45

Appendix A: Troubleshooting

Frequently Asked Questions

Wireless-G Access Point with Power Over Ethernet and Rangebooster

What is the 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?

WLAN features 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, the WLAN series offers a

variety of wireless security methods to enhance security and access control. Users can set it up depending upon

their needs.

Can Linksys wireless products support file and printer sharing?

Linksys wireless products perform the same function as LAN products. Therefore, Linksys wireless products can

work with NetWare, Windows NT/2000, or other LAN operating systems to support printer or file sharing.

What is WEP?

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

in the IEEE 802.11 standard.

46

Appendix A: Troubleshooting

Frequently Asked Questions

Wireless-G Access Point with Power Over Ethernet and Rangebooster

What is a MAC Address?

The Media Access Control (MAC) address is a unique number assigned by the manufacturer to any Ethernet

networking device, such as a network adapter, that allows the network to identify it at the hardware level. For all

practical purposes, this number is usually permanent. Unlike IP addresses, which can change every time a

computer logs on to the network, the MAC address of a device stays the same, making it a valuable identifier for

the network.

How do I avoid interference?

Using multiple Access Points on the same channel and in close proximity to one another will generate

interference. When employing multiple Access Points, make sure to operate each one on a different channel

(frequency).

How do I reset the Access Point?

Press the Reset button on the back of the Access Point for about ten seconds. This will reset the unit to its default

settings.

How do I resolve issues with signal loss?

There is no way to know the exact range of your wireless network without testing. Every obstacle placed between

an Access Point and wireless PC will create signal loss. Leaded glass, metal, concrete floors, water, and walls

will inhibit the signal and reduce range. Start with your Access Point and your wireless PC in the same room and

move it away in small increments to determine the maximum range in your environment.

You may also try using different channels, as this may eliminate interference affecting only one channel. Also,

open the Access Point’s web-based utility. Click the

Wireless

tab and then the

Advanced Wireless

tab. Make

sure the Output Power is set to 100%.

Does the Access Point function as a firewall?

No. The Access Point is only a bridge from wired Ethernet to wireless clients.

I have excellent signal strength, but I cannot see my network.

Wireless security, such as WEP or WPA, is probably enabled on the Access Point, but not on your wireless adapter

(or vice versa). Verify that the same wireless security settings are being used on all devices in your wireless

network.

What is the maximum number of users the Access Point can handle?

No more than 45, but this depends on the volume of data and may be fewer if many users create a large amount

of network traffic.

47

Appendix B: Wireless Security

Security Precautions

Wireless-G Access Point with Power Over Ethernet and Rangebooster

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 (as shown in this User Guide) (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.

To ensure network security, steps one through five should be followed, at least.

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.

48

Appendix B: Wireless Security

Security Threats Facing Wireless Networks

Wireless-G Access Point with Power Over Ethernet and Rangebooster

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.

Change your WEP key regularly

WPA.

Wi-Fi Protected Access (WPA) is the replacement standard for WEP in Wi-Fi security. Two modes are

available: Personal, and Enterprise. Both give you a choice of two encryption methods: TKIP (Temporal Key

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

provide protection against hackers, and AES (Advanced Encryption System), which utilizes a symmetric 128-Bit

block data encryption. Enterprise utilizes a RADIUS server for authentication and the use of dynamic TKIP, AES, 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.

49

Appendix B: Wireless Security

Security Threats Facing Wireless Networks

Wireless-G Access Point with Power Over Ethernet and Rangebooster

WPA Personal

. If you do not have a RADIUS server, select the type of algorithm, TKIP or AES, enter a

password in the Pre-Shared key field of 8-63 characters, and enter a Group Key Renewal period time between

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

WPA Enterprise

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

server is connected to the AP or other device.) First, select the type of WPA algorithm,

TKIP

or

AES

. Enter the

RADIUS server’s IP Address and port number, along with a key shared between the device and the server.

Last, enter a Group Key Renewal period, which instructs the device how often it should change the encryption

keys.

WPA2.

Wi-Fi Protected Access 2 (WPA2) is the latest security standard in Wi-Fi security. Two modes are available:

Personal and Enterprise. WPA2 always uses AES (Advanced Encryption System) for stronger data encryption.

WPA2 Personal

. If you do not have a RADIUS server, enter a password in the Pre-Shared key field of 8-63

characters, and enter a Group Key Renewal period time between 0 and 99,999 seconds, which instructs the

AP or other device how often it should change the encryption keys.

WPA2 Enterprise

. WPA2 used in coordination with a RADIUS server. (This should only be used when a

RADIUS server is connected to the AP 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, enter a Group Key Renewal period,

which instructs the device how often it should change the encryption keys.

WPA2 Mixed.

WPA2 Mixed modes provide users an upgrade path from WPA to WPA2. You can have client devices

running both WPA and WPA2 and the Access Point will automatically select the security method used by the

client.

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.