Re: Jamming the WiFi channel

[Christophe Seguinot]

Oups

I've seen your flowgraph

Sawtooth generator frequency can not exceed sampling_rate/2, but it's set to 1 THz !!!  Should be 100kHz (for 10 µs)

The waterfall can not be used to obtain the measurements you get with a spectrum analyzer.

• with 20 Mhz sampling_rate , each sawtooth period (10µs / 0.1 MhZfrequency) correspond to 20M/0.1M= 200 samples / period.
• when the fft is calculated, is uses fft_size point.
  
• So when a fft is calculated, even with as low as 128 FFT size, it cover a half the sawtooth period and cover approximately half the frequency range of the VCO output.
  
• So to obtain a waterfall one would at least increase sampling_rate to its maximum, while decreasing fft_size. Even if that was possible, the resolution would be too low
  

In fact, a spectrum analyzer is far more performant than any simulator.

On 03/02/2021 17:09, paullescot@mailo.com wrote:

Hello,

I have successfully build a jamming signal for a WI-FI channel and I am able to transmit it using the hackrf.

It is a 10us jamming signal as shown in the picture from a lab spectrum analyser. However, I am trying to have the same visualisation on gnuradio using a waterfall block (I am planning to use this jamming signal in a simulation experiment and I am to be sure that the hackrf does not transform in any way the baseband signal) but I cannot find parameters such as sweep time, bandwidth resolution, span... are there equivalents parameters in gnuradio's QT visualizations blocks ?

Thanking you in advance,

PL

From: Cinaed Simson <cinaed.simson@gmail.com>
To: discuss-gnuradio@gnu.org
Subject: Re: Jamming the WiFi channel
Date: 17/01/2021 22:38:36 Europe/Paris

Hi JM - I agree.  And typically with knowing very little about
anything,  one can jam WIFI using aircrack-ng.

But I would argue the SDR doesn't have to handshake with the receiver or
scan the network, so it may be more efficient.

But on the other hand, you may need more computing power then Raspberry Pi.

-- Cinaed

On 1/17/21 9:51 AM, jean-michel.friedt@femto-st.fr wrote:
> We might hide or we might discuss ... jamming systems are less than 10 euros on amazon [0]
> for any script-kiddie to play with including myself [1]. Why anyone one would want to
> implement this in SDR rather than a NE555+VCO is beyond my understanding by why not ...
> we even got to reverse engineer such a device to check its performance. The military
> will pay you for doing this [2] (and a bit more) so rather than hiding from the real
> world we might as well face it and educate users.
>
> My (useless) 2 cents, but thank you for the most informative reference and its introductory
> citation
> JM
>
> [0] https://www.amazon.fr/IrahdBowen-Bloqueur-Bouclier-Brouilleur-Disjoncteur/dp/B07KSC5LLD
> [1] http://jmfriedt.free.fr/misc_deleurrage.pdf [in French] on GPS jamming and jamming cancellation
> [2] https://www.defense.gouv.fr/aid/appels-a-projets/appel-a-projets-pour-une-mini-charge-utile-d-appui-electronique-sur-drones [in French]
>
> --
> JM Friedt, FEMTO-ST Time & Frequency, 26 rue de l'Epitaphe, 25000 Besancon, France
>
> January 17, 2021 6:24 PM, "Aditya Arun Kumar" <adityaarunkumarphi@gmail.com> wrote:
>
>> Hi Derek,
>> Yeah, I accept all the things, after all, I have to, as I tend to wireless systems and their
>> security and some more stuff with regards to radios and SDR and things. But what I suggest is that
>> we guys start a separate application/discussion area for these kinds of things (because I
>> personally as well to some extent historically believe[ https://doi.org/10.1080/03071847709428739
>> ]) that this must be an integral part of the ecosystem. I accept the part where one needs to have
>> proper RF enclosures or a SCIF to conduct these emission experiments (unless it a wide range of
>> open testing).
>>
>> I propose that we have a separate discussion for things like this, just for educational purposes,
>> because I feel that there is too much "Telecommunications" research happening, but very quiet a
>> limited discussion regarding "What is the best way to build a signal for a jammer from its spectra"
>> or "What happens in spatial resolution compromise in a RADAR system and how this can be a problem".
>> Basically, I am trying to say let's break the taboo about the discussion about EW and SIGINT and
>> ELINT using SDR and GRC. After all, radios are fun.
>>
>> This part goes to Mr.Robert
>> In my humble opinion sir, I don't agree with you not one bit. Technology is a dual-edged sword, and
>> radio is a knife with jagged and pointy edges everywhere. There is no concept of morality (at least
>> it cannot be quantified by any metric). EW is an integral part of our life now. And people who are
>> into it can and should be able to learn it, no matter what, no matter the cost. This is knowledge
>> and as I can say GRC taught me a lot, in terms of learning and sharing their knowledge be it in
>> blogs or conferences or this mail list. In fact, this kind of question needs to be encouraged but
>> with significant warning labels around them.
>>
>> On Sun, Jan 17, 2021 at 9:32 PM Robert Heerekop <robertheerekop@gmail.com> wrote:
>>
>>> To my humble opinion, this is simply not allowed and must therefore from a moral point-a-view not
>>> be promoted.
>>>
>>> Op zo 17 jan. 2021 16:29 schreef Aditya Arun Kumar <adityaarunkumarphi@gmail.com>:
>>>
>>>> On a serious note, I know that all of us know how to build a jammer, in case of questions like this
>>>> how do we deal with it?
>>>> I mean I can do both sides, in the spirit of sharing the knowledge I think that someone should tell
>>>> the person who is doing it on how to build a jammer (in this case) or should we not help the
>>>> person?
>>>> Or should we condemn these acts?
>>>>
>>>> On Sun, Jan 17, 2021 at 10:15 AM Doug McGarrett <dmcgarrett@optonline.net> wrote:
>>>>
>>>>> On 1/16/21 10:58 PM, paullescot@mailo.com wrote:
>>>>>>
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>>>>>> Mailo *1 fichier disponible au téléchargement*
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>>>>>> * hackrf2.png (35 Ko)
>>>>>>
>>>>>> Vous pouvez télécharger ce fichier en cliquant sur ce lien ou en le
>>>>>> copiant dans la barre d'adresse de votre navigateur
>>>>>>
>>>>> <https://www.mailo.com/attachlinks.php?id=MTg2NDQuPGVhLW1pbWUtNjAwM2I1Y2ItMTRjNS0yN2Q0OGNlZUB3d3ctMS
>>>>> tYWlsby5jb20%2b>
>>>>>>
>>>>> https://www.mailo.com/attachlinks.php?id=MTg2NDQuPGVhLW1pbWUtNjAwM2I1Y2ItMTRjNS0yN2Q0OGNlZUB3d3ctMS5
>>>>> YWlsby5jb20%2b
>>>>>> Ce lien restera valable pendant 30 jours.
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>>>>>>
>>>>>> Hello, I have build a VCO jammer using gnuradio and I would like to
>>>>>> emit the jamming signal on a Wi-Fi channel but nothing is being emitted.
>>>>>>
>>>>>> Can anyone please help me ?
>>>>>>
>>>>>> I am newbie to signal processing.
>>>>>>
>>>>>> PL
>>>>>>
>>>>>>
>>>>> Probably even in France it is illegal to jam radio signals. I sure hope
>>>>> that NOBODY helps you!
>>>>> --doug
>>>> --
>>>> S. Aditya Arun KumarSecurity Researcher, Comms+919123517465
>> --S. Aditya Arun KumarSecurity Researcher, Comms+919123517465
> .