title: SSO - how to automatically log into an external website from an intranet (SAML 2.0)?
body: <p>A client has used our PHP web-application for years, but now wants a Single Sign On solution (SSO).</p>
  
  <p>They have a company-intranet where they log in to, and they want to use this same login as an automatic authentication for our web-application (which is on an external domain).</p>
  
  <p>They talk about SAML 2.0, which I had never heard of until now.</p>
  
  <p>I searched the internet, but have a hard time understanding all different concepts (identity provider, etc.). All websites about the subject seem to require some basic knowledge that I don't have. I don't understand how and where the authentication data has to be stored...  (in post-data from a cookie , it seems, but how do you get the authentication xml anywhere the first time you start doing this?!)</p>
  
  <p>Could anybody point me in some directions for this specific situation?</p>