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Reference Manual for the WG602 v2 54 Mbps Wireless Access Point
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Wireless Networking Basics
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WEP Wireless Security
The absence of a physical connection between nodes makes the wireless links vulnerable to
eavesdropping and information theft. To provide a certain level of security, the IEEE 802.11
standard has defined two types of authentication methods, Open System and Shared Key. With
Open System authentication, a wireless PC can join any network and receive any messages that are
not encrypted. With Shared Key authentication, only those PCs that possess the correct
authentication key can join the network. By default, IEEE 802.11 wireless devices operate in an
Open System network. Recently, Wi-Fi, the Wireless Ethernet Compatibility Alliance
(
) developed the Wi-Fi Protected Access (WPA), a new strongly enhanced
Wi-Fi security. WPA will soon be incorporated into the IEEE 802.11 standard. WEP and WPA are
discussed below.
WEP Authentication
The 802.11 standard defines several services that govern how two 802.11 devices communicate.
The following events must occur before an 802.11 Station can communicate with an Ethernet
network through an access point such as the one built in to the WG602 v2:
1.
Turn on the wireless station.
2.
The station listens for messages from any access points that are in range.
3.
The station finds a message from an access point that has a matching SSID.
4.
The station sends an authentication request to the access point.
5.
The access point authenticates the station.
6.
The station sends an association request to the access point.
7.
The access point associates with the station.
8.
The station can now communicate with the Ethernet network through the access point.
An access point must authenticate a station before the station can associate with the access point or
communicate with the network. The IEEE 802.11 standard defines two types of WEP
authentication: Open System and Shared Key.
Open System Authentication
allows any device to join the network, assuming that the device
SSID matches the access point SSID. Alternatively, the device can use the “ANY” SSID
option to associate with any available access point within range, regardless of its SSID.
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Shared Key Authentication
requires that the station and the access point have the same WEP
Key to authenticate. These two authentication procedures are described below.
WEP Open System Authentication
This process is illustrated in below.
Figure B-1:
802.11 open system authentication
The following steps occur when two devices use Open System Authentication:
1.
The station sends an authentication request to the access point.
2.
The access point authenticates the station.
3.
The station associates with the access point and joins the network.
FVM318
Router with Integrated
Access Point
1) Authentication request sent to AP
2) AP authenticates
3) Client connects to network
802.11 Authentication
Open System Steps
Cable or
DLS modem
Client
attempting
to connect
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Reference Manual for the WG602 v2 54 Mbps Wireless Access Point
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Wireless Networking Basics
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WEP Shared Key Authentication
This process is illustrated in below.
Figure B-2:
802.11 shared key authentication
The following steps occur when two devices use Shared Key Authentication:
1.
The station sends an authentication request to the access point.
2.
The access point sends challenge text to the station.
3.
The station uses its configured 64-bit or 128-bit default key to encrypt the challenge text, and
sends the encrypted text to the access point.
4.
The access point decrypts the encrypted text using its configured WEP Key that corresponds
to the station’s default key. The access point compares the decrypted text with the original
challenge text. If the decrypted text matches the original challenge text, then the access point
and the station share the same WEP Key and the access point authenticates the station.
5.
The station connects to the network.
If the decrypted text does not match the original challenge text (i.e., the access point and station do
not share the same WEP Key), then the access point will refuse to authenticate the station and the
station will be unable to communicate with either the 802.11 network or Ethernet network.
FVM318
Router with Integrated
Access Point
1) Authentication
request sent to AP
2) AP sends challenge text
3) Client encrypts
challenge text and
sends it back to AP
4) AP decrypts,and if correct,
authenticates client
5) Client connects to network
802.11 Authentication
Shared Key Steps
Cable or
DLS modem
Client
attempting
to connect
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Key Size and Configuration
The IEEE 802.11 standard supports two types of WEP encryption: 40-bit and 128-bit.
The 64-bit WEP data encryption method, allows for a five-character (40-bit) input. Additionally,
24 factory-set bits are added to the forty-bit input to generate a 64-bit encryption key. (The 24
factory-set bits are not user-configurable). This encryption key will be used to encrypt/decrypt all
data transmitted via the wireless interface. Some vendors refer to the 64-bit WEP data encryption
as 40-bit WEP data encryption since the user-configurable portion of the encryption key is 40 bits
wide.
The 128-bit WEP data encryption method consists of 104 user-configurable bits. Similar to the
forty-bit WEP data encryption method, the remaining 24 bits are factory set and not user
configurable. Some vendors allow passphrases to be entered instead of the cryptic hexadecimal
characters to ease encryption key entry.
128-bit encryption is stronger than 40-bit encryption, but 128-bit encryption may not be available
outside of the United States due to U.S. export regulations.
When configured for 40-bit encryption, 802.11 products typically support up to four WEP Keys.
Each 40-bit WEP Key is expressed as 5 sets of two hexadecimal digits (0-9 and A-F). For
example, “12 34 56 78 90” is a 40-bit WEP Key.
When configured for 128-bit encryption, 802.11b products typically support four WEP Keys but
some manufacturers support only one 128-bit key. The 128-bit WEP Key is expressed as 13 sets of
two hexadecimal digits (0-9 and A-F). For example, “12 34 56 78 90 AB CD EF 12 34 56 78 90”
is a 128-bit WEP Key.
Typically, 802.11 access points can store up to four 128-bit WEP Keys but some 802.11 client
adapters can only store one. Therefore, make sure that your 802.11 access and client adapters
configurations match.
Whatever keys you enter for an AP, you must also enter the same keys for the client adapter in the
same order. In other words, WEP key 1 on the AP must match WEP key 1 on the client adapter,
WEP key 2 on the AP must match WEP key 2 on the client adapter, etc.
Note:
The AP and the client adapters can have different default WEP Keys as long as the keys are
in the same order. In other words, the AP can use WEP key 2 as its default key to transmit while a
client adapter can use WEP key 3 as its default key to transmit. The two devices will communicate
as long as the AP’s WEP key 2 is the same as the client’s WEP key 2 and the AP’s WEP key 3 is
the same as the client’s WEP key 3.
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How to Use WEP Parameters
Wired Equivalent Privacy (WEP) data encryption is used when the wireless devices are configured
to operate in Shared Key authentication mode. There are two shared key methods implemented in
most commercially available products, 64-bit and 128-bit WEP data encryption.
Before enabling WEP on an 802.11 network, you must first consider what type of encryption you
require and the key size you want to use. Typically, there are three WEP Encryption options
available for 802.11 products:
1.
Do Not Use WEP:
The 802.11 network does not encrypt data. For authentication purposes, the
network uses Open System Authentication.
2.
Use WEP for Encryption:
A transmitting 802.11 device encrypts the data portion of every
packet it sends using a configured WEP Key. The receiving 802.11b device decrypts the data using
the same WEP Key. For authentication purposes, the 802.11b network uses Open System
Authentication.
3.
Use WEP for Authentication and Encryption:
A transmitting 802.11 device encrypts the data
portion of every packet it sends using a configured WEP Key. The receiving 802.11 device
decrypts the data using the same WEP Key. For authentication purposes, the 802.11 network uses
Shared Key Authentication.
Note:
Some 802.11 access points also support
Use WEP for Authentication Only
(Shared Key
Authentication without data encryption). However, the WG602 v2 does not offer this option.
WPA Wireless Security
Wi-Fi Protected Access (WPA) is a specification of standards-based, interoperable security
enhancements that increase the level of data protection and access control for existing and future
wireless LAN systems.
The IEEE introduced the WEP as an optional security measure to secure 802.11b (Wi-Fi) WLANs,
but inherent weaknesses in the standard soon became obvious. In response to this situation, the
Wi-Fi Alliance announced a new security architecture in October 2002 that remedies the short
comings of WEP. This standard, formerly known as Safe Secure Network (SSN), is designed to
work with existing 802.11 products and offers forward compatibility with 802.11i, the new
wireless security architecture being defined in the IEEE.
WPA offers the following benefits:

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