What is loopback check?

Loopback check security feature is added in Microsoft Windows Server 2003 Service Pack 1 (SP1. it aims to prevent reflection attacks on your computer. therefore, if you use FQDN or a custom host header that does not match the computer name to access the computer, authentication will fail.

How do I disable loopback check?

1. Set the DisableStrictNameChecking registry entry to 1. ClickStart, ClickRun, Type regedit, and then clickOK.
2. In Registry Editor, locate and then click the following registry key:

   HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Control \ Lsa

3. Right-clickLsa, PointNew, And then clickDWORD Value.
4. Type DisableLoopbackCheck, and then press ENTER.
5. Right-clickDisableLoopbackCheck, And then clickModify.
6. InValue dataBox, type 1, and then clickOK.
7. Quit Registry Editor, and then restart your computer.

 

Update

My colleague Shuo encountered a very strange problem. The link of Manage services on server in the Management Center site disappeared. From the symptoms, it was obviously caused by security trim.

After checking, Farm admin, local admin, and site collection admin have all permissions.

Finally, Shuo solved the problem by turning off the loopback check above.

We have seen the loopback check problem, but the site cannot be opened on its own machine. The solution to this problem is unexpected, so it is recorded here.

 

Translated from:

You receive error 401.1 when you browse a Web site that uses Integrated Authentication and is hosted on IIS 5.1 or a later version

Http://support.microsoft.com/kb/896861

Loop Back Check

Http://www.cnblogs.com/awpatp/archive/2010/06/01/1748994.html

DisableLoopbackCheck & SharePoint: What every admin and developer shold know

Http://www.harbar.net/archive/2009/07/02/disableloopbackcheck-amp-sharepoint-what-every-admin-and-developer-should-know.aspx