Howtoforge posted a guide about installing ModSecurity2 on Debian Etch
This article shows how to install and configure ModSecurity (version 2) for use with Apache2 on a Debian Etch system. ModSecurity is an Apache module that provides intrusion detection and prevention for web applications. It aims at shielding web applications from known and unknown attacks, such as SQL injection attacks, cross-site scripting, path traversal attacks, etc.Installing ModSecurity2 On Debian Etch