ZyXEL Communications XGS3600 Series Manual page 335

H
HTTP
HTTP is an acronym for Hypertext Transfer Protocol. It is a protocol that used to transfer
or convey information on the World Wide Web (WWW).
HTTP defines how messages are formatted and transmitted, and what actions Web
servers and browsers should take in response to various commands. For example, when
you enter a URL in your browser, this actually sends an HTTP command to the Web
server directing it to fetch and transmit the requested Web page. The other main standard
that controls how the World Wide Web works is HTML, which covers how Web pages are
formatted and displayed.
Any Web server machine contains, in addition to the Web page files it can serve, an
HTTP daemon, a program that is designed to wait for HTTP requests and handle them
when they arrive. The Web browser is an HTTP client, sending requests to server
machines. An HTTP client initiates a request by establishing a Transmission Control
Protocol (TCP) connection to a particular port on a remote host (port 80 by default). An
HTTP server listening on that port waits for the client to send a request message.
HTTPS
HTTPS is an acronym for Hypertext Transfer Protocol over Secure Socket Layer. It is
used to indicate a secure HTTP connection.
HTTPS provide authentication and encrypted communication and is widely used on the
World Wide Web for security-sensitive communication such as payment transactions and
corporate logons.
HTTPS is really just the use of Netscape's Secure Socket Layer (SSL) as a sublayer
under its regular HTTP application layering. (HTTPS uses port 443 instead of HTTP port
80 in its interactions with the lower layer, TCP/IP.) SSL uses a 40-bit key size for the RC4
stream encryption algorithm, which is considered an adequate degree of encryption for
commercial exchange.
I
ICMP
ICMP is an acronym for Internet Control Message Protocol. It is a protocol that generated
the error response, diagnostic or routing purposes. ICMP messages generally contain
information about routing difficulties or simple exchanges such as time-stamp or echo
transactions. For example, the PING command uses ICMP to test an Internet connection.
XGS3600 Series User's Guide
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