Netstumbler for Linux

NetStumbler (also known as Network Stumbler) is a free/”beggarware” tool for Windows that can detect WiFi/Wireless LANs using the 802.11b, 802.11a and 802.11g WLAN standards.

An alternative to Netstumbler that works on Linux is called Kismet and uses RFMON to passively detect networks.

Wireless Extension (WE) and Wireless Tools (WT)

If you only have basic wireless detection/scanning requirements on Linux you can use Wireless Extensions (WE) and Wireless Tools (WT) that are usually already included in most Linux distributions.

The Wireless Extension (WE) is a generic API allowing a driver to expose to the user space configuration and statistics specific to common Wireless LANs. The beauty of it is that a single set of tool can support all the variations of Wireless LANs, regardless of their type (as long as the driver supports Wireless Extension). Another advantage is these parameters may be changed on the fly without restarting the driver (or Linux).

The Wireless Tools (WT) is a set of tools allows manipulation of the Wireless Extensions (WE). They use a textual interface and are rather crude, but aim to support the full Wireless Extension. There are many other tools you can use with Wireless Extensions, however Wireless Tools is the reference implementation.

• iwconfig manipulate the basic wireless parameters
• iwlist allow to initiate scanning and list frequencies, bit-rates, encryption keys…
• iwspy allow to get per node link quality
• iwpriv allow to manipulate the Wireless Extensions specific to a driver (private)
• ifrename allow to name interfaces based on various static criteria

Linux Wireless Tools Example

The examples below are from my Nokia N800 Internet tablet. It is running a Debian based Linux and has the Linux wireless tools.

Nokia N800 iwlist wlan0 scanning

Using iwconfig I can see which interfaces support the wireless extensions.

Nokia-N800-23-14:~# iwconfig
lo        no wireless extensions.

wlan0     IEEE 802.11b/g  ESSID:"venetian"
          Mode:Managed  Frequency:2.462 GHz  Access Point: 00:0B:85:FF:FF:FF
          Bit Rate=54 Mb/s   Tx-Power=19 dBm   Sensitivity=0/200
          RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:on
          Link Quality=44/0  Signal level=-49 dBm  Noise level=-93 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:83  Invalid misc:0   Missed beacon:0

Nokia-N800-23-14:~#

In my case wlan0 will be used with Linux wireless tools to get similar information to what Netstumbler provides.

Results for iwlist wlan0 scanning command are below.

Nokia-N800-23-14:~# iwlist wlan0 scanning
wlan0     Scan completed :
          Cell 01 - Address: 00:0B:85:FF:FF:FF
                    ESSID:"venetian"
                    Mode:Master
                    Encryption key:on
                    Channel:11
                    Quality:43/0  Signal level:-51 dBm  Noise level:-94 dBm
                    IE: WPA Version 1
                        Group Cipher : TKIP
                        Pairwise Ciphers (1) : TKIP
                        Authentication Suites (1) : PSK
          Cell 02 - Address: 00:0F:66:FF:FF:FF
                    ESSID:"linksys"
                    Mode:Master
                    Encryption key:off
                    Channel:6
                    Quality:10/0  Signal level:-84 dBm  Noise level:-94 dBm
          Cell 03 - Address: 00:A0:C5:FF:FF:FF
                    ESSID:""
                    Mode:Master
                    Encryption key:on
                    Channel:11
                    Quality:43/0  Signal level:-51 dBm  Noise level:-94 dBm
          Cell 04 - Address: 00:0B:85:FF:FF:FF
                    ESSID:"venetian"
                    Mode:Master
                    Encryption key:on
                    Channel:1
                    Quality:37/0  Signal level:-57 dBm  Noise level:-94 dBm
                    IE: WPA Version 1
                        Group Cipher : TKIP
                        Pairwise Ciphers (1) : TKIP
                        Authentication Suites (1) : PSK

Note: In the results above I have edited the MAC addresses of the access points.

Graphical User Interfaces for Wireless Tools on Linux

Many GUI configuration and management tools are available if you need a graphical view of wireless tools. Below is a screen shot of KWiFiManager, a set of KDE tools using Wireless Extensions.

KWiFiManager - GUI Interface for Wireless Tools

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Windows Vista and Netstumbler

Netstumbler isn’t officially supported on Windows Vista but several alternatives exist that provide similar or better information about wireless networks.

The quickest and simplest way to discover access points is by using the “netsh” command available by default in Windows Vista. The command returns text results for discovered wireless networks. Free tools that take the netsh results and display them in a graphical format are also available.

Netsh Windows Vista Shortcut

The easiest way to use the command is to create a desktop shortcut and run it as needed.

1. Right click on Windows Vista Desktop and select New -> Shortcut
   
2. Type following in field and click Next

   cmd.exe /k netsh wlan show networks mode=bssid
   The “cmd.exe /k” portion of command will keep results window open until closed.

   

3. Save shortcut by clicking Finish

   

4. Run command by double clicking desktop shortcut

   

Netsh cmd vs Windows Vista Graphical Networking View

The netsh shows SSID, signal strength, channel, supported data rates, and access point MAC address (BSSID). Compare this to Windows Vista graphical information which only shows SSID and signal bars.

Netsh

Windows Vista

netsh wlan show networks mode=bssid help

The help information for the command is below.

C:\Users\admin>netsh wlan show networks ?

Usage: show networks [[interface=]] [[mode=]ssid/bssid]

Parameters:

Tag Value
interface - Name of the interface which has this profile configured.
mode - Get detailed bssid information.

Remarks:

Shows the networks available to the system.
Parameter interface and bssid are both optional.

If interface name is given, only the networks on the given interface will be listed.
Otherwise, all networks visible to the system will be listed.

If mode=bssid is given then the visible bssids for each ssid
will also be listed. Otherwise only ssids will be listed.

Examples:

show networks interface=”Wireless Network Connection”
show networks mode=Bssid
show networks

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Outdoor Wireless Planning Tool

This online tool can be used to plan and visualize outdoor wireless networks by plotting device locations and radio frequency (RF) propagation coverage on mapping tools. Radio frequency propagation visualization can be viewed as contours on Google Maps or 3D RF models in Google Earth.

The tool is currently beta software and is available at address below. Feedback and feature requests are welcome.

http://www.wlanbook.com/outdoor-wireless-planner/

How to Use Outdoor Wireless Planning Tool

I plan to add detailed instructions later but for now start by following a three step process - 1) find your location, 2) click on map to plot markers, and 3) view results in Google Earth.

Radio Frequency Propagation Visualization on Google Maps

Currently the radio frequency propagation visualization in Google Earth and Google Map view is the same for all plotted points. This feature will be enhanced so that results are based on user entered data like radio power, frequency, antenna gain, distance, and most importantly terrain data that can be determined from mapping software.

Radio Frequency Propagation Visualization in Google Earth

The Google Earth portion of tool isn’t complete but when done will have the ability to view results with custom pan, tilt, range, and altitude values for location. See below for what the 3D view will look like and download a demo file to view results in Google Earth.

Feedback, Bug Reports, and Features Requests

Please comment in post below or send me a message via my contact form with feedback, bug reports, and feature requests. This software was tested on a Windows Vista PC, Internet Explorer 7, and 1280×800 screen resolution. I’m sure it will behave differently on other systems so when sending bug reports please let me know your operating system, browser version, and screen resolution.

Filed under: WLAN Design, WLAN Tools | no comments yet, your thoughts are welcome

Is It Illegal to Use Other People’s Wireless Internet?

The topic of stealing WiFi Internet access or legality of using someone else’s WiFi Internet access is always entertaining because almost everyone has an opinion on this subject and in almost every case each person is convinced that their view is right. I’m no different — my method to determine if using wireless Internet is illegal answer the question below.

Did you get permission from the owner of the WiFi hardware to connect to it? Permission could be verbal communication or a sign that indicates that the WiFi connection is free.

If your answer is “NO” then you are stealing Internet service and it is against the law. Don’t believe me read this.

Internet Connection Is What They Really Want

An access point is basically connecting users wirelessly to a wired network. Other than hackers, most users that connect to an open wireless network want to get connected to the Internet which is a service that the owner of the wireless network is usually paying a monthly fee for.

So while someone could justify connecting to an open wireless network and convince you that they have done is not wrong. Once they use the owners ISP connection they are stealing a service.

Some folks may argue that if a WiFi connection is not secured then it can’t be considered stealing. Not true, even open access points technically use the SSID to “authenticate” users on to the access point with a process called “open authentication”.

ISP Acceptable Usage Policy (AUP) and Other People’s Wireless Internet

If you get permission you may OK but the person granting the permission may have violated the ISP’s rules. In almost all cases, the person giving the permission may not be allowed to share the Internet connection based on the service provider’s Terms of Services (TOS) and/or Acceptable Usage Policy (AUP).

Filed under: WLAN Legal Matters | no comments yet, your thoughts are welcome

SSID

A SSID (service set identifier) identifies the wireless network and the SSID for your wireless WLAN card must match the SSID for any access point that you want to connect with. If the value does not match, you are not granted access to the network. Each SSID can be up to 32 characters long and is case-sensitive.

Multiple Access Points with the Same SSID

Muliple access points can have the same SSID and in most cases this configuration is known as an extended service set (ESS) when the two access points are connected to the same wired network. Sharing the same SSID can be an issue if the two access points are in close proximity but are not owned or part of the same wired network. In this case end user devices may connect to the incorrect SSID.

How to Discover Non-Broadcasting SSIDs

If the SSID is not being broadcasted, finding the hidden SSID is possible but requires special software that is able to look at wireless data frames to extract the SSID. There are many commercial products that have this RFMON capability and several open source products such as Kismet.

Filed under: WLAN Standards | no comments yet, your thoughts are welcome

Palm Centro Gmail and Google Mail App

Getting Gmail and/or Google Mail App to work on a Centro requires the same software and process as a Treo 650. See previous posts below.

Google Gmail on Treo 650 - Three step process to get Gmail working on a Treo 650 using Google Gmail Mobile App. This process works with free gmail.com Gmail and Google Mail App.

2 Mobile Gmail Apps on Same Phone, Treo 650 - If you have two Gmail email accounts and want to access both via your mobile phone, Palm Treo 650 on Sprint in my case, follow these directions.

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What Does WiFi Stand For?

Nothing.

“Wi-Fi”, Wi hyphen Fi, is a branding term created by Interbrand so that the WiFi Alliance could use the name and logo as the 80.211 interoperability seal and in marketing efforts. The branding effort has been so successful that the term WiFi is synonymous with 802.11 just like “Kleenex”, another invented word, is synonymous with facial tissue paper. Unlike Kleenex, WiFi has functional meaning since it is used to certify the interoperability of wireless devices.

The Wi-Fi Alliance is a global trade association with a mission of enabling the growth of Wi-Fi worldwide. The Wi-Fi Alliance created the term Wi-Fi, which has come to represent a cultural phenomenon. Products which successfully pass the Wi-Fi Alliance testing may use the Wi-Fi CERTIFIED brand. The Alliance tests and certifies the interoperability of wireless LAN products based on the IEEE 802.11 standards.

Wi-Fi CERTIFIED™ Makes it Wi-Fi

The certification process is so important that it is virtually impossible to purchase consumer grade equipment that is not Wi-Fi certified.

Since 2000, Wi-Fi Alliance members have certified more than 4,100 Wi-Fi products. Through comprehensive testing, the Wi-Fi Alliance certification program helps to ensure that Wi-Fi products from multiple manufacturers work together.

Wi-Fi Certification assures tested and proven interoperability among Wi-Fi devices. This certification gives users confidence that Wi-Fi products bearing the Wi-Fi CERTIFIED™ logo have passed rigorous interoperability certification requirements.

Wi-Fi or WiFi?

If want to use the brand correctly then refer to the official style guide. This style guide describes the usage requirements for the trademarks of the Wi-Fi Alliance.

Filed under: WLAN/WiFi News | no comments yet, your thoughts are welcome

WiFi For Dummies

A request I get all the time is recommendations on books that are good for non techies to learn about WiFi. If you search long enough on the Internet you can find free information on the web that will answer your questions, no matter what your topic. What is more difficult, is finding free ebooks that are well organized and well written enough to be worth printing it out.

A great and **FREE** ebook in PDF format related to WiFi is can be downloaded directly from here. This book isn’t an official “WiFi For Dummies” book but covers the topic at a similar level. The second edition of the book was released in 2004 but is still great for anyone just starting to learn about WiFi.

In the authors’ own words:

You are about to have in your virtual hands a free version of the second edition of The Wireless Networking Starter Kit. We’ll be frank: the book got great reviews, and we heard from hundreds of readers how they liked it–but it didn’t sell well enough to continue to update it.

That’s why we’re giving this edition from 2004 away at no cost: there’s still much that’s relevant even after all the changes that Wi-Fi has gone through. (What’s really out of date? There’s little coverage of WPA security and nothing on 802.11n.)

Tech Support Via Email

The motivation for sharing the great resource above is that I receive several emails a week requesting tech support via my contact form. If the question is related to a post I have written I usually try to answer the email right away. In most cases the email request is about a very specific issue that I would have to research and would require several exchanges with the reader to fully understand the problem before trying to respond.

While I wish I had the time to answer all tech support questions, it just isn’t possible. So for now my policy is that I only respond to questions that are related to my posts. If the question is generic enough that others would benefit from the answer I usually write post instead of responding to question directly via email.

If you have a generic question about wireless I recommend you download the free ebook mentioned above. Some of the topics covered are below and I suspect in most cases will answer your questions.

Section I: Wireless Basics
1. How Wireless Works
2. Wireless Standards
3. Wireless Hardware
4. Other Wireless Standards
5. Wireless of the (Near) Future

Section II: Connecting Your Computer
6. Connecting Your Windows XP
7. Configuring Your Centrino Laptop
8. Connecting Your Macintosh
9. Connecting with Linux and FreeBSD
10. Connecting Your Handheld
11. Connecting via Bluetooth
12. Creating an Ad Hoc Wireless Network
13. Sharing Files and Printers
14. Troubleshooting Your Connection

Section III: Building Your Wireless Network
15. Planning Your Wireless Network
16. Buying a Wireless Gateway
17. Setting up a Gateway
18. Wireless Gadgets
19. Creating a Software Access Point
20. Bridging Wireless Networks
21. Indoor Antenna Basics
22. Small Office Wi-Fi Networking
23. Troubleshooting Your Wireless Network

Section IV: Wireless Security
24. Wireless Worries
25. Preventing Access to Your Network
26. Securing Data in Transit
27. Protecting Your Systems

Section V: Taking It on the Road
28. Finding Wi-Fi on the Road
29. Configuring WISP Software
30. Using Cellular Data Networks
31. Prepping for the Road
32. Working on the Road

Section VI: Going the Distance
33. Long-Range Wi-Fi Connections
34. Long-Range Anntena Basics

Appendix A. Networking Basics
Appendix B. Configuring Your Network Settings
Appendix C. How to Troubleshoot

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Which Is Faster Wireless Router or Wired Internet?

Ever wonder which is faster, using a wireless router or plugging directly into the wired Internet? The short answer is that the wired Internet connection will always be faster because you are eliminating the “middle man” — the wireless access point.

Also, because WiFi connections half duplex (can only send or receive not both at same time) and contention based (users/devices and have to wait to transmit) you can never take advantage of the full duplex nature of wired Internet connections.

In reality, this is hard question to answer because it depends on so many factors such as:

• Wireless technology (802.11a, 802.11g, 802.11b, 802.11n)
• ISP connection speeds (upload/download)
• Is wireless Internet (WiFi router) used by multiple users
• Are there other WiFi devices nearby or interfering sources

Estimated throughput for 802.11 a/b/g/n

Even when connected to the access point at 54Mbps your actual throughput will be much less because the speed numbers quoted by vendors are the data rates for the various 802.11 standards/amendments (802.11a, 802.11b, 802.11g, 802.11n) and not throughput for the connected device.

Below are estimated data half duplex throughputs for various 802.11 standards for single client scenarios. For multiple client scenarios the numbers would be shared for all clients and uniformity among clients may not always occur.

802.11a - 19 Mbps
802.11g - 17 Mbps
802.11b - 5 Mbps
802.11n - > 100 Mbps

Internet Connection Bottleneck

While a wired connection will always be faster than the same connection via a wireless access point, most Internet connections are much lower in speed than the wireless router. For example, an asymmetrical cable modem high speed broadband service that is 5 Mbps download speed and 1 Mbs upload speed would most likely have same performance on any 802.11 network for uploading and downloading. While another user with a 15 Mbps down/5 Mbps up Internet connection would not fully use ISP connection on an 802.11b network.

Also, while most ISPs provide download/upload data rates for service offerings, these numbers are burstable data rates. In reality, all ISPs are designed so that guaranteed data rates for all users are much less.

WiFi Speed Test

Another method to figure out if using a wired connection is faster is to test your Internet speed via wired and wireless connection and compare results.

In summary, if you have high end/low latency requirements (gaming, voice over IP, real-time collaboration) it is best to use a wired connection.

Filed under: WLAN Deployment | no comments yet, your thoughts are welcome

SST-PR-1 SSID

SST-PR-1 SSID is ad hoc network SSID used by Sears Home Service van fleet. This SSID is usually an ad hoc network and shows up everywhere. Most wireless users don’t know what it is and try to connect to it causing it to go viral just like the Free Public WiFi SSID.

Sears Home Service

In combination with other technology, the Sears technician can look up parts, repair products, print out receipt, and get info regarding next service call. Very cool photos of Sears setup below.

Truck with domed antenna on roof for automatic vehicle location (AVL).

Netstumbler showing SST-PR-1 ad-hoc SSID.

Ruggedized laptop used by Sears service techs docked in van.

Ruggedized laptop used by Sears service techs undocked.

Disable Ad-hoc Wireless Networking in Windows XP

Disable ad hoc wireless networking in Windows XP to prevent users from connecting to ad hoc networks like SST-PR-1.

If you want more photos related to SST-PR-1 go here.

Filed under: WLAN Security | no comments yet, your thoughts are welcome