Re: FQDNs for netbooted hosts via DHCP?

["John D. Baker" <jdbaker%mylinuxisp.com@localhost>]

On Sat, 14 Jul 2018, Martin Husemann wrote:

> On Sat, Jul 14, 2018 at 06:40:49AM -0400, Greg Troxel wrote:
> > My guess, without reading specs, is that the right thing to do is to
> > change the in-kernel dhcp client to construct fqdn and use it.
> 
> The in-kernel dhcp client is minimalistic and only extracts enough
> data to mount /, and it should not deal with administrative decisions.
> 
> In userland, dhcpcd hooks should set the full name by default, if I read 
> /libexec/dhcpcd-hooks/30-hostname correctly, not sure what goes wrong here
> for John.

I read through that script as well.  If I understand correctly, from
'dhcpcd's point of view in the netboot case, the host name is already
set ('sysctl -n kern.hostname'), so will use that value (i.e.  ignore
the host-name sent by the server).

The converse could be to arrange for "hostname_fqdn=server" when 'dhcpcd'
runs '30-hostname' in the local-disk boot case and get the short name
the same as the netboot case (if host entries, host-name options only
give short name).  That makes MTAs a bit unhappy, though.

Probably the simplest route for netbooted systems is to override the
hostname with the FQDN in "rc.conf" the same as a statically-configured
system.  Also might as well not bother with 'dhcpcd' on netbooted x86en
either.  I'm really only using it to automagically get things like name
servers and NTP servers.  But "/etc/{resolv,ntp}.conf" are trivial to
edit.

(In that case, is there a way to manipulate CLIENTHOST in 'xdm's,
"Xresources" file so that the short name is extracted for use in
the greeter?)


I may have stumbled onto another effect of short name (netboot) vs fqdn
(local disk boot) when the user's home directory is the same in both
cases ('amd'-managed NFS automount), but it will be a while before I
can check it again.

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