IIS -Web application windows authentication issue - login failed because of Access - Loopback check issue

Configuring the Loopback check

Method 1 (recommended): Create the Local Security Authority host names that can be referenced in an NTLM authentication request

To do this, follow these steps for all the nodes on the client computer: 

1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0
3. Right-click MSV1_0, point to
   New, and then click Multi-String Value.
4. In the Name column, type
   BackConnectionHostNames, and then press ENTER.
5. Right-click BackConnectionHostNames, and then click Modify.
6. In the Value data box, type the CNAME or the DNS alias, that is used for the local shares on the computer, and then click OK.
   
   Note Type each host name on a separate line.
   
   Note If the BackConnectionHostNames registry entry exists as a REG_DWORD type, you have to delete the BackConnectionHostNames registry entry.
7. Exit Registry Editor, and then restart the computer.

Method 2: Disable the authentication loopback check

Re-enable the behavior that exists in Windows Server 2003 by setting the DisableLoopbackCheck registry entry in the
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa registry subkey to 1. To set the DisableLoopbackCheck registry entry to 1, follow these steps on the client computer: 

1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
3. Right-click Lsa, point to
   New, and then click DWORD Value.
4. Type DisableLoopbackCheck, and then press ENTER.
5. Right-click DisableLoopbackCheck, and then click Modify.
6. In the Value data box, type
   1, and then click OK.
7. Exit Registry Editor.
8. Restart the computer.

Note You must restart the server for this change to take effect. By default, loopback check functionality is turned on in Windows Server 2003 SP1, and the DisableLoopbackCheck registry entry is set to 0 (zero). The security is reduced when you disable the authentication loopback check, and you open the Windows Server 2003 server for man-in-the-middle (MITM) attacks on NTLM.

Doing the same using PowerShell

Using PowerShell to configure the Loopback check, requires two steps:

1. Add the multistring value to the registry
Get-Item -path “HKLM:\System\CurrentControlSet\Control\Lsa\MSV1_0” | new-Itemproperty -Name “BackConnectionHostNames” -Value (“coolsite.corp.balkestahl.se”, “alias.corp.balkestahl.se”) -PropertyType “MultiString”

2. Restart the IISADMIN service
Restart-Service IISADMIN