Sending a single weird packet

Robert Denier denier at umr.edu
Sat Jul 23 23:41:09 EDT 2005


I suspect the firmware is handling the beacon frames but I'm not an
expert here so...  If this is the case then I can't see how you would
change the power setting without the firmware handling the
miscellaneous.  I could be wrong though.

Another approach might be to use a separate card and get that card to
send out your carefully crafted frame.  That way the only thing that
card needs to do is send out that frame and you can do whatever it takes
to make it do it.  One possible way to approach this might be to create
an iwpriv option that when you type

iwpriv wlan0 dospecial

it sends your frame.

I'm not particularly familiar with the hostap code, but I'd guess that
what your doing is going to involve a fair amount of work.  Remember
also that you have to work within the limits of the existing firmware..
Then again there may be an easier way I don't know about.

-Robert


At any rate if that is the case then changing it might be

On Thu, 2005-07-21 at 10:26 -0400, sunny sunny wrote:
> Hi,
> 
> I know this might sound a bit weird, but I want to send a packet which
> is a bit different from the normal hostap packets.
> 
> I have a laptop working as AP using the hostAP drivers (ver 0.0.4).
> During its normal operation I need to send a single packet which will:
> 
> 1. Be transmitted at a different power
> 2. To a client that is not associated
> 3. At a different channel 
> 
> During the transmission of this single packet the clients connected to
> the AP should not be affected (so I cant use it to make the interface
> in ad-hoc mode and then back to master mode). Here is where I am now:
> 
> 1. Transmitting at different power: This list has helped me figure out
> that the way to do this would be to use 'iwpriv' and set the tx power.
> But this results in beacon frames etc being generated which notify all
> the clients that the AP power has changed. Dont want that to happen.
> 
> 2. Sending msg to a non-associated client. I try to set the arp table
> for this and disable arp from the interface on which hostAP is
> running. But hostAP refuses to send the packet out saying that it
> cannot send the packet to a station not associated with it. I am
> thinking of looking up and adding this station to some associated
> station list (still have to find this) and then remove it. Can I do
> this ? Is there a better approach ?
> 
> 3. Sending on different channel. I understand that to do this the only
> way would be to change the channel using iwconfig?
> 
> Other thoughts: 
> Is there some easy way out of all this? Like setup a VLAN ? or send
> the message using some kind of inter AP protocol (the receiver is not
> an AP but I can change that if required)..
> 
> Thanks for your help. Any pointers are helpful.
> Santosh
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