A file's identification checksum is computed by concatenating the chunks' MD4 checksums in order and hashing the result. Furthermore, valid downloaded chunks are available for sharing before the rest of the file is downloaded, speeding up the distribution of large files throughout the network. That way, if a transmission error is detected, only one chunk is corrupted instead of the whole file. This treats files with identical content but different names as the same, and files with different contents but same name as different.įiles are divided in full chunks of 9,728,000 bytes (9500 KiB) plus a remainder chunk, and a separate 128-bit MD4 checksum is computed for each. As the number of servers and their addresses change frequently, client programs update their server lists regularly.įiles on the eDonkey network are uniquely identified using MD4 root hash of an MD4 hash list of the file. By running an eDonkey server program on a machine connected to the Internet, any user can add a server to the network. Clients and servers are available for Windows, Mac OS X, Linux, and other Unix-like operating systems. eDonkey servers act as communication hubs for the clients, allowing users to locate files within the network. The other eD2k client programs, given time, generally follow suit adopting these protocol extensions.ĮDonkey client programs connect to the network to share files. Examples of eD2k protocol extensions are "peer exchange among clients", "protocol obfuscation" and support for files larger than 4 Gigabytes, etc. As eMule is open source, its code is freely available for peer-review of the workings of the protocol. However, the eD2k protocol is not formally documented (especially in its current extended state), and it can be said that in practice the eD2k protocol is what eMule and eserver do together when running, and also how eMule clients communicate among themselves. The original eD2k protocol has been extended by subsequent releases of both eserver and eMule programs, generally working together to decide what new features the eD2k protocol should support. eMule is in constant development and currently represents about 90% of all clients in the eD2k network. Most notably, eDonkey2000, the original client by MetaMachine, closed-source but freeware, and no longer maintained but very popular in its day and eMule, a free program for Windows written in Visual C++ and licensed under the GNU GPL. There are many programs that act as the client part of the network. The eserver family is currently in active development and support, and almost all eD2k servers as of 2008 run this server software. There are two families of server software for the eD2k network: the original one from MetaMachine, written in C++, closed-source and proprietary, and no longer maintained and eserver, written from scratch by a person Lugdunum in pure C, also closed-source and proprietary, although available free of charge and for several operating systems and computer architectures. The server part of the network is proprietary freeware. Like most sharing networks, it is decentralized, as there is not any central hub for the network also, files are not stored on a central server but are exchanged directly between users based on the peer-to-peer principle.Ĭurrently, the eD2k network is not supported by any organization (in the past it was supported by the MetaMachine Corporation, its creator, which now is out of business) and development and maintenance is being fully provided by its community and client developers. The eDonkey Network (also known as the eDonkey2000 network or eD2k) is a decentralized, mostly server-based, peer-to-peer file sharing network best suited to share big files among users, and to provide long term availability of files.
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