From: Kevin Greene <kgreenek@gmail•com>
To: Thy Shizzle <thashiznets@yahoo•com.au>
Cc: Bitcoin Dev <bitcoin-development@lists•sourceforge.net>
Subject: Re: [Bitcoin-development] Useless Address attack?
Date: Wed, 4 Mar 2015 18:13:38 -0800 [thread overview]
Message-ID: <CAEY8wq701HBWQVmvch=dQF09WJ7cJQX0RZd2XKd-23w_AUTK=w@mail.gmail.com> (raw)
In-Reply-To: <1755215207.4498654.1425519657710.JavaMail.yahoo@mail.yahoo.com>
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Bitcoind protects against this by storing the addresses it has learned
about in buckets. The bucket an address is stored in is chosen based on the
IP of the peer that advertised the addr message, and the address in the
addr message itself. The idea is that the bucketing is done in a randomized
way so that no attacker should be able to fill your database with his or
her own nodes.
From addrman.h
<https://github.com/bitcoin/bitcoin/blob/master/src/addrman.h>:
/** Stochastic address manager
*
* Design goals:
* * Keep the address tables in-memory, and asynchronously dump the entire
to able in peers.dat.
* * Make sure no (localized) attacker can fill the entire table with his
nodes/addresses.
*
* To that end:
* * Addresses are organized into buckets.
* * Address that have not yet been tried go into 256 "new" buckets.
* * Based on the address range (/16 for IPv4) of source of the
information, 32 buckets are selected at random
* * The actual bucket is chosen from one of these, based on the range
the address itself is located.
* * One single address can occur in up to 4 different buckets, to
increase selection chances for addresses that
* are seen frequently. The chance for increasing this multiplicity
decreases exponentially.
* * When adding a new address to a full bucket, a randomly chosen
entry (with a bias favoring less recently seen
* ones) is removed from it first.
* * Addresses of nodes that are known to be accessible go into 64
"tried" buckets.
* * Each address range selects at random 4 of these buckets.
* * The actual bucket is chosen from one of these, based on the full
address.
* * When adding a new good address to a full bucket, a randomly
chosen entry (with a bias favoring less recently
* tried ones) is evicted from it, back to the "new" buckets.
* * Bucket selection is based on cryptographic hashing, using a
randomly-generated 256-bit key, which should not
* be observable by adversaries.
* * Several indexes are kept for high performance. Defining
DEBUG_ADDRMAN will introduce frequent (and expensive)
* consistency checks for the entire data structure.
*/
On Wed, Mar 4, 2015 at 5:40 PM, Thy Shizzle <thashiznets@yahoo•com.au>
wrote:
> Hi, so just a thought as my node relays addresses etc. If I wanted to
> really slow down communication over the P2P network, what's stopping me
> from popping up a heap of dummy nodes that do nothing more than exchange
> version and relay addresses, except I send addr messages with all 1000
> addresses pointing to my useless nodes that never send invs or respond to
> getdata etc so clients connect to my dumb nodes instead of legit ones. I'm
> thinking that if I fill up their address pool with enough addresses to dumb
> nodes and keep them really fresh time wise, it could have a bit of an
> impact especially if all 8 outbound connections are used up by my dumb
> nodes right?
>
> I don't want to do this obviously, I'm just thinking about it as I'm
> building my node, what is there to stop this happening?
>
>
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next prev parent reply other threads:[~2015-03-05 2:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-05 1:40 Thy Shizzle
2015-03-05 2:13 ` Kevin Greene [this message]
2015-03-05 2:16 ` Kevin Greene
2015-03-05 3:18 Thy Shizzle
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