Re: Debian Xen bookworm upgrade - vm interface naming scheme change from eth0 to enX0

["David W. Hodgins" <davidwhodgins@xxxxxxxxx>]

On Sat, 29 Jul 2023 08:02:02 -0400, Chris Myers <chrismyers81@xxxxxxxxx> wrote:

> I upgraded my first Xen host to bookworm this morning. That seemed to go
> fine (so far...it's only been online for an hour.)
>
> After upgrading the first VM to bookworm, the networking service wouldn't
> start up. Looking at the logs it was because instead of being named eg.
> "eth0", the interfaces are now named eg. "enX0".
>
> Doing some poking around on the internet, it seems to have been a change
> with systemd - https://github.com/systemd/systemd/releases/tag/v250
>
>     * The predictable naming logic for network interfaces has been extended
>       to generate stable names from Xen netfront device information.
>
> Mostly sharing to make others aware; most of my VMs will be fine but I have
> one critical firewall VM with a dozen network interfaces that's going to be
> ... interesting.
You can add the kernel boot option net.ifnames=0 to go back to eth0.

The reason systemd made that change is that in some cases where there are
multiple network interfaces, the order they are detected is not guaranteed
by the hardware. If that happens eth0 may switch with eth1.

Regards, Dave Hodgins