Network routed, odd ip6 error, host has no ipv6

One NIC in this new hetzner ubuntu 20.04.3 bare metal setup.
Few instances are running and i wanted to check out the routed way and ordered one more IP.

Since the default profile is lxdbr2, does it maybe conflict with routed and give this odd error?

lxc launch ubuntu:focal myrouted --profile default --profile routed_mail
Creating myrouted
Starting myrouted
Error: Failed to start device "eth0": Error setting up reverse path filter: Failed to run: ip6tables -w -t raw -I PREROUTING -m rpfilter --invert -i veth12a360d7 -j DROP -m comment --comment generated for LXD container myrouted (eth0) rpfilter: Could not open socket to kernel: Address family not supported by protocol
Try `lxc info --show-log local:myrouted` for more info


lxc info --show-log local:myrouted
Name: myrouted
Status: STOPPED
Type: container
Architecture: x86_64
Created: 2022/01/16 16:38 CET

Configs done:
ipv6 is disabled at boot via kernel cmd line options.
net.ipv4.conf..forwarding=1 is set as per Handbook. in sysctl.conf
net.ipv4.conf.enp0s31f6.forwarding=1

config:
  user.network-config: |
    version: 2
    ethernets:
        eth0:
            addresses:
            - [ Public IP 2 ]/32
            ipv6.address: none
            ipv6.firewall: "false"
            nameservers:
                addresses:
                - 185.12.64.1
                - 185.12.64.2
                - 8.8.8.8
                - 8.8.4.4
                search: []
            routes:
            -   to: 0.0.0.0/0
                via: 169.254.0.1
                on-link: true
description: Default LXD profile
devices:
  eth0:
    ipv4.address: [ Public IP 2 ]
    nictype: routed
    parent: enp0s31f6
    type: nic
name: routed_mail
used_by: []

below two lines had no effect but i had to try

ipv6.address: none
ipv6.firewall: “false”

lxc profile show default

config: {}
description: Default LXD profile
devices:
  eth0:
    name: eth0
    network: lxdbr2
    type: nic
  root:
    path: /
    pool: hdd
    type: disk
name: default
used_by:
- /1.0/instances/haproxy
- /1.0/instances/foro
- /1.0/instances/db
- /1.0/instances/nextcloud
- /1.0/instances/onflyoffice
- /1.0/instances/c1
- /1.0/instances/myipvlan

/etc/network/interfaces

source-directory /etc/network/interfaces.d

auto lo
iface lo inet loopback

auto enp0s31f6
iface enp0s31f6 inet static
  address [ Public IP 1]
  netmask 255.255.255.192
  gateway 1XX.YYY.XZX.1
  pointpoint 1XX.YYY.XZX.1 # same as gateway
  dns-nameserver 185.12.64.1 185.12.64.2 8.8.8.8 8.8.4.4
#broadcast 1XX.YYY.XZX.42

#additional IP
  up ip addr add [ Public IP 2]/32 dev enp0s31f6
  down ip addr del [ Public IP 2]/32 dev enp0s31f6

/etc/dnsmasq.conf does not exist

ps aux | grep dnsmasq
lxd         2433  0.0  0.0   7204  3748 ?        Ss   13:30   0:01 dnsmasq --keep-in-foreground --strict-order --bind-interfaces --except-interface=lo --pid-file= --no-ping --interface=lxdbr2 --dhcp-rapid-commit --quiet-dhcp --quiet-dhcp6 --quiet-ra --listen-address=10.0.0.1 --dhcp-no-override --dhcp-authoritative --dhcp-leasefile=/var/snap/lxd/common/lxd/networks/lxdbr2/dnsmasq.leases --dhcp-hostsfile=/var/snap/lxd/common/lxd/networks/lxdbr2/dnsmasq.hosts --dhcp-range 10.0.0.2,10.0.0.254,1h -s lxd --interface-name _gateway.lxd,lxdbr2 -S /lxd/ --conf-file=/var/snap/lxd/common/lxd/networks/lxdbr2/dnsmasq.raw -u lxd -g lxd
jim        452151  0.0  0.0   8504  2516 pts/1    S+   19:49   0:00 grep --color=auto dnsmasq

journactl has no errors


lxc config show --expanded myrouted
architecture: x86_64
config:
  image.architecture: amd64
  image.description: ubuntu 20.04 LTS amd64 (release) (20220111)
  image.label: release
  image.os: ubuntu
  image.release: focal
  image.serial: "20220111"
  image.type: squashfs
  image.version: "20.04"
  user.network-config: |
    version: 2
    ethernets:
        eth0:
            addresses:
            - [ Public IP 2 ]/32
            ipv6.address: none
            ipv6.firewall: "false"
            nameservers:
                addresses:
                - 185.12.64.1
                - 185.12.64.2
                - 8.8.8.8
                - 8.8.4.4
                search: []
            routes:
            -   to: 0.0.0.0/0
                via: 169.254.0.1
                on-link: true
  volatile.apply_template: create
  volatile.base_image: ced57a80f2b761c3cdab867c2296b801c6adfe521f811bacdd61410da4bc2734
  volatile.eth0.hwaddr: 00:16:3e:19:b6:0a
  volatile.eth0.name: eth0
  volatile.idmap.base: "0"
  volatile.idmap.current: '[{"Isuid":true,"Isgid":false,"Hostid":1000000,"Nsid":0,"Maprange":1000000000},{"Isuid":false,"Isgid":true,"Hostid":1000000,"Nsid":0,"Maprange":1000000000}]'
  volatile.idmap.next: '[{"Isuid":true,"Isgid":false,"Hostid":1000000,"Nsid":0,"Maprange":1000000000},{"Isuid":false,"Isgid":true,"Hostid":1000000,"Nsid":0,"Maprange":1000000000}]'
  volatile.last_state.idmap: '[{"Isuid":true,"Isgid":false,"Hostid":1000000,"Nsid":0,"Maprange":1000000000},{"Isuid":false,"Isgid":true,"Hostid":1000000,"Nsid":0,"Maprange":1000000000}]'
  volatile.uuid: 635898b9-e809-47f5-b579-fee6d8fdce7a
devices:
  eth0:
    ipv4.address: [ Public IP 2 ]
    nictype: routed
    parent: enp0s31f6
    type: nic
  root:
    path: /
    pool: hdd
    type: disk
ephemeral: false
profiles:
- default
- routed_mail
stateful: false
description: ""


Went ahead and tested ipvlan profile which works with the public IP but thought i post this routed error, since only thing that shows ipv6 seems to be the lxd dnsmasq.

I suspect your kernel doesn’t have IPv6 support. I’ll see if we can make that reverse path filter conditional based on specifying an IPv6 address.

Hi Tom, yes

GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1 consoleblank=0 systemd.show_status=true elevator=noop console=tty1 console=ttyS0 irqpoll"
GRUB_CMDLINE_LINUX="ipv6.disable=1 irqpoll"

This should fix it: