User Guide
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Chapter 6 Appendix
6.1 Glossary
SNTP
Simple Network Time Protocol (SNTP), using UDP datagram packets at the transport layer, is a
networking protocol for clock synchronization between computer systems over packet-switched,
variable-latency data networks.
HTTP
The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative,
hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web,
which defines information format, transmission mode, WEB server and browser actions. HTTP functions
as a request-response protocol in the client-server computing model. A web browser, for example, may
be the client and an application running on a computer hosting. A web site may be the server. The client
submits an HTTP request message to the server. The server, which provides resources, such as HTML
files and other content, or performs other functions on behalf of the client, returns a response message to
the client. Another primary standard of controlling how World Wide Web works is HTML, which defines
how web pages are formed and displayed. Any web server includes a HTTP daemon background
program in addition to web files. This program is designed to expect and process HTTP requests. A web
browser, as an HTTP client, is used for sending requests to the server. An HTTP client initiates a request
by establishing a Transmission Control Protocol (TCP) connection to a particular port on a server
(typically port 80). An HTTP server listening on that port waits for a client's request message. Upon
receiving the request, the server sends back a status line, and a message of its own.
Auto-negotiation
Auto negotiation is an Ethernet procedure by which two connected devices choose common transmission
parameters, such as speed, duplex mode, and flow control. In this process, the connected devices first
share their capabilities regarding these parameters and then choose the highest performance
transmission mode they both support.
IEEE 802.1X
IEEE 802.1X is an IEEE Standard for port-based Network Access Control (PNAC). It is part of the IEEE
802.1 group of networking protocols. It provides an authentication mechanism to devices wishing to
attach to a LAN or WLAN. IEEE 802.1X defines the encapsulation of EAP over LAN or EAPOL. 802.1X
authentication involves three parties: a supplicant, an authenticator, and an authentication server. The
supplicant is a client device (such as a laptop) that wishes to attach to the LAN/WLAN, though the term
“supplicant” is also used interchangeably to refer to the software running on the client that provides
credentials to the authenticator. The authenticator is a network device, such as an Ethernet switch or
wireless access point; and the authentication server is typically a host running software supporting the
RADIUS and EAP protocols.The authenticator acts as a security guard to a protected network. The
supplicant (i.e., client device) is not allowed access through the authenticator to the protected side of the
network until the supplicant’s identity has been validated and authorized. With 802.1X port-based
authentication, the supplicant provides credentials, such as user name/password or digital certificate, to
the authenticator, and the authenticator forwards the credentials to the authentication server for
verification. If the authentication server determines the credentials are valid, the supplicant (client device)