From: Matt Whitlock <bip@mattwhitlock.name>
To: Patrick Strateman <patrick.strateman@gmail.com>
Date: Thu, 09 Jul 2015 21:36:38 -0400
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Cc: bitcoin-dev@lists.linuxfoundation.org
Subject: Re: [bitcoin-dev] Can we penalize peers who relay rejected
	replacement txs?
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My reasons for wanting this are two-fold:

1.) To reduce the CPU load due to Bitcoind. Presently I am seeing periods of time in which Bitcoind is pegging a CPU core. Given that the flood of spam transactions appears mostly to be invalid under RBF rules, I would like to cut off the flood coming into my node by temp-banning the peers who are relaying invalid replacement transactions.

2.) If enough other nodes also implement this banning rule, then we could potentially cut off the flood of spam right at the source. Then the spammer would be forced to build and publish *non-conflicting* transactions to continue the attack, and this would be much costlier to maintain, as then *all* of the spam transactions could eventually have their fees collected by miners, not just some non-conflicting subset of the spam.


On Thursday, 9 July 2015, at 6:27 pm, Patrick Strateman wrote:
> What do you gain by banning peers doing this?
> 
> I'm thinking practically nothing.
> 
> On Jul 9, 2015 4:55 PM, "Matt Whitlock" <bip@mattwhitlock.name> wrote:
> 
> > I'm presently running my full node with Peter Todd's full replace-by-fee
> > patch set [1]. I am seeing a LOT of messages in the log about replacement
> > transactions being rejected due to their paying less in fees than the
> > transactions they would replace. I understand that this could happen
> > legitimately from time to time, due to my node's receiving a replacing
> > transaction prior to receiving the replaced transaction; however, due to
> > the ongoing spam attack, I am seeing a steady stream of these rejection
> > messages, dozens per second at times. I am wondering if each replacement
> > rejection ought to penalize the peer who relayed the offending transaction,
> > and if the penalty builds up enough, then the peer could be temporarily
> > banned, similar to how other "misbehaving" peers are treated.
> >
> > [1] https://github.com/petertodd/bitcoin/commits/replace-by-fee-v0.10.2