Wifi Analyzer

Admins who are less interested in exploring the devices on their own networks and more interested in the wireless networks in the area should take a look at the classic Wifi Analyzer [21]. The intuitive tool, which is suitable even for non-experts, scans all the wireless networks found in range and presents them in the channel overview as a colored graph (Figure 9), which can be helpful in analyzing reception problems or planning WLANs.

Figure 9: Wifi Analyzer shows all the wireless networks it can find and allows you to search for less frequently used channels.

A needle graph shows the signal strength of an access point in real time, ranging from green (strong) to yellow to gray (weak). If you enable sound, the app can be used like a Geiger counter, giving you acoustic feedback on the quality of reception.

Interference Analysis

Channel evaluation also lets you operate your own wireless network on a channel that is as interference-free as possible. This process rates the individual channels with asterisks and helps to determine the least frequented channel, which is definitely a challenge in densely populated areas.

The AP list, which is designed more for technically interested users or for advanced debugging, gives you the names of the individual networks, channels used, frequencies, encryption type, and signal strength – and even the details of multiple available access points that share the same ESSID.

Apple: No Sniffers

In the iOS camp, the choice of applications has deteriorated significantly since Apple systematically began to remove sniffers from the App Store in mid-2010. The reason? Sniffers rely on unauthorized "private frameworks for spying on access and wireless data" (i.e., they tap the wireless chips directly, instead of using the library calls required by Apple).

However, applications that have their own WiFi database are still allowed; except it is of little use for exploring the wireless networks in your neighborhood. The only solution here is a jailbreak and detour via the alternative Cydia app store, which offers a wider selection of sniffers.

Administrators must decide for themselves whether root access is an alternative; many security experts advise it, quoting the motto, "if it is possible, do it yourself, rather than leave it to a hacker." Nevertheless, this question is a matter for heated debate among security consultants.

If you are less concerned with individual devices but instead want to see the big picture, you will typically already have a monitoring solution like Nagios or Icinga in place. Matching apps and web interfaces are available for both, thus helping admins keep track of all their critical systems on a small screen. The Nagios website even names a number of mobile interfaces [22].