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From: Peter Todd <pete@petertodd.org>
To: Jeremy Spilman <jeremy@taplink.co>
Cc: "bitcoin-development@lists.sourceforge.net"
	<bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Peer Discovery and Overlay
Date: Tue, 24 Dec 2013 09:02:28 -0500	[thread overview]
Message-ID: <20131224140228.GA9838@savin> (raw)
In-Reply-To: <op.w8k9l8qayldrnw@laptop-air.hsd1.ca.comcast.net>

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On Tue, Dec 24, 2013 at 12:52:46AM -0800, Jeremy Spilman wrote:
> Some really nice efforts out there to map and analyze the bitcoin P2P  
> network.
> 
> The current protocol apparently recommends returning up to 2500 addresses  
>  from 'getaddr'. I'm not sure how much clients are expected to probe the  
> address space in order to select 'far-apart' peers, or how much such an  
> process would even attempt to achieve.

The logic is that by simply connecting to peers at random you keep the
network structure as a whole randomized. You don't need to make any
specific attempt at connecting to "far-apart" peers.

> How much does it matter if the ability to discover the entire network of  
> peers is fast or slow? There are probably pros and cons to both.
> 
> Is there any thought to how existing bitcoin node relations, and the ease  
> at which peers can be discovered, becomes a service in itself, or even  
> possibly a vulnerability?

Keep in mind it's easy for better knowledge of the network to be a
vulnerability; the number of full nodes is small enough that DoS
attacking all of them is quite feasible.

The other big vulnerability is that getaddr data is best effort; we
currently have no mechanism to ensure that nodes are in fact operated by
separate individuals. It'd be quite easy for someone to set up a
relatively small number of nodes that only advertise themselves in the
getaddr information. Over time they would get proportionally more
incoming connections than is "fair"

As for node addresses being a service, that's what the DNS seeds are!
bitcoinj clients, for instance, depend very heavily on those seeds and
can be easily compromised in a variety of ways by them.

-- 
'peter'[:-1]@petertodd.org
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  parent reply	other threads:[~2013-12-24 14:02 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-24  8:52 [Bitcoin-development] Peer Discovery and Overlay Jeremy Spilman
2013-12-24 10:47 ` Tier Nolan
2013-12-24 14:02 ` Peter Todd [this message]
2013-12-24 17:11   ` Warren Togami Jr.
2013-12-24 17:15     ` Mike Hearn

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