NetStumbler v0.4.0 Release Notes

Marius Milner <>

Thank you for your interest in NetStumbler. It is provided to you as a convenience, at no cost and without warranty. If you don't like it, or if you feel that it doesn't quite do what you want, you are free to delete it from your system. By installing or using it, you agree to be bound by the terms of the License Agreement.

NetStumbler is "beggarware". This means that you do not have to pay for a license to use it. However if you use it and like it, please consider making a donation at to support future development, web hosting and other costs that I incur as a result of making this software available to you. Please bear in mind that I do this as a hobby in my spare time, not as a full time job.

Commercial and Government users are strongly encouraged to donate. The suggested donation is US$50 per copy. You may donate by visiting the web site You can pay in a variety of ways and may send a Purchase Order if needed.

What is NetStumbler?

NetStumbler is a tool for Windows that allows you to detect Wireless Local Area Networks (WLANs) using 802.11b, 802.11a and 802.11g. It has many uses:


General Requirements

The requirements for NetStumbler are somewhat complex and depend on hardware, firmware versions, driver versions and operating system. The best way to see if it works on your system is to try it.

Some configurations have been extensively tested and are known to work. These are detailed at If your configuration works but is not listed, or is listed but does not work, please follow the instructions on the web site.

The following are rules of thumb that you can follow in case you cannot reach the web site for some reason.

Firmware Requirements

If you have an old WaveLAN/IEEE card then please note that the WaveLAN firmware (version 4.X and below) does not work with NetStumbler. If your card has this version, you are advised to upgrade to the latest version available from Proxim's web site. This will also ensure compatibility with the 802.11b standard.

Other Requirements and Compatibility Issues

Legal note

I am not a lawyer. However as a user of this software, you need to be aware of the following.

In most places, it is illegal to use a network without permission from the owner. The definition of "use" is not entirely clear, but it definitely includes using someone else's internet connection or gathering information about what is on the network. It may include getting an IP address via DHCP. It may even include associating with the network.

The IP address reporting functionality in NetStumbler is for you to check the settings of your own network, and for corporate users to identify rogue access points operating within their organization. If you are doing neither of these things, it is suggested that you disable TCP/IP on your wireless adapter. This will help you to avoid possible legal trouble.

Marius Milner, and accepts no liability for damages caused by use of this software. For further information please consult the License Agreement that can be found both in the installer and in the online help.


Q1. NetStumbler reports "No wireless card found". Why?
A1. Please check the compatibility lists above. Perhaps your adapter is not supported.
Q2. Why doesn't NetStumbler see the access point right next to my machine?
A2A. The access point is configured not to respond to broadcast probes. Most manufacturers call this "disable broadcast SSID" or "closed". NetStumbler cannot see these networks unless you know the SSID and have your machine configured to connect to it.
A2B. Your wireless card is configured to connect to a specific SSID. Try setting it to connect to a blank SSID or to "ANY" (without quotes).
Q3. What 802.11 frames does NetStumbler send?
A3A. It sends out a probe request about once a second, and reports the responses. This is known as Active Scanning.
A3B. (ORiNOCO only and with "Query APs for names" enabled) When it is connected to a BSS network, it will attempt to get the name of the access point. When it is connected to an IBSS network, it will try to get the names of all locally visible peers. This is done via Proxim's proprietary WMP protocol.
A3C. (Only when connected to a Cisco access point and with "Query APs for names" enabled and with a valid IP address ) It will attempt to use Cisco's IAPP protocol to get the name and IP address of the access point.
A3D. If you leave TCP/IP enabled, your adapter may attempt to get a DHCP lease or send other traffic. NetStumbler will record the fact that you were issued an IP address.
Q4. Does NetStumbler listen for beacons, or put my card into promiscuous or RFMON mode?
A4. This is called Passive Scanning and is not in this version.
Q5. I'm seeing access points appear briefly and then disappear for a long time. What's happening?
A5A. Some wireless networks can be configured not to respond to probes every time they hear a request.
A5B. If you see lots of networks that appear briefly and then disappear forever, you may have found a FakeAP installation.
Q6. Why does NetStumbler disconnect me from the network?
A6. If you have "Options->Reconfigure card automatically" checked, it will configure your card with a profile that uses a null SSID and BSS mode (It will not change your WEP settings). Also, when it sees another network that has a better signal than the one you're connected to, it may disconnect the current connection so that it can get the AP name on the other network.
Q7. Does NetStumbler detect ROR and COR installations?
A7. Not usually. They are not always fully compliant with 802.11b and therefore may not be visible to NetStumbler.
Q8. Should I allow Windows XP to manage my wireless settings?
A8. Probably not. When you are not connected to a network, XP will cycle through your favorite network names attempting to connect to them. While this is happening, NetStumbler may not see all available networks. It is recommended that you stop the "Wireless Zero Configuration" service while NetStumbler is running. You can do this by switching on "Auto Reconfigure", from Control Panel, or by running the command "net stop wzcsvc".
Q9. When will you support wireless card X? When will you add new feature Y that I want?
A9. I work on this in my spare time. I can make no commitment to dates for new features or bug fixes. If you would like to help me support a particular piece of hardware, please consider sending me a sample rather than complaining that it isn't supported.
Q10. What does "Auto Reconfigure" actually do?
A10A. When using the ORiNOCO driver, it stops the Wireless Zero Configuration service and makes sure that the card is always set to a blank SSID and BSS mode.
A10B. When using the Prism driver, it stops the Wireless Zero Configuration service and checks for a blank or "ANY" SSID. If necessary, it makes changes to the card's registry settings and prompts you to reinsert the card.
A10C. On all other drivers, it stops the Wireless Zero Configuration service and then does nothing. Usually this is a good thing, but you should experiment with it.

Release History

Version 0.4.0 (April 21, 2004)

Version 0.3.30 (August 18, 2002):

Version 0.3.23 (February 14, 2002):

Version 0.3.22 (August 6, 2001):

Version 0.3.21 (July 16, 2001):

Version 0.3.20 (July 13, 2001):

Version 0.3.10 (July 12, 2001):

Version 0.3.00 (June 19, 2001):

Version 0.2.00 (May 16, 2001):

Version 0.1.00 (May 5, 2001):