Re: on manual configuration / respecting user made changes

[Dan Williams <dcbw redhat com>]

On Wed, 2016-04-06 at 12:13 +0200, Xen wrote:
> Dan Williams schreef op 05-04-16 19:47:
> > On Tue, 2016-04-05 at 10:53 +0200, Xen wrote:
> > > Question:
> > >
> > > Currently when NM manages a link/device (say eth0) any attempt to
> > > manually configure it (using e.g. ifconfig) will quickly result
> > > in
> > > this
> > > action being undone by NM.
> > That should not be the case with NM 1.0 and later.  These versions
> > make
> > huge efforts to preserve additional IP configuration you add to the
> > interface, both addresses and routes.
> Right. It is in (K)ubuntu 16.04, with NM 1.0.4, the interface/device
> had
> default configuration which is DHCP, I had been using DHCP for a
> while
> but needed to test something.
>
> With the remote DHCP server at that point not working, I needed
> manual
> configuration quickly, so I did "ifconfig enp0s25 192.168.1.5"
> followed
> by "ifup enp0s25".
>
> I opened SSH to the host, but my connection got lost within about 20
> seconds and my device ended up being deconfigured (or reconfigured
> for
> dhcp, which didn't work).
>
>
> > Anything you add over-and-above what NM does (even if NM does
> > nothing)
> > should be preserved.  I just tested with NM 1.0.10 and an ethernet
> > interface that NM showed as "disconnected" (because NM had not
> > activated a connection on it).  Simply running "ip addr add
> > 1.2.3.4/24
> > dev enp0s25" caused NM to move the device to "connected" state and
> > report the added IP address.  NM reads the added configuration and
> > won't change it.
> That's good to hear. I have always been bugged by this. For example,
> even on Debian 7 the behaviour was the same, and I had to take NM off
> of
> the interface to be able to do any manual configuration.
>
>
> > > Should there be any sense of not interfering with manual
> > > configuration?
> > Yes, NM spends a lot of effort to do this.
> Right.
>
>
> > > I mean in a general sense what you see happening is this:
> > >
> > > 1. If some device is configured over DHCP in NM, but DHCP might
> > > be
> > > failing and there is nothing configured
> > > 2. Manual configuration of the interface to a certain IP will
> > > work
> > > for
> > > about 20 seconds, after which NM will deconfigure the device.
> > What NM version are you using?  This works for me on NM 1.0 as
> > described above.
> Currently 1.0.4-0ubuntu10 (package name).
>
> Nmcli version is 1.0.4.

I know the cooperation has been getting better during the 1.0 series,
so there could have been a bug in earlier versions.  If you can run
"nmcli g log level debug" and then reproduce the issue and send logs to
the list or privately, we could determine whether the behavior in 1.0.4
has been fixed or is still a bug in 1.0.10 and later.

Thanks!
Dan