ipv6 woes continue - now dhcpd6 is the problem child

[planar3d]

Did a wipe and reinstall on my small x86_64 PC (a Protectli Vault FW6C), updating it to OPNsense 23.7.3-amd64, and the good news is that this problem seems to be gone:

https://forum.opnsense.org/index.php?topic=34661.0

The bad news is dhcpd6 has become very unreliable and assignment of ipv6 address to devices is all over the place.

I've scaled back my ipv6 settings to be as simple as possible. WAN is requesting a /56 from my ISP and the "IPv6 Configuration Type" setting on all the interfaces, such as LAN or OPT1, is set to "Track Interface". I can see ipv6 addresses being assigned to the interfaces. Client devices on the network is where the problems creep in.

Observations.

Upon startup or reboot the dhcpd6 service is ALWAYS red/stopped/dead. I don't know if this is a new issue but I don't remember this behavior in 23.1

Touching/changing Router Advertisements settings causes dhcpd6 to crash.

The "Router Advertisements" setting also seem to make no sense. For example, SLAAC should be the easiest option to get working but using Assisted or Stateless has no effect. Both a Windows 10 desktop and a laptop running Debian Linux 12 failed to acquire an ipv6 address. I first cycled the interfaces and then rebooted the router and the computers to ensure everything was reinitialized but the outcome was the same. Assisted or Stateless yields nothing.

I then tried setting Router Advertisements to Disabled. Both Windows 10 and Linux somehow obtained an ipv6 address and websites like ipv6test.google.com agreed that ipv6 was working.

While that seemed to work for a few hours or even a day, dhcpd6 will just randomly die upon which the clients themselves seem to lose ipv6 connectivity, at least according to ipv6test.google.com.

I am going to try some Android devices and see if I can borrow an Xbox just to observe how different operating systems behave but this isn't looking good. ipv6 support seems SUPREMELY sketchy in 23.7.

[sbellon]

With 23.7 I have the opposite experience: It's finally a version where IPv6 in my heterogeneous network environment finally "just works".

I have GNU/Linux, Windows, Android, iOS and quite a few multimedia/streaming as well as IoT devices on the network, wired and wireless, separated in a few VLANs.

Internally I have configured SLAAC and Stateless DHCPv6. DHCPv6 is used to deliver DNS information. Also I have configured a Virtual IP in the fd01:: network for the LAN and use Dnsmasq on the OPNsense to register a few important IPv6 entries.

On ISP side I have a real dual-stack, and after a forced disconnect the connection immediately reconnects and gets new IPs (using PPPoE) and the IPv6 propagate (via track interface and RAs) into LAN.

Since 23.7 this is "set and forget" ... it works reliably.

[franco]

> Upon startup or reboot the dhcpd6 service is ALWAYS red/stopped/dead. I don't know if this is a new issue but I don't remember this behavior in 23.1

It simply indicates that IPv6 acquire failed... Do you have a delegated prefix under Interfaces: Interview?

> The "Router Advertisements" setting also seem to make no sense.

Now suddenly after we haven't much altered the page since 2015?

> While that seemed to work for a few hours or even a day, dhcpd6 will just randomly die upon which the clients themselves seem to lose ipv6 connectivity

Indicating that your IPv6 disconnects but we have no indication why from the log files you provided.

> ipv6 support seems SUPREMELY sketchy in 23.7

It may just be your ISP or PPPoE being more unreliable than usual. But the answer to this is much more complex depending on what options you use (default gateway switching also had a negative impact on the initial 23.7 but users seldomly mention using it).


Cheers,
Franco

[planar3d]

So the out of the box default config, with no options enabled, seems to work. By this I mean...

Go to Interfaces and make sure that "Allow manual adjustment of DHCPv6 and Router Advertisements" is unchecked.

If you go to "Services -> DHCPv6" you should see no interfaces listed there.

These are the default, out-of-the-box settings. With this, my Windows 10 and Linux clients are getting ipv6 addresses.

Moreover, the ipv6 addresses of the interfaces that these clients are connected to show up under "Services -> DHCPv6 -> Leases". It should be noted that both of these devices are connected directly to the OPNsense box via Ethernet.

However, the minute I turned on ""Allow manual adjustment of DHCPv6 and Router Advertisements" for one of the interfaces, bounced over to "Services -> Router Advertisements" and tried to set "Router Advertisements" to "Unmanaged" the dhcpd6 service instantly crashed.

I waited 30 seconds and then manually restarted it.

I am currently trying "Assisted" and "Stateless" to see if there is any difference in behavior.



> Do you have a delegated prefix under Interfaces: Interview?

Looks like it.

/56 which is what it should be.

Under "Interfaces -> Overview" the WAN interface reports an "IPv6 prefix" of xxxx:xxxx:xxxx:xxxx::/56



> Now suddenly after we haven't much altered the page since 2015?

The descriptions are fine. They just don't seem to have any effect or behave the way they sound.

"Managed" doesn't result in any stateful assignments.

Neither "Unmanaged" or "Stateless" seem to make SLAAC work.



> It may just be your ISP or PPPoE being more unreliable than usual. But the answer to this is much more complex depending on what options you use (default gateway switching also had a negative impact on the initial 23.7 but users seldomly mention using it).

There was definitely some network instability a few days ago on account of some very bad weather but that seems to have settled.

I'll try some Android devices in the coming days since those only support SLAAC.