Proxmox Not Automatically Assigning IPv6 via RA/DHCPv6

K

Kjume

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Sep 30, 2024
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Hello,


I am experiencing an issue where my Proxmox servers are not automatically receiving a public IPv6 address via Router Advertisements (RA) or DHCPv6, while other devices on the same network (such as my Windows laptop) receive an IPv6 address immediately.


Network Setup:​


  • My router is configured to provide IPv6 addresses using DHCPv6.
  • A Windows machine connected to the same network automatically receives a public IPv6 address and is reachable from the internet.
  • However, Proxmox (running on Debian) only receives a link-local address (fe80::/64) but no global IPv6 address.

Troubleshooting Steps Taken:​


  1. Checked IPv6 addresses on Proxmox:

    ip -6 addr show vmbr0
    • Only a link-local address is assigned, no global IPv6.
  2. Tried requesting an address manually:

    dhclient -6 -v vmbr0
    • No public IPv6 is assigned.
  3. Verified IPv6 routes:

    >ip -6 route
    • No default IPv6 route exists.
  4. Manually assigned an IPv6 address for testing:
    • After manual assignment, IPv6 does not work properly.

Question:​


  • Why is Proxmox not automatically receiving an IPv6 address via DHCPv6 or Router Advertisements, even though other devices on the same network do?
  • Is there a known issue with Proxmox not handling RA/DHCPv6 correctly?
  • What is the recommended way to configure Proxmox to ensure it automatically obtains a public IPv6 address upon network restart?

Thank you for your assistance.
 
Kjume said:
  • Why is Proxmox not automatically receiving an IPv6 address via DHCPv6 or Router Advertisements, even though other devices on the same network do?
Click to expand...
Because Proxmox is not using auto settings but inet manual. So no auto for IPv4 and no auto for IPv6.

Not the default I would choose, but it is what it is.

Fortunately you can change this. Proxmox VE is using the Linux network stack.
https://pve.proxmox.com/wiki/Network_Configuration
 
IsThisThingOn said:
Because Proxmox is not using auto settings but inet manual. So no auto for IPv4 and no auto for IPv6.

Not the default I would choose, but it is what it is.

Fortunately you can change this. Proxmox VE is using the Linux network stack.
https://pve.proxmox.com/wiki/Network_Configuration
Click to expand...
idk why but not work at all... i cant manually set IPV6 for my proxmox servers... another devices or normal linux systems works okay but proxmox dont wanna function on IPV6 and idk why... what i can see its "known" problem about IP6 on proxmox i see threads from 2021 and they still not solved...

idk how to set up IPV6 like a normal person :D :D btw IPV6 is smth new for me...
 
can't test it right now but can't you change:

Bash: 
auto vmbr0
iface vmbr0 inet static
        address 10.0.10.2/24
        gateway 10.0.10.1
        bridge-ports ens1
        bridge-stp off
        bridge-fd 0
        bridge-vlan-aware yes
        bridge-vids 2-4094

to somthing like this:

Bash: 
auto vmbr0
iface vmbr0 inet auto
 
IsThisThingOn said:
can't test it right now but can't you change:

Bash: 
auto vmbr0
iface vmbr0 inet static
        address 10.0.10.2/24
        gateway 10.0.10.1
        bridge-ports ens1
        bridge-stp off
        bridge-fd 0
        bridge-vlan-aware yes
        bridge-vids 2-4094

to somthing like this:

Bash: 
auto vmbr0
iface vmbr0 inet auto
Click to expand...
Nope not work at all...

Idk why proxmox can't support IPv 6 i think inet Is Broken
 
Kjume said:
Idk why proxmox can't support IPv 6 i think inet Is Broken
Click to expand...
But it does support IPv6 (like any Debian) as long as you don't disable it. Can you please post the output of this commands from the console?
# Display information about the configured network adresses
ip addr
# Display used kernel boot options, I want to know whether IPv6 was disabled
cat /proc/cmdline
# Display all sysctl settings so we can determine whether IPv6 was disabled with sysctl
sysctl -a
Click to expand...


On my boxes PVE has IPv6, but like IPv4 you need to configure it.
 
Last edited:
:wave: a fix for this was merged in about a week ago, its out now please update your PVE container package
 
What was the actual fix here?

My home lab/LAN has native IPv6 support. PD from service provider for GUA, ULA configured for local private IPv6 addresses for when the service provider changes the prefix (doesnt happen often but does happen).

All client config is via SLAAC and works fine for the various Linux and Windows boxes I have. Its neat.

Proxmox nodes though dont seem to have the option to enable IPv6 with autoconfig. You can only specify a static IPv6 config via the web gui. Thats not good practice for IPv6 addressing.

Normally, a simple `iface vmbr0 inet6 auto` in `/etc/network/interfaces` would do the trick. The `interfaces` file on the Proxmox node clearly says not edit that file by hand which is fine. I added the file `/etc/network/interfaces.d/ifcfg-vmbr0-ipv6` with the correct content to enable SLAAC for that interface but a `systemctl restart networking` doesnt result in an IPv6 config appearing on the interface.

Interestingly, `/etc/network/interfaces` says:

> # If you want to manage parts of the network configuration manually,
> # please utilize the 'source' or 'source-directory' directives to do
> # so.
> # PVE will preserve these directives, but will NOT read its network
> # configuration from sourced files, so do not attempt to move any of
> # the PVE managed interfaces into external files!

I read this to mean that PVE will not actually read in config files from `/etc/network/interfaces.d`.

Most other guis allow operators to just tick a box to say "auto" config for IPv6.

What's the go here?
 
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ausfestivus said:
when the service provider changes the prefix (doesnt happen often but does happen).
Click to expand...
That fact alone would make me reconsider IPv6 for services.
Changing IPv6 prefix, is IMHO (and according to RIPE) a broken IPv6 implementation.
OPnsense can handle that, but Proxmox I am not sure.

ausfestivus said:
Proxmox nodes though dont seem to have the option to enable IPv6 with autoconfig. You can only specify a static IPv6 config via the web gui. Thats not good practice for IPv6 addressing.
Click to expand...
I really don't understand why Proxmox uses their own defaults in the webGUI or why at least they don't offer the options to recreate the Debian defaults.
 
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