[cifs-protocol] cifs client timeouts and hard/soft mounts

Christopher R. Hertel crh at samba.org
Sat Dec 4 12:46:39 MST 2010

Volker Lendecke wrote:
> On Fri, Dec 03, 2010 at 09:54:13PM -0600, Christopher R. Hertel wrote:
>> That may seem to be in the "who cares" category, since those old transports
>> are essentially dead (much more dead than NBT, or even NBF).  Unfortunately,
>> the code to handle the old transports is still there in Windows, so there
>> are behaviors -- things like the timeouts you're talking about and the weird
>> VC=0 shutdown behvior -- that exist because of these old disused transports.
> VC=0, how does Windows treat this facing NAT (masquerading)
> networks? I've done tests in the past where Windows killed
> valid connections from behind a NAT box when a new client
> came in.

I put a lot of info into [MS-CIFS] about how *and why* this works the way it
does.  See [MS-CIFS] 2.1.3.  Unfortunately, since [MS-CIFS] applies only to
W98, NT4, and earlier it doesn't tell you much about W2K and newer
implementations.  There's a KB article that talks about the problem a
little:  KB301673.

I thought that there was a registry setting that would allow you to tell the
Windows server NOT to close existing connections if it received a VC=0 from
the same IP.  Even when working with Microsoft I wasn't able to find
anything like that, beyond what's in that KB article.

Basically, they should give up on the VC=0 thing, since it's a throw-back to
the days when OS/2 could run SMB over connectionless IPX transport over
multiple modems in parallel.

Chris -)-----

"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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