Posted by: Diabolic Preacher | October 25, 2006

P2P: Abused File-sharing technology

a sub-entry of sorts branched off from the bittorrent article to make reading easier and also follow the idea of limiting one post to one topic only.

This is a technology primarily used for file-sharing on a network than for any other purpose. For e.g. files shared on a SMB network can be shared using this technology. This has it’s advantages compared to a server-client model, as there is no expensive file server to be maintained, nor it’s bandwidth be heavily used by all clients on the network using its resources. besides what if the server goes down. happy holiday! 😛 Compared to that, in peer-to-peer, every machine takes part both as a client by browsing the files on various computers on the network as well as contributing to the available files’ vault by acting as a server too. A peer therefore is a machine which is neither a high-privileged one like a server, nor a low-privileged one like a client but one with equal opportunities to be both at the same time. A peer to peer network although has the files stored in a decentralized method may opt for a centralized authentication for all nodes on the network to identify the machine as a trusted one on the network. authentication strictness will depend on the application of the P2P network.

As far as public P2P networks to which P2P clients like kazaalite, bearshare, limewire, gnutella etc. connect to are meant to connect user’s directories/drives (that they have configured to be shared within the application…make sure you choose these directories with care. Also check if the sharing privileges are recursively applied to the directories within). Sharing your files is absolutely optional but most of these networks are designed to thwart machines which are only consuming bandwidth of people by downloading files but not letting people download files from their storage. believe me, the speed crawls to a standstill even on my dataone line. 😀 These publicly accessible P2P networks also take advantage of the fact that since these networks are used for sharing stuff that 1000’s of people will be having a copy of, they have algorithms in place to get chunks or pieces (usually segments of a few hundred kilobytes…fixed size per file) of the file from different sources (sources = all machines that have the exact same copy of the file requested). if the number of sources willing to share the file or having free upload slots (set within the P2P application) are fewer such that the chunksize x no. of users is not equal to filesize, then the available sources are requested multiple times for downloading more chunks of the file from them. if you have used a download manager that fetches parts of the same file from a given set of mirror locations using multithreading you can visualize what i am talking about. Edgar from ILUG gave an interesting analogy of getting a book by running around town fetching pages from various places and filing them in your binder and when all pages are with you…you have your book. what is also to be known as far as P2P is concerned is that the people whom you fetch pages from, should have the entire book each. Also note that the pages are not necessarily fetched entirely in sequential order, though most clients get first few chunks in order such that you can preview the file (majorly valid in terms of multimedia content).

Initially Napster started out with a centralized network to which all machines with an account on the napster servers connected to. This was the weakness of Napster that led to it’s shutdown and to it’s revival as one of the new distribution models which opened a new channel of revenue for the artists and irked the traditional model distributors a little bit more in spite of them having consented to this model. oh yeah! courts n judges don’t matter…they hear both the sides…they listen to their revenue sources. Learning from this, most P2P network that appeared on scene afterward have decentralized networks and claim that they have only provided the tools to share files but have nothing to do with what files are being shared whether legitimate or not. Diabolically…fair enough. 🙂

Wikipedia entry…never referred ;P


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