How to identify the WIFI device?

[pokerbirch]

I'm scripting the "iwconfig" and "airmon-ng" start/stop commands with Python. My script currently calls iwconfig and parses the output to make a list of active devices. It then uses that list to send the "airmon-ng stop xxx" command to each device. So now iwconfig returns:

lo no wireless extensions.
eth1 no wireless extensions.
wifi0 no wireless extensions.
Now i need to restart one of the devices in monitor mode. That is a simple call to "airmon-ng start xxx", but WHICH device? I obviously know that i should use "wifi0" but how would my script make that decision? Is there another command i can call to identify wifi0 as my wifi device? "wifi0" could be hard-coded, but, for instance, my desktop pc names the wifi device "wlan0" which would obviously render the script useless.


EDIT:
A possible solution would be to loop through the list of devices, issuing the "airmon-ng start" command to each one until we get a "(monitor mode enabled)" output and/or reach the end of the list. Would there be any problems in doing this?

[Martin Witte]

when you have a wireless connection iwconfig prints something like


martin@toshibap200:~$ iwconfig
lo no wireless extensions.

eth0 no wireless extensions.

wmaster0 no wireless extensions.

ath0 IEEE 802.11bg ESSID:"SX551D431D8"
Mode:Managed Frequency:2.412 GHz Access Point: 00:01:E3:D4:31:D8
Bit Rate=24 Mb/s Tx-Power=20 dBm
Retry min limit:7 RTS thr:off Fragment thr=2352 B
Power Management:off
Link Quality=48/100 Signal level:-64 dBm Noise level=-95 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0

martin@toshibap200:~$

so in my case ath0 is the wireless interface. Your output doesn't show a wireless interface. An alternative command you can consider is iwgetid


martin@toshibap200:~$ iwgetid
ath0 ESSID:"SX551D431D8"
martin@toshibap200:~$


see this (http://en.wikipedia.org/wiki/Wireless_tools_for_Linux) page as well for some more info on Linux wireless

[pokerbirch]

Yes, that is correct. After i have stopped all wireless devices with the "airmon-ng stop" command my listing is correct. ath0 only appears after i run "airmon-ng start wifi0" which is also correct behaviour. In order to put a wifi device into "monitor" mode, you have to stop it and then restart it which is why i am scripting the commands. What i am asking is: how can i make my script identify that it should use "wifi0" rather than "lo" or "eth1" when issuing the "airmon-ng start" command?

The only solution i have so far is to loop through all the devices until i get an output containing "monitor mode enabled". It's a bit kludgy, but it works. I was hoping there might be a cleaner way...

[soltanis]

Use the one named wifi0. That seems to be how your driver enables the device. Other drivers behave differently: my wireless card is named wlan0.

[pokerbirch]

Use the one named wifi0. That seems to be how your driver enables the device. Other drivers behave differently: my wireless card is named wlan0.

Yes, but hard coding it as "wifi0" is not much use on a different pc...

[soltanis]

Yes, but I notice that for the most part, wireless interfaces have a "w" in the first position. I suggest you use this as a heuristic to pick a card that looks like it would be a wireless card first, then if that fails, cycle through the rest using the brute force method.

[Martin Witte]

Yes, but I notice that for the most part, wireless interfaces have a "w" in the first position. I suggest you use this as a heuristic to pick a card that looks like it would be a wireless card first, then if that fails, cycle through the rest using the brute force method.

Mine is ath0, so it wouldn't be detected under this rule

[tturrisi]

Have a look at airoscript to see how to detect the interface on the system:
http://airoscript.aircrack-ng.org/