Netstumbler for Linux

NetStumbler (also known as Network Stumbler) is a free/”beggarware” tool for Windows that can detect WiFi/Wireless LANs using the 802.11b, 802.11a and 802.11g WLAN standards.

An alternative to Netstumbler that works on Linux is called Kismet and uses RFMON to passively detect networks.

Wireless Extension (WE) and Wireless Tools (WT)

If you only have basic wireless detection/scanning requirements on Linux you can use Wireless Extensions (WE) and Wireless Tools (WT) that are usually already included in most Linux distributions.

The Wireless Extension (WE) is a generic API allowing a driver to expose to the user space configuration and statistics specific to common Wireless LANs. The beauty of it is that a single set of tool can support all the variations of Wireless LANs, regardless of their type (as long as the driver supports Wireless Extension). Another advantage is these parameters may be changed on the fly without restarting the driver (or Linux).

The Wireless Tools (WT) is a set of tools allows manipulation of the Wireless Extensions (WE). They use a textual interface and are rather crude, but aim to support the full Wireless Extension. There are many other tools you can use with Wireless Extensions, however Wireless Tools is the reference implementation.

• iwconfig manipulate the basic wireless parameters
• iwlist allow to initiate scanning and list frequencies, bit-rates, encryption keys…
• iwspy allow to get per node link quality
• iwpriv allow to manipulate the Wireless Extensions specific to a driver (private)
• ifrename allow to name interfaces based on various static criteria

Linux Wireless Tools Example

The examples below are from my Nokia N800 Internet tablet. It is running a Debian based Linux and has the Linux wireless tools.

Using iwconfig I can see which interfaces support the wireless extensions.

Nokia-N800-23-14:~# iwconfig
lo        no wireless extensions.

wlan0     IEEE 802.11b/g  ESSID:"venetian"
          Mode:Managed  Frequency:2.462 GHz  Access Point: 00:0B:85:FF:FF:FF
          Bit Rate=54 Mb/s   Tx-Power=19 dBm   Sensitivity=0/200
          RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:on
          Link Quality=44/0  Signal level=-49 dBm  Noise level=-93 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:83  Invalid misc:0   Missed beacon:0

Nokia-N800-23-14:~#

In my case wlan0 will be used with Linux wireless tools to get similar information to what Netstumbler provides.

Results for iwlist wlan0 scanning command are below.

Nokia-N800-23-14:~# iwlist wlan0 scanning
wlan0     Scan completed :
          Cell 01 - Address: 00:0B:85:FF:FF:FF
                    ESSID:"venetian"
                    Mode:Master
                    Encryption key:on
                    Channel:11
                    Quality:43/0  Signal level:-51 dBm  Noise level:-94 dBm
                    IE: WPA Version 1
                        Group Cipher : TKIP
                        Pairwise Ciphers (1) : TKIP
                        Authentication Suites (1) : PSK
          Cell 02 - Address: 00:0F:66:FF:FF:FF
                    ESSID:"linksys"
                    Mode:Master
                    Encryption key:off
                    Channel:6
                    Quality:10/0  Signal level:-84 dBm  Noise level:-94 dBm
          Cell 03 - Address: 00:A0:C5:FF:FF:FF
                    ESSID:""
                    Mode:Master
                    Encryption key:on
                    Channel:11
                    Quality:43/0  Signal level:-51 dBm  Noise level:-94 dBm
          Cell 04 - Address: 00:0B:85:FF:FF:FF
                    ESSID:"venetian"
                    Mode:Master
                    Encryption key:on
                    Channel:1
                    Quality:37/0  Signal level:-57 dBm  Noise level:-94 dBm
                    IE: WPA Version 1
                        Group Cipher : TKIP
                        Pairwise Ciphers (1) : TKIP
                        Authentication Suites (1) : PSK

Note: In the results above I have edited the MAC addresses of the access points.

Graphical User Interfaces for Wireless Tools on Linux

Many GUI configuration and management tools are available if you need a graphical view of wireless tools. Below is a screen shot of KWiFiManager, a set of KDE tools using Wireless Extensions.

Related posts:

1. Linux Wireless LAN Support
2. Windows Vista Netstumbler
3. 8 Free Alternatives to NetStumbler
4. How NOT To Increase Your Wi-Fi Signal
5. RFMON – Radio Frequency Monitoring, Monitor Mode

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