Suhosin is a great and simple way of increasing your security without having a large impact on overall performance. In this tutorial I will cover the installation and configuration of Suhosin on both debian etch and centos 5. I may cover mod_security in a later tutorial.

They apt-get the packages needed for the patch in examples for two different distributions - Debian (etch) and CentOS. They also show how to set up some basic configuration to get the patch installed and working with your PHP installation.

PHP-IDS is an intrusion detection tool on the application level. Application firewalls know about a certain protocol and its structure (e.g. HTTP) and inspect the protocol to detect attack patterns. Some of them are even capable of learning from usual request signatures and enforcing rules based on the learned data. There are various commercial products to achieve application firewalling. PHP-IDS does the same for free and sits directly on the webserver in the scope of the application.

He recommends it as a good supplement to the hardening you've already done for your server (you have hardened it, haven't you?) to help keep you and your data safe from prying eyes.

I will install both Suhosin parts in this tutorial, the Suhosin patch (for which we need to recompile PHP5) and the Suhosin PHP extension. To see what Suhosin can do, please refer to http://www.hardened-php.net/suhosin/a_feature_list.html. The features of the Suhosin patch are listed under Engine Protection (only with patch); all the other features come with the Suhosin extension.

It's (technically) a three step process, but there's lots of smaller steps under each one. There's also some screenshots of a phpinfo() page to show the results of each of the steps.