[systemd-devel] systemd-networkd, IPv6PrivacyExtensions=kernel, sysctl and devicenames

[Kevin P. Fleming]

Do you have a udev 'persistent network device name' rules file in
/etc/udev/rules.d? Many distributions install such a rules file by
default, and this renames the interfaces to 'standard' names.

On Fri, May 22, 2020 at 3:47 AM Ede Wolf <listac at nebelschwaden.de> wrote:
>
> Hello,
>
> I am trying to enable temporary and/or stable addresses for a link and
> am most likely running into troubles with the device naming. However, I
> do not change any network name myself, neither in udev nor as part or a
> link file, it's just the standard system settings (from Arch, in case
> that matters).
>
> my sysctl.conf (both ens3 and eth0 refer to the same interface):
>
>
> net.ipv6.conf.ens3.addr_gen_mode = 2
> net.ipv6.conf.ens3.use_tempaddr = 2
>
> net.ipv6.conf.eth0.addr_gen_mode = 2
> net.ipv6.conf.eth0.use_tempaddr = 2
>
>
> And the logs read:
>
> journalctl -b0 | grep -E 'sysctl|ens3|eth0'
> 08:56:46 systemd[263]: systemd-sysctl.service: Executing:
> /usr/lib/systemd/systemd-sysctl
> 08:56:46 systemd-sysctl[263]: Couldn't write '2' to
> 'net/ipv6/conf/ens3/addr_gen_mode', ignoring: No such file or directory
> 08:56:46 systemd-sysctl[263]: Couldn't write '2' to
> 'net/ipv6/conf/ens3/use_tempaddr', ignoring: No such file or directory
> 08:56:47 kernel: virtio_net virtio0 ens3: renamed from eth0
> 08:56:47 systemd[1]: sys-subsystem-net-devices-ens3.device: Changed dead
> -> plugged
> 08:56:47 systemd[1]:
> sys-devices-pci0000:00-0000:00:03.0-virtio0-net-ens3.device: Changed
> dead -> plugged
> 08:56:51 systemd-networkd[459]: ens3: Interface name change detected,
> ens3 has been renamed to eth0.
> 08:56:51 systemd-networkd[459]: eth0: Interface name change detected,
> eth0 has been renamed to ens3.
> 08:56:51 systemd-networkd[459]: ens3: IPv6 successfully enabled
> 08:56:51 systemd-networkd[459]: ens3: Link UP
> 08:56:51 systemd-networkd[459]: ens3: Gained carrier
> ...
>
>
> As it appears to me, the eth0 settings from sysctl.conf have been
> accepted - at least no errors are logged in this regard -, but are lost,
> because the interface got renamed afterwards. The ens3 interface was not
> yet known at time of invoking systemd-sysctl, and therefore we get the
> errors. That in turn means, the settings are not being applied.
>
> To make things worse, in sysctl.conf I've additionally set:
>
> net.ipv6.conf.default.stable_secret=<some hex poem>
> net.ipv6.conf.default.addr_gen_mode=2
> net.ipv6.conf.all.addr_gen_mode=2
>
>
> Which results in all IP address having a stable privacy scope link,
> _execpt_ of course ens3. The one that would be by far most important.
>
> What am I missing here? And insight is highly appreciated
>
> Thanks
>
> Ede
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