The DHT bootstrap server can be used as an introducer to the bittorrent
DHT network. Like the ones running at
BitTorrent clients can use this server to join the DHT, assuming some number of clients are agreeing on using the same server.
The command line options are:
usage: dht-bootstrap <external-IP> [options] OPTIONS: --help prints this message. --threads <n> spawns <n> threads (defaults to the number of hardware cores). --nodes <n> sets the number of nodes to keep in the node buffer. Once full, the oldest nodes are replaced as new nodes come in. --ping-queue <n> sets the max number of nodes to keep in the ping queue. Nodes are held in the queue for 15 minutes. --no-verify-id disable filtering nodes based on their node ID and external IP (allow any node in on the node list to hand out). --ipv6 <ip> listen for IPv6 packets on the given address can be specified more than once --version <version> The client version to insert into all outgoing packets. The version format must be 2 characters followed by a dash and an integer. --dir <path> specify the directory where the node buckets are stored on disk. Defaults to ".". --port <listen-port> Sets the port to listen on (for all interfaces) defaults to 6881 --x-pollinate <ip> <port> if the ping queue becomes too small, request more nodes from this DHT node.
The first argument when launching the server is its own IP. This is not only relevant for binding the socket to this interface but is also used when generating its own DHT node ID.
The number of threads defaults to the number of CPU cores but can be
overridden by the
The number of DHT nodes to keep in the cache of nodes to hand out defaults
to 10000000 and can be overridden by
--nodes. It may not be lower than
The ping queue is the max number of nodes allowed in the queue waiting to be pinged. Nodes are (ideally) pinged 15 minutes after seen. If too many nodes are pinging the dht-bootstrapper to hold them all for 15 minutes in the ping buffer, the rate of pinging is throttled to match.
For example, the default of 5000000 nodes in the ping buffer restricts the
ping rate to (5000000 / 900 = ) 5555 pings per second. Experience from
router.utorrent.com suggests that about 45% of pings succeeds and end
up being added to the node buffer. At the default rate, that means the
entire node buffer is replaced every 66 minutes. i.e. once you're in the
node buffer, you'll be handed out to nodes for abut 66 minutes before you
are replaced by someone else.
The current rate at
router.utorrent.com is about 20000 requests per second.
Every request returns 16 nodes. That means every node in the node buffer is
handed out once every (10000000 / 16 / 20000 ~=) 31 seconds.
Only nodes whose node ID match their external IP address (according to this) are pinged.
dht-bootstrap listens on port 6881 by default. You may specify a different
port using the
--port command line option.
A more detailed description of how it's implemented can be found in the
The source for the bootstrap server is released under the MIT license. Please contribute back fixes and improvements!
To build, you need boost and boost-build installed. Build by running:
If you prefer to build manually, just compile
link against the boost.system library as well as adding boost to your include
To build you need a compiler with C++11 support.
Thanks to following people who have contributed code or discovered bugs in bootstrap-dht:
Team_LPJ@BoB working with Zero Day Initiative (ZDI)