Extreme Networks Altitude 3500 Series, Руководство по продукции

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Introduction
Altitude 3500 Series Access Point Product Reference Guide
20
EAP Authentication
The Extensible Authentication Protocol (EAP) feature provides access points and their associated MU’s an
additional measure of security for data transmitted over the wireless network. Using EAP,
authentication between devices is achieved through the exchange and verification of certificates.
EAP is a mutual authentication method whereby both the MU and AP are required to prove their
identities. Like Kerberos, the user loses device authentication if the server cannot provide proof of
device identification.
Using EAP, a user requests connection to a WLAN through the access point. The access point then
requests the identity of the user and transmits that identity to an authentication server. The server
prompts the AP for proof of identity (supplied to the Altitude 35xx by the user) and then transmits the
user data back to the server to complete the authentication process.
An MU is not able to access the network if not authenticated. When configured for EAP support, the
access point displays the MU as an EAP station.
EAP is only supported on mobile devices running Windows XP, Windows 2000 (using Service Pack #4)
and Windows Mobile 2003. Refer to the system administrator for information on configuring a RADIUS
Server for EAP (802.1x) support.
For detailed information on EAP configurations, see “Configuring 802.1x EAP Authentication” on
page 176 .
WEP Encryption
All WLAN devices face possible information theft. Theft occurs when an unauthorized user eavesdrops
to obtain information illegally. The absence of a physical connection makes wireless links particularly
vulnerable to this form of theft. Most forms of WLAN security rely on encryption to various extents.
Encryption entails scrambling and coding information, typically with mathematical formulas called
algorithms , before the information is transmitted. An algorithm is a set of instructions or formula for
scrambling the data. A key is the specific code used by the algorithm to encrypt or decrypt the data.
Decryption is the decoding and unscrambling of received encrypted data.
The same device, host computer or front-end processor, usually performs both encryption and
decryption. The transmit or receive direction determines whether the encryption or decryption function
is performed. The device takes plain text, encrypts or scrambles the text typically by mathematically
combining the key with the plain text as instructed by the algorithm, then transmits the data over the
network. At the receiving end, another device takes the encrypted text and decrypts, or unscrambles,
the text revealing the original message. An unauthorized user can know the algorithm, but cannot
interpret the encrypted data without the appropriate key. Only the sender and receiver of the
transmitted data know the key.
Wired Equivalent Privacy (WEP) is an encryption security protocol specified in the IEEE Wireless Fidelity
(Wi-Fi) standard, 802.11b and supported by the Altitude 35xx AP. WEP encryption is designed to
provide a WLAN with a level of security and privacy comparable to that of a wired LAN. The level of
protection provided by WEP encryption is determined by the encryption key length and algorithm. An
encryption key is a string of case sensitive characters used to encrypt and decrypt data packets
transmitted between a mobile unit (MU) and the access point. An access point and its associated
wireless clients must use the same encryption key (typically 1 through 4) to interoperate.
For detailed information on WEP, see “Configuring WEP Encryption” on page 179 .