Re: Upgraded multiple systems to systemd 249.3 and all had eth1 not started / configured

[Lennart Poettering <lennart@xxxxxxxxxxxxxx>]

On Mo, 16.08.21 16:09, Amish (anon.amish@xxxxxxxxx) wrote:

> Some old scripts that we have expect interface names starting with eth. But
> those names are not predictable.
>
> So to get predictable names starting with eth*, first I temporarily rename
> all interface with tmpeth*. This is done via udev rules.
>
> SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="XX:XX:XX:XX:XX:XX",
> NAME="tmpeth0"
> SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="XX:XX:XX:XX:XX:YY",
> NAME="tmpeth1"
> SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="XX:XX:XX:XX:XX:ZZ",
> NAME="tmpeth2"
>
> Then I have a small service (script) which runs before network-pre.target to
> convert these names back to eth*
>
> #search for network interface with name starting from "tmpeth" and rename
> them to "eth"
> /usr/bin/find /sys/class/net -maxdepth 1 -name "tmpeth[0-9]" -type l -printf
> "%f\n" | while read tmpiface; do /usr/bin/ip link set dev "$tmpiface" name
> "$(echo $tmpiface | sed s/tmpeth/eth/)"; done
>
> This ensures that I have predictable names starting with eth*. And it is
> working fine from 2-3 years. Even with current issue, name assignment is
> working fine.

This cannot work and is necesarily race. Stay out of the ethXYZ
namespace, that's the kernel's namespace. Pick any other names,
i.e. "foobar0", "foobar1", but otherwise you just have a racy racy
mess, because the kernel might take the name whenever it pleases.

Lennart

--
Lennart Poettering, Berlin