Hack 25. Detect Networks with Handheld PCs

Easily monitor wireless networks while walking around.

If you have a handheld PC, you know how convenient it is. What you might not realize is that it makes an excellent wireless testing device. If your handheld has a Compact Flash or PC Card slot, you can use a wireless card in these slots. You might even have a newer model with built-in Wi-Fi and Bluetooth.

Two programs are available to detect wireless networks on Windows-based handhelds. For Pocket PC 3.0, Handheld PC 2000, and Pocket PC 2002, the author of NetStumbler, Marius Milner, has written a miniature version just for Pocket PCs: MiniStumbler. Windows Mobile 2003 support is not reliable in MiniStumbler, and the author is working on an update. You might be able to get it working, but it is not officially supported.

Windows Mobile 2003 users have the option of installing WiFiFoFum, which is designed expressly for this version of PocketPC software and indeed does not run on any earlier versions of the operating system. This hack covers both programs.

2.4.1. MiniStumbler

MiniStumbler is available for download at http://stumbler.net. At the time of this writing, the current version is 0.40. MiniStumbler supports Hermes chipset cards (Lucent/Orinoco/Agere/Avaya/Proxim). Many Prism 2 cards are also known to work. Check http://stumbler.net/compat for updated reports of cards that work.

To install MiniStumbler, download the executable file to your PC, which must have the Microsoft ActiveSync software. Make sure your PocketPC is in its dock or otherwise associated with ActiveSync. Double-click the file and follow the prompts. The installer will figure out which type of processor your PocketPC runs and install the proper binary. You can then run MiniStumbler from the Programs folder of your PocketPC.

As with NetStumbler [Hack #24], you'll want to set some options the first time you launch it. Select View Options and make sure that "Reconfigure card automatically and "Query APs for names" are both checked, as shown in Figure 2-13. On this screen, you can also set the scanning speed, which you'll want to set to Fast.

With MiniStumbler's options properly configured, you're ready to discover wireless networks. If your wireless card is installed and enabled, MiniStumbler will immediately start scanning for networks. A typical scanning session looks something like Figure 2-14.

Figure 2-13. Setting your options

Figure 2-14. MiniStumbler in action

If you've ever used NetStumbler, you should be right at home. The data is displayed in exactly the same way, using the same color scheme for the networks it has detected (green, yellow, or red to indicate signal strength, grey for networks out of range, and a tiny lock icon for networks using WPA/WEP). If you need to pause the scanning process, simply click on the green triangle in the bottom menu.

While the tiny screen of a Pocket PC is wonderfully portable, it makes viewing large amounts of data painful. In order to see all of the data in MiniStumbler, you will have to scroll to the right. This rest of the data revealed includes signal strength, SNR, and noise levels.

MiniStumbler does not support any of the visualization views in NetStumbler, so you can't get a graph of wireless signal over time. However, there is support for location logging using a GPS. Choose View images/U2192.jpg border=0> Options, select the GPS tab (Figure 2-15), and then select the COM port and data type of your GPS. MiniStumbler will then show latitude and longitude locations for all of your wireless networks as it finds them.

Figure 2-15. GPS configuration

Obviously, a GPS can effectively be used only for outdoor network detection, but the extreme portability of Pocket PCs makes them ideal for performing informal site surveys, checking for unauthorized access points, or establishing the coverage area of your wireless network. MiniStumbler might be missing many of the handy features of NetStumbler and Kismet, but it is simple to use and far better than the PocketPC system client for finding networks.

2.4.2. WiFiFoFum

At the time of this writing, this uniquely named program is the better option if your PocketPC runs Windows Mobile 2003. You can download the software from http://www.aspecto-software.com/WiFiFoFum.

There is a list of supported devices and a FAQ if you run into problems. For the purposes of this hack, we have tested Version 0.3.3 on a Dell Axim X30.

There is no installer for WiFiFoFum, so you'll need to download the zip file, uncompress it, and copy the three DLL files and one EXE file over to your PocketPC via ActiveSync, or Bluetooth File Exchange if you have that option. Once the files are copied over, you can start WiFiFoFum directly from the location where you copied it.

As shown in Figure 2-16, the main screen of WiFiFoFum looks much like other wireless network scanners. It does not have all of the details that MiniStumbler provides; there is no SNR, no noise level, and it does not graphically show you relative signal strength by color. You'll have to scroll to the right to see the channels of the access points it finds.

Figure 2-16. WiFiFoFum in action

Depending on your model of PocketPC and the wireless card driver, you will need to change the selected type by clicking on Tools images/U2192.jpg border=0> Device. The default choice is the WLAGS46B1 driver for Orinoco chipsets. In our case, the Dell Axim X30 required us to choose the ODIMWLAGS46B1 driver for WiFiFoFum to begin scanning correctly.

There are some interesting options that you can set, as shown in Figure 2-17. Scan time is adjustable from 100 to 5000 milliseconds. The order of the fields in the scan is customizable. You can choose a location where WiFiFoFum keeps scan logs and pick a WAV file that it plays when new access points are detected. As with MiniStumbler, there is no audio feedback for signal strength. GPS support is also available in the GPS options tab. Pick a serial port and baud rate, and new scans will begin to show latitude and longitude information.

Figure 2-17. Setting your options

A unique feature of the program is the Radar display, which shows the relative locations of access points to your handheld based on their signal strength, as shown in Figure 2-18. Radar does not appear to be geographically accurate, but it does give you a picture of relative distance to access points.

WiFiFoFum is a great little scanning application. While it does not have all the features of MiniStumbler, it comes close, and it is your best choice if you have the most recent PocketPC operating system.

2.4.3. Other Handhelds

If you have a Sharp Zaurus or Compaq iPAQ running Linux, then you're in luck. Kismet [Hack #29] runs well on these machines, giving you the most powerful and tiny network monitoring tool there is. Zaurus users can find a complete HOWTO on installing Kismet at http://aurach.ewu.edu/ield/ield_course/lectures/ield_appC. iPAQ owners should go to http://grox.net/misc/ipaq/kismet for instructions using Familiar Linux.

Figure 2-18. Radar display