Using B.A.T.M.A.N.-Adv and scanning for neighbours

Using B.A.T.M.A.N.-Adv and scanning for neighbours

[Furmans Hannes]

Hello everyone!

We have a setup with four Raspberry Pi, all in IBSS mode and connected via B.A.T.M.A.N.. That all works fine. However we now have troubles scanning on the Pis for the neighbours. 
When we run 
sudo iw wlan0 scan ssid batman-test

We have the output:
BSS 7e:40:ea:05:57:e9(on wlan0) -- joined
	last seen: 2433.130s [boottime]
	TSF: 0 usec (0d, 00:00:00)
	freq: 2412
	beacon interval: 100 TUs
	capability: IBSS (0x0002)
	signal: -17.00 dBm
	last seen: 0 ms ago
	SSID: batman-test
	Supported rates: 6.0* 9.0 12.0* 18.0 24.0* 36.0 48.0 54.0
	DS Parameter set: channel 1
	IBSS ATIM window: 0 TUs
	ERP: Use_Protection
	HT capabilities:
		Capabilities: 0x21
			RX LDPC
			HT20
			Static SM Power Save
			RX HT20 SGI
			No RX STBC
			Max AMSDU length: 3839 bytes
			No DSSS/CCK HT40
		Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
		Minimum RX AMPDU time spacing: 4 usec (0x05)
		HT RX MCS rate indexes supported: 0-7
		HT TX MCS rate indexes are undefined
	HT operation:
		 * primary channel: 1
		 * secondary channel offset: no secondary
		 * STA channel width: 20 MHz
		 * RIFS: 0
		 * HT protection: non-HT mixed
		 * non-GF present: 1
		 * OBSS non-GF present: 1
		 * dual beacon: 0
		 * dual CTS protection: 0
		 * STBC beacon: 0
		 * L-SIG TXOP Prot: 0
		 * PCO active: 0
		 * PCO phase: 0
	Overlapping BSS scan params:
		 * passive dwell: 20 TUs
		 * active dwell: 10 TUs
		 * channel width trigger scan interval: 300 s
		 * scan passive total per channel: 200 TUs
		 * scan active total per channel: 20 TUs
		 * BSS width channel transition delay factor: 5
		 * OBSS Scan Activity Threshold: 0.25 %
	Extended capabilities:
		 * HT Information Exchange Supported
		 * BSS Transition
		 * Operating Mode Notification
	WMM: information: 01 00

Which is not what we expected. We hope to see the RSSI of our neighbours and that should be possible, at least as I understand it. We have already tried iwspy (device doesn’t support it), leaving the ibss group (doesn’t help), iwlist (same problem) and the Mac address you see in the output doesn’t match any of the Pis we use. 

We are stuck here, please help us. Maybe it would be possible to extract that info from batman directly?

The devices in questions are all Raspberry Pi 4 Model B, one with 1 GB RAM, two with 2 GB RAM and 1 with 4 GB RAM. We run: batctl debian-2023.0-1 [batman-adv: 2023.3]

This is the version of our wifi chip driver (sudo lshw -C network):
  *-interface:0
       description: Wireless interface
       product: 43430
       vendor: Broadcom
       physical id: 1
       bus info: mmc@1:0001:1
       logical name: mmc1:0001:1
       logical name: wlan0
       serial: d8:3a:dd:30:1d:4a
       capabilities: ethernet physical wireless
       configuration: broadcast=yes driver=brcmfmac driverversion=7.45.234 firmware=01-996384e2 multicast=yes wireless=IEEE 802.11

Thank you for your time 
Hannes Furmans

ETH Zürich

Re: Using B.A.T.M.A.N.-Adv and scanning for neighbours

[Sven Eckelmann]

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On Monday, 29 April 2024 16:16:21 CEST Furmans  Hannes wrote:
> Hello everyone!
> 
> We have a setup with four Raspberry Pi, all in IBSS mode and connected via B.A.T.M.A.N.. That all works fine. However we now have troubles scanning on the Pis for the neighbours. 
[...]
> Which is not what we expected. We hope to see the RSSI of our neighbours and that should be possible, at least as I understand it.

Why do you want to scan here? If you want to have the RSSI of your "connected" 
neighbors then just run:

    iw dev wlan0 station dump

Btw. this is not really a batman-adv topic. If you want more information about 
the linux wireless stack then you should try the linux-wireless mailing 
list [1] or IRC channel [2]

Kind regards,
	Sven

[1] https://wireless.wiki.kernel.org/en/developers/mailinglists
[2] https://wireless.wiki.kernel.org/en/users/support

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