OpenThread border router DNS - use domain directive from resolve.conf

RE: OpenThread border router DNS - use domain directive from resolve.conf

brown27 — Thu, 17 Aug 2023 12:29:51 GMT

I was able to talk with an OpenThread developer via discussion post on their GitHub repository page. He clarified that the command line interface's "srp domain" commands are for the OpenThread network itself - not the upstream network that the border router is connected to.

As a result, my Thread child will need to use fully qualified domain names in its DNS lookups to get things working. This is OK - I have some ideas for alternative means of communicating the domain name to the Thread child and can use that to compose fully qualified domain names.

RE: OpenThread border router DNS - use domain directive from resolve.conf

Charlie — Tue, 15 Aug 2023 11:03:40 GMT

Hi,

I looked at the source codes from openthread github, it seems the upstream resolver is configured in prosix running on RPI. Could you follow the following discussion to check?

Update the list of upstream dns server when resolv.conf is modified · Issue #9021 · openthread/openthread (github.com)

Best regards,

Charlie

RE: OpenThread border router DNS - use domain directive from resolve.conf

brown27 — Mon, 14 Aug 2023 14:32:19 GMT

Unfortunately `srp server domain [domain-name]` did not solve my issue. If my Thread child device does a DNS lookup for "example" it gets the following response:

"Standard query response 0xabcd No such name A example SOA a.root-servers.net"

However, `$ nslookup example` and `$ dig +search example` on the border router yield the desired IPv4 address. Is there anything else I should be trying or investigating?

RE: OpenThread border router DNS - use domain directive from resolve.conf

Charlie — Thu, 10 Aug 2023 09:37:21 GMT

Thanks for the update!

RE: OpenThread border router DNS - use domain directive from resolve.conf

brown27 — Wed, 09 Aug 2023 12:31:08 GMT

I am currently sending DNS requests to the border router and using its upstream DNS server to fulfil requests. I have set up the border router as instructed here and use `otDnsClientResolveIp4Address()` on the Thread child to initiate these requests.

I think that I might want to use `$ sudo ot-ctl srp server domain [domain-name]` on the border router and `grep` the domain name from `/etc/resolv.conf`. Otherwise, the border router seems to use `default.service.arpa.` as the default domain. I will try this and report back on how it works.

RE: OpenThread border router DNS - use domain directive from resolve.conf

Charlie — Wed, 09 Aug 2023 10:40:07 GMT

Hi,

This may be related to the aConfig argument initialization on your codes.

Could you test the CLI DNS resolution commands similar to https://groups.google.com/g/openthread-users/c/6uYzwjk6VHo/m/KPgjb_3PCQAJ first with your OTBR as DNS server?

openthread/src/cli at main · openthread/openthread (github.com) has the source codes about how this command is implemented, which should show the process of aConfig initialization.

Best regards,

Charlie