title: SharePoint or IIS in general passing Windows Authentication to IFrame calling another site on the same server and domain
body: <p>I have a SharePoint site that is running Windows Authentication (NTLM).<br>
  We have a web part that has an IFrame in it that points to another web page that also uses Windows Authentication (NTLM).<br>
  Both SharePoint and the WebApplication are located on the same machine on IIS running under the same app pool on the same domain using the same SSL cert and the same machine key.  </p>
  
  <p><strong>Example</strong><br>
  We have SP1.test.com (SharePoint Site) and NET1.test.com (.net web application)<br>
  Both running Windows Authentication only (all other auths have been disabled) with NTLM as the provider.<br>
  They both have the same Machine Key.  </p>
  
  <p>Here is the web.config  </p>
  
  <pre><code>&lt;authentication mode="Windows"&gt;
      &lt;forms name=".TESTAUTH" cookieless="AutoDetect" slidingExpiration="true" protection="All" timeout="600" enableCrossAppRedirects="true" domain="*.test.com" /&gt;
  &lt;/authentication&gt;
  &lt;machineKey validationKey="1234" decryptionKey="1234" validation="SHA1" decryption="AES" /&gt;
  </code></pre>
  
  <p>How do we get this to work without the site requiring double authentication?  </p>
  
  <p><strong>NOTE</strong><br>
  Both of these sites are accessed internally and externally.</p>