I have been struggling with this for over a month and still keep running into a brick wall. I am building a new firewall which has six network interfaces, and want to rename them to a known order (wan[0-1], and eth[0-3]). Since Bullseye has stopped honoring udev rules, I have created link files under /etc/systemd/network/ for each interface based on their MAC address. The two WAN interfaces seem to be working reliably but they’re not actually plugged into anything yet (this may be an important but untested distinction).
What I’ve found is that I might get the interfaces renamed correctly when logging in from the keyboard, and this continues to work for multiple reboots. However if I SSH into the machine (which of course is my standard method of working on my servers) it seems to destroy systemd’s ability to rename the interface on the next boot. I have played around with the order of the link file numbers to ensure the renumbering doesn’t have the devices trying to step on each other, but to no avail. Fixing this problem seems to come down to three different solutions…
- I can simply
touchthe eth*.link files and I’m back up afte a reboot. - Sometimes I have to get more drastic, actually opening and saving each of the files (without making any changes). WHY these two methods give me different results, I cannot say.
- When nothing else works, I simply rename one or more of the eth*.link files, giving them a different numerical order. So far it doesn’t seem to matter which of the files I rename, but systemd sees that something has changed and re-reads them.
Another piece of information I ran across is that systemd does the interface renaming very early in the boot process, even before the filesystems are mounted, and that you need to run update-initramfs -u to create a new initrd.img file for grub. OK, sounds reasonable… however I would expect the boot behavior to be identical every time I reboot the machine, and not randomly stop working after I sign in remotely. I’ve also found that generating a new initrd.img does no good unless I also touch or change the link files first, so perhaps this is a false lead.
This behavior just completely baffles me. Renaming interfaces based on MAC addresses should be an extremely simple task, and yet systemd is completely failing unless I change the link files every time I remote connect? Surely someone must have found a reliable way to change multiple interface names in the years since Bullseye was released?
Sorry, I know this is a rant against systemd and this whole “predictable” naming scheme, but all of this stuff worked just fine for the last 24 years that I’ve been running linux servers, it’s not something that should require any effort at all to set up. What do I need to change so that systemd does what it is configured to do, and why is something as simple as a remote connection enough to completely break it when I do get it to work? Please help save my sanity!
(I realize essential details are missing, but this post is already way too long – ask what you need and I shall provide!)
tl;dr – Systemd fails to rename network interfaces on the next cycle if I SSH in and type ‘reboot’