In case you are afraid your website might be a target denial-of-service (DoS) attacks, you should check it IOSEC; a PHP script designed to protect websites from such threats.
To use IOSEC, all you need to do is include "iosec.php" in the PHP files you want to protect. When a large number of HTTP requests are detected, the user sending them is blocked.
When a specific IP is blocked, a warning page appears. If a real user is behind the address IP, he/she can solve a CAPTCHA and continue on the website. If it's a bot, the attack will be blocked.
They can be implemented settings one-time, time-based or implicit blocks. Users can modify many other options in the app's settings file.
Application developers support that IOSEC is used on more than 15.000 web pages.
You can download the IOSEC here.
