nRF9160 ping event with AWS IoT

RE: nRF9160 ping event with AWS IoT

Håkon Alseth — Mon, 30 Oct 2023 08:48:42 GMT

Hi,

[quote user="ksksue"]Ping events from the server are typically processed within the modem firmware, and the application side cannot catch these events.[/quote]

Application can handle ICMP only if opening a SOCK_RAW type socket.

[quote user="ksksue"]Ping events from the server can be captured by opening a raw socket. However, it is not possible to simultaneously capture events with AWS IoT and pings from the server.[/quote]

Yes, this is correct. A SOCK_RAW type socket cannot operate simultaneously as other sockets on one specific PDN.

Kind regards,

Håkon

RE: nRF9160 ping event with AWS IoT

ksksue — Thu, 26 Oct 2023 02:05:54 GMT

Thank you for your consideration.
Having seen your post, this is my understanding:

Ping events from the server are typically processed within the modem firmware, and the application side cannot catch these events.
Ping events from the server can be captured by opening a raw socket. However, it is not possible to simultaneously capture events with AWS IoT and pings from the server.

RE: nRF9160 ping event with AWS IoT

Håkon Alseth — Thu, 19 Oct 2023 12:05:56 GMT

Hello,

Thank you so much for your patience.

When opening a SOCK_RAW type socket, there's restrictions that apply. Mainly, you have two options:

* Open the SOCK_RAW on a dedicated PDN

or:

* Keep all other sockets closed while the raw socket (SOCK_RAW type) is open.

My apologies that these undocumented restrictions apply to this type of socket.

Kind regards,

Håkon

RE: nRF9160 ping event with AWS IoT

Håkon Alseth — Mon, 16 Oct 2023 14:15:19 GMT

Hi,

Thank you for the detailed description.

I was able to reproduce this scenario locally, and I'm awaiting response from R&D to look deeper into what the behavior is in this specific case.

I will update you as soon as I have new information, usually after approx. 2 business days.

Kind regards,

Håkon

RE: nRF9160 ping event with AWS IoT

ksksue — Thu, 12 Oct 2023 18:27:03 GMT

Thanks for the idea.

I try this.

> ICMP reply is handled in slm via a raw socket type:

> https://github.com/nrfconnect/sdk-nrf/blob/v2.4.99-dev2/applications/serial_lte_modem/src/slm_at_icmp.c#L297-L345

But unfortunately, the results did not turn out as expected.
I try to rewrote the code from sample/aws_iot.
https://github.com/ksksue/aws_iot_raw_socket/blob/8872d0894aaa9e67ae22f1ac448ab30a6144d2ec/src/main.c#L479-L655

If raw socket open (call wan_socket_open), I can get ICMP packet. but, I cannot connect AWS IoT.

AWS_IOT_EVT_CONNECTING
...
D:     src xxx.xxx.xxx.xxx, dst xxx.xxx.xxx.xxx
D:   ICMP(8) type 8, code 0, csum 0x910f, id 51, seq 
...
(not AWS_IOT_EVT_CONNECTED)

If connecting AWS IoT (comment out wan_socket_open()), I can't get ICMP packet.

How to catch incoming ping events with connecting AWS IoT?

RE: nRF9160 ping event with AWS IoT

ksksue — Thu, 12 Oct 2023 15:45:40 GMT

I think that the SDK can't use both AWS IoT library and raw socket.
Is this correct or incorrect?

If incorrect, I try this.

> ICMP reply is handled in slm via a raw socket type:
> https://github.com/nrfconnect/sdk-nrf/blob/v2.4.99-dev2/applications/serial_lte_modem/src/slm_at_icmp.c#L297-L345

I don't want to dump the IP trace.

RE: nRF9160 ping event with AWS IoT

Håkon Alseth — Thu, 12 Oct 2023 14:59:56 GMT

Hi,

I'm uncertain about what you're asking about in this case.

Are you asking about ICMP in the generic LTE Network?

Or do you want to dump the IP trace?

If yes, then you can do this by enabling modem traces and using this tool (+ Wireshark): https://infocenter.nordicsemi.com/topic/ug_cellular_monitor/UG/cellular_monitor/intro.html?cp=11_3_1

Kind regards,

Håkon

RE: nRF9160 ping event with AWS IoT

ksksue — Thu, 12 Oct 2023 14:25:22 GMT

If a raw socket is opened, AWS IoT's packet goes to the raw socket. And communication with AWS IoT is no longer possible.

A)
application <--> AWS IoT(mqtt socket zephyr/subsys/net/lib/mqtt/mqtt_transport_socket_tls.c)
<--> ping (can't catch the events)

B) open a raw socket
application <-X-> AWS IoT(mqtt socket zephyr/subsys/net/lib/mqtt/mqtt_transport_socket_tls.c)
<--> raw socket send/recv (It can catch ping events)

If pattern B, unintentionally, raw socket receives AWS IoT's packet and AWS IoT's library stops working.

So, in the case of pattern A, I want to catch the ping events.

RE: nRF9160 ping event with AWS IoT

Håkon Alseth — Thu, 12 Oct 2023 12:49:53 GMT

Hi,

ICMP reply is handled in slm via a raw socket type:

https://github.com/nrfconnect/sdk-nrf/blob/v2.4.99-dev2/applications/serial_lte_modem/src/slm_at_icmp.c#L297-L345

It is polled similar to any other socket type.

[quote user=""]The device uses AWS IoT library, so it can't open a raw socket.[/quote]

Are you thinking of the keepalive for mqtt? This is configured via CONFIG_MQTT_KEEPALIVE

Kind regards,

Håkon