Reference Manual for the WG602 v2 54 Mbps Wireless Access Point

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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.

Reference Manual for the WG602 v2 54 Mbps Wireless Access Point

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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

Reference Manual for the WG602 v2 54 Mbps Wireless Access Point

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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: