How to prevent `Ignoring duplicate dhcp-option 23` warnings in v6?

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1

I'm having a problem with v6, where I'm getting Ignoring duplicate dhcp-option 23 warnings, because I'm using DHCP with other IPv6 DNS servers.

With v5, I put the other servers in /etc/dnsmasq.d/07-dns-servers.conf, and made dhcp-option=option6:dns-server,[::] a comment in /etc/dnsmasq.d/02-dhcp.conf. That removed the warning until another change was made. After which, I just redid my change to /etc/dnsmasq.d/02-dhcp.conf.

But with v6, making dhcp-option=option6:dns-server,[::] a comment in /etc/pihole/dnsmasq.conf, results in the change immediately being undone when pihole-FTL is restarted.

What can I do to remove or disable the dhcp-option=option6:dns-server,[::] line in /etc/pihole/dnsmasq.conf, as there's no obvious way to in /etc/pihole/pihole.toml?

Also, is there a better way to format file paths?

2

Solved by disabling the DCHPv6 server in Pi-hole, and enabling it via a dnsmasq configuration file.

3

To prevent that line from being written, unchecking Enable additional IPv6 support (SLAAC + RA) in Settings | DHCP would have been enough in v5 as well as v6.

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4

Actually, this may not be solved, as unchecking Enable additional IPv6 support (SLAAC + RA) seems to have stopped Pi-hole DHCPv6 announcements in the Pi-hole log file.

So, does the device providing DHCPv6 announcements over the LAN, that aren't being logged by Pi-hole?

5

Of course it would - stopping RAs, that is.

But why would you need Pi-hole to do this?

With IPv6 auto configuration, it's a router's job to advertise network configuration details for clients to use, including DNS server addresses.

About the only time this is helpful would be if your router's only IPv6 DNS option would be to switch RDNSS either on or off completely.

6

Because the RA in Enable additional IPv6 support (SLAAC + RA) stands for Router Announcements, which as the DHCP server, the Pi-hole provided.

I'm not using my router's DHCPv6 server, as I need to broadcast tfpboot options, which my router can't do.

Having said that, I'm using
dhcp-range=::,constructor:eth0,ra-names,ra-stateless,64
in /etc/dnsmasq.d/dhcpv6.conf, which I copied from the Pi-hole dnsmasq configuration file, so the announcements may just not being logged.

7

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