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    How-to disable ipv6 dns server from dhcp (v4) server

    Scheduled Pinned Locked Moved DHCP and DNS
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    • johnpozJ
      johnpoz LAYER 8 Global Moderator
      last edited by

      That is where is dns is pointing to, while I agree he should switch over to his other IPv4 dns when that doesn't answer. Its still not optimal to have IPv6 that doesn't work configured.

      Either fix it so it works, or disable it is best... If he has no working IPv6 he shouldn't be handing link-local out for NS via RA..

      An intelligent man is sometimes forced to be drunk to spend time with his fools
      If you get confused: Listen to the Music Play
      Please don't Chat/PM me for help, unless mod related
      SG-4860 24.11 | Lab VMs 2.8, 24.11

      JKnottJ 1 Reply Last reply Reply Quote 0
      • H
        hadrich
        last edited by

        Thinks for your responses.
        How-to disable Ipv6 or how-to Config RA.
        I'm sorry, I don't understand very well Ipv6 and I don't use it.

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        • JKnottJ
          JKnott @johnpoz
          last edited by

          @johnpoz said in How-to disable ipv6 dns server from dhcp (v4) server:

          That is where is dns is pointing to

          How did that happen, unless someone configured it somewhere. An IPv4 DHCP server cannot be configured to do that and there would have to be IPv6 enabled on the network, not just LL addresses, for it to be configured on a router.

          If he has no working IPv6 he shouldn't be handing link-local out for NS via RA..

          If IPv6 is not enabled on the network, there shouldn't be any RAs to provide a DNS address. If there are RAs, there's an IPv6 enabled router somewhere.

          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...

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          • johnpozJ
            johnpoz LAYER 8 Global Moderator
            last edited by

            Before we get all nuts... Lets make sure you just didn't set this on the client..

            Lets see the output of ipconfig /all

            An intelligent man is sometimes forced to be drunk to spend time with his fools
            If you get confused: Listen to the Music Play
            Please don't Chat/PM me for help, unless mod related
            SG-4860 24.11 | Lab VMs 2.8, 24.11

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            • H
              hadrich
              last edited by hadrich

              The output of ipconfig /all : (for local adapter)

              Ethernet adapter Local Area Connection:
              
                 Connection-specific DNS Suffix  . : xxxxx.local
                 Description . . . . . . . . . . . : Intel(R) PRO/1000 MT Desktop Adapter
                 Physical Address. . . . . . . . . : 08-00-XX-XX-XX-1D
                 DHCP Enabled. . . . . . . . . . . : Yes
                 Autoconfiguration Enabled . . . . : Yes
                 Link-local IPv6 Address . . . . . : fe80::905b:ae6:53db:fc64%11(Preferred)
                 IPv4 Address. . . . . . . . . . . : 192.168.183.171(Preferred)
                 Subnet Mask . . . . . . . . . . . : 255.255.255.0
                 Lease Obtained. . . . . . . . . . : vendredi 24 janvier 2020 20:04:01
                 Lease Expires . . . . . . . . . . : samedi 25 janvier 2020 11:34:08
                 Default Gateway . . . . . . . . . : 192.168.183.254
                 DHCP Server . . . . . . . . . . . : 192.168.183.254
                 DHCPv6 IAID . . . . . . . . . . . : 235405351
                 DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-25-BC-61-2B-08-00-XX-XX-XX-1D
              
                 DNS Servers . . . . . . . . . . . : fe80::a76:ffff:feb3:aa72%11
                                                     192.168.183.254
                 NetBIOS over Tcpip. . . . . . . . : Enabled
              
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              • johnpozJ
                johnpoz LAYER 8 Global Moderator
                last edited by

                And do you have dhvpv6 or RA enabled on pfsense?

                RA.jpg

                An intelligent man is sometimes forced to be drunk to spend time with his fools
                If you get confused: Listen to the Music Play
                Please don't Chat/PM me for help, unless mod related
                SG-4860 24.11 | Lab VMs 2.8, 24.11

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                • H
                  hadrich
                  last edited by

                  Screenshot from 2020-01-25 12-47-08.png

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

                    @hadrich

                    What about the RA tab? IPv6 can use RDNSS to provide the DNS address.

                    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...

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                    • johnpozJ
                      johnpoz LAYER 8 Global Moderator
                      last edited by

                      Yeah but RAs would have to be running..

                      Do you see radvd running in Status / Services

                      Its not suppose to run if you don't have IPv6 setup on your lan interfaces.. Simple enough to sniff to see if your seeing the RAs - and from where..

                      sniffRA.jpg

                      An intelligent man is sometimes forced to be drunk to spend time with his fools
                      If you get confused: Listen to the Music Play
                      Please don't Chat/PM me for help, unless mod related
                      SG-4860 24.11 | Lab VMs 2.8, 24.11

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

                        @johnpoz

                        Well, it's coming from somewhere. The OP can run Packet Capture or Wireshark, filtering on ICMP6, to see where and find out the MAC address.

                        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...

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                        • johnpozJ
                          johnpoz LAYER 8 Global Moderator
                          last edited by johnpoz

                          ^ agreed, which is why I gave an example of doing just that!

                          The sniff will give us positive proof/info of where its coming from.

                          An intelligent man is sometimes forced to be drunk to spend time with his fools
                          If you get confused: Listen to the Music Play
                          Please don't Chat/PM me for help, unless mod related
                          SG-4860 24.11 | Lab VMs 2.8, 24.11

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                          • H
                            hadrich
                            last edited by

                            Screenshot from 2020-01-28 13-22-15.png
                            The result of : sudo tcpdump ip6

                            13:16:53.314987 IP6 fe80::ed39:2950:1669:fe0c > ff02::16: HBH ICMP6, multicast listener report v2, 1 group record(s), length 28
                            13:16:53.314993 IP6 fe80::ed39:2950:1669:fe0c > ff02::16: HBH ICMP6, multicast listener report v2, 1 group record(s), length 28
                            13:16:53.315092 IP6 fe80::fab1:56ff:feca:a7f > ff02::1:ff00:0: ICMP6, neighbor solicitation, who has ::, length 32
                            13:16:53.316529 IP6 fe80::ed39:2950:1669:fe0c > ff02::16: HBH ICMP6, multicast listener report v2, 1 group record(s), length 28
                            13:16:53.316533 IP6 fe80::ed39:2950:1669:fe0c > ff02::16: HBH ICMP6, multicast listener report v2, 1 group record(s), length 28
                            13:16:53.317795 IP6 fe80::ed39:2950:1669:fe0c.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 inf-req
                            13:16:53.317799 IP6 fe80::ed39:2950:1669:fe0c.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 inf-req
                            13:16:53.322526 IP6 fe80::ed39:2950:1669:fe0c > ff02::16: HBH ICMP6, multicast listener report v2, 1 group record(s), length 28
                            13:16:53.322530 IP6 fe80::ed39:2950:1669:fe0c > ff02::16: HBH ICMP6, multicast listener report v2, 1 group record(s), length 28
                            13:16:53.323345 IP6 fe80::ed39:2950:1669:fe0c.61385 > ff02::1:3.llmnr: UDP, length 28
                            13:16:53.323348 IP6 fe80::ed39:2950:1669:fe0c.61385 > ff02::1:3.llmnr: UDP, length 28
                            13:16:53.326481 IP6 fe80::a76:ffff:feb3:aa72.dhcpv6-server > fe80::ed39:2950:1669:fe0c.dhcpv6-client: dhcp6 reply
                            13:16:53.428126 IP6 fe80::ed39:2950:1669:fe0c.61385 > ff02::1:3.llmnr: UDP, length 28
                            13:16:53.428139 IP6 fe80::ed39:2950:1669:fe0c.61385 > ff02::1:3.llmnr: UDP, length 28
                            13:16:53.521076 IP6 :: > ff02::1:ff69:fe0c: ICMP6, neighbor solicitation, who has fe80::ed39:2950:1669:fe0c, length 24
                            13:16:53.521078 IP6 :: > ff02::1:ff69:fe0c: ICMP6, neighbor solicitation, who has fe80::ed39:2950:1669:fe0c, length 24
                            13:16:53.521120 IP6 fe80::ed39:2950:1669:fe0c > ip6-allrouters: ICMP6, router solicitation, length 16
                            13:16:53.521122 IP6 fe80::ed39:2950:1669:fe0c > ip6-allrouters: ICMP6, router solicitation, length 16
                            13:16:53.521191 IP6 fe80::ed39:2950:1669:fe0c > ff02::16: HBH ICMP6, multicast listener report v2, 2 group record(s), length 48
                            13:16:53.521197 IP6 fe80::ed39:2950:1669:fe0c > ff02::16: HBH ICMP6, multicast listener report v2, 2 group record(s), length 48
                            13:16:53.565274 IP6 fe80::ed39:2950:1669:fe0c > ff02::1:ffb3:aa72: ICMP6, neighbor solicitation, who has fe80::a76:ffff:feb3:aa72, length 32
                            13:16:53.565278 IP6 fe80::ed39:2950:1669:fe0c > ff02::1:ffb3:aa72: ICMP6, neighbor solicitation, who has fe80::a76:ffff:feb3:aa72, length 32
                            13:16:53.566265 IP6 fe80::a76:ffff:feb3:aa72 > fe80::ed39:2950:1669:fe0c: ICMP6, neighbor advertisement, tgt is fe80::a76:ffff:feb3:aa72, length 32
                            
                            
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                            • johnpozJ
                              johnpoz LAYER 8 Global Moderator
                              last edited by

                              Well open that RA up and look at it with wireshark... Your dump not showing enough info.

                              An intelligent man is sometimes forced to be drunk to spend time with his fools
                              If you get confused: Listen to the Music Play
                              Please don't Chat/PM me for help, unless mod related
                              SG-4860 24.11 | Lab VMs 2.8, 24.11

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                              • H
                                hadrich
                                last edited by

                                Sorry for the long time to response because i was very busy and i take a time to understand wireshark and a little ipv6 😋. The problem come from another router that i disabled his dhcp service to use it as AP (wireless). Then i disabled its ipv6 to resolve the problem.

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