[cd34]

How about linkchecker software? Some TGP software doesn't send a referrer and would thus get a forbidden and possibly remove the gallery. I don't know about the software being used by freesite/linklist software.

I have a way to do it with a mod_perl filter that would be rather robust, wouldn't require cookies or anything -- wouldn't get involved in passing the file, it would purely insert itself in the handler to verify that it should accept or decline the link. I could write a DSO to do it, but, I would think that 99% of the people probably cannot insert modules into their apache config. Even mod_perl is iffy, but, it would be about the highest performance method I can think of. I can think of a method using PHP, but, since I cannot insert a php script into the request handler, mod_perl seems like the most portable and high performance option.

The problem is, no matter what method is used, there is either a simple reliance on some piece of data somewhere that can be easily circumvented. But, if we make it hard enough for enough people, combined with other efforts, it might make it worthwhile.

And regrettably, anyone using an edge cache won't be able to prevent hotlinking which might be why the big-boys allow hotlinking.