Howto block unwanted requests to your apache server with DD-WRT

Recently I made a mistake while configuring my Apache web server and the whole world found out that I have an open proxy (which I don't... at least not anymore). My apache was bombarded with proxy requests and I could barely load up any of my websites (this blog included) from both internal network as well as from outside. So, I started to search the web in hopes of finding people with similar problems and their solutions. Here is what I have found on this website:

Access DD-WRT web interface via apache's reverse proxy

Recently I started having problems accessing my DD-WRT web interface via a subdomain of mine. For some reason the web interface would not apply any of the CSS styles and thus making it completely useless. After viewing page's source code using Chrome browser, I found out that clicking on any css links resolved in 400 Bad Request Cross Site Action detected!.

After some googling, I've stumbled upon a forum post that provided a solution, which is quite simple: remove the referer header from the request.
Here is how I did it: