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Chapter 6 Wireless Security Configuration
6.6.1 User Authentication
WPA applies IEEE 802.1x and Extensible Authentication Protocol (EAP) to authenticate
wireless clients using an external RADIUS database. See later in this chapter and the
appendices for more information on IEEE 802.1x, RADIUS, EAP and PEAP.
If you don’t have an external RADIUS server you should use WPA-PSK (WPA -Pre-Shared
Key) that only requires a single (identical) password entered into each access point, wireless
gateway and wireless client. As long as the passwords match, a client will be granted access to
a WLAN.
6.6.2 Encryption
WPA improves data encryption by using Temporal Key Integrity Protocol (TKIP), Message
Integrity Check (MIC) and IEEE 802.1x.
Temporal Key Integrity Protocol (TKIP) uses 128-bit keys that are dynamically generated and
distributed by the authentication server. It includes 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.
TKIP regularly changes and rotates 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 pair-wise key 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), TKIP makes it much more difficult to decode data on a Wi-Fi
network than WEP, making it difficult for an intruder to break into the network.
The encryption mechanisms used for WPA and WPA-PSK are the same. The only difference
between the two is that WPA-PSK uses a simple common password, instead of user-specific
credentials. The common-password approach makes WPA-PSK susceptible to brute-force
password-guessing attacks but it’s still an improvement over WEP as it employs an easier-to-
use, consistent, single, alphanumeric password.
6.6.3 WPA(2)-PSK Application Example
A WPA(2)-PSK application looks as follows.
Summary of Contents for ZyAIR G-3000H
Page 1: ...G 3000H 802 11g Wireless Access Point User s Guide Version 3 50 1 2006 ...
Page 22: ...G 3000H User s Guide 22 List of Figures ...
Page 26: ...G 3000H User s Guide 26 List of Tables ...
Page 114: ...G 3000H User s Guide 114 Chapter 9 VLAN ...
Page 134: ...G 3000H User s Guide 134 Chapter 11 Certificates ...
Page 164: ...G 3000H User s Guide 164 Chapter 15 Introducing the SMT ...
Page 180: ...G 3000H User s Guide 180 Chapter 17 LAN Setup ...
Page 218: ...G 3000H User s Guide 218 Chapter 24 System Maintenance and Information ...
Page 224: ...G 3000H User s Guide 224 Appendix C Power over Ethernet PoE Specifications ...
Page 226: ...G 3000H User s Guide 226 Appendix D Brute Force Password Guessing Protection ...
Page 238: ...G 3000H User s Guide 238 Appendix E Setting up Your Computer s IP Address ...
Page 242: ...G 3000H User s Guide 242 Appendix F IP Address Assignment Conflicts ...
Page 254: ...G 3000H User s Guide 254 Appendix G Wireless LANs ...
Page 262: ...G 3000H User s Guide 262 Appendix H IP Subnetting ...
Page 264: ...G 3000H User s Guide 264 Appendix I Command Interpreter ...
Page 268: ...G 3000H User s Guide 268 Appendix J Log Descriptions ...
Page 272: ...G 3000H User s Guide 272 Appendix L Power Adaptor Specifications ...
Page 280: ...G 3000H User s Guide 280 Appendix M Text File Based Auto Configuration ...
Page 294: ...G 3000H User s Guide 294 Appendix N Wireless LAN Manager ...
Page 299: ...G 3000H User s Guide Index 299 ZyNOS F W Version 196 zyxel prowireless mib 287 ...