Last week, we started a tutorial series on stumbling and sniffing networks in Linux. First we reviewed some general stumbling and sniffing information. Then we looked at a NetStumbler look-a-like, SWScanner.

Now we'll continue stumbling with KwiFiManager; which can also serve as your wireless connection manger. Then we'll start sniffing with tcpdump, a command-line utility.

Stumbling (and managing) with KwiFiManager

If you regularly need to scan the airwaves for APs and networks, you might consider using KwiFiManager. It not only includes some stumbling and surveying features, but it lets you manage your Wi-Fi connections. This might not be the right tool for a full survey, but it's convenient for quick scans. Since it serves as your wireless manager, stumbling is always one click away.

Once you install and run KwiFiManager, its icon showing the signal bars and value for the current connection appears in the system tray. To open the application, click the icon. The details for the current connection is shown on the main screen, as you see in Figure 2. This includes the channel, data rate, MAC address of the AP, and your assigned IP address.

Figure 1: KwiFiManager's main screen shows the details of your current wireless connection.

The main screen also sports a set of signal bars and the signal value. Though this is not the dBm value, a preferable measurement for surveying, its shows an effective signal level, the 'Quality' value. Either your wireless card will report this Quality value or it will be calculated by subtracting the noise level from the signal strength in dBm. However in some cases, the card won't report the Quality value, it will simply be the signal strength. To force KwiFiManager to calculate it, click Settings > Use Alternative Strength Calculation.

When you want to do some stumbling, click the Scan for Networks button. This pops up a window that shows the network names, modes, signal quality values, and encryption statuses for each AP picked up. If you want to actually connect to a network, select it from the list and click the Switch to Network button.

Two other surveying features are available from the Settings menu on the toolbar of the main KwiFiManager screen. To view a live graph (see Figure 2) of the signal and noise levels of your current connection, click Statistics. This is great for when troubleshooting connectivity issues or determining AP placement. KwiFiManager can also help you track down rogue or forgotten APs. From the Settings menu, you can also bring up the detector feature. When enabled, you'll hear beeping which gets louder and quicker as you get closer to the AP.

Figure 2: You can monitor the signal and noise levels of your current Wi-Fi connection with KwiFiManager.

Next: Sniffing With tcpdump »