If your site runs on Apache and you’re familiar with .htaccess, the 5G Blacklist is an effective way to secure your site against malicious HTTP activity.
[Update: The 6G Blacklist is now available.]
The 5G Blacklist is a simple, flexible blacklist that checks all URI requests against a series of carefully constructed HTAccess directives. This happens quietly behind the scenes at the server level, saving resources for stuff like PHP and MySQL for all blocked requests.
Simply add the following code to your site’s .htaccess file. Make sure you make a copy of your existing file before making any changes.