Raw ethernet socket

Hi all,
I've got the following scenario

Access Point (AP) connected to rest of the nework
Mobile Node (MN) connected to AP through a WiFi 802.11g link

AP is Master mode
MN is Managed mode

AP plus MN create a subnet (defined by themselves only)

On both AP and MN a process is running which opens a raw ethernet
socket; I just fill the Header Source, Destination and Type Options of
the packet and send it; everything works fine, the parsing is working
and when I receive a request packet on the AP it replies with response
to MN and viceversa in a symmetric way

Everything messes up when I try the same with broadcast destination
option (FF:FF:FF:FF:FF:FF): when I try this the result is Asymmetric
and as I send one request from MN, I can se 3 of them on the log
created by my process on the AP. Then of course I get 3 replies on the
MN.
Do you have any clue why this is happening?

I want to give a couple of hints that maybe could help:
1) when I read the packets received in the AP through Ethereal I try
to read them both from the interface ath0 and from the device wifi0
and I get different results, like in the process of forwarding the
packet from the hardware device to its interface a new request is
created.
2) ethereal on MN and AP reads different number of packets (promisquus
mode or not)
-----
What I think is some sort of repeater inside the AP which clone the
packet and queue the clones in the stack for some reasons... if you
have any clue please let me know! Thank you!

InuY4sha wrote:
> Hi all,
> I've got the following scenario
>
> Access Point (AP) connected to rest of the nework
> Mobile Node (MN) connected to AP through a WiFi 802.11g link
>
> AP is Master mode
> MN is Managed mode
>
> AP plus MN create a subnet (defined by themselves only)
>
> On both AP and MN a process is running which opens a raw ethernet
> socket; I just fill the Header Source, Destination and Type Options of
> the packet and send it; everything works fine, the parsing is working
> and when I receive a request packet on the AP it replies with response
> to MN and viceversa in a symmetric way
>
> Everything messes up when I try the same with broadcast destination
> option (FF:FF:FF:FF:FF:FF): when I try this the result is Asymmetric
> and as I send one request from MN, I can se 3 of them on the log
> created by my process on the AP. Then of course I get 3 replies on the
> MN.
> Do you have any clue why this is happening?
>
> I want to give a couple of hints that maybe could help:
> 1) when I read the packets received in the AP through Ethereal I try
> to read them both from the interface ath0 and from the device wifi0
> and I get different results, like in the process of forwarding the
> packet from the hardware device to its interface a new request is
> created.
> 2) ethereal on MN and AP reads different number of packets (promisquus
> mode or not)
> -----
> What I think is some sort of repeater inside the AP which clone the
> packet and queue the clones in the stack for some reasons... if you
> have any clue please let me know! Thank you!
>

There are two options: either the MN sends it three times (for some
reason) and thus the packet is send three times over the air. Or as you
suggest, it is only sent once over the air but is duplicated on the AP.
You can use a wireless sniffer to pinpoint the cause.

If your AP has wired interfaces, you can try sending the broadcast
packet to a wired interface. This may be easier to debug using a third
host and a hub. You may/may not see the same behaviour.