Using Windows Authentication in Ruby on Rails

I'm working on a Rails app for an internal project and 开发者_StackOverflowcan't work out how to set up the users model to use Windows Authentication for logging in. I had a look and can't find anything that was covering this topic. I've managed to configure Rails to use SQLServer fine but I'm just blanking here.

Thanks in advance.

Maybe this article helps: http://www.zorched.net/2007/06/04/active-directory-authentication-for-ruby-on-rails/