802.11 monitor mode changes coming

Lars Engels lars.engels at 0x20.net
Tue May 19 13:52:33 UTC 2009

Quoting Sam Leffler <sam at errno.com>:

> The patch here:
> http://people.freebsd.org/~sam/monitor-20090518.patch
> has significant changes to monitor mode operation.  Most importantly it
> replaces DLT_IEEE802_11 support in net80211 by DLT_IEEE802_11_RADIO and
> removes the latter from the underlying device.  The upshot is that you
> can no longer do:
> tcpdump -i ath0
> instead you will now need a wlanX ifnet; e.g.
> ifconfig wlan create wlandev ath0 wlanmode monitor channel 6 up
> tcpdump -i wlan0 -y IEEE802_11_RADIO
> This addresses the longstanding issue that applications like kismet
> that want radiotap data needed to open two ifnets, one to receive data
> and one to do channel changes.  My main concern is whether losing
> DLT_IEEE802_11 support will affect any apps.  Those that depend on it
> should be easy to change; you just request a different DLT and strip
> the radiotap header from tap'd frames (or similar).
> In sweeping the drivers to do these changes I've made radiotap support
> more consistent and improved some drivers.  Drivers not tested so far:
> malo, ipw, wpi, and upgt.  I tested iwi and it appears broken in that
> no frames are rx'd but I'm not sure I'll look at it before 8.0.
> I plan to commit these changes by the end of the week.
>    Sam

Thanks, this should improve operability of aircrack-ng, too.
I will try this tomorrow.
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