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 18:16:07 -0800 [thread overview]
Message-ID: <CAEY8wq78CeguA0QyGfud_CorhXA5j=vn--2tYOcYyE4x4eXVfA@mail.gmail.com> (raw)
In-Reply-To: <CAEY8wq701HBWQVmvch=dQF09WJ7cJQX0RZd2XKd-23w_AUTK=w@mail.gmail.com>
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Also (I am fuzzy on the details for this), Bitcoind will detect when a node
is misbehaving and (I believe) it will blacklist misbehaving nodes for a
period of time so it doesn't continually keep trying to connect to tarpit
nodes, for example.
On Wed, Mar 4, 2015 at 6:13 PM, Kevin Greene <kgreenek@gmail•com> wrote:
> 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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>>
>>
>
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next prev parent reply other threads:[~2015-03-05 2:16 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
2015-03-05 2:16 ` Kevin Greene [this message]
2015-03-05 3:18 Thy Shizzle
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