If you’d like to keep your wireless network secure then turning on the best possible encryption is usually a very good place to start. There may still be room for problems, though (as I discovered, when my brother accidentally turned off his encryption entirely while trying to set up a TV), so it could be worth using NirSoft’s Wireless Network Watcher to keep a lookout for wifi intruders.

As usual with NirSoft programs, Wireless Network Watcher is compact in the extreme, a tiny download (even when unpacked it requires less than 700KB drive space) which requires no installation: just unzip it and go.

And by default the program will then run a quick inventory of your network, returning various details for every device it encounters: IP address, device name, MAC address  and the device manufacturer (sometimes, anyway).

Wireless Network Watcher makes it easy to see what's connected to your network at any one time

Click Options > Background Scan, Options > Beep On New Device, though, and the program will run regular scans of your network, alerting you to any unexpected visitors it might find.

How often? The program runs a “continuous” background scan, apparently. This sounds a little alarming, but the Help file claims that “the background scan is slower and less intensive then the regular scan, so it won’t overload your computer”. And as Task Manager shows no real resource use at all, we think this is probably true.

If you’re concerned, though, clicking Options > Advanced Options allows you to choose how often the background scan is run. And you’re able to customise what happens when a new device is detected, too, with options to play a custom audio file, or execute the command of your choice.

As wireless monitoring systems go, Wireless Network Watcher is, well, plainly a little on the basic side. It’s also free, effective, lightweight, configurable and very easy to use, though, and if your security needs are simple then the program will probably serve you very well.