IPv6 SLAAC after Upgrading from 6.4 to 7.1-6

[blendon]

Hello,
I recently upgraded my local proxmox instance from version 6.4 to 7.1-6 by following the official guide for it. After the update I no longer have a public ipv6 address for my proxmox host. I'm aware that mac adresses could have changed but that shouldn't affect SLAAC at all. I also tried a clean install (7.1-6) but the issue persists. After I tried a clean install of 6.4 it did work flawlessly again. This issue only affects the proxmox host, if I create a Ubuntu Vm for example slaac does work normally. I would appreciate any help.

/etc/network/interfaces

auto lo
iface lo inet loopback

iface enp1s0 inet manual

auto vmbr0
iface vmbr0 inet static
        address 192.168.0.20/24
        gateway 192.168.0.1
        bridge-ports enp1s0
        bridge-stp off
        bridge-fd 0

ip6tables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

ping6 ipv6.google.com
ping6: connect: Network is unreachable

ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vmbr0 state UP group default qlen 1000
    link/ether c8:5b:76:b2:d9:77 brd ff:ff:ff:ff:ff:ff
3: wlp2s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 58:00:e3:48:cf:71 brd ff:ff:ff:ff:ff:ff
4: vmbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether c8:5b:76:b2:d9:77 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.20/24 scope global vmbr0
       valid_lft forever preferred_lft forever
    inet6 fe80::ca5b:76ff:feb2:d977/64 scope link
       valid_lft forever preferred_lft forever

 

[guesty321]

Hi there,

I'm have the exact same issue. Using "ip a" I can see IPv6 address being correctly assigned to host and furthermore VM's are picking up an IPv6 address and can access the internet over, however, the Proxmox host cannot.

Did you ever find a fix?

 

[blendon]

Hi,
Yes thankfully I found a fix. I can't really remember what exactly the problem was that causes this bug but basically I found an quite old GitHub issue that described how to fix it. You only have to edit your /etc/network/interfaces configuration file and add some lines. Be aware that I use the default config so if you have made changes to your config file already make sure that you don't delete them by copy pasting.

auto lo
iface lo inet loopback

iface enp1s0 inet manual

auto vmbr0
iface vmbr0 inet static
        address 192.168.0.20/24
        gateway 192.168.0.1
        bridge-ports enp1s0
        bridge-stp off
        bridge-fd 0
#This line needs to be here so that the next two get recognized
pre-up echo 2 > /proc/sys/net/ipv6/conf/vmbr0/accept_ra
post-up echo 2 > /proc/sys/net/ipv6/conf/vmbr0/accept_ra


iface wlp2s0 inet manual

Also don't forget to edit your "iface vmbr0 inet static" according to your already present configuration (it's very likely for example, that you chose an other static internal IP).

After a reboot with this fix my IPv6 was completely working again (host + VM's).

Edit: I found the corresponding GitHub Issue here