hashtablep2pbittorrentdhtkademlia

How to use DHT library dht-example.c for distributed hash tables


I want to use BitTorrent DHT library as distributed hash tables from within a C program. Therefore I downloaded and compiled it on my machine - worked flawless. Now I have an executable dht-example which outputs:

Usage: dht-example [-q] [-4] [-6] [-i filename] [-b address]...
                   port [address port]...

What can I do with this example? How to play with the DHT: Connect distributed machines, fill it or read hash tables from it?

Thanks lot Achim


Solution

  • dht-example.c is a minimalistic example provided in the mentioned DHT library.

    After running make for compilatation you are supposed to run ./example-dht 6882 67.215.246.10 6881. This will open a listening UDP socket on local port 6882 for talking to the DHT network.

    But before your new peer is able to connect to the network, it needs at least one connected peer from which it can get more peers. This is where the third and fourth parameter/argument comes into action. It is the IP address and port combination of a known good node on the network, in this case router.bittorrent.com. This process is called bootstraping.

    The program does not accept instructions from standard input, but instead via kernel signals SIGINT, SIGUSR1 and SIGUSR2. Use kill -L to list signal numbers on your machine and then command ps aux | grep example-dht while example-dht is running to obtain the process ID of example-dht.

    For starting a search for peers of the infohash, hardcoded in dht-example.c, issue the command kill -XX YYYYY, where XX is the number of the SIGUSR1 signal and YYYYY is the process ID of dht-example. Observe the standard output of the dht-example program.

    For dumping other nodes in our bucket and bucket 0, issue the command kill -XX YYYYY, where XX is the number of the SIGUSR2 signal and YYYYY is the process ID of dht-example. Observe the standard output of the dht-example program.

    For stopping dht-exmample, issue the command kill -XX YYYYY where XX is the number of the SIGINT signal and YYYYY is the process ID of dht-example. Observe the standard output of the dht-example program.