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bandwidth throttling LTSP machines.


We run thin clients similar to ltsp in college.  Video apps (xine, mplayer,
goom, screen savers, flash, java, vmware! ...) can cause mayhem.

With a small group of colleagues it is easy enough to just tell people not
to do this.  However, in a school with many LTSP clients and very many
students, that's not so easy.  Some kids may do it by mistake, some of the
more mischevious ones may notice that this is a subtle way to cause mayhem.
One way or the other, when it happens it makes the thin client systems look
terribly flakey and vulnerable.  Particularly to someone who doesn't
understand what's going on.

It seems to me that this is even more of an issue in light of Knut's
current posts about centralised thin client server farms.

One approach is to remove all the offending applications.  I don't like
this idea much and I don't think it's very practical anyway.  Even
important things like the java and flash plugins can be offenders in this.
Besides, a smart kid could compile his/her own if they really wanted to be
a pest.

A few guys in Oslo mentioned that big flash animations can cause problems.
Mozilla has a nice extenion called flashblock which, installed globally,
would help cut down a lot of the frivilous flash adverts in web pages.
The users can still view them with a single click, but they don't
automatically display which is nice for the user and for the network.


A more radical solution which a colleague suggested interested me.  He
suggested that an init script be placed in the LTSP image.  This would
create stadard iproute throttling rules which would cause the ltsp client
to constrict it's own bandwidth usage to something reasonable/tunable (like
say 4MB/sec default).  This will mean when someone does something silly,
the machine will simply starve itself of bandwidth rather than saturate the

I hold my hands up straight away and say that I don't know in detail how to
do this right now.  However, it seems like it should be quite doable.


Does anyone have any opinions about the idea?  Feel free to show me the
door ;-)


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