 Preventing hot linking of images and other file
types
Note: This portion of tutorial written by
JavaScript Kit
In the webmaster community, "hot linking" is a curse phrase. Also known as
"bandwidth stealing" by the angry site owner, it refers to linking
directly to non-html objects not on one own's server, such as images, .js
files etc. The victim's server in this case is robbed of bandwidth (and in
turn money) as the violator enjoys showing content without having to pay
for its deliverance. The most common practice of hot linking pertains to
another site's images.
Using .htaccess, you can disallow hot linking on your server, so those
attempting to link to an image or CSS file on your site, for example, is
either blocked (failed request, such as a broken image) or served a
different content (ie: an image of an angry man) . Note that
mod_rewrite
needs to be enabled on your server in order for this aspect of .htaccess
to work. Inquire your web host regarding this.
With all the pieces in place, here's how to disable hot linking of
certain file types on your site, in the case below, images, JavaScript
(js) and CSS (css) files on your site. Simply add the below code to your
.htaccess file, and upload the file either to your root directory, or a
particular subdirectory to localize the effect to just one section of your
site:
RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://(www\.)?mydomain.com/.*$ [NC]
RewriteRule \.(gif|jpg|js|css)$ - [F]
Be sure to replace "mydomain.com" with your own. The above code creates a
failed request when hot linking of the specified file types occurs. In the
case of images, a broken image is shown instead.Serving
alternate content when hot linking is detected
You can set up your .htaccess file to actually serve up different
content when hot linking occurs. This is more commonly done with images,
such as serving up an Angry Man image in place of the hot linked one. The
code for this is:
RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://(www\.)?mydomain.com/.*$ [NC]
RewriteRule \.(gif|jpg)$ http://www.mydomain.com/angryman.gif [R,L]
Same deal- replace mydomain.com with your own, plus angryman.gif.
Time to pour a bucket of cold water on hot linking!
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