Messages received in TTN Console's gateway traffic but no longer in application

Yo peeps,

Anyone else noticed TTN is not doing the stuff its meant to be doing that last few days?

I have a DHT22 sensor which has been posting readings back over TTN for a month now without any issue, I noticed 3 days ago this is no longer happening.

I checked the gateway and the logs are moving nicley and showing the packets being received, and in the console I can see the packets in the gateway traffic page but in the application’s device page I cannot see any data in the data page and the integration to do the HTTP callback to my API is not being fired either.

Has anyone else had any issues? Is there any more I need to check which could be my fault? Obviously I double check the network, app key and device id on the device all are set fine.

Looking forward to some help / insight.

Best Regards,

Rob

In case you use ABP it could be that you run into “Frame Counter Checks” a security measure to protect from replay attacks.

check:

  • “CNT” field of your received frame in gateway traffic statistics

  • “Frames up” of your Device in Applications.

in case “CNT” is lower than “Frames up”, reset frame counter in Application->Device. To disable Frame Counter Checks permanently if you can life with the reduced security, untick “Frame Counter Checks” in Device Settings.

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Hi @salfare,

Thanks for the advice I will try this now and report back if its succesful.

Best Regards,

Rob

Hi @salfare,

Yep appears to be receiving data again now, please can you provide some advice about how this affects security? Would I be right in suggesting this occurs when the device power cycles and hence on a device without means to store the frame count the frame counter resets to 0 and tries to resubmit packets which have already been “seen” so to speak?

Best Regards,

Rob

An eavesdropper could capture the packet on-air and just resend it without knowing any of the security keys. Depending on your use-case this might be an issue or not.
See also: https://www.thethingsnetwork.org/wiki/LoRaWAN/Security#security-in-lorawan-and-ttn_frame-counters

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THis was my case too. It was running fine with two different gateways (Dragino and Raspberry Pi3 + RAK831) then suddenly failed: packets would show in gateway traffic in TTN but not in application. Reset Frame counter solved it.

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