This SPR plugin loads seemoo lab's nexmon, which enables monitor mode on the built-in wifi radio. without nexmon this is not otherwise posible on the raspberry pi 4b.
Warning, this will overwrite your broadcom firmware on disk. Consider first making a copy of /lib/firmware/brcm/brcmfmac43455-sdio.bin
This expects the SPR pi image with a 6.2 Ubuntu kernel -- 6.2.0-1015-raspi. You can downgrade with flash-kernel --force 6.2.0-1015-raspi until there are more builds available
docker compose build
docker compose up -d
# tcpdump -i wlan0 ...
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on wlan0, link-type IEEE802_11_RADIO (802.11 plus radiotap header), snapshot length 262144 bytes
22:50:27.005540 1876482302us tsft 1.0 Mb/s 2412 MHz 11b -68dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.046106 1876522917us tsft 1.0 Mb/s 2412 MHz 11b -46dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.107930 1876584711us tsft 1.0 Mb/s 2412 MHz 11b -70dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.148500 1876625317us tsft 1.0 Mb/s 2412 MHz 11b -46dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.210323 1876687100us tsft 1.0 Mb/s 2412 MHz 11b -67dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.250927 1876727725us tsft 1.0 Mb/s 2412 MHz 11b -46dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.353387 1876830134us tsft 1.0 Mb/s 2412 MHz 11b -46dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.415150 1876891900us tsft 1.0 Mb/s 2412 MHz 11b -67dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.455780 1876932515us tsft 1.0 Mb/s 2412 MHz 11b -46dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.517581 1876994317us tsft 1.0 Mb/s 2412 MHz 11b -68dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.619973 1877096718us tsft 1.0 Mb/s 2412 MHz 11b -68dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.660499 1877137311us tsft 1.0 Mb/s 2412 MHz 11b -46dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.722352 1877199099us tsft 1.0 Mb/s 2412 MHz 11b -68dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.762911 1877239713us tsft 1.0 Mb/s 2412 MHz 11b -46dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.824758 1877301507us tsft 1.0 Mb/s 2412 MHz 11b -67dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.865300 1877342110us tsft 1.0 Mb/s 2412 MHz 11b -46dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.927152 1877403898us tsft 1.0 Mb/s 2412 MHz 11b -69dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:27.967757 1877444502us tsft 1.0 Mb/s 2412 MHz 11b -46dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:28.029491 1877506279us tsft 1.0 Mb/s 2412 MHz 11b -68dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:28.070097 1877546905us tsft 1.0 Mb/s 2412 MHz 11b -46dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:28.131952 1877608687us tsft 1.0 Mb/s 2412 MHz 11b -69dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:28.172498 1877649302us tsft 1.0 Mb/s 2412 MHz 11b -46dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:28.267684 1877745972us tsft 1.0 Mb/s 2412 MHz 11b -63dBm signal 0dBm noise Probe Request (wifiap) [1.0 2.0 5.5 6.0 9.0 11.0 12.0 18.0 Mbit]
22:50:28.268706 1877747115us tsft 1.0 Mb/s 2412 MHz 11b -62dBm signal 0dBm noise Probe Request (wifiap) [1.0 2.0 5.5 6.0 9.0 11.0 12.0 18.0 Mbit]
22:50:28.269562 1877747974us tsft 1.0 Mb/s 2412 MHz 11b -63dBm signal 0dBm noise Probe Request (wifiap) [1.0 2.0 5.5 6.0 9.0 11.0 12.0 18.0 Mbit]
22:50:28.274840 1877751689us tsft 1.0 Mb/s 2412 MHz 11b -46dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:28.377343 1877854092us tsft 1.0 Mb/s 2412 MHz 11b -46dBm signal 0dBm noise Beacon (wifi-2.4) [1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0 Mbit] ESS CH: 1, PRIVACY
22:50:28.393455 1877871861us tsft 1.0 Mb/s 2412 MHz 11b -60dBm signal 0dBm noise Probe Request (wifiap) [1.0 2.0 5.5 6.0 9.0 11.0 12.0 18.0 Mbit]
22:50:28.394594 1877873004us tsft 1.0 Mb/s 2412 MHz 11b -60dBm signal 0dBm noise Probe Request (wifiap) [1.0 2.0 5.5 6.0 9.0 11.0 12.0 18.0 Mbit]
22:50:28.395453 1877873863us tsft 1.0 Mb/s 2412 MHz 11b -61dBm signal 0dBm noise Probe Request (wifiap) [1.0 2.0 5.5 6.0 9.0 11.0 12.0 18.0 Mbit]
22:50:28.396315 1877874722us tsft 1.0 Mb/s 2412 MHz 11b -61dBm signal 0dBm noise Probe Request (wifiap) [1.0 2.0 5.5 6.0 9.0 11.0 12.0 18.0 Mbit]
^C
You should see raw frames
docker exec -it supernexmon /nexmon/nexutil -k36/40 docker exec -it supernexmon /nexmon/nexutil -k4/20
Configure the plugin path in SPR. The plugin will be reachable at http://spr.lan/plugins/nexmon/
curl -u admin:admin localhost/plugins/nexmon/change_channel?channel=1/20 -X PUT
The nexmon patch is not perfect and needs some care. Some commands like changing channels with iw no longer work as expected, and the nexmon utility should be used instead.