Additional Wep Key Security Features - Cisco CB21AG Installation And Configuration Manual
Aironet 802.11a/b/g wireless lan client adapters
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Also See for CB21AG:
- Installation and configuration manual (286 pages) ,
- Install wizard (34 pages) ,
- User manual (22 pages)
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Setting Security Parameters
5.
6.
Note
This feature does not need to be enabled on the client adapter or access point; it is supported
automatically by both devices. However, the access points must use the specified firmware versions
or later.
Additional WEP Key Security Features
The three security features discussed in this section (MIC, TKIP, and broadcast key rotation) are
designed to prevent sophisticated attacks on your wireless network's WEP keys. These features do not
need to be enabled on the client adapter; they are supported automatically in the client adapter software.
However, they must be enabled on the access point.
Refer to the documentation for your access point for instructions on enabling these security features.
Note
Message Integrity Check (MIC)
MIC prevents bit-flip attacks on encrypted packets. During a bit-flip attack, an intruder intercepts an
encrypted message, alters it slightly, and retransmits it, and the receiver accepts the retransmitted
message as legitimate. The MIC adds a few bytes to each packet to make the packets tamper-proof.
The Advanced Status window indicates if MIC is being used, and the Advanced Statistics window
provides MIC statistics.
Temporal Key Integrity Protocol (TKIP)
This feature, also referred to as WEP key hashing, defends against an attack on WEP in which the
intruder uses the initialization vector (IV) in encrypted packets to calculate the WEP key. TKIP removes
the predictability that an intruder relies on to determine the WEP key by exploiting IVs. It protects both
unicast and broadcast WEP keys.
TKIP is enabled automatically when WPA is enabled, and it is disabled when WPA is disabled.
Note
Broadcast Key Rotation
When you enable broadcast WEP key rotation, the access point provides a dynamic broadcast WEP key
and changes it at the interval you select.
Cisco Aironet 802.11a/b/g Wireless LAN Client Adapters (CB21AG and PI21AG) Installation and Configuration Guide
5-18
The client sends the MAC address of access point A and the reason code for the failure to access
point B.
Access point B logs the failure in the system log.
Chapter 5
Configuring the Client Adapter
OL-4211-02
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Troubleshooting
