BitTorrent Ports Tip to Speed Up Clients
Some users of the BitTorrent client report experiencing slow downloads when sharing P2P files. This is most likely to occur on computers behind a home router or software firewall.
Being behind firewalls, the BitTorrent client may block incoming Bit Torrent network connections. Given the load balancing and "swarming" nature of the BitTorrent network, clients unable to take incoming requests for uploads will naturally be allowed less bandwidth for downloads.To solve this problem, consider the following:
- When a user starts a BitTorrent client, the client sets up a
network resource called a "port" to allow other Bit Torrent clients to
connect ot it. Each port possesses a unique number called the "TCP port
number."
- A BitTorrent client normally associates the TCP port number
6881. However, if this port is busy for some reason, the client will
instead try successively higher ports (6882, 6883, and so on up to a
limit of 6999). In order for outside BitTorrent clients to reach this
one, they must be able to connect to the correct port.
- When connecting to another BitTorrent client, the requesting
client will first try port 6881, then 6882, and so on. However, if the
computer is on a firewalled network, the incoming request may not reach
these ports. On the other hand, if these requests succeed, the accepting
client will be able to download faster.
- Firewalls can block nearly all of the ports used by P2P
clients. To ensure the BitTorrent ports are made available to requesting
clients, a home router or firewall can be manually configured to accept
them. Most home routers possess a feature called "Port Range
Forwarding" to do this. This feature allows the administer to tell the
firewall where traffic for a given port number should be directed.
- For BitTorrent, many home users set up port forwarding on the
TCP range 6881-6889. These ports must be directed to the computer
running the BitTorrent client. If more than one computer on the network
may run BitTorrent, a different range such as 6890-6899 or 6990-6999 can
be used for each. Remember that BitTorrent uses ports in the 6881-6999
only.
- Many people don't realize that Windows XP computers include the built in Windows Firewall.
If port forwarding is set up on a home router, but Windows Firewall is
running on the BitTorrent client computer, incoming requests may still
fail to reach the client. Ensure the Windows Firewall is either disabled
or is set up to allow the appropriate BitTorrent ports to pass through.
The same recommendation applies to other software firewalls.
- On home networks without a router, the software firewall (Windows Firewall, ZoneAlarm, or other) must be set up to provide the equivalent forwarding or pass-through capability as needed.
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