[Click] Help!! Madwifi Monitor Mode vs Ad-Hoc Mode... Annotations?

[Harald Schiöberg]

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g91d5350 at campus.ru.ac.za wrote:
> Javier, Harald - Thanks, you guys rock!
> 
> The psuedo-ibss code works a treat, thanks!  The version in my  
> /click/conf/wifi seems to be out-of-date (although my click should be  
> current), so I really appreciate having some working sample code as a  
> starting point.
> 
> But when I try to ping across the psuedo-ibss connection, I get  
> duplicate packets (see ping log below).  Yet SSH seems to work fine.   
> Any idea why this would be?

do you use kernel or userspace? in userspace you may want the
SNIFFER=false option to your FromDevice element, otherwise both click
and the kernel forward the packet.

another thing: if you create a monitor interface and an ibss interface
on the same atheros card, the ibss interface silently goes into promisc.
mode, gave me some headache with duplicated packets while routing with
more than 2 nodes


> I am still battling to understand why I have to encapsulate my frames  
> and can't send them RAW.  

Well, because you are using an 802.11 network. and as such you need
802.11 headers which are totally different from 802.3 headers.

It's just the linux device driver that emulates an 802.3 interface if
you are using anything but monitor mode. In reality the driver will do a
 conversion from 802.3 to 802.11 for you. so even if you run tcpdump on
the athX interface, you will see 802.3 frames, but those where never
send over the network.

try creating a monitor vif on the same physical iface that you are
running your click on, and run a tcpdump there, you'll see that actually
802.11 frames are transmitted, you'll never ever see a 802.3 frame there.

If you use monitor mode you have to do all the conversion yourself, and
basically everything else that the driver does for you, such as rate
control, power mgmt, associations, ....


> As far as I can see, I can deliver RAW  
> frames across the network OK ... I just seem to have problems  
> forwarding them to Linux.  Oh well... by this time next week I'll have  
> twice the Click experience I have now; I'll learn.  :-)
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