Creating a Monitor Mode Interface

This document does not apply to "old" versions of MadWifi (Prior to November 2005).

To create an interface (called ath0) in monitor mode, issue the command: 

wlanconfig ath0 create wlandev wifi0 wlanmode monitor

Or, 

wlanconfig ath create wlandev wifi0 wlanmode monitor

The only difference is the lack of '0' in the second command. The kernel will give the interface the lowest free integer as its suffix. More information and examples can be found in man wlanconfig 8, and UserDocs/MonitorMode.

To finish bring the interface up 

ifconfig ath0 up

By default, monitor mode receives packets with prism2 headers prepended on them. To change this, you must run one of the following:

  • Only 802.11 headers: echo '801' > /proc/sys/net/ath0/dev_type
  • Prism2 headers: echo '802' > /proc/sys/net/ath0/dev_type
  • Radiotap headers: echo '803' > /proc/sys/net/ath0/dev_type
  • Atheros Descriptors: echo '804' > /proc/sys/net/ath0/dev_type