NETGEAR ME103v4 Router Manual PDF (Setup & Configuration Guide)

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Reference Manual for the ME103 802.11b ProSafe Wireless Access Point

B-6

Wireless Networking Basics

August 2003

Note:

Some 802.11 access points also support

Use WEP for Authentication Only

(Shared Key

Authentication without data encryption). However, the ME103 does not offer this option.

Key Size

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.

Note:

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.

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Reference Manual for the ME103 802.11b ProSafe Wireless Access Point

Wireless Networking Basics

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August 2003

WEP Configuration Options

The WEP settings must match on all 802.11 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 802.11 access points and all of the 802.11 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.

Wireless Channels

IEEE 802.11b wireless nodes communicate with each other using radio frequency signals in the

ISM (Industrial, Scientific, and Medical) band between 2.4 GHz and 2.5 GHz. Neighboring

channels are 5 MHz apart. However, due to spread spectrum effect of the signals, a node sending

signals using a particular channel will utilize frequency spectrum 12.5 MHz above and below the

center channel frequency. As a result, two separate wireless networks using neighboring channels

(for example, channel 1 and channel 2) in the same general vicinity will interfere with each other.

Applying two channels that allow the maximum channel separation will decrease the amount of

channel cross-talk, and provide a noticeable performance increase over networks with minimal

channel separation.

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Reference Manual for the ME103 802.11b ProSafe Wireless Access Point

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Wireless Networking Basics

August 2003

The radio frequency channels used are listed in

Table B-1

:

Note:

The available channels supported by the wireless products in various countries are different.

The preferred channel separation between the channels in neighboring wireless networks is 25

MHz (5 channels). This means that you can apply up to three different channels within your

wireless network. There are only 11 usable wireless channels in the United States. It is

recommended that you start using channel 1 and grow to use channel 6, and 11 when necessary, as

these three channels do not overlap.

Table B-1.

802.11b Radio Frequency Channels

Channel

Center Frequency

Frequency Spread

1

2412 MHz

2399.5 MHz - 2424.5 MHz

2

2417 MHz

2404.5 MHz - 2429.5 MHz

3

2422 MHz

2409.5 MHz - 2434.5 MHz

4

2427 MHz

2414.5 MHz - 2439.5 MHz

5

2432 MHz

2419.5 MHz - 2444.5 MHz

6

2437 MHz

2424.5 MHz - 2449.5 MHz

7

2442 MHz

2429.5 MHz - 2454.5 MHz

8

2447 MHz

2434.5 MHz - 2459.5 MHz

9

2452 MHz

2439.5 MHz - 2464.5 MHz

10

2457 MHz

2444.5 MHz - 2469.5 MHz

11

2462 MHz

2449.5 MHz - 2474.5 MHz

12

2467 MHz

2454.5 MHz - 2479.5 MHz

13

2472 MHz

2459.5 MHz - 2484.5 MHz

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Reference Manual for the ME103 802.11b ProSafe Wireless Access Point

Wireless Networking Basics

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August 2003

Understanding 802.1x Port Based Network Access Control

802.1x is well on its way to becoming an industry standard, and provides an effective wireless

LAN security solution. Windows XP implements 802.1x natively, and the ME103 802.11b

ProSafe Wireless Access Point supports 802.1x. The 802.11i committee is specifying the use of

802.1x to eventually become part of the 802.11 standard.

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

must use the same encryption key. Each sending station encrypts data with a WEP key before

transmission, and the receiving station decrypts it using an identical key. This process reduces the

risk of someone passively monitoring the transmission and gaining access to the data transmitted

over the wireless connections.

However, 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. In order to use different keys, you

must manually configure each access point and wireless adapter with new keys.

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

update the keys. This might not be too much of concern with a few users, but the job of renewing

keys on larger networks can be a monumental task. As a result, companies either don't use WEP at

all or maintain the same keys for weeks, months, and even years. Both cases significantly heighten

the wireless LAN's vulnerability to eavesdroppers.

IEEE 802.1x offers an effective framework for authenticating and controlling user traffic to a

protected network, as well as dynamically varying encryption keys. 802.1x ties a protocol called

EAP (Extensible Authentication Protocol) to both the wired and wireless LAN media and supports

multiple authentication methods, such as token cards, Kerberos, one-time passwords, certificates,

and public key authentication. For details on EAP specifically, refer to IETF's RFC 2284.

Page 80 / 118

Reference Manual for the ME103 802.11b ProSafe Wireless Access Point

B-10

Wireless Networking Basics

August 2003

1.

The client sends an EAP-start message. This begins a series of message exchanges to

authenticate the client.

2.

The access point replies with an EAP-request identity message.

3.

The client sends an EAP-response packet containing the identity to the authentication server.

4.

The authentication server uses a specific authentication algorithm to verify the client's identity.

This could be through the use of digital certificates or other EAP authentication type.

5.

The authentication server will either send an accept or reject message to the access point.

6.

The access point sends an EAP-success packet (or reject packet) to the client.

7.

If the authentication server accepts the client, then the access point will transition the client's

port to an authorized state and forward additional traffic.

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