ath9k: packets sent twice 1Mbps & 54Mbps

ath9k: packets sent twice 1Mbps & 54Mbps

[Anthony]

Hi all,
I'm using:
Ubuntu 9.10
Atheros card with ath9k
compat-wireless latest stable version
ad-hoc 802.11g with 2 nodes (same hardware & software configuration)

I tried to inject packets using mac80211 (similar way as in packetspammer)
Radiotap header contains only Flag=0 & Rate=1Mbps (total size = 14 bytes)
However when I use wireshark to capture traffic, I discovered that
each frame was sent twice:
first time with 14 bytes radiotap header
second time with 13 bytes of radiotap header (Rate omitted), so 54Mbps here.

Is this a problem of ath9k or a default feature of 802.11 ???

Another question: if I set the FCS flag to send frame with all zeros
FCS, the receiver reported frame as bad FCS, but still deliver it to
upper layer. Why? I think the frame should be discarded ? I want to
simulate broken phy link by jamming FCS. Is there any alternative way
?

Hope some one can help.

Thank you.

Anthony

Re: ath9k: packets sent twice 1Mbps & 54Mbps

[Gábor Stefanik]

On Wed, Mar 24, 2010 at 9:43 AM, Anthony <lazugau@gmail.com> wrote:
> Hi all,
> I'm using:
> Ubuntu 9.10
> Atheros card with ath9k
> compat-wireless latest stable version
> ad-hoc 802.11g with 2 nodes (same hardware & software configuration)
>
> I tried to inject packets using mac80211 (similar way as in packetspammer)
> Radiotap header contains only Flag=0 & Rate=1Mbps (total size = 14 bytes)
> However when I use wireshark to capture traffic, I discovered that
> each frame was sent twice:
> first time with 14 bytes radiotap header
> second time with 13 bytes of radiotap header (Rate omitted), so 54Mbps here.

Are you sure it is not the AP relaying the packet?

>
> Is this a problem of ath9k or a default feature of 802.11 ???
>
> Another question: if I set the FCS flag to send frame with all zeros
> FCS, the receiver reported frame as bad FCS, but still deliver it to
> upper layer. Why? I think the frame should be discarded ? I want to
> simulate broken phy link by jamming FCS. Is there any alternative way
> ?
>
> Hope some one can help.
>
> Thank you.
>
> Anthony
> --
> To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>



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Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-)

Re: ath9k: packets sent twice 1Mbps & 54Mbps

[Gábor Stefanik]

2010/3/24 Gábor Stefanik <netrolller.3d@gmail.com>:
> On Wed, Mar 24, 2010 at 9:43 AM, Anthony <lazugau@gmail.com> wrote:
>> Hi all,
>> I'm using:
>> Ubuntu 9.10
>> Atheros card with ath9k
>> compat-wireless latest stable version
>> ad-hoc 802.11g with 2 nodes (same hardware & software configuration)
>>
>> I tried to inject packets using mac80211 (similar way as in packetspammer)
>> Radiotap header contains only Flag=0 & Rate=1Mbps (total size = 14 bytes)
>> However when I use wireshark to capture traffic, I discovered that
>> each frame was sent twice:
>> first time with 14 bytes radiotap header
>> second time with 13 bytes of radiotap header (Rate omitted), so 54Mbps here.
>
> Are you sure it is not the AP relaying the packet?

Sorry, I had a blonde moment and didn't notice that you are using adhoc.

>
>>
>> Is this a problem of ath9k or a default feature of 802.11 ???
>>
>> Another question: if I set the FCS flag to send frame with all zeros
>> FCS, the receiver reported frame as bad FCS, but still deliver it to
>> upper layer. Why? I think the frame should be discarded ? I want to
>> simulate broken phy link by jamming FCS. Is there any alternative way
>> ?
>>
>> Hope some one can help.
>>
>> Thank you.
>>
>> Anthony
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>
>
>
> --
> Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-)
>



-- 
Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-)