Node with same nwskey, appskey and app eui

ChirpStack Network Server
1

Hi broocar,
I have two globalsat node, CO and CO2. It has same nwskey, appskey and app eui. While i turn on CO sensor, it’s has no problem with loraserver. But while at the same time i turn on CO and CO2 sensor for a couple of hours, CO2 data overwrite CO data in loraserver after 6 hours, it’s like i just turn on 1 sensor. Is it able to add node with same nwskey and appskey? Fyi, i use ABP.

Thanks

2

Do they share the same DevAddr and / or DevEUI too?

3

No, DevAddr and DevEUI is unique
But the nwskey, appskey and appeui is same.
After ±6 hours, CO data overwrite CO2 data. Can i configured node with same appskey and nwskey?

4

CO2 data overwrite CO data in loraserver after 6 hours

To make sure I understand your question correctly, what data do you mean?

5

I mean session in loraserver
image
CO deveui is 000DB53112743544
CO2 deveui is 000DB5311277355B
In first time, it running normal. But after ± 6 hours, CO2 data is insert into deveui 000DB53112743544 session and no incoming data from CO node. I trace in lora-gateway-bridge, both deveui is send data to network server(loraserver).
I know CO2 data is overwrited CO session because in my node-red, i got very high CO PPM. After i trace, i found this. In my case, CO2 is insert into deveui 000DB53112743544 session, when it should be deveui 000DB5311277355B session for CO2
Sorry for a confusing explanation.

6

Are you use nwskey and appskey for creating session? or it just combined from devAddr and DevEui?

7

The NwkSKey is used to validate the MIC. So:

  • Based on DevAddr, LoRa Server retrieves the list of DevEUIs using the given DevAddr
  • LoRa Server iterates through the returned list of DevEUIs, testing the FCnt and MIC using the NwkSKey of that DevEUI (from the node-session)
  • When FCnt + MIC are valid, LoRa Server knows that the PHYPayload was sent by that DevEUI

Are you really sure that both nodes do not share the same DevAddr? It could also be that from previous configuration attempts, there is still a pointer in the database from a single DevAddr to both DevEUIs.

Anyway, it should work as long as both devices never shared the same DevAddr, however, it is better (especially security wise) give every node an unique set of credentials.

You’ll find the DevAddr + MIC + FCnt -> NodeSession lookup here:
https://github.com/brocaar/loraserver/blob/master/internal/session/session.go#L135

8

Hi broocar, thanks for reply.
I’ll try to trace again. If i shared devAddr accidentally, what should i do? Because I’ve tried to dump frame log table in loraserver postgresql and node table in lora-app-server, the result is same.

Thanks

9

Best would be to use different keys of course. What you can do is check the content of the lora:ns:devaddr:{DEVADDR} Redis key, where you replace {DEVADDR} with the DevAddr of your nodes. That lists to which DevEUIs that DevAddr has been registered. You should be able to use the SMEMBERS Redis command. See also: https://redis.io/commands/smembers.

10

Hi broocar, sorry for late response. I’m doing a lot of work yesterday, i’ll try and inform you later.

Thanks

11

Hi brocaar, i’ve same problem, only with globalsat lt100 device,
381/5000

when I add a second device, sync stops after a while, I tried to change appskey and netwskey from the serial (RealTerm), but nothing. I also tried to make another Device-profile, but nothing, I am attaching below a photo of how the sensors arrive at the gateway, do you have any solution to help me?

thanks in advance for your work,
David

problemlt100
problemlt100.PNG1061×883 43 KB