Traffic of non registered sensors

Hi team

We installed a GW and some sensors in the network. After that, we remarked on the GW page “LIVE LORWAN FRAMES” that we can see all traffic even for non-registered sensors. Is it normal?

Yes. Unless the Gateway Bridge has been configured to filter traffic based on NetID (or join requests based on JoinEUI), it will forward all traffic it sees. The network server will then drop it as appropriate.


But filtering it’s not the role of the network server?

@brocaar can speak to the spec better than I can, but I believe it is the role of the network server to drop unrecognized payloads.

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@bconway is correct. Note that filtering on the gateway is not a technical requirement but more of an optimization to save bandwidth and some of the load on the NS. However if neighboring networks are using the same NetID, your gateways would still forward data of devices that aren’t yours. The NS will try to match the received uplinks against the devices it knows about, and will drop everything else (including potential replay-attacks, in which case the NS detects that the frame-counter was not incremented).

Actually Chirpstack is not doing any filtration, and we can receive all neighbor sensor data, as per understanding, NS should filtrate.

You’re looking at the raw lorawan part of the network server monitoring, before any validation.

In fact the network server does filter out the frames of unregistered devices, due to the simple fact that it doesn’t have knowlege of the secrets needed to validate their cryptographic checksums or decode their actual encrypted payloads or even have any lookup records to start that process by turning their device addresses back into a plausible known node identity whosee stored secrets could be tried on the packet.

What you are seeing is that it shows the raw unfiltered frames as its input, but shows no corresponding output for unregistered devices - because it cannot process them.