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    Services / Router Advertisement - DHCPv6 server - strange behavior

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    • E
      eagle61
      last edited by eagle61

      I noticed a strange behavior on Android devices in a local network segment used for IoT-Devices only of my pfsense.

      The Router Advertisement Mode for the IoT-Segment are set to Managed. Netgate Docs writes about this mode: "The firewall will send out RA packets and addresses will only be assigned to clients using DHCPv6" and that what i want. All devices shall get either only a IPv4-Adress and a fixed IPv6Adress from activated KEA DHCPv6-Server. So far that works well.

      But just because of curiosity and testing purposes i did add an older WIFI-Access Point to this segment and noticed strange behavior of my Android devices if using this WIFI-Access Point.
      My phone and my tablet, one using Android 13, the other Android 12. got in this segment also not link local IPv6-Adresses (not starting with fe80 but wth 2a01). That's strange, since, by all i did read so far, Android does not come with any DHCPv6-Client and can not get IPv6-Adresses from any DHCPv6-Server, but only by SLAAC.

      So i am curious why the Android Devices gets IPv6-Adresses, if "Managed-Mode" means by definition of Netgate Docs, SLAAC is disabled then and only DHCPv6 shall work and Android can't use DHCPv6-Server for that purpose!?

      Oh and the DHCPv6-Server Logs does not show any request for a Lease for this two Android Devices. So even if Netgate Docs writes the opposite, SLAAC seems to be still active even if Router Advertisements are set to Managed.

      GertjanG Bob.DigB JKnottJ 3 Replies Last reply Reply Quote 0
      • GertjanG
        Gertjan @eagle61
        last edited by

        Would like to have the situation clarified also.
        More precise : why "Android" doesn't want to use DHCP6 ? What do they have against it ? Is DHCP6 payware for them ? Royalties ?

        @eagle61 said in Services / Router Advertisement - IDHCPv6 server - strange behavior:

        So i am curious why the Android Devices gets IPv6-Adresses

        If your "2a01" is part of your prefix, I can't imaginable that the android device "just auto assigns" an IPv6 'GUA'.

        Btw : your are using KEA. For real testing, try also the good old messy "ISC" DHCP6.

        No "help me" PM's please. Use the forum, the community will thank you.
        Edit : and where are the logs ??

        E 1 Reply Last reply Reply Quote 0
        • E
          eagle61 @Gertjan
          last edited by eagle61

          @Gertjan said in Services / Router Advertisement - IDHCPv6 server - strange behavior:

          Would like to have the situation clarified also.
          More precise : why "Android" doesn't want to use DHCP6 ? What do they have against it ? Is DHCP6 payware for them ? Royalties ?

          There is no DHCPv6-Client part of Android OS. I have no idea why not. But with no DHCPv6-Client its impossible to request IPv-6-Adress on any DHCPv6-Server.

          Btw : your are using KEA. For real testing, try also the good old messy "ISC" DHCP6.

          "ISC" DHCPv6 and also -v4 is deprecated, does not get updates anymore.
          KEA is therefore its replacement.

          And since there is no rquents of the Android device in the KEA-Log, the Android does not use DHCPv6. So this quenstion cant not be answered by using another DHCPv6-Server but is why is SLAAC still active if Router Advisements shall set SLAAC inactive.

          And since i just switched my Firewall 6 weeks ago from IPFire to pfsense, i am still very aware how Android behaves if no SLAAC is present. IPFire did not support any IPv6 at all. That's why i now use pfsense instead.

          WIth no IPv6-Support, means no SLAAC in the network, Android creates only link local IPv6-Adress, starting with fe80::

          Android never creates any other then link local IPv6-Adress without SLAAC in the network.

          GertjanG 1 Reply Last reply Reply Quote 0
          • GertjanG
            Gertjan @eagle61
            last edited by

            @eagle61 said in Services / Router Advertisement - IDHCPv6 server - strange behavior:

            "ISC" DHCPv6 and also -v4 is deprecated, does not get updates anymore.

            Yeah, I know, since 2022 or so. For some reason this became suddenly 'an issue', no no security issues have been found yet.
            If so, after all, it would have been said here.

            I could find was :

            ISC DHCP is very mature code

            So, I feel safe ^^ as I trust what the authors say.

            However, it is time to start thinking about a migration plan to a more modern system that is actively maintained

            As I - I'm just another pfSense user - 'need' Static MAC leases and some DHCP options, kea is still on my 'I think about it' list.

            I'll adopt Kea as soon as Netgate has adopted it ^^

            No "help me" PM's please. Use the forum, the community will thank you.
            Edit : and where are the logs ??

            E 1 Reply Last reply Reply Quote 0
            • E
              eagle61 @Gertjan
              last edited by

              @Gertjan said in Services / Router Advertisement - DHCPv6 server - strange behavior:

              I'll adopt Kea as soon as Netgate has adopted it ^^

              That's already done. View attachment.
              KEA.png

              1 Reply Last reply Reply Quote 0
              • Bob.DigB
                Bob.Dig LAYER 8 @eagle61
                last edited by Bob.Dig

                @eagle61 said in Services / Router Advertisement - DHCPv6 server - strange behavior:

                But just because of curiosity and testing purposes i did add an older WIFI-Access Point to this segment

                Maybe it is the reason. Because I just tested both, ISC and KEA (without rebooting though) and none of them showed this behavior for me. My "AP" is using VLANs from pfSense.

                1 Reply Last reply Reply Quote 0
                • JKnottJ
                  JKnott @eagle61
                  last edited by

                  @eagle61

                  Thanks to some genius at Google, Android does not support DHCPv6.

                  PfSense running on Qotom mini PC
                  i5 CPU, 4 GB memory, 32 GB SSD & 4 Intel Gb Ethernet ports.
                  UniFi AC-Lite access point

                  I haven't lost my mind. It's around here...somewhere...

                  E 1 Reply Last reply Reply Quote 0
                  • E
                    eagle61 @JKnott
                    last edited by

                    @JKnott said in Services / Router Advertisement - DHCPv6 server - strange behavior:

                    Thanks to some genius at Google, Android does not support DHCPv6

                    Same genius at Google for its Chrome OS ;-)
                    Does also not fully support RFC 3315

                    See: https://en.wikipedia.org/wiki/Comparison_of_IPv6_support_in_operating_systems

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