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From: Peter Todd <pete@petertodd.org>
To: "Raystonn ." <raystonn@hotmail.com>
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>,
	"Patrick Mccorry \(PGR\)" <patrick.mccorry@newcastle.ac.uk>
Subject: Re: [Bitcoin-development] New attack identified and potential solution	described: Dropped-transaction spam attack against the block	size limit
Date: Mon, 8 Jun 2015 17:33:36 -0400	[thread overview]
Message-ID: <20150608213336.GA19826@muck> (raw)
In-Reply-To: <COL131-DS2729F02884BC43E54C8D63CDBF0@phx.gbl>

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On Mon, Jun 08, 2015 at 02:14:01PM -0700, Raystonn . wrote:
> > there is no memory pool cap currently
> 
> Real hardware does not have an infinite amount of RAM.  Memory pool sizes 
> cannot grow unbounded.  Some transactions with insufficient fees do get 
> dropped today after many hours.

Actually they don't, which is an unfortunate problem with the existing
mempool implementation; the only way a transaction can be removed from a
Bitcoin Core mempool is through it getting mined, double-spent, or the
node restarting.

The protection that we have against that attack is that you need access
to a lot of bitcoins to pay enough fees. With the 0.01mBTC/KB minimum
relay fee and $230 USD/BTC that works out to about $2.3kUSD/GB of ram
consumed, and furthermore, actually getting that many transactions to
propagate over the network is non-trivial. (no, I'm not going to tell
you how)

The obvious solution is to cap the size of the mempool and evict
transactions lowest fee/KB first, but if you do that they you (further)
break zeroconf security. On the other hand, if you don't break zeroconf
security an attacker can prevent reasonable fee transactions from
propagating.

I probably should get around to fixing this...

-- 
'peter'[:-1]@petertodd.org
0000000000000000127ab1d576dc851f374424f1269c4700ccaba2c42d97e778

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  reply	other threads:[~2015-06-08 21:33 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-08  0:36 [Bitcoin-development] Block Size Experiment Underway Tom Harding
2015-06-08 20:07 ` [Bitcoin-development] New attack identified and potential solution described: Dropped-transaction spam attack against the block size limit Raystonn .
     [not found]   ` <AD4A025F-D782-4094-9CBC-EBEF0DD04838@newcastle.ac.uk>
2015-06-08 21:14     ` Raystonn .
2015-06-08 21:33       ` Peter Todd [this message]
2015-06-08 21:40         ` [Bitcoin-development] New attack identified and potential solution described: Dropped-transaction spam attack against the blocksize limit Raystonn .
     [not found]         ` <4A74E0B9-869E-448A-BFC7-7FD2F50F142F@newcastle.ac.uk>
2015-06-08 22:26           ` [Bitcoin-development] New attack identified and potential solution described: Dropped-transaction spam attack against the block size limit Peter Todd
     [not found]       ` <7E7DF414-6DDB-48A6-9199-D6883209B67D@newcastle.ac.uk>
2015-06-08 21:33         ` Raystonn .
2015-06-08 21:44           ` Peter Todd
2015-06-08 22:01             ` [Bitcoin-development] New attack identified and potential solution described: Dropped-transaction spam attack against the blocksize limit Raystonn .
2015-06-08 22:07               ` Btc Drak
2015-06-08 22:10                 ` Raystonn .
2015-06-08 22:18               ` Peter Todd
2015-06-08 22:46                 ` Raystonn .
2015-06-08 22:06             ` [Bitcoin-development] New attack identified and potential solution described: Dropped-transaction spam attack against the block size limit Bob McElrath
2015-06-08 22:28               ` Peter Todd
2015-06-09  9:33   ` Loi Luu
2015-06-09 13:36     ` Gavin Andresen
2015-06-09 14:18       ` Tier Nolan
2015-06-09 17:52       ` Raystonn .
2015-06-09 18:25         ` Gavin Andresen
2015-06-09 19:03           ` Raystonn .
2015-06-20  3:49             ` David Vorick

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