just a BitTorrent DHT Sniffer (based on python-libtorrent)
$ sudo apt-get install python-libtorrent
First, prepare a torrent for joining the network.
$ wget http://releases.ubuntu.com/12.04/ubuntu-12.04.3-server-amd64.iso.torrent
Then, execute below. btsniff listens on tcp port 6881.
$ python btsniff.py ubuntu-12.04.3-server-amd64.iso.torrent
or
$ nohup python btsniff.py ubuntu-12.04.3-server-amd64.iso.torrent >/dev/null 2>&1 &