[bitfolk] Re: Debian 12 bookworm - a reminder about eth0 → enX0

Hi Frederik, On Tue, Jun 13, 2023 at 10:39:48PM +0800, Frederik Vanrenterghem via BitFolk Users wrote: I'm taking that as meaning "add both eth0 and enX0 to /etc/network/interfaces". That should work, but seems a little messy. In this situation there isn't really any need to guess: unless you take some action, the version of systemd/udev in Debian 12 WILL rename your eth0 to enX0 when you next boot. So I would either: - rename eth0 to enX0 in /etc/network/interfaces, or; - add net.ifnames=0 to the kernel command line (GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub and then update-grub) to prevent this happening at all. I suppose adding both eth0 and enX0 does have the advantage that you can do it now while you remember and then things continue to work even if you do reboot without upgrading. The described "safety net" of "manual override" also seems viable; that involves creating a .link file that will match your network interface, so you get to choose the name. You can call it wan0 or bf0 or whatever. That's described here: https://wiki.debian.org/NetworkInterfaceNames#CUSTOM_SCHEMES_USING_.LINK_FI… and should work for any version of Debian that has systemd. You can match by MAC address like the example does (this will not change for the life of your VM) although do note that if you add some kinds of virtual interface they may use the same MAC as your real one, which would make systemd try to rename those too, leading to a mess. I would suggest matching also on Type=ether as there shouldn't be any other Ethernet interface with the same MAC. I think Kind=vif may also match it. The systemd.link(5) man page covers all this: https://manpages.debian.org/bookworm/udev/systemd.link.5.en.html While getting this wrong may be irritating, it should not be disastrous; you can always connect to Xen Shell and use "console" command to get on the hvc0 console of your VM. From there you can see what the network interface is actually called. It's a very good idea to make sure you can connect to the Xen Shell console before doing anything like an upgrade to the next major release. Cheers, Andy -- https://bitfolk.com/ -- No-nonsense VPS hosting