Re: "Ethernet trouble" thread
On Tue 04 Feb 2020 at 13:20:35 (+0100), Tom H wrote:
> On Mon, Feb 3, 2020 at 2:54 PM Greg Wooledge <wooledg@eeg.ccf.org> wrote:
> > On Sat, Feb 01, 2020 at 05:45:26PM +0100, Tom H wrote:
> >>
> >> You state that it's no longer udev that renames NICs. The following's
> >> from a sid VM using svsinit+sysvrc.
> > [...]
> >> udev is renaming "eth0".
> >>
> >> You can still use "/etc/udev/rules.d/" to rename NICs. Just like with
> >> "/etc/systemd/network/*.link", you gain simple names linked to a NIC's
> >> MAC address, but lose the predictable names' advantage that swapiing
> >> out a NIC preserves its name.
> >
> > Yes, it MIGHT still work. Or it might not. Support for it has
> > been officially removed. Whatever the 70-persistent-net.rules file
> > does on your system is unique to your system.
> >
> > https://wiki.debian.org/NewInBuster#Network_interface_name_migration
> >
> > "The buster release notes warn that the
> > /etc/udev/rules.d/70-persistent-net.rules method for assigning
> > persistent network interface names is no longer supported."
> >
> > https://www.debian.org/releases/buster/amd64/release-notes/ch-information.en.html#migrate-interface-names
> >
> > "If your system was upgraded from an earlier release, and still uses
> > the old-style network interface names that were deprecated with stretch
> > (such as eth0 or wlan0), you should be aware that the mechanism of
> > defining their names via /etc/udev/rules.d/70-persistent-net.rules is
> > officially not supported by udev in buster (while it may still work
> > in some cases)."
>
> Thanks. Even though this is the official policy/statement, I don't buy it.
>
> The problem's that "70-persistent-net.rules" has been used to rename
> NICs within the kernel "ethX" namespace. Until udev upstream declares
> the "SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="mac_address",
> NAME="net0" syntax and mechanism deprecated/obsoleted, I'll assume
> that the Debian release notes and wiki are wrongly melding the fact
> that renaming a NIC to "ethX" is deprecated (and that it might not
> work in the future), with the fact that
> "/etc/udev/rules.d/<something>.rule" can still be used to associate a
> NIC's MAC address with a name.
I assume that's why they wrote "while it may still work in some cases".
The trouble is that so many people seem overly attached to "eth0" as
the name of their interface, even though it's about the worst name
to choose under all the new regimes, and notwithstanding that there's
an almost infinite namespace now available.
But myunderstanding is that if you're going to use udev to change
the interface name, it's important to know that it has completed
before trying to bring up the interface. That can be tricky enough,
but is made doubly difficult when the name is the same at the end
as it was to start with. What do you wait on?
Cheers,
David.
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