Re: hostname-mode : short vs fqdn name

[Beniamino Galvani <bgalvani redhat com>]

On Thu, Apr 09, 2020 at 11:20:17AM +0200, Thomas HUMMEL wrote:
> On 4/9/20 10:59 AM, Beniamino Galvani wrote:
>
> > > how is this hostname fully qualified who sets it ? The original hostname
> > > always seems to be this one.
> >
> > I don't know, it is set before NM starts.
>
> Ok, I'll look into this but this is not related to my initial problem
> indeed.
>
>
> > In the 'none' log, the FQDN is set before NM starts
>
> Indeed (read from D-Bus by NM)
>
> > . Around 14:53:41
> > someone adds a new connection and activates it, disconnecting the
> > previous DHCP connection.
>
> This can only be the postscript I mentionned creating the xcat- NM profile
>
> > At the same time the kernel hostname is
> > changed externally to NM. I can't say who does this.
>
> Hmm this is odd. I may have missed something then. I'll look further into
> it.
>
> > > - dhcp (end up with fqdn).
> >
> > In this case the short hostname got via DHCP is set by NM at
> > 15:05:49. But later, somebody adds and activates a new connection
> > 'xcat-enp33s0f0' with static addresses
>
> The postscript.
>
> > and so the DHCP hostname is
> > removed, restoring the initial one.
>
> Ok but then you mean the one set BEFORE NM starts (again, the one read from
> D-Bus at the begining) you mentionned above ? Because man said for
> hostname-mode == dhcp that there is no fallback (like to reverse lookup the
> ip address).

Correct, no fallback to reverse lookup is done. NM keeps either the
last hostname set outside of NM or the one present when NM was started.

> I was initially confused by this : it LOOKED LIKE even in dhcp mode, NM was
> performing a reverse lookup fallback as in fact it just reset to the one it
> saw initially, correct ?

Right.

Beniamino