website's domain address itself (or one of its addresses), then the request comes from an external website and it should be discarded. To monitor Http requests, you need to write your own Http Handler(s) to handle requests to images and other file types that must not be accessed by any external website.

As the "System.Web.UI.PageHandlerFactory" handler handles .aspx files, you will see in this article a handler that handles .jpg, .jpeg, .gif, .css, and .js files. You can write as many Http handlers as you want for your web application. The same Http handler can be used for multiple applications.