Ethernet interface name change after Arch update

deadpete · 2021-12-31 16:59:46

Hi folks,

Yesterday, I updated an Archlinux installation (pacman -Syu). There were no error messages during the update, and the machine booted. However, after the update the ethernet interface changed name from eth0 to enX0.

I tried to add a network rule to udev, but it had no effect at all.

The machine is a virtual machine under Xen 4.11. Current kernel 5.15.12-arch1-1.

I use to update the machine about once every 2 months, sometimes a bit more often, so it's never completely out of date.

I somebody have got information, I would be grateful.

Best regards,

Peter

Head_on_a_Stick · 2021-12-31 17:20:58

The "predictable" interface nomenclature has been used by systemd/udev since version 197 so that suggests your system has been left un-upgraded for quite some time and certainly longer than 2 months.

daedpete wrote:

I tried to add a network rule to udev, but it had no effect at all.

Well you should probably share that attempt here then so we can spot any mistakes you may have made. Be sure to include the name of the file.

Have you tried any of the other methods listed here?

Trilby · 2021-12-31 18:18:01

Ah ... how long has it been since the last update (and/or reboot)? This change happened a long long time ago (in a galaxy far far away ... Lennartland).

The "solution" if you want the old eth0 name is not to add a udev rule, but to get rid of or mask the one that is already doing the rename:
https://wiki.archlinux.org/title/Networ … rface_name

deadpete · 2021-12-31 20:21:34

Hi,

The machine was installed a little more than 3 years ago. Systemd version 239 at the time, so the "predictable" interfaces should already have been applied there. The last full updates were in September, and mid November. When installing the new machine, eth0 was automatically defined as the ethernet interface. When installing other distributions using systemd (Debian, CentOS), eth0 is the default interface in virtual machines. Installing on physical machines, the "predictable" interface naming is used. Archlinux is more bleeding edge than the mentioned distributions, and I noticed that systemd was updated from 249 to 250. Have there been any changes here, renaming default ethernet interfaces? I have quite a bunch of other virtual machines (mostly Debian), so if there is some policy shift in systemd from 249 to 250, I will definitely be busy when that day comes.

On the Archlinux machine, there are no rules at all under /etc/udev/rules.d. Empty.

I don't care how the interfaces are named, and what principles are used. I accept what the OS suggests during install. Less fiddling, less headache that way. What is definitively a problem is, that the name was changed when updating.

Thanks for your input.

Peter

Trilby · 2021-12-31 20:43:40

Sorry, I posted a link to the wrong section, it should have gone here:
https://wiki.archlinux.org/title/Networ … face_names

If you have nothing in /etc/udev/rules.d that whan you are seeing is to be expected: you are getting the "predictable" rather than traditional interface name. Ironically the traditional name is predictable, but the "predictable" one is not. And up is down, and left is right, and systemd makes sense.

Head_on_a_Stick · 2021-12-31 20:44:40

deadpete wrote:

I noticed that systemd was updated from 249 to 250. Have there been any changes here, renaming default ethernet interfaces?

Perhaps this:

    * The predictable naming logic for network interfaces has been extended
      to generate stable names from Xen netfront device information.

https://github.com/systemd/systemd/releases/tag/v250

deadpete wrote:

On the Archlinux machine, there are no rules at all under /etc/udev/rules.d. Empty.

The rule to which Trilby is referring is under /usr/lib/udev/rules.d/ — the suggestion in the linked wiki page over-rides that with a rule of the same name under /etc/udev/rules.d/.

deadpete · 2021-12-31 21:10:57

Hi,

Thanks a lot. That explains why the interface name suddenly changed. The netfront device seems to have been exempt from this naming scheme. At least I will probably have a few years to fix this on my Debian vms ;-)

I wish you a nice and happy new year.

Peter

Arch Linux

#1 2021-12-31 16:59:46

Ethernet interface name change after Arch update

#2 2021-12-31 17:20:58

Re: Ethernet interface name change after Arch update

#3 2021-12-31 18:18:01

Re: Ethernet interface name change after Arch update

#4 2021-12-31 20:21:34

Re: Ethernet interface name change after Arch update

#5 2021-12-31 20:43:40

Re: Ethernet interface name change after Arch update

#6 2021-12-31 20:44:40

Re: Ethernet interface name change after Arch update

#7 2021-12-31 21:10:57

Re: Ethernet interface name change after Arch update

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