If you're not sure what "hotlinking" is...It's the practice of using images, videos, or other large files hosted on a foreign web site as if they were part of your web pages.
If you run any type of adult site that contains images, you will learn why hotlinking is bad, and costly, very quickly. It's absolutely imperative that you have something in place to keep shady webmasters and surfers from using your images to promote their own goals.
The basic idea is to block ALL hotlinking by default, and then add specific sites which are allowed. It's easier to make a small list of allowed sites than it is to constantly add to a large list of disallowed sites. And this way you're protected by default, instead of waiting to be robbed.
The following code added into your .htaccess file after (or before) your other rewrite rules will block all hotlinking of jpg images, except for sites you specify:
Code:
## Allow image hotlinks from my domains
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://(www\.)?amateurpornspy\.com?.*$
RewriteCond %{HTTP_REFERER} !^http://(www\.)?hardcorepornspy\.com?.*$
RewriteCond %{HTTP_REFERER} !^http://(www\.)?thumbhustler\.com?.*$
RewriteCond %{HTTP_REFERER} !^http://(www\.)?milfuniverse\.com?.*$
RewriteCond %{HTTP_REFERER} !^http://(www\.)?thatpornpage\.com?.*$
RewriteCond %{HTTP_REFERER} !^http://(www\.)?netpond\.com?.*$
RewriteRule .*\.jpg$ - [F,L]
You can see above I have a small list of some of my sites, and Netpond, so I can hotlink my own images in my posts (or my sig) if I want to. You can also set things up to block GIF and other types of images, but 95% of adult site images are jpg. If we don't make it check for gifs and other more obscure file types, the server has less to process.
If you're starting to put some of these things together into your own .htaccess, it can make things a lot easier if you keep a "master" file already set up, and simply add each of your new domains to the hotlink section as you build them. Then you end up with 1 htaccess file that you can upload to any of your sites. You'll be able to use all your images on any of your domains that you want, but they will all be protected right from the start without having to rewrite the file every time.
It should also be noted that these rules will only work for NON-VIDEO files. Because of the way video player software works, hotlinking of videos can not be effectively blocked without the use of more sophisticated scripts and rewrite rules.