Blocking Image Bandwidth Theft/Hotlinking with URL Rewriting
You can stop others from hotlinking your site’s files by placing a file called .htaccess in your Apache site root (main) directory. The period before the name means the file is hidden, so you may want to edit your file as htaccess.txt, upload it to your server, then rename the txt file to .htaccess in your directory or Apache config file httpd.conf
Contact your web host on how to access your directories and configure your .htaccess file.
Example: Your site url is www.mysite.com. To stop hotlinking of your images from other sites and display a replacement image called wtf.jpg placed in your images directory, place this code in your .htaccess file:
RewriteEngine On
RewriteCond %{HTTP_REFERER} !^http://(.+.)?pario.no/ [NC]
RewriteCond %{HTTP_REFERER} !^$
RewriteRule .*.(jpe?g|gif|bmp|png)$ /gfx/wtf.png [L]
The first line of the above code begins the rewrite. The second line matches any requests from your own mysite.com url. The [NC] code means “No Case”, meaning match the url regardless of being in upper or lower case letters. The third line means allow empty referrals. The last line matches any files ending with the extension jpeg, jpg, gif, bmp, or png. This is then replaced by the nohotlink.jpe file in your images directory. This JPEG image is using the extension jpe instead of jpg to prevent blocking your own replacement image.
To stop hotlinking from specific outside domains only, such as myspace.com, blogspot.com and livejournal.com, but allow any other web site to hotlink images:
RewriteEngine On
RewriteCond %{HTTP_REFERER} ^http://(.+.)?myspace.com/ [NC,OR]
RewriteCond %{HTTP_REFERER} ^http://(.+.)?blogspot.com/ [NC,OR]
RewriteCond %{HTTP_REFERER} ^http://(.+.)?livejournal.com/ [NC]
RewriteRule .*.(jpe?g|gif|bmp|png)$ /images/nohotlink.jpe [L]
You can add as many different domains as needed. Each RewriteCond line should end with the [NC,OR] code. NC means to ignore upper and lower case. OR means “Or Next”, as in, match this domain or the next line that follows. The last domain listed omits the OR code since you want to stop matching domains after the last RewriteCond line.
You can display a 403 Forbidden error code instead of an image. Replace the last line of the previous examples with this line:
RewriteRule .*.(jpe?g|gif|bmp|png)$ - [F]
Warning: Do not use .htaccess to redirect image hotlinks to another HTML page or server that isn’t your own (such as this web page). Hotlinked images can only be replaced by other images, not with an HTML page.
As with any htaccess rewrites, you may block some legitimate traffic (such as users behind proxies or firewalls) using these techniques.