hardcoded port 445

Christopher R. Hertel crh at samba.org
Tue Nov 8 14:46:11 MST 2011

...at bottom...

Andrew Bartlett wrote:
> On Mon, 2011-10-31 at 17:17 -0500, Christopher R. Hertel wrote:
>> Christopher R. Hertel wrote:
>>> Andrew Bartlett wrote:
>>>> On Mon, 2011-10-31 at 15:11 -0500, Christopher R. Hertel wrote:
>>>>> Oskar Liljeblad wrote:
>>>>>> Hi!
>>>>>> I will be using Samba4 to operate in client mode.  The tunneling is simple,
>>>>>> set up with ssh.  E.g.:
>>>>> Samba is not a client, it is a server.  The Samba project provides a client
>>>>> library called libsmbclient.  Is that what you what you will be using?
>>>> Chris,
>>>> Oskar is using the Samba4 DCE/RPC client library (as used by
>>>> OpenChange).
>>> Cool.  That's the piece of information I was missing.  Thanks!
>>> Looking at the code snippets that Oskar sent in his original message, in
>>> both cases the code uses the remote port number to decide whether or not to
>>> send an NBT Session Request message.
>>> That is, in fact, the correct approach.  If the remote port is 445, then it
>>> is reasonable to assume that NBT transport is NOT in use.  If the port is
>>> 139, then it would be reasonable to assume that NBT transport IS in use.
>>> For any other port number you have to guess, and sending the NBT Session
>>> Request is as good a guess as any.
>>> Samba servers do not care whether or not they receive the NBT Session
>>> Request, no matter what port it is using.  Windows is more picky.
>>> According to my book (http://ubiqx.org/cifs/SMB.html#SMB.3.3.1 ... now
>>> somewhat out of date), if you try naked transport first and the Windows
>>> server expects NBT transport it will return a Negative Session Response.
>>> That is typically quick to handle.
>>> Unfortunately, if you send an NBT Session Request to a Windows server that
>>> is expecting Naked TCP transport, it will send no reply at all (tested
>>> against W2K, see http://ubiqx.org/cifs/SMB.html#SMB.3.3.2, last paragraph).
>>> So...  Once again, I agree with the logic in the code segment that Oskar
>>> originally sent, as long as the code checks for a Negative Session Response
>>> and tries again.
>> Ooops.  Switch that around.  The best way to go is to try naked transport
>> first since that will work immediately whether or not is expecting naked
>> transport.
>> If you try NBT transport first (which is the default in the code Oskar
>> presented), and the server port is expecting naked transport, then you will
>> have to time out before you can try again.
> Chris,
> I'm having terrible trouble keeping on top of all the things I've got
> outstanding, as well as trying to get some time away from intensive
> Samba development.  Could you have a go at trying to code this up for
> Oskar?


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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