[pve-devel] seem than ifupdown2 is installed by default on upgrade (a friend reported me an ipv6 slaac bug)

DERUMIER, Alexandre alexandre.derumier at groupe-cyllene.com
Fri Nov 24 11:12:24 CET 2023

After investigate a litte bit,

I think this is because  ifupdown1  is setting accept_ra=2  by default.

and with ifupdown2, by security, we setup accept_ra=0   until it's
really setup in /etc/network/interfaces

iface vmbr0 inet6 auto
          accept_ra 2

(So maybe adding a note in documentation about this behaviour change
should be enough ?)

-------- Message initial --------
De: Thomas Lamprecht <t.lamprecht at proxmox.com>
À: Proxmox VE development discussion <pve-devel at lists.proxmox.com>,
"DERUMIER, Alexandre" <alexandre.derumier at groupe-cyllene.com>
Objet: Re: [pve-devel] seem than ifupdown2 is installed by default on
upgrade (a friend reported me an ipv6 slaac bug)
Date: 24/11/2023 10:07:30

Am 23/11/2023 um 18:50 schrieb DERUMIER, Alexandre:
> Hi,
> I have a friend who's reported my than ifupdown2 had been installed
> by
> default on pve 8.1 upgrade.
> I think it's because pve-network have "Recommends: ifupdown2".

Well, that was the case since almost forever, but since we added a
recommends for libpve-network-perl to pve-container, qemu-serber and
pve-manager, the SDN packages gets pulled in if
is true (by default for most installation) and then also ifupdown2.

But the apt full-upgrade output before the "continue?" prompt shows
and allows an admin to still avoid that switch.

I mean also Debian devs ponder about changing the default from
ifupdown2 for
a future release [0], as ifupdown is mostly on life-support since a


We have not yet decided when to fully drop support for old ifudpown,
for PBS we only ever supported ifupdown2 (we use only the CIDR notation
passing addresses), but I think that might only be one or two major
releases away – the ifupdown network parsers would *really* benefit
a bigger overhaul, and dropping support for legacy network might make
that a bit easier.

> Seem that it have impacted the slaac config.   (I had double check
> some
> months ago ipv6 with ifupdown2, all was ok,  but maybe default
> accept_ra is different if ifupdown2, not 100% sure ye)

If we can improve the transition it'd be naturally nice, but I do not
to drop that recommendation again for ifupdown2.


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