Ble mesh: autoprovisioning and address selection

RE: Ble mesh: autoprovisioning and address selection

Elfving — Wed, 07 May 2025 12:59:40 GMT

No problem at all 🙂 Let us know if there is anything else.

Though once again, I just want to say that these features in BLE Mesh are there for the security of the network. So keep in mind that if you are eg. running bt_mesh_rpl_reset() on a customer product you might open yourself up to replay attacks.

Regards,

Elfving

RE: Ble mesh: autoprovisioning and address selection

stefanogradozzi — Tue, 06 May 2025 14:15:00 GMT

Hi,

I think that you have brilliantly solved my problem.

Probably I made things only more confused in the last part of my previous message.

Thank you again for your effort

RE: Ble mesh: autoprovisioning and address selection

Elfving — Tue, 06 May 2025 13:07:49 GMT

[quote user="stefanogradozzi"]if I want to use an older address for DK, I have to reflash and readdress also all dongles in the network. Correct?[/quote]

Well, that would fix things, but I wouldn't say you are required to do that. You could eg. clear the RPL manually from all the other nodes ( bt_mesh_rpl_reset ), or store these settings from the old node, and reflash it on the new one.

[quote user="stefanogradozzi"]If I use a new address after reflashing DK, it is not necessary reflash all dongles. Correct?[/quote]

Correct. That is atleast my understanding of your problem. This is because the dongles will have their own storage of messages recieved from this new unicast address, which will start from 0 on all nodes.

[quote user="stefanogradozzi"]I have to change its main address for communicating with dongles (and you have just explained me why). What I have not understood?[/quote]

So you have changed the main address of the DK? If so, what I am describing here is likely not the problem.

Regards,

Elfving

RE: Ble mesh: autoprovisioning and address selection

stefanogradozzi — Mon, 05 May 2025 16:35:06 GMT

Hi,

I understand that:

if I want to use an older address for DK, I have to reflash and readdress also all dongles in the network. Correct?
If I use a new address after reflashing DK, it is not necessary reflash all dongles. Correct?

About group addresses: actually, I'm using them. For example: 0xC001 is the group address for light client/server of DK and of all dongles, but anyway when reflashing DK (and group address does not change) I have to change its main address for communicating with dongles (and you have just explained me why). What I have not understood?

Thanks and regards

RE: Ble mesh: autoprovisioning and address selection

Elfving — Mon, 05 May 2025 13:59:42 GMT

I see. And you only reflash one device, ie. the DK and not the dongles? I guess one issue could be that the sequence number of the DK is now restarted, while the others are much higher.

To avoid replay attacks, the nodes store the sequence number of the latest message, and disregard all older ones. Sending a few more (given that a few messages are what has been sent in the past) of these messages should make the sequence number go up high enough. What is recommended is to use new addresses for a new unit instead of using the old ones. If addressing is what is stopping you from doing that, then I would recommend group addresses. Is there any reason why you can not use this approach?

I am not sure if we have an API for setting and getting the RPL (replay protection list), potentially for safety reasons. But if you are interested in going this route, I can check.

Regards,

Elfving

RE: Ble mesh: autoprovisioning and address selection

stefanogradozzi — Sat, 03 May 2025 09:43:19 GMT

I make erase all and then reflash the entire SW.

RE: Ble mesh: autoprovisioning and address selection

Elfving — Fri, 02 May 2025 12:43:13 GMT

Hi Stefano,

[quote user=""]

But if I make an erase/flash operation on the board and then I rewrite the same address in the same memory location, the board stops communicating with the other nodes.

[/quote]

And by this, do you mean an erase-all and reflashing of the entire SW? Or how exactly are you erasing and flashing?

Regards,

Elfving