title: Adding ADFS authentication to a WebForms asp.net app
body: <p>My C# .net 4.5 asp.net app currently uses forms authentication. We need to implement SSO on it via an on-premises ADFS 3.0 server that will link to external ADFS servers using Claims Provider Trusts.</p>
  
  <p>The thing is that some users will continue logging in the old Forms Auth way while others will be authenticating using their ADFS credentials.</p>
  
  <p>Can ADFS and Forms Auth be mixed? How can I direct the different users to the different logins?</p>
  
  <p>I read here that I might need to code my own Custom Auth Provider...this seems pretty complicated. Is there another simpler way?</p>