Not sure how to go about this...basically we need to perform load testing on a web application, but the problem is, all the pages are accessible only by authenticated users. The authentication is performed by the application itself (ie NOT HTTP auth), by means of a form in the login page; once the user authenticates, session info is stored in a cookie which is sent back with each request to prove authentication to the server, and the user can access all the pages.
In the past, I've used tools like Siege for this kind of thing, but it seems it can't do authentication. Is there any tool that can do what we need? Thanks.