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

Christopher R. Hertel crh at ubiqx.mn.org
Wed Oct 5 11:47:58 MDT 2011

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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