| 单词 | port |
| 释义 | port 1. A point of physical access or physical interface between a circuit and a device or system at which signals are injected or extracted. A given computer system may be equipped with a number of ports for various, specific purposes and with various attributes appropriate to the application. Ports can be defined as analog or digital and as optical or electrical, for example. The port speed is always defined, as well. A PBX, for example, may include a number of printed circuit boards (PCBs), each of which contains a number of specific interfaces. A PBX digital line card commonly contains 4, 8, 16, or 32 digital line ports, each of which provides the electrical interface between a digital telephone set and the PBX common equipment, and operates either at 64 kbps or, if ISDN, at 144 kbps.The line ports also are designed to support the appropriate signaling and control protocols, which commonly are proprietary protocols defined by the PBX manufacturer. A PBX digital trunk card may include one or more trunk ports specifically designed to interface with T1 (1.544 Mbps) or E-1 (2.048 Mbps) electrical circuits. A router may have a number of ports, some of which may be optical interfaces to fiber optic transmission systems (FOTS) running at speeds of 2.5 Gbps or perhaps 10 Gbps, and others of which may be electrical interfaces for connection to copper circuits running at T1 or E-1 speeds. 2. A logical connection, identified by a protocol address in a packet header, associated with a Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) service. Ports provide a mechanism by which computers running the TCP/IP protocol suite can multiplex a number of concurrent connections at a single Internet Protocol (IP) address. In combination, the IP address and the port number identify a socket, with a source socket and destination socket defining a TCP connection. Port numbers are 16-bit values ranging from 0 to 65,535.Well-known ports are numbered 0 through 1,023 for the use of system (root) processes or of programs executed by privileged users. Examples of well-known ports include 25 for SMTP (Simple Mail Transfer Protocol), 80 for HTTP (HyperText Transport Protocol), and 107 for Remote TELNET Service. Registered ports, which are registered by the Internet Assigned Numbers Authority (IANA) as a convenience to the community, can be used by ordinary user processes or programs on most systems and can be executed by ordinary users.These same port assignments, numbered in the range 1,024 through 49,151, are used with the User Datagram Protocol (UDP) to the extent possible. Dynamic ports and/or private ports are those from 49,152 through 65,535. 3. To modify or translate a software program so that it will run on a different computer operating system (OS). 4. To move files from one computer to another. |
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