[X2Go-Dev] Traffic shaping nightmare - missing SSH TOS bits

[Mike Gabriel]

Hi John,

On Di 21 Feb 2012 17:09:57 CET "John A. Sullivan III" wrote:

> On Tue, 2012-02-21 at 10:11 +0100, Jan Engelhardt wrote:
>> On Tuesday 2012-02-21 09:43, John A. Sullivan III wrote:
>>
>> >On Tue, 2012-02-21 at 09:30 +0100, Jan Engelhardt wrote:
>> >> On Tuesday 2012-02-21 07:05, John A. Sullivan III wrote:
>> >>
>> >> >I've been working on a project to implement traffic shaping
>> >> >to conform to 95th percentile billing including our X2Go virtual
>> >> >desktops. One of the challenges is prioritizing the interactive X2Go
>> >> >traffic (screen, keyboard, mouse) differently from bulk traffic like
>> >> >local share transfers, printing, and possibly sound.  I thought this
>> >> >would be trivial because of the SSH transport since SSH sets the
>> >> >minimize-delay bit for interactive traffic and the maximize-throughput
>> >> >bit for bulk transfers.
>> >>
>> >> If a user has his own machine, he can of course do whatever he wants.
>> >> Second, if he can pass options to ssh, he can set the QOS type
>> >> arbitrarily, and even where that is not available for control, one
>> >> can still cause the openssh client to use interactive TOS marking for
>> >> bulk transfers, since secondary ssh channels (e.g. tunnels) do not
>> >> pass up the TOS mark.
>> ><snip>
>> >However, Windows and Mac clients may not be using OpenSSH.
>>
>> That too. All these reasons is why TOS is not a reliable characteristic
>> to determine the question of bulk-or-interactive.
>>
>> >PS - out of curiosity, now does one set the QoS type in OpenSSH?
>>
>> ssh -o IPQoS={bulk|interactive|0x12345} ...
>>
>> ssh -L 2000:localhost:22 foohost &
>> rsync -HPave 'ssh -p 2000' bulky.iso localhost:
>>
>> and in fact, wouldn't the output `ls -Rl /` in an interactive shell also
>> best be count as bulk...
> <snip>
> Interesting.  Looks like that was introduced in 5.6.  Squeeze is running
> 5.5 but it should default to 0x10/0x08 if not set.  I'm not seeing any
> TOS bits set which is why I suspect it is the libssh call as I assume
> that does not reference the openssh configuration.
>
> If someone can point out where the socket options are set, I can take a
> look and see if I can figure out how to fix it but I don't know a thing
> about socket programming.  I assume one has to make some kind of a call
> to IP_TOS or perhaps it is part of setsockopts and SO_PRIORITY.  Thanks
> - John

The sockets are probably created and configured in here...
http://code.x2go.org/gitweb?p=x2goclient.git;a=blob;f=sshprocess.cpp

Mike



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