title: Avoiding authentication required popup while using integrated windows authentication and accessing application from internet
body: <p>I need to implement something like Single Sign On for a application that is being used on both  Intranet and Internet.
  Now , the application uses its own table for storing User information and has <strong>more users</strong> than that present in the AD for the Company. Example contract workers/3rd party vendors etc and hence many users who don't belong to the Active directory of domain are listed in the User Table.</p>
  
  <p>The Application is a bit old and currently it uses Form to authenticate the users.
  But strangely authentication mode in the web.config file has the following entry for authentication. <code>&lt;authentication mode="None" /&gt;</code>  </p>
  
  <p>I changed the authentication mode to Windows in web.config and in IIS 6 selected integrated Windows authentication and unchecked the anonymous access.</p>
  
  <p>Now I have following two scenarios.</p>
  
  <p><code>#1 Intranet</code><br>
  User logs in to the system using the System Credential which is stored in a AD 
  Now if user hits the link for the web application he should be logged in. 
  I have implemented this part by using Page.User.Identity.name in the Page load of login.aspx to check if the user exists in the DB.</p>
  
  <p><code>#2 Internet</code><br>
  If I check it from a external network the browser prompts me for credential.<br>
  <strong>The requirement is that the user should not be prompted for credential instead should be shown the current Login page</strong></p>
  
  <p>I googled and ended up on stackoverflow every time. Sadly the solutions did not work out for me.</p>
  
  <p>I stumbled upon this post by Scott <a href="http://weblogs.asp.net/scottgu/archive/2006/07/12/Recipe_3A00_-Enabling-Windows-Authentication-within-an-Intranet-ASP.NET-Web-application.aspx" rel="nofollow noreferrer" >Enabling Windows Authentication within an Intranet ASP.NET Web application </a> and if you check the comments Scott refers to use of solution by commenter <code>ripster</code> in case application is accessed from internet as well as intranet. Though it didn't work out for me or may be I didn't do it properly.</p>