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

[John A. Sullivan III]

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