Getting Monitor Mode to work for the Alfa AWUS036H

If you’ve done much work with BackTrack and wireless penetration testing you’re likely using (or at least have heard of) the Alfa AWUS036H. If you haven’t, it is simply a USB-connected wireless adapter that supports long range, various external antennas, has built-in driver support in BackTrack, and supports the all-important (for this type of work) monitor mode.

After doing a bit of reading, and preparing my lab equipment, I fired up BackTrack, attempted to put the card into monitor mode and… nothing. The following is a listing of the steps I took and what I did to get it working. At this point I should also note that I’m doing this work on an HP EliteBook 2760p which has its own in-built wireless adapter.

Start the wireless adapter by issuing ifconfig wlan1 up (my in-built adapter was wlan0). Running ifconfig confirmed that my adapter was seen by the operating system

Then I attempted to list the available interfaces for monitoring using the aircrack-ng tools

and it would just hang here for as long as I wanted to wait.

I spent a good bit of time poking around and trying to ascertain what was/wasn’t working and assumed that maybe it was a driver issue. I ran lshw –c network to get a list of my network devices and the drivers that they were using.

From this, I could see that both devices were loaded and appeared to be running the correct drivers. On a whim, I decided to eliminate extra variables and disable the in-built wireless card by issuing modprobe –r iwlagn (the driver for the built-in card).

I then went back to see if airmon-ng would see my Alfa card, which it did:

Encouraged by this, I attempted to put it in monitor mode (airmon-ng start wlan1) which also succeeded:

At this point, running ifconfig showed both the wireless card and the monitor-mode device.

And running WireShark or other tools were now able to see the device and capture packets.