Re: Q: 802.11 vap monitor mode

Weongyo Jeong wrote:
> During testing a new driver, I got a problem to test a monitor mode at
> 802.11 vap I'm using.
>
> # uname -a
> FreeBSD kkk 8.0-CURRENT FreeBSD 8.0-CURRENT #6: Wed May 14 11:27:37 KST
> 2008     root_at_kkk:/usr/obj/usr/src/sys/GENERIC  i386
> # ifconfig wlan0 create wlandev upgt0 wlanmode monitor
> # ifconfig wlan0 up
> # ifconfig
> [...]
> upgt0:
> flags=108943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST,NEEDSGIANT>
> metric 0 mtu 2290
>         ether 00:0f:b5:dd:6f:36
>         media: IEEE 802.11 Wireless Ethernet autoselect mode 11g
> <monitor>
>         status: running
> wlan0:
> flags=28943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST,PPROMISC>
> metric 0 mtu 1500
>         ether 00:0f:b5:dd:6f:36
>         inet6 fe80::20f:b5ff:fedd:6f36%wlan0 prefixlen 64 scopeid 0xd 
>         media: IEEE 802.11 Wireless Ethernet autoselect mode 11g
> <monitor>
>         status: running
>         ssid "" channel 1 (2412 Mhz 11g) bssid 00:0f:b5:dd:6f:36
>         country US authmode OPEN privacy OFF txpower 0 scanvalid 60
>         protmode CTS
>
> As seeing, it looks work but the problem is happend when I ran stumbler
> (src/tools/tools/net80211/stumbler) program.
>
> The error message is "ioctl(BIOCSDLT): Invalid argument" that it's
> emitted to screen when I execute the following command:
> # ./stumbler wlan0
>
> Are there something I missed?
>   
What DLT is stumbler using?  If it's requesting IEEE802_11_RADIO then 
this will fail as that is not available for the vap, only for the 
underlying device.  This is an open issue that I'm looking for help 
with--previously an 802.11 device supported 3 DLT's: 802.3, 802.11, and 
radiotap but now it only supports the first 2.  The net80211 layer does 
not have all the data required to dispatch radiotap headers (only the 
driver does) so we need to push the information up to net80211 for each 
rx'd packet (possibly expensive) or provide some net80211-level support 
for dispatching radiotap data through vap's.

    Sam