In case you are afraid that your website could be the target of denial-of-service (DoS) attacks, you should check out 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 you want to protect. When a large portion 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 IP address, he/she can solve a CAPTCHA and continue to the website. If it is a bot, the attack will be blocked.
One-time, time-based or implicit blocks can be applied. Users can modify many other options in the application's configuration file.
The application's developers claim that IOSEC is used on more than 15,000 websites.
You can download IOSEC here. A video is also available on YouTube.
