Re: How to avoid systemd/udev unpredictable NIC names
Greg Wooledge <greg@wooledge.org> writes:
> On Mon, Aug 30, 2021 at 04:41:55PM -0400, Dan Ritter wrote:
> > Steve Keller wrote:
> > > I plan to upgrade a server from Debian stretch to buster. Having read
> > > the release notes I wonder what's the best way to avoid the new scheme
> > > of unpredictable network interface names.
> >
> > In /etc/default/grub, assuming that you are booting with grub,
> >
> > GRUB_CMDLINE_LINUX_DEFAULT="quiet net.ifnames=0"
> >
> > The "quiet" is not necessary and is a different feature.
>
> This gives unpredictable results if the system has more than one
> ethernet interface, or more than one wireless interface.
>
> It's fine on systems that have 0-1 ethernet and 0-1 wireless NICs.
OK, several people suggested the kernel command-line option
net.ifnames=0. Since I almost never change hardware configurations
this is probably OK even with my two NICs, one on the mainboard, the
second is a PCI card. If the kernel should really change the
enumeration of the cards in some future, I will do something about
that.
In buster I still need to disable the
/etc/udev/rules.d/70-persistent-net.rule file since the kernel cmdline
option doesn't deactivate this. AFAIK, the kernel cmdline option only
ends up in the environment of process 1, i.e. systemd. Will systemd
communicate this to udev in a future Debian release or how is that
supposed to work. The wiki says, the plan for buster was to not
support this .rules file.
My other option would be customized names using systemd.link files.
While I prefer eth<n> I would then probably use en<0>, since the wiki
recommends not using eth<n>. I still don't understand, why eth<n> in
a systemd.link file would be a problem, since in the udev .rules this
has worked for years.
Steve
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