Re: dns update for ipv6 using dhcpv6

[Tim Coote <tim+gnome org coote org>]

On 13 Dec 2016, at 19:08, Thomas Haller <thaller redhat com> wrote:

On Tue, 2016-12-13 at 16:13 +0000, Tim Coote wrote:

Hi Tim,

Hi Thomas,

sidenote:

When you use dhcp plugin "dhclient" (in NetworkManager.conf), then
NetworkManager generates a suitable dhclient configuration in
/var/lib/NetworkManager/dhclient-*.conf

Don't modify that file, because it will be overwritten.

Thanks. I’d got that.  That’s why I’m trying to find the upstream configuration location.

NM merges other sources files into this file, so you can put your
options there:
https://cgit.freedesktop.org/NetworkManager/NetworkManager/tree/src/dhcp/nm-dhcp-dhclient.c?id=eb77d4ed28fb7d72020fc4bce2a7f3477f0b8c1d#n219

If you turn on debug-logging, NM will also log lines like:

Dec 13 12:15:29 x250 NetworkManager[388]: <debug> [1481627729.0469] dhcp4 (wlp3s0): creating composite dhclient config /var/lib/NetworkManager/dhclient-wlp3s0.conf
Dec 13 12:15:29 x250 NetworkManager[388]: <debug> [1481627729.0469] dhcp4 (wlp3s0): looking for existing config /etc/NetworkManager/dhclient-7111201a-568f-4568-a0ed-cd1d4df11e8f.conf
Dec 13 12:15:29 x250 NetworkManager[388]: <debug> [1481627729.0470] dhcp4 (wlp3s0): looking for existing config /etc/NetworkManager/dhclient-wlp3s0.conf
Dec 13 12:15:29 x250 NetworkManager[388]: <debug> [1481627729.0470] dhcp4 (wlp3s0): looking for existing config /etc/NetworkManager/dhclient.conf
Dec 13 12:15:29 x250 NetworkManager[388]: <debug> [1481627729.0470] dhcp4 (wlp3s0): looking for existing config /etc/dhcp/dhclient-wlp3s0.conf
Dec 13 12:15:29 x250 NetworkManager[388]: <debug> [1481627729.0471] dhcp4 (wlp3s0): looking for existing config /etc/dhclient-wlp3s0.conf
Dec 13 12:15:29 x250 NetworkManager[388]: <debug> [1481627729.0471] dhcp4 (wlp3s0): looking for existing config /etc/dhcp/dhclient.conf
Dec 13 12:15:29 x250 NetworkManager[388]: <debug> [1481627729.0471] dhcp4 (wlp3s0): looking for existing config /etc/dhclient.conf
Dec 13 12:15:29 x250 NetworkManager[388]: <debug> [1481627729.0471] dhcp4 (wlp3s0): no existing dhclient configuration to merge

I’ll try that.  I did try using /etc/NetworkManager/dhclient6-eth0.conf, but it didn’t seem to get merged. I need to review the syntax, I think.

But can you not just configure ipv6.dhcp-send-hostname and ipv6.dhcp-
hostname:

 nmcli connection modify $NAME ipv6.dhcp-send-hostname yes \
   ipv6.dhcp-hostname wibble.example.com

Well that was how I was setting ipv6.dhcp-hostname, but after systemctl restart NetworkManager, it had been reset to '—‘. Now, I must have changed something, as it doesn’t change the value at all!

As an aside, the naming is a bit confusing to me: I’ve always understood hostname as a property of a computer, fqdn as a property of an interface.  I used to run a prof. services function of a discovery tool and the mean number of computers with a hostname of venus in a sizeable enterprise was 7. We’d find up to the small hundreds of fqdns per computer (physical boxes used for testing web functionality).

I’d assumed that if that worked across a service restart, I’d be able to find the file that it got stored in.

Thomas

Thanks

Tim