Hack 82. Link Monitoring in Linux with Wavemon

Monitor radio parameters in real time using Wavemon, a curses-based tool for Linux.

When using Linux, the standard wireless tools provide a wealth of status information. These tools get their information from the standard kernel interface /proc/net/wireless. While ideal for providing pinpoint accuracy in measuring signal strength and noise data, these tools are not designed to give an indication of performance over time.

Wavemon (http://www.wavemage.com/projects.html) is a terrific little tool that does precisely this. It polls /proc/net/wireless many times each second to give you a rolling report of how your wireless connection is performing. Its simple curses interface keeps the code quite small and is ideal for including in embedded distributions to get real-time link data from remote access points.

The main interface provides a nice graphical representation of the current link state (Figure 9-3).

Figure 9-3. Wavemon in action.

All of the statistics are updated in real time, making it ideal for monitoring point-to-point links and fine-tuning antennas on long distance shots. For an even easier to read display, hit F2 to bring up the Level Histogram (Figure 9-4).

Figure 9-4. Pretty little scrolling waves of data.

This display is easy to read on a laptop even in bright sunshine, making it an ideal tool for outdoor work. The histogram slowly sweeps to the left, giving you a history of the last few moments of wireless connectivity. Wavemon runs in a terminal, so you can easily run more than one instance to monitor multiple radio links simultaneously.

When you need a high performance signal and noise meter for Linux, Wavemon is hard to beat. The current version is available from Freshmeat at http://freshmeat.net/projects/wavemon/.

Rob Flickenger