Pi Holes ipv6 Adress isn't renewed after it becomes deprecated

[Mathew_Green]

Hi there,

I'm using Raspberry Pi 4b with ubuntu its 20.4 and ipv6. PiHole is configured as DHCP server. If I reboot everything it's working fine. However my pi doesn't update it's external ipv6 after it's deprecated. How can I make it to automatically renew it's ipv6?

*If you are Experiencing issues with a Pi-hole install that has non-standard

Standard Configuration ipv6 enabled

Expected Behaviour:

The Pi running ubuntu 20.4 its with PiHole should automatically realize when it's ipv6 address becomes depreciated. It should than get a new one or renew the old one.

Actual Behaviour:

If I reboot the pi it gets a working external ipv6. However it will not update this ipv6 when it becomes deprecated or even when it can't be used any longer.

Output of "ip -6 address show" is:

eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
    inet6 2a02:3033:414:e659:e65f:1ff:fe71:aa06/64 scope global deprecated dynamic mngtmpaddr noprefixroute 
       valid_lft 3582sec preferred_lft 0sec

Rebooting the pi will fix this issue but only for 1h. Because afterwards it deprecated again.

Debug Token:

https://tricorder.pi-hole.net/l6qXNpaR/

[Bucking_Horn]

Pi-hole isn't involved here.

The IPv6 address shown has a EUI-64 interface identifier, i.e. that identifier is derived from your eth0 network interface's MAC address by your OS of your Pi-hole host.
The OS then constructs the complete IPv6 by combining the IPv6 prefix as advertised by your router with that EUI-64 interface identifier.

Note that while deprecated IPv6 addresses will not be used to establish outgoing communication, incoming communication on such a deprecated address would still be accepted, until its valid lifetime expires and it will be removed completely.

If it doesn't get properly renewed prior to expiration, that would be an OS level issue.

[Mathew_Green]

Thx anyway. I can't find a solution to make ubuntu automatically renew it's address. Hence I will still stick do ipv4. Is there an easy guide how to configure piHole with ipv6? I can only find ones with Fritzbox. But my router doesn't allow me to make this changes. I can only disable DHCP entirely and hope for PiHole to make all the changes.

[Bucking_Horn]

Since IPv6 configuration is highly specific to your router's make, model and sometimes even firmware version, I can only provide some generic advice.

Note that DHCP is strictly an IPv4 protocol - the Stateful DHCPv6 flavour would be a close equivalent for IPv6 (but indeed a separate protocol of its own, using different ports). Also note that with IPv6, a client may support one or more of multiple ways to join a network (SLAAC/NDP, Stateless DHCPv6 and Stateful DHCPv6). It would depend on the client OS (and potentially its individual configuration) which ways it would support, e.g. Androids do not support DHCPv6 at all.

Your router's configuration UI may not make that clear a distinction when it comes to DHCP, though. You'd have to consult your router's documentation and support for exact details.

In addition to enabling or disabling DHCPv6 and the corresponding RAs for SLAAC/NDP, your router may or may not allow configuration of an IPv6 DNS server address. If it does, you'd have to make sure it would advertise solely Pi-hole's IPv6 address, preferably its ULA address (or in lieu of that, its link-local, as long as your network is one segment only).
Again, you'd have to consult your router's documentation and support channels for exact details.
Note however that some few router models show a misbehaviour of distributing their own IP address along with any custom address regardless.

In any case, as long as your router is advertising its own IPv6 address as DNS server, any device may by-pass Pi-hole via IPv6.

You'd absolutely have to find a way to configure your router to advertise your Pi-hole host machine's IPv6 as sole DNS server instead of its own.

You'd have to consult your router's documentation sources on further details for its IPv6 configuration options.

If your router doesn't support configuring IPv6 DNS, you could consider disabling IPv6 altogether.

If your router doesn't support that either, your IPv6 capable clients will bypass Pi-hole via IPv6.

[Mathew_Green]

Hi Bucking_Horn,
thx for the generell Information helped already a lot. I consulted Zyxel the provider of my router. Let's see if there's anything they can do. For the manual clearly doesn't provide any information on ipv6.
Thx Daniel