8 free Wi-Fi security tools

These apps for Windows, Mac OS X and Linux will help you see and get info on all your Wi-Fi access points.

Even if you have an enterprise-level Wi-Fi spectrum analyzer, like Wi-Spy or AirMagnet, free Wi-Fi tools can also come in handy. You might use them during the planning or installation stages of your wireless LAN, while troubleshooting, or when performing maintenance. They could even serve as your primarily tools in smaller and less-complex environments.

Here are several free programs you can use to do Wi-Fi stumbling and surveying on all the popular platforms -- Windows, Mac OS X, and Linux. You'll be able see all the nearby wireless access points and their details, including channels, signal levels, and MAC address.


NetStumbler is one of the oldest and most known Wi-Fi stumblers and runs on Windows and Windows CE/Mobile. It lists nearby APs and displays their basic details: SSID, channel, speed, MAC address, vendor, and encryption. Unlike most other stumblers, it also shows the signal, noise, and signal-to-noise ratio levels.  Additionally, it has GPS support to record AP locations when wardriving.

Keep in mind, NetStumbler hasn't been updated since 2004. It may not run well on Windows Vista or 7, or even 64-bit Windows XP. Additionally, it doesn't show the real encryption methods of APs. If an AP has encryption enabled it's always marked as WEP, regardless if it's WEP, WPA, or WPA2.


Vistumbler is a newer open source stumbler first released in 2007 and updated as recently as 2010. It displays the basic AP details, including the exact authentication and encryption methods, and can even speak the SSID and RSSI of APs.

Similar to NetStumbler, you can view a list of all APs or drill down to those categorized by authentication, encryption, channel, network type, and SSID. You can also view graphs of the AP signals in addition to viewing text readouts. It's highly customizable and offers flexible configuration options. In addition to basic GPS support to record AP locations, it supports live tracking within the application using Google Earth. However unlike NetStumbler, Vistumbler only gives you the signal levels and doesn’t include the noise levels.


InSSIDer is a relatively new open source Wi-Fi stumbler. It shows the usual list of AP details, but doesn't show the exact authentication method. Like most other stumblers, inSSIDer doesn’t include the noise or signal-to-noise (SNR) values; it just gives you the RSSI values.

However, it features very intuitive graphs. The time graph shows the signal levels (in dB values) of each AP for the past 5 minutes. Then there’s a graph for each 2.4GHz and 5GHz channel, showing the current signal levels and channel width usage of each AP. And you can filter out APs based upon the AP's band, channel, signal, security, and age status. It also features GPS support and lets you export to Google Earth.


NetSurveyor is a free but closed source Wi-Fi stumbler and basic analyzer last updated in 2009. It displays the basic AP details, but doesn't specify the exact authentication or encryption method (it just indicates Yes or No for encryption) and doesn't offer any customization.

Though NetSurveyor doesn’t report noise levels, it does offer more graphs than most other free stumblers, including AP Timecourse, AP Differential, Channel Usage, Channel Timecourse, Channel Heatmap, and Channel Spectrogram. It can also record data for extended periods and play it back in the future. You can create useful reports in Adobe PDF format, which includes a snapshot of the AP details and all the graphs


Kismet is a free and open Wi-Fi stumbler, packet sniffer, and intrusion detection system for Windows, Mac OS X, Linux, and BSD. It shows the AP details, including the SSID of "hidden" networks. Plus it reports the noise levels and gives you the signal-to-noise values. It can also capture the raw wireless packets to a PCAP file, so you can import into Wireshark, TCPdump, and other tools.

Kismet, however, in Windows only works with CACE AirPcap wireless adapters due to the limitation of Windows drivers, though it does support a variety of wireless adapters in Mac OS X and Linux.

Xirrus Wi-Fi Inspector

Xirrus Wi-Fi Inspector is a free but closed source Wi-Fi stumbler and basic analyzer. Along with displaying all the usual AP details, it shows a radar view and 8-mintue signal history graph. It also displays the signal and address info for any current connections. Additionally, it offers a simple tool to test connectivity of the main network components, and shortcuts to Web-based speed and connection quality tests. Its export feature lets you save a snapshot of the AP details to a CSV file.Though it doesn’t let you save AP names, it lets you customize some settings, such as the signal unit type (dBm or percentage), RSSI method, and polling interval.

Meraki WiFi Stumbler

This is a simple Web-based stumbler, freely available on the Meraki website. It runs in most browsers on Macs and PCs, and even works when offline. It displays most of the basic wireless details (with signal levels in percentages) and offers a bar graph of APs per channel.

It doesn't allow any customization and doesn't offer any additional functionality beyond displaying the network basics and letting you perform searches of the data. However, this stumbler is still useful if you want to check wireless signals from a computer that doesn't already have a stumbler installed.

If you're a Mac user, you might consider using the KisMAC stumbler and security tool, similar to Kismet. It also reveals "hidden" SSIDs. Along with the other basic details, it can show the AP's clients (with MAC Addresses, IP addresses and signal strengths). Plus it reports the noise levels and gives you the signal-to-noise values. It also supports GPS and mapping, and PCAP import and export. It even includes tools to attack Wi-Fi networks for penetration testing.

Geier is a freelance tech writer—become a Twitter follower to keep up with his writings. He’s also the founder of NoWiresSecurity, which helps businesses easily protect their Wi-Fi network with Enterprise (802.1X) security.

Copyright © 2011 IDG Communications, Inc.