title: Connecting Umbraco backend with on premise AD authentication from Azure
body: <p>We are migrating our web applications from an on premise environment to Azure app services.</p>
  
  <p>One of the webapps is causing a little bit of trouble, it's an Umbraco website that uses LDAP for connecting with an external AD for backend authentication. </p>
  
  <p>It appears the authentication server is not being called.</p>
  
  <p>The client receives the following message (after a while of waiting):</p>
  
  <pre><code>{  
    "Message":"An error has occurred.",
    "ExceptionMessage":"The server is not operational.\r\n",
    "ExceptionType":"System.Runtime.InteropServices.COMException",
    "StackTrace":" at System.DirectoryServices.DirectoryEntry.Bind(Boolean throwIfFail)\r\n at System.DirectoryServices.DirectoryEntry.Bind()\r\n at System.DirectoryServices.DirectoryEntry.RefreshCache()\r\n at System.Web.Security.DirectoryInformation..ctor(String adspath, NetworkCredential credentials, String connProtection, Int32 clientSearchTimeout, Int32 serverSearchTimeout, Boolean enablePasswordReset)"
  }
  </code></pre>
  
  <p>Unfortunately I'm not an Azure expert and searching for this problem didn't result in any solutions. 
  From the error message I can conclude that the on premise cannnot be reached from Azure, but I don't understand why.</p>
  
  <p>Is Azure blocking the 636 port?
  Is this setup even possibly in Miscrosoft Azure?</p>
  
  <p>Any pointers in the right direction are greatly appreciated.</p>