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
Summary of Contents for 802.11a/g Wireless CardBus Card ZyXEL AG-120
Page 2: ......
Page 8: ...Safety Warnings NWA 3500 NWA 3550 User s Guide 8...
Page 10: ...Contents Overview NWA 3500 NWA 3550 User s Guide 10...
Page 20: ...Table of Contents NWA 3500 NWA 3550 User s Guide 20...
Page 22: ...22...
Page 34: ...Chapter 1 Introducing the NWA NWA 3500 NWA 3550 User s Guide 34...
Page 52: ...Chapter 4 Management Mode NWA 3500 NWA 3550 User s Guide 52...
Page 108: ...108...
Page 146: ...Chapter 9 SSID Screen NWA 3500 NWA 3550 User s Guide 146...
Page 160: ...Chapter 10 Wireless Security Screen NWA 3500 NWA 3550 User s Guide 160...
Page 178: ...Chapter 14 IP Screen NWA 3500 NWA 3550 User s Guide 178...
Page 186: ...Chapter 15 Rogue AP Detection NWA 3500 NWA 3550 User s Guide 186...
Page 198: ...Chapter 16 Remote Management Screens NWA 3500 NWA 3550 User s Guide 198...
Page 260: ...Chapter 21 Load Balancing NWA 3160 Series User s Guide 260...
Page 264: ...Chapter 22 Dynamic Channel Selection NWA 3160 Series User s Guide 264...
Page 276: ...Chapter 23 Maintenance NWA 3500 NWA 3550 User s Guide 276...
Page 277: ...277 PART III Troubleshooting and Specifications Troubleshooting 279 Product Specifications 285...
Page 278: ...278...
Page 284: ...Chapter 24 Troubleshooting NWA 3500 NWA 3550 User s Guide 284...
Page 292: ...292...
Page 368: ...Appendix D Importing Certificates NWA 3500 NWA 3550 User s Guide 368...
Page 386: ...Appendix F Text File Based Auto Configuration NWA 3500 NWA 3550 User s Guide 386...