Using a Nordic NRF52840 with Wireshark to sniff then dissect Digimesh

[Dazz]

Hi

I want to use a Nordic NRF52840 to sniff and dissect a Digimesh network.  Digi do not provide a sniffer or/and dissector for their products.  There is no promiscuous version of the firmware.  Reaching out to Digi support has only yielded minimal support.  Specifically they say DigiMesh firmware has been built with 802.15.4 as its base. which is not that helpful.   The nil availability of a sniffer/dissector is a major deficiency with Digimesh. 

After doing some research I found the NRF52840 and associated SDK include a sniffer interfaced to Wireshark 802.15.4 Sniffer.  That is fantastic.  I have ordered a USB dongle.

So my plan is to modify the SDK sniffer to read Digimesh messages and write a dissector for Wireshark.   

I have written 8051/8086 assembler, programmed Raspberry Pi's, Arduino etc so I am comfortable writing code.  I have not delved into the detail of 802.15.4 before.    The Digimesh commands are detailed in on-line manuals.  I don't have any info on Digimesh meta data messages. 

I am seeking advice on where to start with this.  My thoughts are that I first need identify Digimesh messages (packets) that don't comply with 802.15.4 and make any necessary changes to the sniffer firmware.

I think the next step would be to modify an existing wireshark dissector and convert to Digimesh.

Am I on the right path here?

Has someone done this already?  A search on Google failed to find any.

Are there any major potholes I need to be aware of?

Any advice would be much appreciated.

[dejans]

Hi Darren,

You can start by reading from the page you have already linked. 
You could first find out if DigiMesh is fully based on 802.15.4. If it is, then our sniffer could potentially be used for your purpose and you would probably not need to make changes to the firmware.

Best regards,
Dejan

[Dazz]

Hi

I have asked Digi provide any differences between  Digimesh and 802.15.4, specifically including the meta data. If Digimesh is wholly compliant with 802.15.4, then I am hoping I will only need to modify the Wireshark dissector.    Digi does provide detailed information on the message formats that the user has access to.   Those user guides do not provide any info on the comms messages that are sent between modules and are not visible to users.

Please note that the expected lead time for a dongle is between 8 to 16 weeks because of Covid.  There will be long periods when I won't have anything to say here.

[dejans]

Hi Darren,

Dazz said:

Please note that the expected lead time for a dongle is between 8 to 16 weeks because of Covid.  There will be long periods when I won't have anything to say here.

This is fine.  If you have need for any further assistance, you can come back here after some longer period.

Best regards,
Dejan