NETGEAR MR814v3 Router Manual PDF (Setup & Configuration Guide)

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Reference Manual for the MR814 v3 Cable/DSL Wireless Router

Wireless Networking Basics

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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.

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.

This process is illustrated in below.

Figure 8-1:

802.11b open system authentication

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.

FVM318

Access Point

1) Authentication request sent to AP

2) AP authenticates

3) Client connects to network

802.11b Authentication

Open System Steps

Cable or

DLS modem

Client

attempting

to connect

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Reference Manual for the MR814 v3 Cable/DSL Wireless Router

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Wireless Networking Basics

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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 802.11b network or Ethernet network.

This process is illustrated in below.

Figure 8-2:

802.11b shared key authentication

Overview of WEP Parameters

Before enabling WEP on an 802.11b 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 802.11b products:

1.

Do Not Use WEP:

The 802.11b network does not encrypt data. For authentication purposes, the

network uses Open System Authentication.

2.

Use WEP for Encryption:

A transmitting 802.11b 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.

FVM318

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

802.11b Authentication

Shared Key Steps

Cable or

DLS modem

Client

attempting

to connect

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Reference Manual for the MR814 v3 Cable/DSL Wireless Router

Wireless Networking Basics

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3.

Use WEP for Authentication and Encryption:

A transmitting 802.11b 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

Shared Key Authentication.

Note:

Some 802.11b access points also support

Use WEP for Authentication Only

(Shared Key

Authentication without data encryption).

Key Size

The IEEE 802.11b 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, 802.11b 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.

Note:

Typically, 802.11b access points can store up to four 128-bit WEP Keys but some 802.11b

client adapters can only store one. Therefore, make sure that your 802.11b access and client

adapters configurations match.

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WEP Configuration Options

The WEP settings must match on all 802.11b devices that are within the same wireless network as

identified by the SSID. In general, if your mobile clients will roam between access points, then all

of the 802.11b access points and all of the 802.11b client adapters on the network must have the

same WEP settings.

Note:

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.

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:

•

Enhanced data privacy

•

Robust key management

•

Data origin authentication

•

Data integrity protection

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The Wi-Fi Alliance is now performing interoperability certification testing on Wi-Fi Protected

Access products. Starting August of 2003, all new Wi-Fi certified products will have to support

WPA. NETGEAR will implement WPA on client and access point products and make this

available in the second half of 2003. Existing Wi-Fi certified products will have one year to add

WPA support or they will loose their Wi-Fi certification.

The 802.11i standard is currently in draft form, with ratification due at the end of 2003. While the

new IEEE 802.11i standard is being ratified, wireless vendors have agreed on WPA as an

interoperable interim standard.

How Does WPA Compare to WEP?

WEP is a data encryption method and is not intended as a user authentication mechanism. WPA

user authentication is implemented using 802.1x and the Extensible Authentication Protocol

(EAP). Support for 802.1x authentication is required in WPA. In the 802.11 standard, 802.1x

authentication was optional. For details on EAP specifically, refer to IETF's RFC 2284.

With 802.11 WEP, all access points and client wireless adapters on a particular wireless LAN must

use the same encryption key. A major problem with the 802.11 standard is that the keys are

cumbersome to change. If you don't update the WEP keys often, an unauthorized person with a

sniffing tool can monitor your network for less than a day and decode the encrypted messages.

Products based on the 802.11 standard alone offer system administrators no effective method to

update the keys.

For 802.11, WEP encryption is optional. For WPA, encryption using Temporal Key Integrity

Protocol (TKIP) is required. TKIP replaces WEP with a new encryption algorithm that is stronger

than the WEP algorithm, but that uses the calculation facilities present on existing wireless devices

to perform encryption operations. TKIP provides important data encryption enhancements

including 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. Through

these enhancements, TKIP addresses all of known WEP vulnerabilities.

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