WHAT IS DIRECT CONNECT (IN A NUTSHELL)
Note: pieced together from various sources
The Direct Connect network is a decentralized network, made up of individual servers (hubs) that users join to share files with other members on that hub. Each hub is individually run by a fellow user of the Direct Connect network, and may have special themes that define the look, membership and shared content the hub offers. Hub Owners pick the software, scripts, programs and rules to regulate their hub as they see fit; if nobody likes it, they usually get tired and discontinue their hub, but some hubs have become immensely popular and entertain thousands of users daily.
Direct Connect allows you to share files over the Internet without restrictions or limits. Clients are free of advertisements and have easy to use interfaces. Firewall and router support is integrated and it is easy and convenient to use functionality like multi-hub connections, auto-connections and resuming of downloads.
Developed by Neo Modus, DC is one of the older file-sharing communities still in existence. What began as a small community of a few thousand individuals has grown into a major P2P player with a speculative population over 500,000. Its network architechure and philosphy is similar to OpenNap. Like OpenNap, the Direct Connect development team creates the client and server software, however distributes the programs to the community. It is up to the DirectConnect community to maintain the network. Direct Connect is still living in the dark ages of file-sharing, as it has no multi-source swarming, official hashing system or connectivity of servers. It offers a community-oriented, open, user-controlled network. Moreover, Direct Connects network architecture is built on a peer-to-peer foundation; users run, control, and maintain the network. Users are able to share any type of file - with some restrictions. These files are easily viewed through a familiar organized windows-explorer interface. To conveniently access the plethora of files, advanced searching capabilities and filters are provided. All of these features are integrated into Direct Connects unique communal file-sharing system.
DC depends on a hub-system where users connect to hubs (servers) where they share and download files. When connected to a hub the user can see all other users connected to the hub and a list of the files they share. To be able to download the user must find the file at a computer with a free slot. The design makes Direct Connect more like IRC than KazzA. Lists of hubs are available from within the DirectConnect program. Many hubs have specialties, which include music, movies and CD images, etc. While music is quite prolific on this network, DirectConnect is best known for the latter two.
While the DirectConnect network may seem enticing, it is not for everyone. Many hub operators set strict entry criteria, which is mostly based on the amount of information you share. For example, many hubs will not allow you to connect if you do not share at least 1 gigabyte of information. With such requirements, only those on broadband connections can take advantage of this network. Although these requirements may seem harsh to those on dialup, it has significantly reduced problems related to leeching, flaming and general lamership.
The much preferred client for the Direct Connect network is called DC++. It has many more features than the original Direct Connect client (which is defunct) and a friendly user interface. Many modified clients have been developed to use the DC network, including builds for the Mac and Linux operating systems. zK++ is the open source alternative to DC++. Both connect to the same network, but the experience is very different. Compared to DC++, zK++ has a lot of extra features and is very easy to use. Its streamlined interface makes this network usable for just about anyone. There are many advantages it has over DC++. They include, but are not limited to: detection data, segmented downloading, constant development, cool and smart window interface, better GUI, bandwidth management, smaller download and considerably more stable.
Therefore, Direct connect is a peer-to-peer file-sharing protocol. The most popular Windows client implementing this protocol currently is DC++. Direct connect clients connect to a central hub (usually on port 411) and can download files directly from one machine to another.
Hubs feature a list of clients or users connected to them. Users can search for files and download them from other clients, as well as chat with other users.
HUB
Direct Connect hubs are servers to which clients connect. A "hub" is a piece of software which routes chat, search requests/results and facilitates clients to connect each other. It's not called a server because it doesn't share any files. All file transfers are being made directly between clients, not through the hub. One can find hubs to connect to through the various hublists available in their client our found throughout the Internet. Hubs provide information about the clients, as well as file searching and chat capabilities. File transfers are done directly between clients, in true peer-to-peer fashion.
Hubs often have special areas of interest. Many have requirements on the total size of the files that their members share (share size), and restrictions on the content and quality of shares. Hubs can allow users to register and provide user authentication. Some private reghubs only let in users already registered.
PROTOCOL
The Direct connect protocol suffers from high bandwidth usage, unusual requirements for parsing, lacklustre internationalization support, and parts that seem to have been crafted to overcome network handling bugs in older versions of Microsoft Visual Basic (which NMDC was developed in). The protocol does not try to hide the identities of the peers, nor is it optimized to swarm-download such as BitTorrent, since it lacks partial file-sharing and (in many clients) segmented downloading.
Continued interest exists in features such as ratings and language packs. One added feature is Tiger-Tree Hashing of shared files (TTH). The advantages of this include verifying that a file is downloaded correctly, and the ability to find files independent of their names. Users in the hubs also enjoy chatting personally, in small groups (such as Opchat), or all together in the hub's main window. Many hubs offer responsive bots and games for users to engage in.
The authors of DC++ have been actively working on a complete replacement of the Direct connect protocol called ADC, designed to address the former's weaknesses.