Register DHCPv6 hostnames in DNS



  • Hi!

    I'm running a DHCPv6 server for my LAN clients and the DNS resolver as well. If I ping a hostname who has an IPv6 adress, I only can lookup its IPv4. Is it possible to automatically register the IPv6 adresses in the DNS resolver?



  • Hosts don't provide a hostname to the DHCPv6 server, as it's not part of the specification. As a result, there's no way to directly associate a DHCPv6 address with a hostname.



  • I have a setup where the hostnames register in external BIND forward and reverse via pfsense-dhcpv6. Win10, CentOS and fedora works, Android and macOS not.



  • @virgiliomi said in Register DHCPv6 hostnames in DNS:

    Hosts don't provide a hostname to the DHCPv6 server, as it's not part of the specification. As a result, there's no way to directly associate a DHCPv6 address with a hostname.

    It is part of the DHCPv6 spec, it is just that ISC DHCP used by FreeBSD, and so also pfSense doesn't support it.



  • @isaacfl Your information seems to be outdated. Pfsense does support it ! I started to use it under 2.4.3. Pfsense dhcpv6 registers hostname and PTR's to ISC BIND under FreeBSD. Look at the "DHCPv6 Server & RA" settings. The only part that could be optimized is update transport over IPv6
    "DDNS Server IP (Enter the primary domain name server IPv4 address for the dynamic domain name.)"


  • Rebel Alliance Developer Netgate

    Right, but that is using a BIND server with client self-registration and not what is built into the pfSense base system (DNS Resolver or Forwarder)

    The same method used for IPv4 won't work for IPv6 because ISC DHCPD doesn't record hostnames in the lease database, if it even receives them from clients.



  • @jimp Ok, agree to the technical details. I wanted to give a hint for how to solve OT's need for automatic registering.

    I checked again how it works. The information comes definitive via DNS-KEY from the pfsense gateway IP. I see no need to store the name in dhcp too when the passtrough to BIND works this way.
    Obfuscated output from BIND-log:

    28-Sep-2018 21:03:12.656 update: client @0x8087fec00 172.31.18.1#22770/key ddns-key: view internal: updating zone 'int.somedomain.org/IN': update unsuccessful: some-host.int.somedomain.org: 'name not in use' prerequisite not satisfied (YXDOMAIN)
    28-Sep-2018 21:03:12.658 update: client @0x8087fec00 172.31.18.1#22770/key ddns-key: view internal: updating zone 'int.somedomain.org/IN': deleting rrset at 'some-host.int.somedomain.org' TXT
    28-Sep-2018 21:03:12.658 update: client @0x8087fec00 172.31.18.1#22770/key ddns-key: view internal: updating zone 'int.somedomain.org/IN': adding an RR at 'some-host.int.somedomain.org' TXT "024fba2obfuscatednumb2a25secret75b"
    28-Sep-2018 21:03:12.658 update: client @0x8087fec00 172.31.18.1#22770/key ddns-key: view internal: updating zone 'int.somedomain.org/IN': deleting rrset at 'some-host.int.somedomain.org' AAAA
    28-Sep-2018 21:03:12.658 update: client @0x8087fec00 172.31.18.1#22770/key ddns-key: view internal: updating zone 'int.somedomain.org/IN': adding an RR at 'some-host.int.somedomain.org' AAAA 2a0x:xxxx:xxxx:5af1:xxxx:xxxx:ef8f:xxxx
    28-Sep-2018 21:03:12.661 update: client @0x8087fec00 172.31.18.1#22770/key ddns-key: view internal: updating zone '1.f.a.x.x.x.x.x.x.x.x.x.x.x.a.2.ip6.arpa/IN': adding an RR at 'x.5.7.x.x.8.f.e.x.x.2.a.x.d.4.2.1.x.a.5.1.x.x.x.x.x.x.x.x.0.a.2.ip6.arpa' PTR some-host.int.somedomain.org.
    


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