Mark Butler wrote:
Andy Furniss wrote:
Mark Butler wrote:
There is no problem manipulating the TCP window per se. The problem
is advertising a window and then shrinking it faster than it is
naturally reduced by incoming data, essentially granting credit to
transmit x bytes, and then revoking that credit. The net result is
the peer transmits data the advertiser said it was going to accept,
and then the advertiser drops it on the floor. RFC793 only has a
SHOULD NOT for this practice, but it is universally condemned
nonetheless.
Thanks Mark, I guess packeteer closes window down properly, I thought
Dave's reply meant that doing that was Treason.
Packeteer is almost certainly being cavalier about the way it reduces
windows. It could be a serious problem, depending on the way it treats
traffic on the return path. The "treason" thing is a joke. It is like
a bank extending you a credit line one day, and revoking it the next.
I don't use or know of anyone who uses Packeteer - or have you tested?
My post was just a suggestion because I think that it uses adv window
manipulation. I misunderstood DaveMs reply -
"it is illegally advertising a smaller window that it previously
did."
to mean that it was illegal to close down a window at all - you cleared
that up - ie it is legal if you close it by <= the amount of data that
has just been acked. I assume this won't cause the Treason messaage so
don't really understand why it is cavalier - or do you just mean the
whole idea of window manipulation to shape may be dodgey but legal?
Andy.
-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
