Anyone know what bit 4 is in the flags2 field on the SMB header?

Christopher R. Hertel crh at
Thu Feb 8 22:47:45 GMT 2007

Gerald (Jerry) Carter wrote:
> Christopher R. Hertel wrote:
>> My book has bits 3,4,5 and 7,8,9,10 as being
>> "reserved".  That's probably based on the SNIA docs
>> as well as source code from Samba and jCIFS.
> I know.  I looked.  But I can't find any reference
> other than that.  On page 207 of your book it says
> "Reserved (must be zero)" but apparently the reservation
> is for MS.  :-)  Do you remember where you got the
> note that bit 4 was reserved?  I just can find any
> reference to it in any of the old docs I have.

I *think* that I wrote "must be zero" based on a note somewhere that
undefined FLAGS values should be zero.   ...and yeah, I'm sure the
reservation is for Microsoft (though it might have belonged to IBM originally).

Those are the only references I found when I looked.

>> It's possible, I suppose, that Windows systems just
>> ignore these bits and that there is no behavior associated
>> with their being set.  I'm interested in finding
>> out otherwise as a couple of people working on
>> implementations have sent me queries over the last few months.
> I'm about at the end of my curiosity this time around.
> Wish I had better closure.  Thanks for the chat.

Likewise, though the folks who asked me about it also said they'd let me
know if they trip over anything.  If I hear something I'll pass it along.

Chris -)-----

"Implementing CIFS - the Common Internet FileSystem" ISBN: 013047116X
Samba Team --     -)-----   Christopher R. Hertel
jCIFS Team --   -)-----   ubiqx development, uninq.
ubiqx Team --     -)-----   crh at
OnLineBook --    -)-----   crh at

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