BitTorrent is a protocol designed for transferring files. It is peer-to-peer in nature, as users connect to each other directly to send and receive portions of the file. However, there is a central server (called a tracker) which coordinates the action of all such peers. BitTorrent is designed to work better as the number of people interested in a certain file increases, in contrast to other file transfer protocols.

There are several choices. Here are the most popular clients:

• Azureus - A very nice Java client that incorporates a full-featured GUI with extensive visualizations/statistics about the transfer. You will need the 1.4 JRE installed to run this, which can be obtained from this link.


• Official client - This is the "official" client in that it is the latest supported version from Bram Cohen, architect of BitTorrent. It has the fewest features of all the clients, and releases are much more conservative than the experimental versions. Use this if you want stability but don't need any of the common features of the other clients, such as upload rate limiting.


• �Torrent - A small and stable client that supports configurable disk caching, speed limiting and quick-resumes.


• BitComet - BitComet is a powerful, clean, fast, and easy-to-use bittorrent client. It supports simultaneous downloads, download queue, selected downloads in torrent package, fast-resume, chatting, disk cache, speed limits, port mapping, proxy, ip-filter, etc.

Try closing and restarting your web browser. When BitTorrent installs, it registers a new MIME-Type (application/x-bittorrent) and this change will not take effect until the next time the web browser is opened.

The quick summary: You need to forward your ports if you have NAT in order to get the fastest speeds. This is probably the most common thing that people fail to do when using BitTorrent.

Prior to version 3.2, BitTorrent by default uses ports in the range of 6881-6889. As of 3.2 and later, the range has been extended to 6881-6999. (These are all TCP ports, BitTorrent does not use UDP.) For most people it's sufficient to open 6881-6889.

BitTorrent will usually work fine in a NAT (network address translation) environment, since it can function with only outbound connections. Such environments generally include all situations where multiple computers share one publicly-visible IP address, most commonly: computers on a home network sharing a cable or xDSL connection. If you are unsure of whether you have NAT or not, then try this link which will try to determine if you are behind a NAT gateway.

However, you will get better speeds if you can accept incoming connections as well. To do this you must use the "port forwarding" feature of whatever is performing the NAT/gateway task. For example, if you have a cable or DSL connection and a router/switch/gateway/firewall, you will need to go into the configuration of this device and forward ports 6881-6889 to the local machine that will be using BitTorrent. If your device makes it hard to enter a range of ports (if you must enter each one separately), then you can just do the first 10 or so ports, or however many simultaneous clients you plan to ever have open. If more than one person behind such a gateway wishes to use BitTorrent, then each machine should use a different port range, and the gateway should be configured to forward each port range to the corresponding local machine.

If you have one of these broadband router/NAT devices (such as the Linksys BEFSR41, D-Link DI-701/704, Netgear RT311, SMC Barricade, 3Com Home Ethernet Gateway, etc.) you will usually need to enter the web configuration of the device.

If you are running another type of software firewall (such as Zone Alarm Pro, Norton Firewall, McAfee Firewall, BlackICE Defender, etc.), you may have to do something similar to allow inbound access on ports 688x to the BitTorrent client (usually btdownloadgui.exe.)

For example, in Zone Alarm Pro, in the Program Listings, click on the program's name (btdownloadgui.exe) and then click the Options button and then enter the ports to use. If you're having trouble connecting, you might try giving BitTorrent access to all ports.