Intellinet 525497 Bedienungsanleitung PDF herunterladen (Seite 80)

5.13 What is Preamble Type?

There are two preamble types defined in IEEE 802.11 specifications. A long preamble basically gives

the decoder more time to process the preamble. All 802.11 devices support a long preamble. The short

preamble is designed to improve efficiency (for example, for VoIP systems). The difference between

the two is in the synchronization field. The long preamble is 128 bits, and the short is 56 bits.

5.14 What is SSID Broadcast?

Broadcast of SSID is done in access points by the beacon. This announces your access point (including

various bits of information about it) to the wireless world around it. By disabling that feature, the SSID

configured in the client device must match the SSID of the access point. Some wireless devices don't

work properly if SSID isn't broadcast (for example the D-link DWL-120 USB 802.11b adapter).

Generally, if your client hardware supports operation with SSID disabled, it's not a bad idea to run that

way to enhance network security. However it's no replacement for WEP, MAC filtering or other

protections.

5.15 What is Wi-Fi Protected Access (WPA)?

Wi-Fi’s original security mechanism, Wired Equivalent Privacy (WEP), was long ago recognized as

insufficient for securing confidential business communications. Before the long-term solution — the

IEEE 802.11i standard — was developed, a significant short-term enhancement to Wi-Fi security was

introduced: Wi-Fi Protected Access. To upgrade older WLAN networks to support WPA, access points

require a WPA software upgrade, and clients may require a software upgrade for the network interface

card and possibly a software update for the operating system. For enterprise networks, an

authentication server, typically one that supports RADIUS and the selected EAP authentication

protocol, would need to be added to the network.

5.16 What is WPA2?

It is the second generation of WPA. WPA2 is based on the final IEEE 802.11i amendment to the

802.11 standard.

5.17 What is 802.1x Authentication?

802.1x is a framework for authenticated MAC-level access control, and defines the Extensible

Authentication Protocol (EAP) over LANs (WAPOL). The standard encapsulates and leverages much

of EAP, which was defined for dial-up authentication with Point-to-Point Protocol in RFC 2284.

Beyond encapsulating EAP packets, the 802.1x standard also defines EAPOL messages that convey the

shared key information critical for wireless security.

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