Wireless Security.pdf - PDF Archive

506 Chapter 21
Damage & Defense
Known WPA-PSK Vulnerability
WPA-PSK utilizes a 256-bit pre-shared key or a passphrase that can vary in length
from 8 to 63 bytes. Short passphrase-based keys (less than 20 bytes) are vulnerable
to the offline dictionary attack. The pre-shared key that is used to set up the WPA
encryption can be captured during the initial communication between the access
point and the client card. Once an attacker has captured the pre-shared key, he can
use that to essentially “ guess ” the WPA key using the same concepts used in any
password dictionary attack. In theory, this type of dictionary attack takes less time
and effort than attacking WER Choosing a passphrase that is more than 20 bytes
mitigates this vulnerability.
Enter either your RADIUS server information and Shared Secret for WPA or a strong
passphrase that is more than 20 bytes long, and then click Apply to save your settings and
enable WPA.
21.2.2 Configuring the Linksys WRV54G VPN Broadband Router
The Linksys WRV54G VPN-Broadband Router may require a firmware upgrade to allow
WPA capability. Firmware version 2.10 or later is required for WPA functionality on the
WR.V54G. To enable WPA, you need to log in to the WRV54G, as shown in Figure 21.5 .
Point your browser to the IP address of the WRV54G. By default, this is 192.168.1.1.
There is no username required and the default password is admin .
Next, click the Wireless tab to display the Wireless Network Settings, as seen in Figure 21.6 .
Then, choose the Wireless Security option to display the Wireless Security settings, as
seen in Figure 21.7 .
The Security Mode drop-down box displays the four modes of security available on the
WRV54G:
●
●
●
●
WPA Pre-Shared Key
WPA Radius
RADIUS
WEP
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