Re: [threadx-dev] Technical support question?

[Snorri Kristjánsson <snorri@xxxxxxxxxx>]

Hi Frédéric,

Many thanks for your help.

Your suggestion works. The host-name I supply in the call to nx_dhcp_create works.

I can see in our DHCP server logs that the device gets its IP address and in the log file I can see the host name that I gave it.

BTW - we use Microsoft Windows servers for all our networking - and I'm using Windows 10 as my workstation

But the problem remains that I can't still ping the device using the host-name, nslookup also returns no results - even if the FQDN is used (I run ipconfig /flushdns of course before these tests).

FYI - It seems that our DHCP server extends the host name supplied by a client to the internal LAN FQDN. E.g. If the client supplied hostname is "Tester0" and the local LAN domain name is "Acme.local" the FQDN becomes "Tester0.Acme.local". This is what I see in the DHCP server logs.

I've also tried ping and nslookup on a Ubuntu linux VM that I have - with the same negative results, and I tried on a different PC - same results.

Then - after some googling I found this thread dhcp-reservation-not-registering-in-dns-for-some-devices that seems to be regarding the problem I'm dealing with.

Unfortunately I'm not a network expert - but it looks like the DHCP client needs to request a DNS update explicitly when communicating with the DHCP server (or we change the setting on the DHCP server service: configure-dns-dynamic-updates-windows-server - is-there-a-downside-to-always-updating-dns-from-dhcp).

It seems that the default setting for Windows DHCP/DNS services is to have the DHCP client explicitly request a DNS update.

It would of course be interesting to try to change the DHCP server setting - but the reason I'm doing these experiments is to evaluate the Eclipse ThreadX (Azure RTOS) "fit for purpose" - for future products of the company I'm working for - and changing the DHCP service settings would defeat that.

The example project that I built and tested is Nx_TCP_Echo_Server running on a STM32 Nucleo-H723ZG board.

Sorry about the long rambling post - but it helps my thinking process to write this all down...

So the question is:

Is there a way to have the DHCP client (nx_dhcp_create) request the DNS update?

I've had a look at RFC2131 (the DHCP protocol) but could not find anything specific regarding this "DNS update request" problem. It may be something Microsoft specific but I don't know.

Best regards,

Snorri

On Tue, 30 Apr 2024 at 20:01, Frédéric Desbiens <frederic.desbiens@xxxxxxxxxxxxxxxxxxxxxx> wrote:

Hi Snorri.

Yes, this is the right place for such questions. 

You will find the documentation for the DHCP client here: https://github.com/eclipse-threadx/rtos-docs/blob/80bd9fe9a33fa79257c75629be1b4438b84db7bc/rtos-docs/netx-duo/netx-duo-dns

I am no expert, but from what I understand, the name you give to the DHCP client instance seems to be used as the hostname. 

UINT nx_dhcp_create(
    NX_DHCP *dhcp_ptr,
    NX_IP *ip_ptr,
    CHAR *name_ptr);

Line 6784 in nxd_dhcp_client.c sets the proper option and the value for dhcp_ptr -> nx_dhcp_name comes from *name_ptr in the method above.

 _nx_dhcp_add_option_string(buffer, NX_DHCP_OPTION_HOST_NAME, name_length, (UCHAR *) dhcp_ptr -> nx_dhcp_name, &index);

Best,

Frédéric DESBIENS

Program Manager and Evangelist — Embedded, IoT, and Edge Computing | Eclipse Foundation

Mastodon: @fdesbiens@xxxxxxxxxxxxxxxxxxxxx

On Tue, 30 Apr 2024 at 12:04, Snorri Kristjánsson via threadx-dev <threadx-dev@xxxxxxxxxxx> wrote:

Hello devs,

Where can I ask a technical question?

Is this the correct place?

In short - I need to know how to set the hostname for a (DHCP enabled) device that is running the ThreadX - NetX DUO network stack.

--

Best regards,

Snorri

Snorri Kristjánsson

Software Developer • Kvikna Medical • +354 578 8400 • kvikna.com

 

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