Like passwords, keys open (decrypt) and close (encrypt) messages. While many encryption
algorithms are commonly known and public, the key must be kept secret.
Local-Area Network (LAN)
A small data network covering a limited area, such as a building or group of buildings. Most
LANs connect workstations or personal computers. LANs let many users share devices such as
printers as well as data. LANs also facilitate communication through e-mail or chat sessions.
Media Access Control (MAC) Address
Address associated with every hardware device on the network. Every 802.11 wireless device
has its own specific MAC address. This unique identifier is hard-coded into the device and can
be used to provide security for WLANs. When a network uses a MAC table, only the 802.11
radios that have their MAC addresses added to that network's MAC table can access the
network.
Network Address Translation (NAT)
An Internet standard that lets a LAN use one set of IP addresses for internal traffic and a
second set of addresses for external traffic.
Network Time Protocol (NTP)
A protocol that lets devices synchronize their time with a time server. NTP uses TCP or UDP
port 123 by default.
Passphrase
A text string that automatically generates WEP keys on wireless client adapters.
Power Over Ethernet (PoE)
A PoE provides power to PoE-enabled devices using an 8-pin CAT 5 Ethernet cable,
eliminating the need for a power source.
Preamble
Synchronizes transmissions in a WLAN. The preamble type defines the length of the Cyclic
Redundancy Check block for communication between a device and roaming wireless stations.
Protected Extensible Authentication Protocol (PEAP)
Authentication protocol of IEEE 802.1x used to send authentication data and passwords over
802.11 WLANs.
Quality of Service (QoS)
A network’s ability to deliver data with minimum delay. QoS also refers to the networking
methods used to provide bandwidth for real-time multimedia applications.
Remote Authentication Dial-In User Service (RADIUS)
Networking protocol that provides centralized authentication, authorization, and accounting
management for computers to connect and use a network service. Because of its broad
support and ubiquitous nature, the RADIUS protocol is often used by ISPs and enterprises to
manage access to the Internet or internal networks, WLANs, and integrated e-mail services.
Service Set Identifier (SSID)
