Appendix B Wireless LANs
NWA-3500/NWA-3550 User’s Guide
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If the AP or the wireless clients do not support WPA2, just use WPA or WPA-PSK
depending on whether you have an external RADIUS server or not.
Select WEP only when the AP and/or wireless clients do not support WPA or WPA2.
WEP is less secure than WPA or WPA2.
Encryption
Both WPA and WPA2 improve data encryption by using Temporal Key Integrity
Protocol (TKIP), Message Integrity Check (MIC) and IEEE 802.1x. WPA and WPA2
use Advanced Encryption Standard (AES) in the Counter mode with Cipher block
chaining Message authentication code Protocol (CCMP) to offer stronger
encryption than TKIP.
TKIP uses 128-bit keys that are dynamically generated and distributed by the
authentication server. AES (Advanced Encryption Standard) is a block cipher that
uses a 256-bit mathematical algorithm called Rijndael. They both include a per-
packet key mixing function, a Message Integrity Check (MIC) named Michael, an
extended initialization vector (IV) with sequencing rules, and a re-keying
mechanism.
WPA and WPA2 regularly change and rotate the encryption keys so that the same
encryption key is never used twice.
The RADIUS server distributes a Pairwise Master Key (PMK) key to the AP that
then sets up a key hierarchy and management system, using the PMK to
dynamically generate unique data encryption keys to encrypt every data packet
that is wirelessly communicated between the AP and the wireless clients. This all
happens in the background automatically.
The Message Integrity Check (MIC) is designed to prevent an attacker from
capturing data packets, altering them and resending them. The MIC provides a
strong mathematical function in which the receiver and the transmitter each
compute and then compare the MIC. If they do not match, it is assumed that the
data has been tampered with and the packet is dropped.
By generating unique data encryption keys for every data packet and by creating
an integrity checking mechanism (MIC), with TKIP and AES it is more difficult to
decrypt data on a Wi-Fi network than WEP and difficult for an intruder to break
into the network.
The encryption mechanisms used for WPA(2) and WPA(2)-PSK are the same. The
only difference between the two is that WPA(2)-PSK uses a simple common
password, instead of user-specific credentials. The common-password approach
makes WPA(2)-PSK susceptible to brute-force password-guessing attacks but it’s
still an improvement over WEP as it employs a consistent, single, alphanumeric
password to derive a PMK which is used to generate unique temporal encryption
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Страница 8: ...Safety Warnings NWA 3500 NWA 3550 User s Guide 8...
Страница 10: ...Contents Overview NWA 3500 NWA 3550 User s Guide 10...
Страница 20: ...Table of Contents NWA 3500 NWA 3550 User s Guide 20...
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Страница 40: ...Chapter 2 The Web Configurator NWA 3500 NWA 3550 User s Guide 40...
Страница 80: ...Chapter 3 Tutorial NWA 3500 NWA 3550 User s Guide 80...
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Страница 92: ...Chapter 5 Management Mode NWA 3500 NWA 3550 User s Guide 92...
Страница 108: ...Chapter 6 AP Controller Mode NWA 3500 NWA 3550 User s Guide 108...
Страница 144: ...Chapter 8 Wireless Configuration NWA 3500 NWA 3550 User s Guide 144...
Страница 168: ...Chapter 10 Wireless Security Screen NWA 3500 NWA 3550 User s Guide 168...
Страница 182: ...Chapter 13 MAC Filter Screen NWA 3500 NWA 3550 User s Guide 182...
Страница 186: ...Chapter 14 IP Screen NWA 3500 NWA 3550 User s Guide 186...
Страница 194: ...Chapter 15 Rogue AP Detection NWA 3500 NWA 3550 User s Guide 194...
Страница 216: ...Chapter 17 Internal RADIUS Server NWA 3500 NWA 3550 User s Guide 216...
Страница 244: ...Chapter 19 Log Screens NWA 3500 NWA 3550 User s Guide 244...
Страница 270: ...Chapter 21 Load Balancing NWA 3160 Series User s Guide 270...
Страница 274: ...Chapter 22 Dynamic Channel Selection NWA 3160 Series User s Guide 274...
Страница 286: ...Chapter 23 Maintenance NWA 3500 NWA 3550 User s Guide 286...
Страница 287: ...287 PART III Troubleshooting and Specifications Troubleshooting 289 Product Specifications 297...
Страница 288: ...288...
Страница 296: ...Chapter 24 Troubleshooting NWA 3500 NWA 3550 User s Guide 296...
Страница 304: ...304...
Страница 398: ...Appendix F Text File Based Auto Configuration NWA 3500 NWA 3550 User s Guide 398...
Страница 408: ...Index NWA 3500 NWA 3550 User s Guide 408...