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Date: Thu, 18 Apr 2013 12:19:43 +0200
Message-ID: <CANEZrP0T7y8jqhMDUsf-HNw1sJnVuXngMa3x5+O5qgRE6eswew@mail.gmail.com>
From: Mike Hearn <mike@plan99.net>
To: Peter Todd <pete@petertodd.org>
Content-Type: multipart/alternative; boundary=001a11c1c420f5667104da9ff00e
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Anti DoS for tx replacement
Precedence: list

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Indeed, as I mentioned in my first mail, nodes can be told how much
bandwidth they're allowed to use and then prioritize within that, so I
don't see any way convergence can fail. And regardless, I used 10mbit for
the calculations, that isn't exactly unlimited. My home internet connection
is better than that. It's just an arbitrary choice that lets us get a feel
for the numbers. We can see that even with a lot of replacements, an
attacker would have a hard time matching up his flood with when a block is
actually solved.

On the wider point - how many people DoS things with their own bandwidth?
The point of DNS reflection and/or botnets is you use other peoples
bandwidth. The attacks on Mt Gox are supposedly 80 gigabit+, which is
enough to take out all of the main network simultaneously. We can't do
anything about that. So I agree we should work to avoid opening up new DoS
attacks, but we should also be realistic about what can be accomplished.
The kind of people trying to manipulate Mt Gox could nuke the entire P2P
network off the face of the internet with the flick of a switch, presumably
the reason they aren't doing that it would to use Satoshi's phrasing
"undermine the validity of their own wealth".


> sure it's worth doing, at least immediately. Weakening the non-final ==
>
non-standard test to give a window of, say, 3 blocks, would be fine I
> think.
>

Sure. I think Gavin wants some kind of wider memory pool limiter policy
which would encompass such a thing already.

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<div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote"><div=
 style>Indeed, as I mentioned in my first mail, nodes can be told how much =
bandwidth they&#39;re allowed to use and then prioritize within that, so I =
don&#39;t see any way convergence can fail. And regardless, I used 10mbit f=
or the calculations, that isn&#39;t exactly unlimited. My home internet con=
nection is better than that. It&#39;s just an arbitrary choice that lets us=
 get a feel for the numbers. We can see that even with a lot of replacement=
s, an attacker would have a hard time matching up his flood with when a blo=
ck is actually solved.</div>
<div><br></div><div style>On the wider point - how many people DoS things w=
ith their own bandwidth? The point of DNS reflection and/or botnets is you =
use other peoples bandwidth. The attacks on Mt Gox are supposedly 80 gigabi=
t+, which is enough to take out all of the main network simultaneously. We =
can&#39;t do anything about that. So I agree we should work to avoid openin=
g up new DoS attacks, but we should also be realistic about what can be acc=
omplished. The kind of people trying to manipulate Mt Gox could nuke the en=
tire P2P network off the face of the internet with the flick of a switch, p=
resumably the reason they aren&#39;t doing that it would to use Satoshi&#39=
;s phrasing &quot;undermine the validity of their own wealth&quot;.</div>
<div>=C2=A0</div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px =
0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-l=
eft-style:solid;padding-left:1ex">
<div class=3D"im"><span style=3D"color:rgb(34,34,34)">sure it&#39;s worth d=
oing, at least immediately. Weakening the non-final =3D=3D</span><br></div>=
</blockquote><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px =
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-=
style:solid;padding-left:1ex">

non-standard test to give a window of, say, 3 blocks, would be fine I<br>
think.<br></blockquote><div><br></div><div style>Sure. I think Gavin wants =
some kind of wider memory pool limiter policy which would encompass such a =
thing already.</div></div></div></div>

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