Phorm Check API

Phormcheck is an interesting third party solution, analogous to the DNS system.

It comprises a database of  ISP address ranges.

An API is provided allowing you to perform a database lookup, to determine whether a given user originates from a Phormed Internet Service Provider.

The site provides sample client code for the API, and other useful countermeasures... such as a dynamic robots.txt, a warning banner function, and techniques for detecting cookie interference.

Benefits of a database driven approach include the accuracy of the lookup; you don't have to maintain local copies of an htaccess block file, or maintain a blocking script.

However, to maintain optimum scalability and performance you should use the caching client API, or optimise the calls to reduce frequency of lookups.