[Xastir] UDP frames

[J. Lance Cotton]

Alan Crosswell wrote:
> Bill Vodall wrote:
>> Hmmm.   Taking this a bit further.  Won't an 802.11x device have to be
>> in ESS (peer-to-peer mode) instead of IBSS (controlled by an Access 
>> Point)
>> before it can pick up raw UDP packets?    This shouldn't be hard to 
>> test..
> 
> Nope.  UDP is just UDP.  What the infrastructure (or lack thereof) does 
> is irrelevant.  Think of it as working simplex (ESS) vs. working via a 
> repeater/digipeater (IBSS) is all.

Except that if your 802.11b card is blasting away UDP packets in ad-hoc 
mode with the 'ssid' set to "abcd" and my 802.11b card is sitting next 
to it in ad-hoc mode with the 'ssid' set to "wxyz", my card doesn't hear 
anything from yours. So there has to be some amount of coordination. 
It's obviously not the same as AP association, but it's similar. Kismet, 
the 802.11 sniffer requires that your wireless card driver allows the 
card to be put in 'rfmon' mode, which is like promiscuous mode for wired 
ethernet. There has to be some kind of 'association' using the ssid or 
you have the equivalent of an ethernet card with no cable plugged in.

Now, if we could get a wedge program that would turn on rfmon mode in 
the wireless driver, then we could have a 1-to-1 equivalent with 
AX.25/APRS...

-Lance

> You use UDP all the time when you watch streaming video or other 
> applications like that which can tolerate some packet loss and keep 
> working.  You drop some video packets, the picture just gets a little 
> jumpy but it keeps working.
> 
> /a
> 
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-- 
J. Lance Cotton, KJ5O
joe at lightningflash.net
http://map.findu.com/kj5o-12
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