[rt73usb] Master Mode almost done; problem with ARP

[rt73usb] Master Mode almost done; problem with ARP

[Alexandre Becholey]

Hi,

As the subject says, the master mode for rt73usb is almost fixed. Here 
is my setup:
- An access point running hostapd with an ethernet interface (eth0) and 
a wireless interface (wlan0, the wifi usb dongle) which are bridge 
together (br0)
- a computer directly (or through a switch with other computer) 
connected to the AP's eth0
- two computers associated to wlan0
(they all are on Linux)

Here is what I can do:
- Stations can associate with the wifi usb dongle
- Stations can ping, ssh,... the AP
- Stations can ping, ssh,... any other stations
- Stations can ping, ssh,... any computers on the LAN
- AP can ping any computers on the LAN
- Computers on the LAN can ping the AP

And what I can't do:
- Computers on the LAN can't ping the stations (Destination Host 
Unreachable)
- AP can't ping the stations

I ran wireshark on a computer on the LAN, on the AP (here I used tcpdump 
on all interfaces because I don't have the possibility to have X) and on 
a stations. I would say that's a problem with ARP packets.
When I try to ping a station from the AP or a LAN computer, ARP requests 
arrive to the AP (I see them on eth0, wlan0 and br0), but they don't 
arrive to the stations (I can't see any ARP packets in the air and I use 
a different wireless interface to monitor than the one that is 
associated with the AP).
When with that station I ping the AP (or the lan computer, it doesn't 
matter), the first ping (from AP or lan) works until I stop the ping 
started on the station.

I was wondering if the fix I did (the one we were discussing the 5th 
March) on the rt73 driver may be the cause of that problem.

Best regards,

Alexandre Becholey

Re: [rt73usb] Master Mode almost done; problem with ARP

[Johannes Berg]

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On Fri, 2009-05-08 at 11:08 +0200, Alexandre Becholey wrote:

> And what I can't do:
> - Computers on the LAN can't ping the stations (Destination Host 
> Unreachable)
> - AP can't ping the stations
> 
> I ran wireshark on a computer on the LAN, on the AP (here I used tcpdump 
> on all interfaces because I don't have the possibility to have X) and on 
> a stations. I would say that's a problem with ARP packets.

Here's a similar bug -- the debugging I did there you should do here.

http://bugzilla.kernel.org/show_bug.cgi?id=13237

johannes

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Re: [rt73usb] Master Mode almost done; problem with ARP

[Alexandre Becholey]

Johannes Berg wrote:
> On Fri, 2009-05-08 at 11:08 +0200, Alexandre Becholey wrote:
>
>   
>> And what I can't do:
>> - Computers on the LAN can't ping the stations (Destination Host 
>> Unreachable)
>> - AP can't ping the stations
>>
>> I ran wireshark on a computer on the LAN, on the AP (here I used tcpdump 
>> on all interfaces because I don't have the possibility to have X) and on 
>> a stations. I would say that's a problem with ARP packets.
>>     
>
> Here's a similar bug -- the debugging I did there you should do here.
>
> http://bugzilla.kernel.org/show_bug.cgi?id=13237
>
> johannes
>   
I said something wrong: from any stations, I can't ssh the AP (it works 
only if from the station pings the AP during the ssh). I made a few 
other observations:

I start a ping from a LAN computer to a futur associated station (all IP 
are fix). When the station finished the association, the ping works for 
20 sec (it seems to correspond to the time an entry stays in the ARP 
table) and then Destination Host Unreachable.
As soon as I start a ping from the station to the LAN computer, the LAN 
computer's ping receive the responses, but when I stop the ping from the 
station, the LAN computer's ping don't receive the respond any more even 
if I stop it before 20sec are elapsed... I think it's more than just a 
problem with the ARP table.


I looked at the patch given in the bug you gave me, the ralink driver 
seems do the things correctly.

Alexandre