[cifs-protocol] [REG:11100564603264] [MS-NBTE] and NetBIOS name case.

Bryan Burgin bburgin at microsoft.com
Wed Oct 5 11:59:35 MDT 2011

[Dochelp to bcc]
[Adding casemail and case info]

Hi, Chris,

I created 11100564603264 to track this issue.  Someone from the team will contact you soon.


-----Original Message-----
From: Christopher R. Hertel [mailto:crh at ubiqx.mn.org] 
Sent: Wednesday, October 05, 2011 10:48 AM
To: Interoperability Documentation Help; cifs-protocol at samba.org; pfif at tridgell.net
Subject: [MS-NBTE] and NetBIOS name case.

In [MS-NBTE], dated Sept. 20, 2011...

Section 2.2.1 has the following statement:

  Neither [RFC1001] nor [RFC1002] discusses whether names are
  case-sensitive. This document clarifies this ambiguity by specifying
  that because the name space is defined as sixteen 8-bit binary bytes,
  a comparison MUST be done for equality against the entire 16 bytes. As
  a result, NetBIOS names are inherently case-sensitive.

I agree with that statement, but would add further that under NBT (as defined by RFC1001 and RFC1002) it is, therefore, sufficient to compare the Second Level Encoded strings directly off the wire.

...but here is my question.  In section 2.2.3, in the description of the LMHosts file, there is the following bullet-point:

  * Entry Names are not case-sensitive.

This, of course, conflicts with the earlier statement.  If LMHosts are not case-sensitive, how are they encoded in order to bypass the inherent case sensitivity of the NBT system?

Further, is there a standard behavior or Windows behavior used to ensure that names are not case sensitive?

I believe that the answer will be that Windows *always* coverts names to uppercase before encoding them for the NBT transport, but I would like to have that clarified in the document.

* Does Windows convert all NetBIOS names to upper case?
* Is it possible that a NetBIOS application, running on Windows, could
  bypass the conversion to upper-case?

I believe that the answer to both of those questions will be "yes", but I cannot find such information in [MS-NBTE].

Chris -)-----
...and it's NBT, not NetBT.  No one calls it NetBT except the doc author.

"Implementing CIFS - the Common Internet FileSystem" ISBN: 013047116X
Samba Team -- http://www.samba.org/     -)-----   Christopher R. Hertel
jCIFS Team -- http://jcifs.samba.org/   -)-----   ubiqx development, uninq.
ubiqx Team -- http://www.ubiqx.org/     -)-----   crh at ubiqx.mn.org
OnLineBook -- http://ubiqx.org/cifs/    -)-----   crh at ubiqx.org

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