Proxmox Host IPv6 DHCP not working

F

foerkede

New Member
Nov 25, 2019
10
0
1
Hello,
I am trying to get a IPv6 address for my proxmox host via dhcp, so I set up my /etc/network/interfaces like it is suggested in the debian docs:

Code: 
iface vmbr0.100 inet6 dhcp

But that doesn't work, it doesn't set an address. Is there something I need to activate for this to work? When I set a static IPv6 it works.
 
Do you have a DHCPv6 server in your environment? Keep in mind that this is different than SLAAC (stateless autoconfiguration - which should be configured with 'auto' instead of 'dhcp' in /etc/network/interfaces)

if this is not the issue - then check the system journal after booting for messages explaining the problem.
I hope this helps!
 
Stoiko Ivanov said:
Do you have a DHCPv6 server in your environment? Keep in mind that this is different than SLAAC (stateless autoconfiguration - which should be configured with 'auto' instead of 'dhcp' in /etc/network/interfaces)

if this is not the issue - then check the system journal after booting for messages explaining the problem.
I hope this helps!
Click to expand...
Sorry for the late reply, but it still won't work. I tried to set it to 'auto', but then I get this from ifreload -a: "unsupported address method 'auto'".

And when I set it to dhcp (as I want it), it doesn't seem to contact the dhcp server at all. I have a pfSense firewall running, but in the logs I can't see it contacting the dhcpv6 server.

Could you tell me exactly where I could find logs regarding this, or this system journal?
 
please share your complete '/etc/network/interfaces' and the journal when running `ifreload -a` and `ifdown -a; ifup -a` (take care since this might disconnect the machine)
 
Stoiko Ivanov said:
please share your complete '/etc/network/interfaces' and the journal when running `ifreload -a` and `ifdown -a; ifup -a` (take care since this might disconnect the machine)
Click to expand...
I'm sorry but I don't know what you mean by 'journal'?

Code: 
auto lo
iface lo inet loopback

iface eno1 inet manual

iface eno2 inet manual

auto bond0
iface bond0 inet manual
    bond-slaves eno1 eno2
    bond-miimon 100
    bond-mode 802.3ad
    bond-xmit-hash-policy layer2+3

auto vmbr0
iface vmbr0 inet manual
        bridge_ports bond0
        bridge_stp off
        bridge_fd 0
        bridge-vlan-aware yes
          bridge-vids 2-4094

auto vmbr0.100
iface vmbr0.100 inet static
  address 10.0.100.20/24
  gateway 10.0.100.1

iface vmbr0.100 inet6 dhcp
 
Last edited:
Did you setted up an dhcpv6 server? It isn't as easy to setup one as for ipv4.
 
foerkede said:
I'm sorry but I don't know what you mean by 'journal'?
Click to expand...
the system-journal is the place where logs get written to in linux-distributions using systemd (as Debian and thus PVE does)
see `man journalctl` and `man systemd-journald` and `man journald.conf`
 
I have this same issue. I've tried everyhting dhcpv6 related in this forum and nothing worked.

I've
Code: 
iface vmbr0 inet6 dhcp
set in /etc/network/interfaces but I'm not getting anything. When I run dhclient -6 vmbr0 I'm getting an IP address. Any ideas as to why? Other hosts seem to work fine.
 
try with iface vmbr0 inet6 auto

debian behaves different with "dhcp" as ubuntu for example. if there is no dhcp6 server debian hangs and tryes forever to get one. While Ubuntu switches to slaac.

at least it's what i think what happens.
auto does slaac. i think simply that you all are confused with router advertisement vs real dhcpv6.
However try with auto.

Cheers
 
Ramalama said:
try with iface vmbr0 inet6 auto

debian behaves different with "dhcp" as ubuntu for example. if there is no dhcp6 server debian hangs and tryes forever to get one. While Ubuntu switches to slaac.

at least it's what i think what happens.
auto does slaac. i think simply that you all are confused with router advertisement vs real dhcpv6.
However try with auto.

Cheers
Click to expand...
auto AFAIK means SLAAC right? But I've setup a DHCPv6 server via opnsense which works for VMs under proxmox, but not proxmox itself. When I use dhclient -6 vmbr0 it picks the static ipv6 address I've set in opnsense.
 
Hmmh, then i believe you.
But dhcpv6 works different for ipv6, what i mean is, it's not only broadcast packets like with ipv4.
So probably something isn't picked up.

Maybe an idea is to switch between ifupdown v1 and ifupdown2.
(this is the "service/binary" that reads /etc/network/interfaces and applyes the config)
 
Ramalama said:
Hmmh, then i believe you.
But dhcpv6 works different for ipv6, what i mean is, it's not only broadcast packets like with ipv4.
So probably something isn't picked up.

Maybe an idea is to switch between ifupdown v1 and ifupdown2.
(this is the "service/binary" that reads /etc/network/interfaces and applyes the config)
Click to expand...
I've installed ifupdown2. From what I'm seeing here, it looks like dhclient doesn't start on boot.
 
okay, you can test that.

if you booted up, and you don't get an ip over dhcpv6.
do you get one if you do
systemctl restart networking
?
and you can see what error it gives with status.
 
Ramalama said:
okay, you can test that.

if you booted up, and you don't get an ip over dhcpv6.
do you get one if you do
systemctl restart networking
?
and you can see what error it gives with status.
Click to expand...
nothing much. This is the only relevant thing I could find:

Code: 
no link-local IPv6 address for vmbr0

Although I can see a link local address with ip a
 
hmmh, probably it's a bug of ifupdown itself with the combination of a linux bridge.

i have probably a workaround idea, if your dhcp client works, you can add the command via post-up or up:
https://cumulusnetworks.github.io/ifupdown2/ifupdown2/userguide.html#specifying-user-commands

but don't ask me, if you need to use post-up/pre-up/up because that's super crappy documentated at which stages they run.

The idea is simply that you add:
up dhclient -6 vmbr0
under your interface.
i would change it then to "manual" instead of dhcp/auto too. Since "manual" does simply not involve any "automatic" scripts.

What i've readed in the github of ifupdown2 is, that iface vmbr0 inet dhcp, implies automatically inet6 dhcp too.
But if you use a static ipv4, that's a nogo for you anyway.

Cheers
 
Ramalama said:
hmmh, probably it's a bug of ifupdown itself with the combination of a linux bridge.

i have probably a workaround idea, if your dhcp client works, you can add the command via post-up or up:
https://cumulusnetworks.github.io/ifupdown2/ifupdown2/userguide.html#specifying-user-commands

but don't ask me, if you need to use post-up/pre-up/up because that's super crappy documentated at which stages they run.

The idea is simply that you add:
up dhclient -6 vmbr0
under your interface.
i would change it then to "manual" instead of dhcp/auto too. Since "manual" does simply not involve any "automatic" scripts.

What i've readed in the github of ifupdown2 is, that iface vmbr0 inet dhcp, implies automatically inet6 dhcp too.
But if you use a static ipv4, that's a nogo for you anyway.

Cheers
Click to expand...

I've removed ifupdown2 and it works now... I'd like to keep it though, it helps with applying network configs via the GUI AFAIK
 
debsque said:
I've removed ifupdown2 and it works now... I'd like to keep it though, it helps with applying network configs via the GUI AFAIK
Click to expand...
that's what I meant initially with switching between ifupdown and ifupdown2 xD

But there are probably cases where you need the other probably too, however, both are fine.
Glad you found a solution.

Cheers
 
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Ramalama said:
that's what I meant initially with switching between ifupdown and ifupdown2 xD

But there are probably cases where you need the other probably too, however, both are fine.
Glad you found a solution.

Cheers
Click to expand...
Thanks for the pointers. I'll try and troubleshoot what's with ifupdown2 not working. I'll report if I find something.

Edit: I've tried using a cronjob to start dhclient after boot, but it doesn't pickup an IPv6 prefix change as well as ifupdown1. Most likely I don't know how to build a proper script. So I've just switched to ifupdown1.
 
Last edited:
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