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Date: Mon, 15 Jul 2013 03:32:24 -0400
From: Peter Todd <pete@petertodd.org>
To: John Dillon <john.dillon892@googlemail.com>
Message-ID: <20130715073224.GA4885@savin>
References: <CAPaL=UVqD1RaguqvaUi-0KnabobvuJ27gF6vK5tTAxEGNO9Xww@mail.gmail.com>
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User-Agent: Mutt/1.5.21 (2010-09-15)
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Protecting Bitcoin against network-wide
 DoS attack
Precedence: list


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On Sun, Jul 14, 2013 at 10:12:00PM +0000, John Dillon wrote:
> For a non-SPV-mode client we can easily do anti-DoS by requiring the peer=
 to do
> "useful work". As the incoming connections slots get used up, simply kick=
 off
> the incoming peers who have relayed the least fee-paying transactions and=
 valid
> blocks, keeping the peers who have relayed the most. We can continue to u=
se the
> usual, randomized, logic for outgoing peers to attempt to preserve the
> randomized structure of the bitcoin network. Without an ongoing attack no=
des
> making new connections are unaffected, and during an attack new connectio=
ns are
> made somewhat easier by the increased numbers of incoming slots made avai=
lable
> as the attackers connections timeout.

My mempool rewrite defined a CMemPoolTx subclass for CTransaction - it
shouldn't be too hard to add the required per-node accounting once nodes
get unique identifiers. (can be assigned randomly in the beginning,
later can be used for permanent node identifiers w/ ssl and message
signing)

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