GristyMcFisty used our news submit to tell us about this very interesting look at BitTorrent. There have been so many P2P apps produced over the years that it was inevitable that one would finally come along that stood head and shoulders above the rest. But, did any of us imagine that one P2P application would be responsible for a staggering 53 percent of all P2P traffic? Below, is a section of the study that I thought many here would be interested in. It shows how some of the information was gathered for the study.
In this section, we will discuss some details of our measurement software and the collected data. Our measurement software consists of two parts with three scripts each. The first part is used for monitoring the global BitTorrent/Suprnova components, and consists of the Mirror script which measures the availability and response time of the Suprnova mirrors, the HTML script which gathers and parses the HTML pages of the Suprnova mirrors and downloads all new .torrent files, and the Tracker script which parses the .torrent files for new trackers and checks the status of all trackers. The second part of our software is used for monitoring actual peers. To follow thousands of peers at one minute time resolution we used 100 nodes of our Distributed ASCI Supercomputer (DAS, cs.vu.nl/das2). The Hunt script selects a file to follow and initiates a measurement of all the peers downloading this particular file, the Getpeer script contacts the tracker for a given file and gathers the IP addresses of peers downloading the file, and the Peerping script contacts numerous peers in parallel and (ab)uses the BitTorrent protocol to measure their download progress and uptime. The Hunt script monitors once per minute every active Suprnova mirror for the release of new files. Once a file is selected for measurement, the Getpeer and Peerping scripts are also activated at the same time resolution. In this way we are able to obtain the IP addresses of the peers that inject new content and we can get a good estimate of the average download speed of individual peers. In doing our measurements, we experienced three problems. First, our measurements were hindered by the wide-spread usage of firewalls [11]. When a peer is behind a firewall, our Getpeer script can obtain its IP number, but the Peerping script cannot send any message to it. Therefore, our results for download speed are only valid for non-firewalled peers. The second problem was our inability to obtain all peer IP numbers from a tracker directly. The BitTorrent protocol specifies that a tracker returns only a limited number (with a default of 20) of randomly selected peer IP numbers. We define the peer coverage as the fraction of all peers that we actually discovered. In all our measurements we obtained a peer coverage of over 95 per cent. Our final measurement problem was caused by modifications made to the BitTorrent system itself. Which created minor gaps in our traces. |
We can see here that it is possible to create a script that will automatically follow a particular file and log it's progress and the IP numbers of a high percentage of those sharing said file. So much for the frustration of catching identities with BitTorrent come and go networks. The way I read this, they have managed to get around the protocol of limiting how many IP numbers are returned by the software. What do you think?
Source: The Register
