SysAdmin Blog

network interfaces renamed following Proxmox 7 upgrade

Alexander Bochmann Wednesday 24 of November, 2021
After upgrading my standalone Proxmox host from PVE 6 to 7, the interface names were suddenly changed back from "predictable" to the old ethX names. The setup is Proxmox on Debian, so when I initially set up the system, I manually installed Debian 10 first and then added the Proxmox 6 repositories and packages.

After some debugging it turned out there was an old systemd network configuration file that prevented systemd-udevd from starting up correctly:

systemd-udevd[xxxx]: /etc/systemd/network/99-default.link: No valid settings found in the [Match] section, ignoring file. To match all interfaces, add OriginalName=* in the [Match] section.

I currently have no idea where the file /etc/systemd/network/99-default.link originated from (it doesn't have a package owner after the upgrade), but apparently it contains an invalid syntax for the systemd-udevd in Debian Bullseye. Removing the file solved the problem, and I'm now back to the interface names in the ifupdown2 configuration used by Proxmox (I rebooted the system to be sure it comes up in the right way now).