Ed2k: URI scheme

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ed2k links are used by the eDonkey2000 family of P2P programs, such as eDonkey2000 itself, eMule, Hybrid, MLDonkey, and others. These links are primarily used to provide a unique identifier for file without referring to a specific location, like in FTP and HTTP links. This is done by using a hash function on the file to calculate its checksum.

ed2k links allow the file to be automatically downloaded in eMule, eDonkey2000 or other compatible software. This linking feature was one of the first to be introduced in peer to peer file sharing. Now [[Magnet: URI scheme|Magnet links]] serves a similar role but is not limited to the ed2K hash but can be other hashes such as SHA or MD5 etc.

The ed2k hash function is based on MD4 but differs for files in excess of approximately 9.5 MB. The file is divided into 9.28Mb (the exact value is 9,728,000 byte) chunks and the hash is calculated for each one. The resulting hash table is hashed once again, and the final value is used as a part of the ed2k link.

Hash link format

The typical ed2k link also includes the filename and the filesize. An example (a link to the 15Mb Purist Edit trailer) is provided below:

ed2k://|file|The_Two_Towers-The_Purist_Edit-Trailer.avi|14997504|965c013e991ee246d63d45ea71954c4d|/

The ed2k links can also include a reference to the IP address and port of the specific client that shares a file. This is done by adding a list of sources after the main part of the link:

ed2k://|file|The_Two_Towers-The_Purist_Edit-Trailer.avi|14997504|965c013e991ee246d63d45ea71954c4d|/|sources,202.89.123.6:4662|/

The "file" part indicates that this is a file link, as opposed to a server link. A server link is a reference to an eDonkey2000 server; clicking on such a link typically adds it to the server list:

ed2k://|server|207.44.222.51|4242|/

After installing an eDonkey2000 client on Microsoft Windows, the ed2k:// protocol is optionally registered so that clicking on it in the browser automatically starts the download.

Ed2k: URI scheme

Hash link format

More ed2k links