With IPv4 set to DHCP and IPv6 set to SLAAC in Proxmox, my Debian 13 LXC containers have:
in their config.
The installed ifupdown2 3.0.0-1.3 reports “unsupported address method 'auto'”, but launches dhclient -6 anyway. My network uses SLAAC, not DHCPv6 address assignment. IPv4 works while networking.service stays stuck starting indefinitely.
From a cursory glance at the ifupdown2 code, it just doesn't seem to support SLAAC properly. It merges the IPv4 and IPv6 stanzas into one interface object, retaining the first stanza’s dhcp method while combining both address families.
Proxmox’s official Debian 13 template build recipe explicitly installs ifupdown2. This is not a manually selected guest networking package.
This template change was apparently made here for better DHCP compatibility, but breaking SLAAC is probably not an intended consequence.
I found two earlier reports of the same behavior in the forum:
DHCPv6 used without timeout when configuring SLAAC
PMG LXC stuck starting when using SLAAC
What is the proper fix for the official Debian 13 template?
Selecting SLAAC should for sure not start an indefinite DHCPv6 wait.
Host: PVE 9.2.11. Affected deployed guests: Debian 13, ifupdown2 3.0.0-1.3.
Code:
iface eth0 inet dhcp
iface eth0 inet6 autoThe installed ifupdown2 3.0.0-1.3 reports “unsupported address method 'auto'”, but launches dhclient -6 anyway. My network uses SLAAC, not DHCPv6 address assignment. IPv4 works while networking.service stays stuck starting indefinitely.
From a cursory glance at the ifupdown2 code, it just doesn't seem to support SLAAC properly. It merges the IPv4 and IPv6 stanzas into one interface object, retaining the first stanza’s dhcp method while combining both address families.
Proxmox’s official Debian 13 template build recipe explicitly installs ifupdown2. This is not a manually selected guest networking package.
This template change was apparently made here for better DHCP compatibility, but breaking SLAAC is probably not an intended consequence.
I found two earlier reports of the same behavior in the forum:
DHCPv6 used without timeout when configuring SLAAC
PMG LXC stuck starting when using SLAAC
What is the proper fix for the official Debian 13 template?
Selecting SLAAC should for sure not start an indefinite DHCPv6 wait.
Host: PVE 9.2.11. Affected deployed guests: Debian 13, ifupdown2 3.0.0-1.3.
