Has Microsoft recently introduced "Loopback check" functionality in Windows 2000?

[Trust No One®]

Hi Folks,

I think the answer to my question is "Yes", but hopefully someone can
confirm and/or point me to the particular security patch that introduced it.

Recently - on the 14th of November when we rolled out a number of Microsoft
patches, a number of our Windows 2000 servers had problems where
applications running on these servers were no longer able to map to local
shares using an alias (DNS CNAME) for the server. Attempting the map the
share resulted in a request for login credentials.

Up to this point this kind of drive mapping worked flawlessly in Windows
2000, provided the DisableStrictNameChecking key was set as detailed in:

http://support.microsoft.com/kb/281308

During my investigation I found that the registry value
DisableLoopBackCheck=0 now appears in the registry of our Windows 2000
servers. This is related to the LoopBack check functionality which was first
introduced in Windows 2003 SP1. (see http://support.microsoft.com/kb/896861)

If I set "DisableLoopBackCheck=1" or alternately specify the desired alias
in a "BackConnectionHostNames" entry, then everything works, as per the KB
article for Windows 2003 SP1.

So it looks like a recent security patch has introduced the loopback check
functionality previously only applicable to Windows 2003 SP1 onwards.

Can anyone else confirm this behaviour?

Regds,

 

[cemkeles]

Hi,
We have faced same on our windows servers. Server can't access itself
using alias, but can with hostname or IP.
Recently installed patches are these:
- Security Update for Windows 2000 (KB957095)
- Security Update for Windows 2000 (KB958644)
- Security Update for Windows 2000 (KB957097)
- Security Update for Microsoft .NET Framework 1.1 Service Pack 1
(KB947742)
- Cumulative Security Update for Internet Explorer 6 Service Pack 1
(KB956390)
- Security Update for Internet Explorer 6 for Windows 2000 (KB938464)
- Cumulative Security Update for ActiveX Killbits for Windows 2000
(KB956391)
- Security Update for Windows 2000 (KB954211)
And DisableLoopBackCheck is in registry now with value of 0
I'm sure one of these adds this in the registry, but I couldn't make
sure which. Actually I checked kb pages of all these on Microsoft's
homepage but couldnt find anything yet. If someone can help us, that
will be really appreciated.

Cem