I am interested if Apache's mod_proxy can be configured to filter the content sent through it. For example, if a user makes a request to site A then send request X to the server otherwise send an unmodified request.
Client ------> Proxy -------> Server | | Filter
The filter would be written as a script that gets invoked by the proxy and would also control what kind of response would go on to the server.
Is this even possible? If so, how is this called?