30

Appendix A: Troubleshooting

Frequently Asked Questions

Wireless-G Ethernet Bridge

Can I run an application from a remote computer over the wireless network?

This will depend on whether or not the application is designed to be used over a network. Consult the

application’s user guide to determine if it supports operation over a network.

Can I play multiplayer games with other users of the wireless network?

Yes, as long as the game supports multiple players over a LAN. Refer to the game’s user guide for more

information.

What is ad-hoc mode?

When a wireless network is set to ad-hoc mode, the wireless-equipped computers are configured to

communicate directly with each other. The ad-hoc wireless network will not communicate with any wired

network.

What is infrastructure mode?

When a wireless network is set to infrastructure mode, the wireless network is configured to communicate with

a wired network through a wireless access point.

What is roaming?

Roaming is the ability of a portable computer user to communicate continuously while moving freely throughout

an area greater than that covered by a single wireless network access point. Before using the roaming function,

the workstation must make sure that it is the same channel number as the wireless network access point of the

dedicated coverage area.

To achieve true seamless connectivity, the wireless LAN must incorporate a number of different functions. Each

node and wireless network access point, for example, must always acknowledge receipt of each message. Each

node must maintain contact with the wireless network even when not actually transmitting data. Achieving these

functions simultaneously requires a dynamic RF networking technology that links wireless network access points

and nodes. In such a system, the user’s end node undertakes a search for the best possible access to the system.

First, it evaluates such factors as signal strength and quality, as well as the message load currently being carried

by each wireless network access point and the distance of each wireless network access point to the wired

backbone. Based on that information, the node next selects the right wireless network access point and registers

its address. Communications between end node and host computer can then be transmitted up and down the

backbone.

As the user moves on, the end node’s RF transmitter regularly checks the system to determine whether it is in

touch with the original wireless network access point or whether it should seek a new one. When a node no

longer receives acknowledgment from its original wireless network access point, it undertakes a new search.

Upon finding a new wireless network access point, it then re-registers, and the communication process

continues.

Downloaded from

www.Manualslib.com

manuals search engine

31

Appendix A: Troubleshooting

Frequently Asked Questions

Wireless-G Ethernet Bridge

What is ISM band?

The FCC and their counterparts outside of the U.S. have set aside bandwidth for unlicensed use in the ISM

(Industrial, Scientific and Medical) band. Spectrum in the vicinity of 2.4 GHz, in particular, is being made available

worldwide. This presents a truly revolutionary opportunity to place convenient high speed wireless capabilities in

the hands of users around the globe.

What is Spread Spectrum?

Spread Spectrum technology is a wideband radio frequency technique developed by the military for use in

reliable, secure, mission-critical communications systems. It is designed to trade off bandwidth efficiency for

reliability, integrity, and security. In other words, more bandwidth is consumed than in the case of narrowband

transmission, but the trade-off produces a signal that is, in effect, louder and thus easier to detect, provided that

the receiver knows the parameters of the spread-spectrum signal being broadcast. If a receiver is not tuned to

the right frequency, a spread-spectrum signal looks like background noise. There are two main alternatives,

Direct Sequence Spread Spectrum (DSSS) and Frequency Hopping Spread Spectrum (FHSS).

What is DSSS? What is FHSS? And what are their differences?

Frequency Hopping Spread Spectrum (FHSS) uses a narrowband carrier that changes frequency in a pattern that

is known to both transmitter and receiver. Properly synchronized, the net effect is to maintain a single logical

channel. To an unintended receiver, FHSS appears to be short-duration impulse noise. Direct Sequence Spread

Spectrum (DSSS) generates a redundant bit pattern for each bit to be transmitted. This bit pattern is called a chip

(or chipping code). The longer the chip, the greater the probability that the original data can be recovered. Even if

one or more bits in the chip are damaged during transmission, statistical techniques embedded in the radio can

recover the original data without the need for retransmission. To an unintended receiver, DSSS appears as low

power wideband noise and is rejected (ignored) by most narrowband receivers.

Would the information be intercepted while transmitting on air?

Linksys products feature two-fold protection in security. On the hardware side, as with Direct Sequence Spread

Spectrum technology, it has the inherent security feature of scrambling. On the software side, Linksys products

offer the encryption function (WEP) to enhance security and access control. Users can set it up depending upon

their needs.

What is WEP?

WEP is Wired Equivalent Privacy, a data privacy mechanism based on a 40/64 bit shared key algorithm, as

described in the IEEE 802.11 standard.

Downloaded from

www.Manualslib.com

manuals search engine

32

Appendix B: Wireless Security

Security Precautions

Wireless-G Ethernet Bridge

Appendix B: Wireless Security

Linksys wants to make wireless networking as safe and easy for you as possible. The current generation of

Linksys products provide several network security features, but they require specific action on your part for

implementation. So, keep the following in mind whenever you are setting up or using your wireless network.

Security Precautions

The following is a complete list of security precautions to take (at least steps 1 through 5 should be followed):

1.

Change the default SSID.

2.

Disable SSID Broadcast.

3.

Change the default password for the Administrator account.

4.

Enable MAC Address Filtering.

5.

Change the SSID periodically.

6.

Use the highest encryption algorithm possible. Use WPA if it is available. Please note that this may reduce

your network performance.

7.

Change the WEP encryption keys periodically.

For information on implementing these security features, refer to “Chapter 7: Using the Wireless-G Ethernet

Bridge Web-based Utility Setup.”

Security Threats Facing Wireless Networks

Wireless networks are easy to find. Hackers know that in order to join a wireless network, wireless networking

products first listen for “beacon messages”. These messages can be easily decrypted and contain much of the

network’s information, such as the network’s SSID (Service Set Identifier). Here are the steps you can take:

Change the administrator’s password regularly.

With every wireless networking device you use, keep in mind

that network settings (SSID, WEP keys, etc.) are stored in its firmware. Your network administrator is the only

person who can change network settings. If a hacker gets a hold of the administrator’s password, he, too, can

change those settings. So, make it harder for a hacker to get that information. Change the administrator’s

password regularly.

Note:

Some of these security features are

available only through the network router or

access point. Refer to the router or access

point’s documentation for more information.

Downloaded from

www.Manualslib.com

manuals search engine

33

Appendix B: Wireless Security

Security Threats Facing Wireless Networks

Wireless-G Ethernet Bridge

SSID.

There are several things to keep in mind about the SSID:

1.

Disable Broadcast

2.

Make it unique

3.

Change it often

Most wireless networking devices will give you the option of broadcasting the SSID. While this option may be

more convenient, it allows anyone to log into your wireless network. This includes hackers. So, don’t broadcast

the SSID.

Wireless networking products come with a default SSID set by the factory. (The Linksys default SSID is “linksys”.)

Hackers know these defaults and can check these against your network. Change your SSID to something unique

and not something related to your company or the networking products you use.

Change your SSID regularly so that any hackers who have gained access to your wireless network will have to

start from the beginning in trying to break in.

MAC Addresses.

Enable MAC Address filtering. MAC Address filtering will allow you to provide access to only

those wireless nodes with certain MAC Addresses. This makes it harder for a hacker to access your network with

a random MAC Address.

WEP Encryption.

Wired Equivalent Privacy (WEP) is often looked upon as a cure-all for wireless security

concerns. This is overstating WEP’s ability. Again, this can only provide enough security to make a hacker’s job

more difficult.

There are several ways that WEP can be maximized:

1.

Use the highest level of encryption possible

2.

Use “Shared Key” authentication

3.

Change your WEP key regularly

WPA.

Wi-Fi Protected Access (WPA) is the newest and best available standard in Wi-Fi security. Two modes are

available: Pre-Shared Key and RADIUS. Pre-Shared Key gives you one encryption method: TKIP (Temporal Key

Integrity Protocol), which utilizes a stronger encryption method and incorporates Message Integrity Code (MIC) to

provide protection against hackers.RADIUS (Remote Authentication Dial-In User Service) utilizes a RADIUS server

for authentication and the use of dynamic TKIP or WEP.

Important:

Always remember that each

device in your wireless network MUST use

the same encryption method and encryption

key or your wireless network will not function

properly.

Downloaded from

www.Manualslib.com

manuals search engine

34

Appendix B: Wireless Security

Security Threats Facing Wireless Networks

Wireless-G Ethernet Bridge

WPA Pre-Shared Key

. If you do not have a RADIUS server, Select the type of algorithm, TKIP, and enter a

password in the Pre-Shared key field of 8-64 characters, and enter a Group Key Renewal period time between

0 and 99,999 seconds, which instructs the Router or other device how often it should change the encryption

keys.

RADIUS

. WEP used in coordination with a RADIUS server. (This should only be used when a RADIUS server is

connected to the Router or other device.) First, enter the RADIUS server’s IP Address and port number, along

with a key shared between the device and the server. Then, select a WEP key and a level of WEP encryption,

and either generate a WEP key through the Passphrase or enter the WEP key manually.

Implementing encryption may have a negative impact on your network’s performance, but if you are transmitting

sensitive data over your network, encryption should be used.

These security recommendations should help keep your mind at ease while you are enjoying the most flexible

and convenient technology Linksys has to offer.

Downloaded from

www.Manualslib.com

manuals search engine