RE: [beepwg] Re: A couple of features to limit BEEP no reply attack

"Thomson, Martin" <> Mon, 23 March 2009 17:58 UTC

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Subject: RE: [beepwg] Re: A couple of features to limit BEEP no reply attack
Date: Mon, 23 Mar 2009 12:59:12 -0500
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From: "Thomson, Martin" <>
To: "Francis Brosnan Blazquez" <>, "Martin Thomson" <>
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Sorry about the delay in responding...

RTT discovery is performed by every TCP stack.  It's part of working out the necessary window size to maximize throughput.  I don't know if this information is made available by any TCP stacks, but it isn't impossible to measure.  Even above TCP where retransmits could interfere its' probably still doable.

I'd still say that the main concern I have is that your interpretation of what constitutes a "protocol violation" is too narrow a view.  More holistically, a badly behaving peer needs to be treated as such, regardless of where the errors occur.  Niceties like proper channel and session closure are luxuries - a badly behaving peer does not deserve to be treated in such a civilised fashion.


> -----Original Message-----
> From: []
> On Behalf Of Francis Brosnan Blazquez
> Sent: Wednesday, 18 March 2009 6:14 AM
> To: Martin Thomson
> Cc: Vortex;
> Subject: Re: [beepwg] Re: A couple of features to limit BEEP no reply
> attack
> Hi Martin,
> > I think that David has said almost everything that I was going to.
> No
> > point me wasting my time reiterating it.
> Ok.
> > One further note on reply-limit that might be related to David's
> > second point: there are no provisions made for round trip time.  The
> > serving peer might respond within the specified time, but that time
> > might have elapsed by the time at the client before then, or before
> > the response arrives.
> Though I see your point, I find no easy solution to implement a
> round-trip discovery extension, which, again, can be blocked in the
> same
> way.
> It is expected that BEEP peers will provide appropriate values for this
> reply-limit which includes such round-trip delay.
> Cheers!
> > Ta,
> > Martin
> --
> Francis Brosnan Blazquez <>
> Advanced Software Production Line, S.L.

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