Understanding How Gnutella Functions

At its height, Napster was arguably the most visited website ever. Within a year, it skyrocketed to 60 million monthly visitors before being shut down due to copyright infringement, only to return in 2003 as a legitimate music-download service.

Napster's explosive popularity was driven by its one-of-a-kind offering: free music accessible with minimal effort from an enormous database. Gone were the days of visiting music stores, paying for albums, or searching for a CD and a cassette to record it on. Almost every song imaginable was available at your fingertips.

The original Napster's primary flaw was its design, particularly the way its system was structured to distribute illegal content. When the courts determined that Napster facilitated copyright infringement, it was relatively straightforward for them to shut it down through a court order.

Despite the copyright violations associated with Napster, its users were unconcerned. Most of them migrated to a new file-sharing system called Gnutella. In this article, we’ll explore how Gnutella differs from the old Napster, allowing it to continue thriving despite a challenging legal landscape.

Understanding Napster's Architecture

On the Web, as commonly set up, Web servers store data and handle requests for that data (refer to How Web Servers Work for more information). Web browsers let users connect to these servers and view the requested data. Large websites with heavy traffic may need to purchase and maintain numerous machines to handle the volume of user requests.

Napster was the pioneer of the peer-to-peer file sharing model. In the original version of Napster (before it relaunching in 2003 as a legitimate, pay-for-music platform), users would store the files they wanted to share (usually MP3 music files) on their hard drives and directly exchange them with others. The Napster software allowed this file sharing, turning each user’s machine into a mini server.

Here’s what happened when you logged into the old Napster to download a song:

The creator of Napster had several reasons for this design choice:

This method worked exceptionally well, taking full advantage of the Internet’s structure. By distributing the task of downloading files across millions of machines, Napster achieved what would have been impossible otherwise.

The central database for song titles was Napster’s critical weakness. When the court mandated that Napster cease its operations, the lack of a central database led to the collapse of the entire original Napster network.

After the original Napster shut down, around 100 million people worldwide were still eager to share more and more files. It was only a matter of time before another system emerged to fill the void.

Gnutella's Architecture

Currently, the leading platform for file-sharing is another peer-to-peer network called Gnutella, or simply the Gnutella network. There are two key similarities between Gnutella and the old Napster:

There are also two major distinctions between Gnutella and the original Napster:

Due to these features, it would be challenging for a court order to bring down Gnutella. The court would need to figure out a way to block all traffic from the Gnutella network at the ISP and backbone levels of the Internet to prevent file sharing.

Gnutella Clients

Napster initially had a single piece of "client software" -- the program that users ran on their devices to connect to the Napster servers. In contrast, Gnutella offers a wide range of client software options. Some of the widely used Gnutella clients are:

How a Gnutella client locates a song

Given the absence of a central server that stores the names and locations of all the available files, how does Gnutella software find a song on someone else's machine? Here's a basic rundown of how it works:

It's a remarkably simple yet clever method for quickly distributing a query across thousands of machines.

This method has a major advantage -- Gnutella operates continuously. As long as you can access even one other machine running Gnutella software, you can send queries throughout the network. No legal order can bring this system down, as there is no single machine in control. However, Gnutella does come with at least three significant drawbacks:

Apparently, these limitations are negligible, as users have downloaded hundreds of millions of copies of Gnutella clients.

XoloX Example: Searching

XoloX is a straightforward, relatively simple application designed to connect to the Gnutella network. While it lacks some of the advanced features of more complex clients, it gets the job done. The program is small in size (around 600 kilobytes), free from any "spyware" or bundled pop-up advertising, and is very user-friendly. Its simplicity makes it a great tool to illustrate how a typical Gnutella client operates.

With XoloX, there are three main tasks you can perform: search for files, transfer files to your computer, and view your downloaded files. The top of the XoloX window features three buttons that allow you to switch between these functions.

The image above displays a typical search screen. To begin, simply type the name (or keywords) of the file you're searching for. You can also specify the file type, such as audio or video, or select "All Types." Your XoloX client sends a request with your search query, and within 30 to 60 seconds, a results window will populate with results from thousands of other machines processing your request.

In the search results, you’ll notice a score. This score indicates how many machines are currently online and have the same file available. By selecting a file with a higher score, you increase your chances of obtaining the file you want.

XoloX Example: Downloading

To download a file, just double-click on it in the search window. This action sends the file name to the Transfer window. Once the filename appears in the transfer window, your XoloX client will establish a connection with the peer machine to retrieve the file. One of the great features of XoloX/Gnutella is that if multiple machines have the file, your client can simultaneously connect to several of them, speeding up the download process. In the image below, you can see that Filename1.avi is taking advantage of this feature, downloading at a rate of 69.2 kilobytes per second. XoloX estimates it will take 43 minutes to complete the download of over 100 megabytes.

Sometimes, when you choose a file to download, nothing happens. This could mean that XoloX cannot connect to the machine hosting the file, or that the machine is busy helping other users. To fix this, you can either wait for the machine to become available, select files with higher scores (which indicates a greater chance of finding an available machine), or remove a stalled file from the transfer window and replace it with another one from the search results.

After downloading files, you can find them in a designated XoloX directory and in the Files window within the XoloX interface. If you want, you can share these files with others. To do so, first go to the Preferences dialog and select the directories and file types you want to share.

You also have the option to manage how much outbound bandwidth XoloX uses when others download files from you.

This can help prevent others from using up all your available upstream bandwidth.

Is Gnutella Legal?

Gnutella itself is not illegal. Sharing files that are in the public domain is perfectly legal. However, when users start sharing copyrighted content like music and movies on Gnutella, it crosses into illegal territory. This issue is what led to the downfall of Napster. While the music industry has voiced concerns about Gnutella, there is no clear way to effectively control it at the moment.

One way to disrupt file-sharing on Gnutella is by attacking its architecture. Currently, two main tactics are being used to do this:

Gnutella's dedicated developers have faced similar challenges before, so it is likely that new software updates will be able to overcome these obstacles and maintain the flow of files.

Currently, there is ongoing debate about the actual financial impact of file-sharing. Is downloading a shared file considered theft, or does it serve as a form of free promotion and exposure, much like how radio airtime functions?