FAQ: WiFi General Information

Wireless PCMCIA card range

Postby g0tr00t » Thu Jul 18, 2002 10:16 am

Question: What is the average range of a wireless PCMCIA card? (Built-in antenna)

Answer: It appears that each manufacturer will supply different ranges, but for averages the table below should suffice.

11 Mbit/s
Range in meters­(feet)
Open Office 160 m (525 ft)
Semi Open Office 50 m (165 ft)
Closed Office 25 m (80 ft)
Closed Office 25 m (80 ft)
Receiver Sensitivity -82
Delay Spread (at FER of <1%) 65ns

5.5 Mbit/s
Range in meters­(feet)
Open Office 270 m (885 ft)
Semi Open Office 70 m (230 ft)
Closed Office 35 m (115 ft)
Closed Office 35 m (115 ft)
Receiver Sensitivity -87
Delay Spread (at FER of <1%) 225ns

2 Mbit/s
Range in meters­(feet)
Open Office 400 m (1300 ft)
Semi Open Office 90 m (300 ft)
Closed Office 40 m (130 ft)
Closed Office 40 m (130 ft)
Receiver Sensitivity -91
Delay Spread (at FER of <1%) 400ns

1 Mbit/s
Range in meters­(feet)
Open Office 550 m (1750 ft)
Semi Open Office 115 m (375 ft)
Closed Office 50 m (165 ft)
Closed Office 50 m (165 ft)
Receiver Sensitivity -94
Delay Spread (at FER of <1%) 500ns

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Postby Mojo-_-Jojo » Thu Jul 18, 2002 12:55 pm

Your range is going to be a function of several factors:

Transmit Power (ERP at the antenna)
Receive Sensitivity
Antenna Gain
RF Propogation Pattern
Obstructions between source and reception

The manufacturers numbers may or may not be typical. (I find that most vendors overstate their numbers.) Building construction varies from wood and sheet rock to concrete and metal.

Not to get overly technical, your mileage will vary!


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WEP information

Postby JimmyPopAli » Thu Jul 25, 2002 11:04 pm

Q: Different equipment is marked as 40-bit, 64-bit, 104-bit and 128-bit WEP. Where can I learn more about WEP?

A: Actually, there are only two classes of WEP. However, due to the manner in which it is expressed, each class may be called by one of two different names. What you need to remember:

40-bit WEP is the same as 64-bit WEP.
104-bit WEP is the same as 128-bit WEP.

This is because the initialization vector used in the encryption is 24 bits. Therefore, 40+24=64, and 104+24=128. They are the same classes, just a different way to express it.

One other detail to note: Only 40/64-bit WEP is defined in the 802.11b standard. 104/128-bit WEP is implemented by many manufacturers, but it is not part of the standard. This means that different brands of equipment may not communicate with other brands using 104/128-bit WEP. While some do communicated well (e.g. Linksys and ORiNOCO), many units will work only at the 40/64-bit level with other brands of equipment .


Q: Where can I learn more about WEP?

A: Here are some good sites loaded with information on WEP.

Weaknesses in the Key Scheduling Algorithm of RC4

Attack to Break WEP

Cracking WEP Keys. Presented at Blackhat 2001

Practical Exploitation of RC4 Weaknesses in WEP Environments

802.11b Wireless Security
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FCC Regulations

Postby Thorn » Thu Aug 08, 2002 4:57 am

Q: I keep hearing about the FCC and regulations. Where can I find out more?

A: The Industrial, Scientific and Medical (ISM) band, which WiFi is part of, falls under the Federal Communications Commission's Part 15 Rules. http://www.fcc.gov

An excellant summary of the Part 15 regulations can be found at: http://www.lns.com/papers/part15/ . It was written by Tim Pozar, one of the founders of the Bay Area Wireless User's Group and a broadcast engineer.
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FCC Search

Postby stonent » Fri Aug 23, 2002 11:08 pm

If you want to see the inside of your WAP, Router or WiFi card, just go here:

For example, type in "Linksys" and find the FCC ID. Click on the documents link and then the "Inside Photos"
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Postby c-mag » Sat Sep 21, 2002 4:55 pm

Two major chipset control Wireless networking. The Prism and WaveLan. Find out which is Windows XP friendly.


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Without WEP, with VPN

Postby blackwave » Wed Oct 02, 2002 1:01 pm

Question: If I'm connecting to my access point (or any, for that matter) without WEP enabled, but I'm connecting through a VPN, is my information that I'm transmitting safe? What if I'm just browsing with explorer on the net, though an encrypted page? If my transmissions are intercepted, will they be able to see what I entered in the web page?

Answer: There are different types of safe.

Your data going through an encrypted tunnel is safe from sniffers.

Not using WEP only exposes your network from someone associating to it, so they may have the ability to surf the net as well as whatever else is exposed on your network...

For best results please follow Thorn's RFC
NetStumbler.com Forums > Misc Forums > Off-Topic > RFC: Wireless security checklist

Originally asked by phil22407
Answered by blackwave
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APs and WEP

Postby fawking » Thu Jan 16, 2003 1:56 pm

Question: I know WEP is encrypting packets, but does it prevent you from connecting to the AP to try and use internet access? (As long as there are not MAC filters or anything else in the way.)

Answer: Yes, as the AP will only accept the encrypted packets.

Reportedly some APs will accept both encrpyted and non-encrypted traffic at the same time, so make sure you RTM when you're setting it up.

Originally asked by fawking
Answered by Thorn
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SSID for Client Adapter so it grabs any AP availible

Postby aphex » Sun Mar 09, 2003 1:25 pm

Q: What is the SSID that will connect with whatever WiFi network is availible to it?

A: The SSID is "ANY" (without the quotes.)

Answered by DigitalMDX
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Common acronyms

Postby Thorn » Fri Mar 28, 2003 7:36 am

Q: What are all those acronyms you guys at throwing around?

A: Here are some common acronyms:

AP Access Point
BSS Basic Service Set
CPE Customer Premises Equipment
DSSS Direct Sequence Spread Spectrum
EIRP Effective Isotropic/Intentional Radiated Power
EMI ElectroMagnetic Interference
ESSID Extended Service Set IDentifierFH
FHSS Frequency Hopping Spread Spectrum
ISM Industrial, Scientific, and Medical
LOS Line Of Sight
OFDM Orthonagol Frequency Division Multiplexing
PtMP Point-to-MultiPoint
PtP Point-to-Point
RF Radio Frequency
RFI Radio Frequency Interference
RSSI Receive Signal Strength Indication
SSID Service Set IDentifier
UNII Unlicensed-National Information Infrastructure
WEP Wired Equivalent Privacy
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How Do I setup a SSH tunnel

Postby renderman » Wed Jul 23, 2003 12:33 pm

Q: How do I setup a SSH tunnel for <Insert service> over wireless

A: First you require an SSH capable server that you can log into, as well as a SSH client on the client computer

From there, follow these instructions to configure your client:

http://borosenclave.com/putty-ssh/ - For windows

http://internetconnection.net/support/tech-sshtunnels.shtml - For Unix

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Q: What signal level should I consider usable for a good wireless link?

Postby Dutch » Tue Feb 08, 2005 4:25 pm

Marius just posted an excellent explanation on his own site. I've taken the liberty to copy it here:
Marius wrote:
I get asked this question rather too often, so I'm posting my short answer here. The answer is rather more complex than it ought to be, and depends on a huge number of factors.

The most important is the receive sensitivity of your equipment. Many manufacturers fail to publish this data, but those that do will generally rate their radios by dBm at various data rates. As an example, let us take the venerable ORiNOCO Gold 802.11b "Classic" card. Its receive sensitivity is:
-94 dBm at 1 Mbps

-91 dBm at 2 Mbps

-87 dBm at 5.5 Mbps

-82 dBm at 11 Mbps

In theory this means, in order to operate at 11 Mbps, this card must be consistently receiving a minimum signal level of -82 dBm. Any less and it is likely to drop to one of the lower rates]Q: [/B] What signal level should I consider usable for a good wireless link?
A: Depends on your equipment and your environment.

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