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English Forums => 26.1 Series => Topic started by: staticznld on February 05, 2026, 10:46:14 AM

Title: [Solved] Prefix delegations when PD is not enabled in ISC DHCPv6
Post by: staticznld on February 05, 2026, 10:46:14 AM
When looking in "Services - ISC DHCPv6 - Leases - Delegated Prefixes", I noticed that a prefix had been delegated.
My LAN interface is tracking the WAN interface with prefix ID "AAAA", with manual configuration turned off.

When checking /var/log/dhcpd/latest.log, I saw the delegated prefix as shown below:

Code Select
<190>1 2026-02-05T05:37:11+01:00 firewall.redacted.com dhcpd 71898 - [meta sequenceId="2"] Reply NA: address 2a02:REDA:CTED:aaaa::1245 to client with duid 00:02:00:00:ab:11:1c:2f:ae:81:d3:02:e2:c3 iaid= 146797512 valid for 7200 seconds
<190>1 2026-02-05T05:37:11+01:00 firewall.redacted.com dhcpd 71898 - [meta sequenceId="3"] Reply PD: address 2a02:REDA:CTED:ff00::/60 to client with duid 00:02:00:00:ab:11:1c:2f:ae:81:d3:02:e2:c3 iaid = 146797512 valid for 7200 seconds
How is it possible that a prefix is delegated when all related options are turned off?
The device requesting the prefix is a hardware Globalping probe.
Title: Re: Prefix delegations when PD is not enabled in ISC DHCPv6
Post by: miketubby on February 05, 2026, 12:11:45 PM
I have no idea how that happened, but I took the hint and moved over the Kea DHCP as ISC DHCP is End-of-Life and deprecated.
Title: Re: Prefix delegations when PD is not enabled in ISC DHCPv6
Post by: staticznld on February 05, 2026, 12:15:25 PM
That's why I saw that a prefix was delegated.
I'm also looking into switching to Kea or dnsmasq in the near future.
Title: Re: Prefix delegations when PD is not enabled in ISC DHCPv6
Post by: franco on February 05, 2026, 12:27:43 PM
> My LAN interface is tracking the WAN interface with prefix ID "AAAA", with manual configuration turned off.

If I interpret this correct "manual configuration" off means "automatic configuration" on.  Part of this is distributing PDs when your WAN prefix is big enough.


Cheers,
Franco
Title: Re: Prefix delegations when PD is not enabled in ISC DHCPv6
Post by: staticznld on February 05, 2026, 12:34:36 PM
See the attached screenshot for the LAN settings.
I thought that when "Manual configuration" is turned off, only radvd distributes IPv6 addresses.

I am assigned a /48 prefix by my ISP.
Title: Re: Prefix delegations when PD is not enabled in ISC DHCPv6
Post by: staticznld on February 05, 2026, 12:50:24 PM
According to the documentation, "Identity Association" allows manual configuration. I will try that later.

QuoteIdentity Association offers similar functionality like Track Interface (legacy), but without automatic ISC-DHCPv6 and Radvd configuration. It is intended for pure RA and DHCPv6 configuration using Dnsmasq or Kea/Radvd.
Title: Re: Prefix delegations when PD is not enabled in ISC DHCPv6
Post by: franco on February 05, 2026, 02:33:59 PM
It's a hard-off for the automatic ISC-DHCPv6 and Radvd, yes.


Cheers,
Franco
Title: Re: Prefix delegations when PD is not enabled in ISC DHCPv6
Post by: Maurice on February 05, 2026, 02:41:35 PM
Quote from: staticznld on February 05, 2026, 12:34:36 PMI thought that when "Manual configuration" is turned off, only radvd distributes IPv6 addresses.

Disabling "Manual configuration" enables the ISC DHCPv6 server in automatic mode.

If you don't want to use ISC DHCPv6, uninstall it (it's a plugin now) and use "Identity Association".

Cheers
Maurice
Title: Re: Prefix delegations when PD is not enabled in ISC DHCPv6
Post by: staticznld on February 05, 2026, 02:51:07 PM
Everything seems clear to me now! Thanks for the awesome support!
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