Kad network
The Kad network is a peer-to-peer (P2P) network which implements the Kademlia P2P overlay protocol. The majority of users on the Kad Network are also connected to servers on the eDonkey network, and Kad Network clients typically query known nodes on the eDonkey network in order to find an initial node on the Kad network.
Usage
The Kad network uses UDP to:
- Find sources for eD2k hashes.
- Search for eD2k hashes based on keywords in the file name.
- Find comments and ratings for files (hashes).
- Provide buddy services for firewalled (Low ID) nodes.
- Store locations, comments and (keywords out of) filenames.
Note that the Kad network is not used to actually transfer files across the P2P network. Instead, when a file transfer is initiated, clients connect directly to each other (using the standard IP network).
As with all decentralized networks, the Kad network requires no official or common servers. As such, it cannot be disabled by shutting down a given subset of key nodes. However, because nodes are constantly communicating with each other, it can place a higher strain on individual machines when compared to connecting to a central database server.
Clients
Only few major clients currently support the Kad network implementation. However, they comprise greater than 80% of the user base and are probably closer to 95% of ed2k installations. The clients are:
- eMule: An open source Windows client which is the most popular client, with 80% of network users. Also runs on Linux under Wine. Some projects based on this software hold Kad network like: aMule (which is a Linux client similar to eMule)), eMule Mods (not eMule Plus, though) and possibly some others.
- MLDonkey: An open source, cross-platform client that runs on many platforms and supports numerous other file-sharing protocols as well.
- iMule: An open source, cross-platform client.
- Lphant: A freeware, cross-platform client that supports the BitTorrent protocol too.
There are a number of minor variants or forks of eMule which support the same basic features as eMule itself.
Search
The Kad network supports searching of files by name and a number of secondary characteristics such as size, extension, bitrate, etc.