When a web browser is pointed to a directory on your web site which does not have an index.html file in it, the files in that directory can be listed on a web page.

Blocking users or sites that originate from a particular domain is another useful trick of .htaccess. Lets say you check your logs one day, and see tons of referrals from a particular site, yet upon inspection you can’t find a single visible link to your site on theirs. The referral isn’t a “legitimate” one, with the site most likely hot linking to certain files on your site such as images, .css files, or files you can’t even make out. Remember, your logs will generate a referrer entry for any kind of reference to your site that has a traceable origin. Before I get to the code itself, it’s important to note that blocking access by referrer in .htaccess requires the help of the Apache module mod_rewrite to make out the referrer first. This module is installed by default on most servers (ask your host if you’re not sure). So, to deny access all traffic that originate from a particular domain (referrers) to your site, use the following code: