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.

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