[SOLVED] DHCPv6 Static DNS Server - Some Clients Not Receiving Address

[iamperson347]

Hello All,

I'm trying to set a static DNS server when using DHCPv6. I am currently doing this with ipv4 DHCP and it is working great. If it matters, I am using DHCP-PD on the WAN interface and other interfaces are tracking that with a prefix ID set for each non-WAN interface. I also have RA setup in assisted mode (with "Use the DNS settings of the DHCPv6 server" selected).

I set the static DNS Server address in the DHCPv6 settings for my LAN interface. Different clients appear to be receiving different DNS servers for ipv6.

Windows client: Receiving LAN gateway address as ipv6 DNS server. (ipv4 static DNS server address is good)
Android Client: Receiving specified DNS server address as ipv6 DNS server. (ipv4 static DNS server address is good as well)
iOS Client: Receiving specified DNS server address AND LAN gateway address as ipv6 DNS servers. (ipv4 static DNS server address is good)

Any settings I should check? Ideally, I would like all DHCP clients to receive the DNS server addresses I set for both ipv4 and ipv6.

Please let me know if I can do anything to help diagnose the problem.

Thank you.

[iamperson347]

I'm not super knowledgeable with the inner workings of opnsense. However, I noticed /var/dhcpd/etc/dhcpdv6.conf is getting set to the interface address instead of the DNS server address specified. The main config.xml under conf does get set appropriately though.

[marjohn56]

Yes, you are correct, any entries there are not overiding the system settings.


I've issued a PR, in the meantime, try this patch: a9553b8

[marjohn56]

I have also found something else that would cause a problem when using an override dhcpd6 on a tracked interface. If you applied the previous patch then please reverse it by applying the same patch again and then use this patch ID given below. This then allows all parameters entered into dhcpd6 settings to be used when in a tracked override mode, rather than just the ranges.


Patch ID: 3d5a5d0

[iamperson347]

Looks like that did the trick. My iOS client isn't here to test right now, but the config file previously mentioned got updated appropriately and my windows client is getting the right ipv6 DNS server now.

Edit: iOS client got the correct DNS  servers well.

Thank you for the quick turnaround!

[marjohn56]

Good, pleased it fixed it for you.


This will NOT be in 18.7.1, so if you update you will have to re-apply the patch, I may have to modify it, but I'll test it against 18.7.1 when it's released shortly; if needed I'll update the patch.


Sorry about that, but 18.7.1 already had it's foot halfway out of the door before I wrote this and sent in a PR.

[iamperson347]

No worries. Thanks again for your help.

[iamperson347]

Hey again.

I looked through the pull requests and I thought it looked like this was resolved for 18.7.2. However, it looks like the problem returned.

[marjohn56]

I'll look and see why this has not gone through.

[marjohn56]

I've raised an issue for this: https://github.com/opnsense/core/issues/2713

[franco]

I'm sorry if any misunderstanding has arisen from this. The fix was added to the master branch but not released in 18.7.2 as implied by the release notes.

I've talked to Martin, tested again, and it is ok to release now in 18.7.3 now that we are all on the same page about the issue at hand.

From my knowledge the original issue appeared in 18.7-RC1 with the addition of the manual DHCPv6/RADVD feature for tracked interfaces.

Sometimes patches are not immediately moved to the release to give them more time in the development version to double-check and mature if necessary.


Cheers,
Franco

[iamperson347]

No worries! Thank you all for all that you do for the project.

Interestingly enough, the old patch from marjohn56 still worked, so I just applied that in the mean time.

Thanks again!