Re: dhclient adding second address to desktop with static IP

[Mike Fleetwood <mike fleetwood googlemail com>]

On Fri, 9 Aug 2019 at 15:04, Thomas Haller <thaller redhat com> wrote:
> On Fri, 2019-08-09 at 14:43 +0100, Mike Fleetwood wrote:
> > I fixed this earlier this morning.  I stopped the systemd managed
> > NetworkManager service.  Even with the service stopped dhclient was
> > still running in the control group managed by systemd.  Manually
> > killed
> > dhclient [1].
> > (Rethorical question, how is that even allowed?  Surely the point of
> > systemd using CGroups is so that it can identify all processes for a
> > service, which it did, and that when stopping a service it ensures
> > all
> > processes stop or are killed, but it didn't).
> >
> > Then I manually removed the unwanted DHCP assigned IP address again
> > and
> > restarted the NetworkManager servers.  No dhclient running this time
> > [2].
>
> Hi,
>
> your reply here is not very clear (regarding my earlier question), but
> I presume that you earlier only modified the profile without further
> action.

No I didn't do anything to activate the profile.  I didn't know it was
even necessary.  I've been learning about NM as this thread progresses.

Prior to starting this thread I did use the Network Connections GUI app
to view the current configuration.  It was set for static IP addressing.
I did press save anyway, which I assume would have changed and activated
the profile but must not have.

Thanks for your help,
Mike


> Note that there is a difference between a connection profile and a
> (what NetworkManager calls) a device.
>
> A profile is just a a bunch of settings that describe how to configure
> a device. You see that in `nmcli connection show`, and that is what
> what the commands under `nmcli connection` operate on.
>
> A device is what you see in `nmcli device`, and (in case of most device
> types like ethernet) corresponds to what you see in `ip link show`. A
> device is subject to be configured by NetworkManager: by "activating" a
> connection profile.
>
>
> If you only modify a profile that is currently active, then these
> changes don't take effect immediately. Commonly you need to re-activate
> the profile first, like `nmcli connection up $PROFILE`.
>
>
> Rebooting you machine would work too... but reboot is certainly not the
> suggested way. Instead, just reactive the profile.
>
>
>
> > [1] Stopped NetworkManager, but dhclient still running.  Killed it.
>
> When you stop the NetworkManager service it aims to leave all devices
> up. The purpose is so that you can restart/update the service without
> disconnecting yourself from the network.
>
> Optimally, restarting NetworkManager should be seamless and you
> shouldn't even notice. Hence, restart NetworkManager is never the right
> approach to have some changes (to a profile) to take effect, because
> NeworkManager tries *not* to do any changes.
>
> You should (almost) never be required to restart NetworkManager.
> Of course, you may restart to update the service or change certain
> configuration options in NetworkManager.conf that cannot be reloaded
> via `systemctl reload NetworkManager.service`. But usually it's the
> wrong thing to do.
>
>
> Systemd doesn't kill dhclient because
>
>   # systemctl cat NetworkManager.service | grep KillMode
>   KillMode=process
>
>
>
> best,
> Thomas