MQTT With GSM PPP and TLS

RE: MQTT With GSM PPP and TLS

Belalshinnawey — Mon, 03 Apr 2023 02:36:07 GMT

I completely gave up on mbedtls. I ported WolfSSL to Zephyr and used it with POSIX to connect with TLS 1.3 . The difference was really just the more meaningful error messages that helped me tune my application. Anyone reading this on NCS v 2.3.0, just download wolfssl and use it, it's way easier and you get error messages that are helpful. Also the code -7780 is an mbedtls error, its not a an nrf error code, it means SSL - A fatal alert message was received from our peer. For some reason, mbedtls was selecting a cipher then returning an error after the server accepted the cipher, all while saying the server returned a fatal alert, even thought the server logs are saying connection is accepted. I couldn't get it to work so I used a library I'm familiar with.

RE: MQTT With GSM PPP and TLS

Øyvind — Tue, 28 Mar 2023 09:01:47 GMT

What version of the nRF Connect SDK are you using?

[quote user="Belalshinnawey"]I saw an example on NCS repo for PSA-TLS[/quote]

I'm not familiar with this sample. It is not used by our developers in regards to TLS. Please look at how TLS is used in e.g. Download_client.

[quote user="Belalshinnawey"]TLS handshake error: -7780[/quote]

This is an error which unfamiliar to me, i.e. it is not found in errno.h.

[quote user="Belalshinnawey"]Could you at least give me an example that works with MBEDTLS and no offloading.[/quote]

Have you looked at the samples for MQTT in the Zephyr repository and the equivalent documentation? I.e. MQTT Publisher sample and MQTT networking API.

You could look at the AWS IoT Core sample found under nRF9160 samples. This is our own cellular device which connects to LTE-M or NB-IoT.

RE: MQTT With GSM PPP and TLS

Belalshinnawey — Tue, 28 Mar 2023 07:29:49 GMT

Could you at least give me an example that works with MBEDTLS and no offloading. The SIM800A doesn't support offloading for anything beyond tls1 so Its not going to work anyway. Is there a possibility of making mqtt and tls work directly on the nrf52840 while using PPP as a transport only? surely there is a way, I saw an example on NCS repo for PSA-TLS is it possible to port that to my app. Also I am trying to get more logs out of the tls handshake but I only get <err> net_sock_tls: TLS handshake error: -7780, How do I make the log level for this DBG? I couldnt't find a way.

RE: MQTT With GSM PPP and TLS

Øyvind — Tue, 28 Mar 2023 06:45:13 GMT

Hello,

I'm afraid I can't speak for the SIM800A, as this is not part of our product portfolio and I'm not aware how this part works. You have a fairly complex application with Zigbee, crypto, and a lot of extra setting compared to the standard gms_modem sample and e.g. mqtt_publiser from the Zepyr samples.

What version of the nRF Connect SDK are you running?

You could ask the Zephyr community on Discord, as they might have more experience with the SIM800A.

Kind regards,
Øyvind

RE: MQTT With GSM PPP and TLS

Belalshinnawey — Tue, 28 Mar 2023 04:49:04 GMT

Dears Any help on this? I am very close to changing the platfrom all together with something else that has working TLS examples. I tried to use the psa-tls Examples from the NCS repo and still get get errors in connections (Namely MBEDTLS 0x7780 Error and 0x7080) Is there something I am missing? you can review my broker TLS settings on www.ssllabs.com/.../analyze.html it looks fine to me. Please offer any input.