Forums - can I get an ap list while in monitor mode?

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can I get an ap list while in monitor mode?
jshenry1963
Join Date: 17 Nov 20
Posts: 28
Posted: Thu, 2021-10-28 08:02

Simple Question part: Does the QCA9377 support monitor mode and ap listing?

More info:

I have a QCA9377-7, USB module, working great in AP mode, working great in STA mode, and working great in true monitor mode (con_mode=4). This is on a linux box, using the qcacld-2.0 USB driver as provided by 8devices, one of the preferred/suggested vendors for the USB version of this chip from Qualcomm.

When I load the monitor at boot with con_mode=4, I am able to set it up to go to a channel/frequency, and tcpdump all of the traffic over the air. 

I would also like to be able to get a list of the access points on all channels. "iwlist wlan0 scan" just returns an immediate Scan completed message. I am running as root.

When I attempt the same with iw instead, iw wlan0 scan, it just sits there, forever, and never gives an output. This works on other ICs.

EDIT: Sorry, using "iw dev wlan0 scan -u" to be precise. 

If I "tcpdump -iwlan0 -ne" I definitely see it working in monitor mode, capturing all of the WiFi traffic on the channel I set by setMonChan.

I then ctrl-c the tcpdump, and invoke the iwlist wlan0 scan, and it doesn't even see the APs on the channel I had set to for tcpdump.

I can just change channels and do my own tcpdump, sit n spin for a 100-200ms or so, extract a list of APs on that channel, go to the next, etc. etc. but would be nice if I could just "scan" for APs using a known iwlist or iw feature.

Best, and thanks for any responses in advance, any questions, let me know

John

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ddeepakk Moderator
Join Date: 27 Jun 17
Posts: 140
Posted: Mon, 2021-12-06 07:13

Hi John,

You are installing the driver in Monitor Mode and then expect the "iw wlan0 scan" command to work as it works in normal STA mode, when you insmod the driver without any "con_mode" argument. Is this correct understanding of your requirement?

If so, I'm not sure if we support such use case and as far as I know such use case was never tested.

Let us know if further questions.

Thanks.

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jshenry1963
Join Date: 17 Nov 20
Posts: 28
Posted: Wed, 2022-05-11 11:32

Hello ddeepakk,

Thank you very much for your response.

For this application, when I insert the driver, I am using insmod wlan.ko con_mode=4. In this instance, I am only using the QCA9377-7 in monitor mode. When I do this, invoking "iw wlan0 scan" at the command line never returns any APs and never returns. I have to ^C control C out of it.

When I start up the driver as either an AP or a STAtion, then the iw wlan0 scan does work.

I do not know if "iw wlan0 scan" (the ability to get an AP list quickly) when the driver is inserted in monitor mode (con_mode=r) is a supported use case in this driver, That is my question.

But I do know that I have used other WiFi chipsets in the past that do support "AP Scanning"/"iw wlan0 scan" while the driver was started up in monitor mode

Thanks

John

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ddeepakk Moderator
Join Date: 27 Jun 17
Posts: 140
Posted: Sun, 2022-05-22 22:17

Hi John,

>>I do not know if "iw wlan0 scan" (the ability to get an AP list quickly) when the driver is inserted in monitor mode (con_mode=r) is a supported use case in this driver, That is my question.
[QC] It is not supported by our driver.
Is this limitation a dealbreaker for you? If so, we can try to see if it's a trivial change that can enable scanning.
BTW, what's the volume that you foresee?

Thank You,
Deepak

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jshenry1963
Join Date: 17 Nov 20
Posts: 28
Posted: Fri, 2022-05-27 18:19

Hello Deepak,

No, it isn't a deal breaker, but it just makes things less efficient and more complicated to find the Access Points in the area across multiple channels. One has to switch channels, dwell for a period of time, and build the list manually. Whereas it is so much easier and quicker and reliable to capture all access points on all channels with a single fairly quick command. It works great when in station mode. I can issue the command and get a good list of nearby Access Points, and not lose connection to the current router / access point.

Volume, I am not permitted to talk about.

Thanks for the input,

John

 

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ddeepakk Moderator
Join Date: 27 Jun 17
Posts: 140
Posted: Sun, 2022-05-29 00:02

Hi John,

Thanks for clarifying.
If such is your requirement, then we assume that you are OK to temporarily stop the Sniffer operation so that scan can take place.
And if that is correct understanding, then even the current limitation could be workable (although I agree that it's less efficient), with just one added step of unloading and loading back the driver.
I can discuss it with the internal team and let you know later on their guidance.

Thanks.
Deepak

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jshenry1963
Join Date: 17 Nov 20
Posts: 28
Posted: Mon, 2022-05-30 19:45

Hello Deepak,

Thank you very much for your inputs.

I can use the "slow scan and store" method I am using for now.

It would be great if this could be added. But not a dealbreaker.

Thanks

John

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