Sunday, 2 October 2011


In these days, it has been common in our day-to-day life that if we need some software or video we buy cd’s or dvd’s from the store or download it from site. We also upload files, play games , use social networks to chat and do other activities on our PC but often we do not think about the technology behind it. P2P is one such network where we get access to all of these (free of cost and less hastle)

What is P2P?

p2p basically refers to Peer to Peer communication. Peers are both consumers and suppliers of data, in contrast to client-server model where only server supplies and clients consume data. It is the platform where the user acts as both an active editor and contributor, creating and linking to form interlinked “web”of links.

How P2P Works?

Like a search engine on the Internet, P2P software allows a user to type in a search term. The search will turn up files with that term in them. “The search pulls from any computer currently connected to the Internet running that P2P software.” You can then select the files you want to download; you could be downloading some files from a computer in China and rest of them from a computer in USA.

What is P2P Network?

It is basically interconnection of computers (peers) by which users can share files. A peer to peer network doesn’t rely on dedicated server or hierarchy among the computers that are linked together. Each computer that is linked to the network is responsible for its own administration so the users can decide who will be allowed access to which components on the network.

Difference Between Client-Server & P2P

The basic difference between client-server model and p2p is that in p2p there is no centralized server.p2p is good to handle small business and works easier than client-server model .For example -If at this point, you want to share a printer or an Internet Connection then you may not need to go to the whole of installing client-server network. A p2p network may be ideal to handle all your networking needs.

Types Of P2P Communication

Basically there are two types of p2p networks.

· Pure p2p
· Hybrid p2p
In pure p2p the entire network consists of equipotent peers.There is only routing later , as there are no preferred nodes with any special infrastructure function.Examples are -Gnutella and Freenet.Hybrid p2p systems allow such infrastructure nodes to exist,often called supernodes.Examples are Kazaa and eMule.



Examples of P2P Communication

We have many examples of P2P communication. The most commonly used P2P communicating sources are utorrent, bittorent,bitcomet,lime wire,skype,gnutella,G2 and many more too. File sharing can be done from one peer to other using any of these sources.

Let’s take the example of Bit Torrent to know more about P2P communication.

Bit Torrent is a protocol used for transferring files. It is a peer to peer (p2p) file sharing system which means that users connect directly to one another in order to transfer portions of the file. It is used to distribute large amounts of data. Bit torrent can be used to share different types of files including music, games, pictures etc.

To watch video from explaining Bit Torrent click here.

Bit torrent involves a lot of phrases that can become confusing. This is a list of definitions for some of the phrases involved in bit torrent usage.

Torrent file- This stores the metadata( location of different pieces of target file and URL of many trackers).

Peer-A peer is another computer that u connect to,to download parts of the file.

Seed – A computer that has a complete copy of a certain file.

Swarm – A group of peers who are connected as they are downloading a particular file.

Tracker – A server that coordinates the action of a bit torrent client.

Leecher –A peer who downloads more but uploads less.

You can download bittorrent from

Lets look at a sample snapshot of Bit Torrent.

How The Bit Torrent Works?

A file is originally distributed by one person(seeder). Once it’s torrent file has been uploaded, other users can browse the web to find the torrent file that they are interested in. These users then download the torrent file and open it with bittorrent. The purpose of the torrent client is to connect to the tracker and any other ‘peer’ who is using it.

Downloading from Bittorrent

Type the keyword you want to search and select the one which you want to download. It will automatically start the download. At the bottom there are various options available about the download. The Info field provides information about the statistics of the download. We can see the peers available for p2p communication sharing this file on this torrent. To check this, click on peers as shown below .

There are many other options to modify your download like pause,stop,change download limit,upload limit,remove torrent and data,etc.

There are other torrent clients available for other operating systems as well:-

For Linux-



While Macintosh has p2p network capability included in its OS. You can choose to setup the network with phone lines and very simple connectors.

utorrent, tranmission clients are also available for Macintosh PC.

Advantages of P2P

· Due to decentralized nature of p2p networks,it also increases robustness.

· With more clients,even the resources get added to the system.

· It is of low cost as the resources are shared by the user itself but not the server.

· Clients provide resources which may include bandwidth ,storage space and computing power.

· It works very fast as it downloads from peers and not the web .

· Collaborating computing.

Disadvantages of P2P

Over 150 million people world-wide use p2p communication. But all of them are not safe.

  • Illegal-Unfortunately the most common uses of p2p are illegal ones such as copyrighted music, copyrighted software ,etc hence promoting piracy.
  • Virus-When downloading a shared file , the main threat is to download virus or Trojan horse onto your computer.
  • Spyware-Many of the p2p programs automatically install spyware on our computer as a part of p2p installation process.
  • Pornographic Downloads-Today 35% of p2p downloads are related to pornographic material.
  • How to Safeguard misuse of resources?
  • We can secure a P2P network by installing a software that keeps a watch out for malicious software on every workstation.
  • Hackers usually have two things in mind: control of the file sharing mechanism and the hardware wired to the network; hence software for monitoring of these is a must.
  • File sharing companies came up with checks in their own software that plug serious malware and hacking. Hence, it is now duty of the antivirus to keep the network secure.
  • Modern hashing ,chunk verification and different encryption techniques have made most networks resistant to almost any type of attack.
  • P2P file sharing generally consists of heavy bandwidth uses due to continuous file transfer. To reduce bandwidth wastage ISP’s(Internet Service Providers) implement “P2P caching” ,where ISP stores the most accessed content by P2P client.


    Prasoon Dwivedi and Suhanth Boddu

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