Internet Security Router User
’s Manual
Appendix 16. Glossary
145
from 0 to 255, separated by periods, e.g., 209.191.4.240. An IP address consists of a
network ID that identifies the particular network the host belongs to, and a host ID
uniquely identifying the host itself on that network. A network mask is used to define
the network ID and the host ID. Because IP addresses are difficult to remember, they
usually have an associated domain name that can be specified instead. See also
domain name, network mask.
ISP
Internet Service Provider
A company that provides Internet access to its customers, usually for a fee.
LAN
Local Area Network
A network limited to a small geographic area, such as a home, office, or small building.
LED
Light Emitting Diode
An electronic light-emitting device. The indicator lights on the front of the Internet
Security Router are LEDs.
MAC address
Media Access Control address
The permanent hardware address of a device, assigned by its manufacturer. MAC
addresses are expressed as six pairs of characters.
mask
See network mask.
Mbps
Abbreviation for Megabits per second, or one million bits per second. Network data
rates are often expressed in Mbps.
NAT
Network Address Translation
A service performed by many routers that translates your network
’s publicly known IP
address into a private IP address for each computer on your LAN. Only your router
and your LAN know these addresses; the outside world sees only the public IP
address when talking to a computer on your LAN.
NAT rule
A defined method for translating between public and private IP addresses on your LAN.
network
A group of computers that are connected together, allowing them to communicate with
each other and share resources, such as software, files, etc. A network can be small,
such as a LAN, or very large, such as the Internet.
network mask
A network mask is a sequence of bits applied to an IP address to select the network ID
while ignoring the host ID. Bits set to 1 mean "select this bit" while bits set to 0 mean
"ignore this bit." For example, if the network mask 255.255.255.0 is applied to the IP
address 100.10.50.1, the network ID is 100.10.50, and the host ID is 1. See also
binary, IP address, subnet, "IP Addresses Explained" section.
NIC
Network Interface Card
An adapter card that plugs into your computer and provides the physical interface to
your network cabling, which for Ethernet NICs is typically an RJ-45 connector. See
Ethernet, RJ-45.
packet
Data transmitted on a network consists of units called packets. Each packet contains a
payload (the data), plus overhead information such as where it came from (source
address) and where it should go (destination address).
ping
Packet Internet (or Inter-Network) Groper
A program used to verify whether the host associated with an IP address is online. It
can also be used to reveal the IP address for a given domain name.
port
A physical access point to a device such as a computer or router, through which data
flows into and out of the device.
PPP
Point-to-Point Protocol
A protocol for serial data transmission that is used to carry IP (and other protocol) data