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| Router | <networking> /roo't*/ A device which forwards packets between networks. The forwarding decision is based on network layer information and routing tables, often constructed by routing protocols. |
| Packet Sniffer | <networking, tool> A network monitoring tool that captures data packets and decodes them using built-in knowledge of common protocols. Sniffers are used to debug and monitor networking problems. |
| Protocol Stack | <protocol> A layered set of protocols which work together to provide a set of network functions. Each intermediate protocol layer uses the layer below it to provide a service to the layer above. |
| Protocol Layer | <networking> The software and/or hardware environment of two or more communications devices or computers in which a particular network protocol operates. A network connection may be thought of as a set of more or less independent protocols, each in a different layer or level. The lowest layer governs direct host-to-host communication between the hardware at different hosts; the highest consists of user application programs. Each layer uses the layer beneath it and provides a service for the layer above. Each networking component hardware or software on one host uses protocols appropriate to its layer to communicate with the corresponding component (its "peer") on another host. Such layered protocols are sometimes known as peer-to-peer protocols. |
| TCP/IP | <protocol> Transmission Control Protocol over Internet Protocol. |
| FTP | (FTP) A client-server protocol which allows a user on one computer to transfer files to and from another computer over a TCP/IP network. Also the client program the user executes to transfer files. It is defined in STD 9, RFC 959. |
| Telnet | /tel'net/ 1. The Internet standard protocol for remote login. Runs on top of TCP/IP. Defined in STD 8, RFC 854 and extended with options by many other RFCs. Unix BSD networking software includes a program, telnet, which uses the protocol and acts as a terminal emulator for the remote login session. Sometimes abbreviated to TN. TOPS-10 had a similar program called IMPCOM. |
| UDP | User Datagram Protocol |
