Interlogix NS3550-8T-2S User Manual - Manual (Page 487)

User’s Manual of NS3550-8T-2S
487
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.
IEEE 802.1X
IEEE 802.1X is an IEEE standard for port-based Network Access Control. It provides authentication to devices
attached to a LAN port, establishing a point-to-point connection or preventing access from that port if authentication
fails. With 802.1X, access to all switch ports can be centrally controlled from a server, which means that authorized
users can use the same credentials for authentication from any point within the network.
IGMP
IGMP is an acronym for Internet Group Management Protocol. It is a communications protocol used to manage the
membership of Internet Protocol multicast groups. IGMP is used by IP hosts and adjacent multicast routers to establish
multicast group memberships. It is an integral part of the IP multicast specification, like ICMP for unicast connections.
IGMP can be used for online video and gaming, and allows more efficient use of resources when supporting these
uses.
IGMP Querier
A router sends IGMP Query messages onto a particular link. This router is called the Querier.
IMAP
IMAP is an acronym for Internet Message Access Protocol. It is a protocol for email clients to retrieve email messages
from a mail server.
IMAP is the protocol that IMAP clients use to communicate with the servers, and SMTP is the protocol used to
transport mail to an IMAP server.
The current version of the Internet Message Access Protocol is IMAP4. It is similar to Post Office Protocol version 3
(POP3), but offers additional and more complex features. For example, the IMAP4 protocol leaves your email
messages on the server rather than downloading them to your computer. If you wish to remove your messages from
the server, you must use your mail client to generate local folders, copy messages to your local hard drive, and then
delete and expunge the messages from the server.