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    IPv6 static leases when ISP changes the prefix

    Scheduled Pinned Locked Moved IPv6
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    • D
      DrPhil
      last edited by

      Hi.

      I am in the process of configuring IPv6 on my network (to be able to connect to IPv6 only servers on the cloud in the near future).

      I have a DHCPv6 server on LAN, and I would like to assign static leases to a few clients (similar to my v4 setup). The problem is that my ISP changes my prefix at every router reboot. Which breaks my static assignments.

      I can think of two theoretical possible options.

      1. If I could assign static leases based on just the interface ID (excluding the prefix)
      2. If I could request my ISP to not change my prefix each time (somehow through the settings, I am not ready to call them yet).

      Maybe I am bringing too much of my (limited knowledge) IPv4 mindset to it. So, I'll take any v6 native recommendations as well.

      johnpozJ JKnottJ 2 Replies Last reply Reply Quote 0
      • johnpozJ
        johnpoz LAYER 8 Global Moderator @DrPhil
        last edited by johnpoz

        @DrPhil said in IPv6 static leases when ISP changes the prefix:

        o be able to connect to IPv6 only servers on the cloud in the near future

        Curious what "near" means to you.. Do you have some example of some service that is IPv6 only? That isn't some dark web or p0rn fetish sort of site? ;)

        If I could request my ISP to not change my prefix each time

        you could try setting.

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        • P
          PlyrStar93
          last edited by PlyrStar93

          Who is your ISP and do they provide static IPv6 ranges? If you are on Comcast Business they can provide a static /56, which can be divided into /59s for downstream routers.
          For Comcast residential, my experience is that I keep the same /64 prefix at each reboot; occasionally I would get new /64 prefix but it should normally remain the same for an extended period of time.

          If your ISP cannot provide a static prefix to you and it changes after every reboot, I'm not sure if there is something you can do with them. Of course, HE tunnel may be an option if you have a public WAN IPv4 (not CGNAT) that can be pinged from the Internet, and the IPv4 address should ideally remain the same too.

          EDIT: Should have seen your other thread. Seems you are with Verizon FiOS.

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          • D
            DrPhil @johnpoz
            last edited by DrPhil

            That isn't some dark web or p0rn fetish sort of site? ;)

            I am sure there's plenty of that too.

            Curious what "near" means to you.. Do you have some example of some service that is IPv6 only?

            The goal posts might change, but my "near" term expectation is sometime this year.

            The cloud servers I am referring to are servers for inhouse use (primarily development and staging servers only). We're a bit stingy about cloud expenses. Since AWS will be charging for any IPv4 addresses going forward we want to have the option to switch to IPv6 only for non end client facing stuff.

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            • D
              DrPhil @PlyrStar93
              last edited by

              Who is your ISP and do they provide static IPv6 ranges?

              Verizon FIOS. I am sure they can provide static IPv6. I was hoping to not have to call them, but I will.

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              • JKnottJ
                JKnott @DrPhil
                last edited by

                @DrPhil

                Under System > Advanced > Networking, there's a setting Do not allow PD/Address release. Is that selected? If not, your prefix will change for something as simple as disconnecting & reconnecting the WAN cable.

                When I first started using pfSense that option was not available. However, my prefix has now been stable for almost 5 years.

                If that doesn't work, you might consider using Unique Local Addresses. With ULA, the addresses will be permanent and can be used in the DNS.

                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...

                D 1 Reply Last reply Reply Quote 2
                • D
                  DrPhil @JKnott
                  last edited by

                  Under System > Advanced > Networking, there's a setting Do not allow PD/Address release. Is that selected? If not, your prefix will change for something as simple as disconnecting & reconnecting the WAN cable.

                  Thank you!
                  That's exactly what I was hoping to hear. I've now checked that box, and will monitor. If the ISP still changes the prefix on me, I'll just call them.

                  L 1 Reply Last reply Reply Quote 0
                  • L
                    ler762 @DrPhil
                    last edited by

                    @DrPhil said in IPv6 static leases when ISP changes the prefix:

                    Under System > Advanced > Networking, there's a setting Do not allow PD/Address release. Is that selected? If not, your prefix will change for something as simple as disconnecting & reconnecting the WAN cable.

                    Thank you!
                    That's exactly what I was hoping to hear. I've now checked that box, and will monitor. If the ISP still changes the prefix on me, I'll just call them.

                    I'm on Verizon FIOS and they do change the prefix all too often. Even without a reboot or anything that would cause the interface to bounce the delegated prefix can change :(
                    The good news is that if you leave the prefix off of the IPv6 address in the DHCPv6 config the server will supply the prefix for you.

                    I haven't figured out how to predict the DUID so I just let the system assign an ipv6 address from the free pool & then go to the ' Status / DHCPv6 Leases' page, find the entry that I want to convert to a static address, and under Actions click the 'Add static mapping' button. That brings up the ' Services / DHCPv6 Server & RA / LAN / DHCPv6 Server / Edit Static Mapping' page and then I put just the "::host addr" in the IPv6 address field. The system will fill in the delegated prefix part of the address when it gives out the DHCPv6 address later on.
                    .

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