Owner's manual

104
Chapter 8 - Glossary
Filtering
To screen out selected types of data, based on filtering
rules. Filtering can be applied in one direction (ingress or
egress), or in both directions.
Filtering rule
A rule can specify what kinds of data the routing device will
accept and/or reject. Filtering rules are dened to operate
on an interface (or multiple interfaces) and in a particular
direction (upstream, downstream, or both).
FTP File Transfer Protocol
A program used to transfer files between computers
connected to the Internet. Common uses include uploading
new or updated les to a web server, and downloading les
from a web server.
host
A device (usually a computer) connected to a network.
HTTP
Hyper-Text Transfer Protocol
HTTP is the main protocol used to transfer data from web
sites so that it can be displayed by web browsers. See also
web browser, web site.
ICMP Internet Control Message Protocol
An Internet protocol used to report errors and other
network-related information. The ping command makes
use of ICMP.
IGMP Internet Group Management Protocol
An Internet protocol that enables a computer to share
information about its membership in multicast groups with
adjacent routers. A multicast group of computers is one
whose members have designated as interested in receiving
specic content from the others. Multicasting to an IGMP
group can be used to simultaneously update the address
books of a group of mobile computer users or to send
company newsletters to a distribution list.