[Bitcoin-development] Useless Address attack?

Kevin Greene kgreenek at gmail.com
Thu Mar 5 02:16:07 UTC 2015

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 at 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 at 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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