Once your wireless card in Linux has been placed in monitor mode, you are ready to start capturing wireless traffic. Recall that wireless cards can only capture traffic on a single channel at any given time. If you know the wireless channel you want to capture traffic on, configure your wireless card to listen on that channel using the iwconfig utility:

# iwconfig ath0 channel 1# iwconfig ath0

Replace ath0 with the name of your wireless interface, and the number 1 with the channel number you want to capture traffic on. As seen from the output of the iwconfig command, the card is currently configured to listen on 2.412 GHz (channel 1).

If you don t know the target channel number you want to use to capture traffic, you can configure your wireless card to perform channel hopping. Unfortunately, Linux doesn t come with a built-in tool for channel hopping; however, you can configure channel hopping manually with a short shell script. Enter the text found in Code 6.1 into a short shell script using your favorite text-editor. Line numbers have been added for clarity; do not enter the line numbers when creating this script.

1.  #!/bin/bash2.  IFACE=ath03.  IEEE80211bg="1 2 3 4 5 6 7 8 9 10 11"4.  IEEE80211bg_intl="$IEEE80211b 12 13 14"5.  IEEE80211a="36 40 44 48 52 56 60 64 149 153 157 161"6. ...