[ath9k-devel] Packet Injection in Monitor Mode Sending Packets Twice

[Michael Stahn <michael.stahn.42@gmail.com>]

The reason is because you're in monitor mode: Your card receives
anything in the air, even it's from its own source. Because you're in
monitor mode, you receive the packet you've just sent out as the card
sees it's own signals, too. Your radiotap header should slightly differ
for both packets in most cases.

-mike

On 25.03.2015 15:42, Federico Tramarin wrote:
> In our experiments, with a very similar PCI card, we saw exactly the same behavior?.
> 
> However, are you using wireshark on the same PC your are using for transmission?
> 
> Since in this case you will see the duplicate packets, while on an external monitoring (passive) PC you will see 
> your single packet, as expected.
> 
> Let me know
> 
> Cheers,
> 
> Federico
> 
> 
>> Il giorno 25/mar/2015, alle ore 15:26, Mark Gannon <mark@truenorth.nu> ha scritto:
>>
>> On Wednesday, March 25, 2015 10:49:43 AM Thomas V wrote:
>>> There is a possibility that the 1st frame is retried. Can you check for the
>>> "retry bit"  in the sniffer capture.
>>
>> The retry flag in the IEEE 802.11 section is set to zero for both the first and 
>> second packet.  Here is a text version of Wireshark's exported packet 
>> dissection for the second packet:
>>
>> IEEE 802.11 Data, Flags: .......T
>>    Type/Subtype: Data (0x0020)
>>    Frame Control Field: 0x0801
>>        .... ..00 = Version: 0
>>        .... 10.. = Type: Data frame (2)
>>        0000 .... = Subtype: 0
>>        Flags: 0x01
>>            .... ..01 = DS status: Frame from STA to DS via an AP (To DS: 1 
>> From DS: 0) (0x01)
>>            .... .0.. = More Fragments: This is the last fragment
>>            .... 0... = Retry: Frame is not being retransmitted
>>            ...0 .... = PWR MGT: STA will stay up
>>            ..0. .... = More Data: No data buffered
>>            .0.. .... = Protected flag: Data is not protected
>>            0... .... = Order flag: Not strictly ordered
>>    .000 0000 0000 0000 = Duration: 0 microseconds
>>    Receiver address: Broadcast (ff:ff:ff:ff:ff:ff)
>>    BSS Id: Broadcast (ff:ff:ff:ff:ff:ff)
>>    Transmitter address: 13:22:33:44:55:66 (13:22:33:44:55:66)
>>    Source address: 13:22:33:44:55:66 (13:22:33:44:55:66)
>>    Destination address: 13:22:33:44:55:66 (13:22:33:44:55:66)
>>    Fragment number: 0
>>    Sequence number: 2145
>>
>> Thanks for your help!
>>
>> Regards,
>>
>> Mark Gannon
>>
>> -- 
>> You have to accept whatever comes, and the only important thing is that you 
>> meet it with the best you have to give. 
>>
>> 	? Eleanor Roosevelt_______________________________________________
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