[Samba] SMB Multichannel not working?

Carter Sheehan
2023-02-02T17:19:50Z

Rowland,

Here are a few screenshots of the protocol negotiation packets between my client
(172.27.252.57) and my Samba server (172.27.252.11): https://imgur.com/a/nXk3QRV
[https://i.imgur.com/wCcFvhc.png?fb]<https://imgur.com/a/nXk3QRV>
imgur.com<https://imgur.com/a/nXk3QRV>
Imgur: The magic of the Internet
imgur.com


In the screenshots, there is an initial SMB request from the client (no
capabilities specified), an SMBv2 reply from the server stating it does NOT
support multi channel, a 2nd request from the client (now in SMBv2 protocol),
and an SMBv2 reply from the server saying it supports multichannel. The two
replies from the server contradict one another. The "Session Request"
packets after the protocol negotiations show the session request did not have
multichannel enabled. I suspect this is because the client saw the first
protocol negotiation reply that said the server did not support multichannel and
so the client did not enable multichannel in it's request for a session.

Carter Sheehan
Cloud Engineer
o: +1 (781) 224-7753<tel:+1%20(781)%20224-7753>
e: csheehan at vestmark.com<mailto:csheehan at vestmark.com>

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From: samba <samba-bounces at lists.samba.org> on behalf of Rowland Penny
via samba <samba at lists.samba.org>
Sent: Thursday, February 2, 2023 10:23 AM
To: samba at lists.samba.org <samba at lists.samba.org>
Cc: Rowland Penny <rpenny at samba.org>
Subject: Re: [Samba] SMB Multichannel not working?


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On 01/02/2023 20:58, Carter Sheehan via samba wrote:
> Hello Jeremy,
>
> I looked at low-level packets captured in Wireshark and I see some
interesting things happening during the SMB session negotiations
>
> In the packet stream, I see 4 SMB "Negotiate Protocol"
request/response packets and I see 4 "session setup" packets. During
the protocol negotiation, the Samba server's first reply states multi
channel support is "0", the second reply says it is supported.
>
> Then, in the "session setup" packets, the client request does not
have multichannel support enabled so the session does not utilize the feature.
>
> I can send you a screenshot of the wireshark capture if you have a separate
email, the samba list has a max email cap so I can't send pictures
>

You could do what everyone else does, post them somewhere and provide a
link.

Also I don't think a screenshot is going to do.

Rowland


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