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Port

Used by computers and networks as an addition to an IP address to identify data and its source and to connect it to its endpoint. Email is sent on Port 63. HTTP traffic is carried on port 80. PORTS become of concern when trying to identify authorized users on the network. The network identifies the port from which data is being sent and then approves or denies use of the network to the user. Ports are also the physical outlets on computers and peripherals which you use wires to connect to one another.

Links: Webopedia on PORT

by Pat Thornburn

Port

n) (1) An interface on a computer to which you can connect a device. Personal computers have various types of ports. Internally, there are several ports for connecting disk drives, display screens, and keyboards. Externally, personal computers have ports for connecting modems,printers, mice, and other peripheral devices. Almost all personal computers come with a serial RS-232C port or RS-422 port for connecting a modem or mouse and a parallel port for connecting a printer. On PCs, the parallel port is a Centronics interface that uses a 25-pin connector. SCSI (Small Computer System Interface) ports support higher transmission speeds than do conventional ports and enable you to attach up to seven devices to the same port. All Apple Macintosh computers since the Macintosh Plus have a SCSI port.

(2) In TCP/IP and UDP networks, an endpoint to a logical connection. The port number identifies what type of port it is. For example, port 80 is used for HTTP traffic.

(v) To move a program from one type of computer to another. To port an application, you need to rewrite sections that are machine dependent, and then recompile the program on the new computer. Programs that can be ported easily are said to be portable.

by Marty Sierra-Perry

Port

Port is a term has several uses in networking terminology. First there are the physical interfaces usually found on the front, back and sides of modern computers. These include parallel, serial, modem, ethernet, SCSI ports among others. These ports all allow data to enter from outside sources, or the attachment of a wide variety of peripherals.

The term PORT also is a networking term. In TCP/IP and UDP, a port is the endpoint to a logical connection. The port number identifies what port it is. For example port 80 is for HTTP (Webopedia). Ports, sometimes called sockets, are software implementations that allow data packets to be moved from the lower layers (OSI Model) to the upper layers. For example, an incoming datagram with port 80 would be destined for a browser in the application layer. (Daryl's TCP/IP) TCP/IP has over 65,000 available ports. The first 255 are set aside for the public. These include FTP, HTTP, SMTP, and others. The ports from 256 to 1023 are set aside for companies to use in their applications. The remaining are used by the upper layers to set up sessions with other hosts and by TCP to use as a source and destination addresses in the TCP segment. For a description of the first 1023 ports see Todd Lammile and Donald Porter's CCNA Study Guide, Sybex, 1996. This comprehensive listing is difficult to find outside of official RFC documentation.

How would I use ports?
One of the first things to do in computer trouble shooting is to check the physical interfaces of the computer and devices connected. Also, basic knowledge about some port behaviors is essential. For instance, connecting a SCSI device to a computer while it is turned on can damage a computer. Knowing whether a computer has the physical interface to support a peripheral device is important. An expensive Firewire hard drive is worthless without the port (which leads to a Firewire hardware) to support the device.

TCP ports are important to understand how data from a source application is routed to a destination application. It is also critical to understanding how firewalls and network security functions.

by Paul Smith

PORT

A port can be defined several ways:

1. It is a system or network access point for data entry or exit.
2. It is a connector on a device to which cables for other devices such as monitors and printers are attached.
3. It is sometimes referred to as an adapter, however there can be more than one port on an adapter. It represents a physical connection to the link hardware.
4. It is a specific logical connector between the Transmission Control Protocol (TCP) or the User Datagram Portocol (UDP) and a higher-level protocol or application.
5. As a verb, it means to modify a computer program to enable it to run on a different platform.

IBM Dictionary of Computing - http://www.networking.ibm.com/nsg/Gatmst27

by Gloria Henke

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