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TCP Ports
Last updated: 7/12/01

Q.  What are TCP Ports?

A.  Data transmitted over a network using the Transport Control Protocol/Internet Protocol (TCP/IP), such as the Internet, includes address information that identifies the computer (32-bit IP address) and a port.  Ports number (16-bit number) the ends of logical connections used for long-term data transfers between applications.  For example port 80 is the standard File Transfer Protocol (FTP) port used by HyperText Transfer Protocol (HTTP) to send and retrieve web pages.  Service contact ports or "well-known ports" are used to provide services to unknown callers.  Port numbers are divided into three categories and ranges:

  • Well Known Ports are those from 0 through 1023
  • Registered Ports are those from 1024 through 49151
  • Dynamic and/or Private Ports are those from 49152 through 65535

The list of TCP and User Datagram Protocol (UDP) ports is maintained by the Internet Assigned Numbers Authority (IANA).

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