One of the most infuriating things is when a PHP script fails, and there are no error messages on what happened. If you run your script and all you see is a white screen with no error messages you know the problem. It has been dubbed the PHP White Screen of Death, after the infamous Windows Blue screen of Death. Without error messages, it is almost impossible to fix a bug. Here is a guide on how to find the errors so you can actually fix a PHP white screen of death problem.
A site in Algeria was sending thousands of requests to a server that I manage. On various pages of their site they had hotlinked an image from our site. However, our site did not have that image on it, so I have no idea what it trying to do. Since it was getting a 404, it was not really bogging down the server, but I would rather it get stopped at the firewall level. That way it would not slow down Apache at all. To do that I used Fail2Ban. Here are the steps I used to do this.