Gnutella

Gnutella (pronounced with a silent 'g') is a distributed software project to create a true peer-to-peer file sharing network, without a central server.

Table of contents
1 History
2 Protocol features and extensions
3 Clients
4 See also

History

The first client was developed by Justin Frankel and Tom Pepper of Nullsoft, a division of AOL, in early 2000. On March 14, the program was made available for download on Nullsoft's servers. The source code was to be relased later, supposedly under the GNU General Public License (GPL). The event was prematurely announced on Slashdot, and thousands downloaded the program that day.

The next day, AOL stopped the availability of the program over legal concerns and restrained the Nullsoft division from doing any further work on the project. This did not stop Gnutella; after a few days the protocol had been reverse engineered and compatible open source clones started showing up. This parallel development of different clients by different groups remains the modus operandi of Gnutella development today.

The Gnutella network would be a fully distributed alternative to semi-centralized systems like Napster. Initial popularity of the network was spurred on by Napster's threatened legal demise in early 2001. This growing surge in popularity revealed the limits of the initial protocol's scalabilty. In early 2001, variations of the protocol (implemented first in closed source clients) allowed scalabilty to improve somewhat. Instead of treating every user as client and server, some users were now treated as "ultrapeers", routing search requests and responses for users connected to them.

This allowed the network to grow in popularity. In late 2001, the Gnutella client LimeWire, which had driven much of the protocol's development, was released as open source. Morpheus a commercial file sharing group, on 28th Feb 2002 abandoned their FastTrack based peer-to-peer software and released a new client based on the open source Gnutella client Gnucleus.

Sometimes the word 'Gnutella' refers not to a particular project or particular piece of software, but to the open protocol used by various clients. Since new clients are under development all over, and since a new protocol is apparently on the way too, it is hard to say what the word 'Gnutella' will mostly stand for in the future.

The name is a word play on GNU and Nutella. Supposedly, Frankel and Pepper ate a lot of nutella working on the original project, and they were going to use the GNU GPL license on the finished program. Gnutella is not associated with the GNU project.

Protocol features and extensions

The outdated Gnutella version 0.4 network protocol employs five different packet types, namely

  • ping: discover hosts on network
  • pong: reply to ping
  • query: search for a file
  • query hit: reply to query
  • push: download request (for firewalled servants)

These are mainly concerned with searching the Gnutella network. File transfers are handled using established HTTP protocols.

The development of Gnutella is lead nowadays by the GDF (Gnutella Developer Forum). Many protocol extensions have been and are being developed, by the software vendors and free gnutella developers of the GDF. They include intelligent query routing, SHA checksums, parallel downloading in slices (swarming), etc.

There are efforts to finalize these protocol extensions in the Gnutella 0.6 specification at the Gnutella Protocol Development Website. The Gnutella 0.4 standard although being still the latest protocol specification since all extensions only exist as proposals so far is outdated. In fact, it is hard to impossible connecting with the 0.4 handshake.

In January 2003 Shareaza announced the Gnutella2 protocol which uses UDP rather then TCP/IP network protocol for searches, an extensible binary xml-like packet format and includes many of the above mentioned extensions. The draft specification was released by them on March 26, 2003. For details see the Gnutella2 home page. Gnutella2 (G2) is not supported by the rest of the "old" Gnutella network - except for Gnucleus - and the developers of Gnutella refer to it as "MP" (Mike's Protocol) because it was never approved by the GDF.

Clients

Some popular Gnutella clients are:

See also




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