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    In a firewall rule, what is included in "LAN net" for IPv6?

    Scheduled Pinned Locked Moved IPv6
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    • M
      mrsunfire
      last edited by

      I did the same. Also for mDMS I created an extra rule.

      Netgate 6100 MAX

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      • IsaacFLI
        IsaacFL @mrsunfire
        last edited by

        @mrsunfire said in In a firewall rule, what is included in "LAN net" for IPv6?:

        I did the same. Also for mDMS I created an extra rule.

        It would probably be better, if there was a way to write a rule, that allowed multicast thru to the router daemon, which decides what to do with it, but not forward it out of the subnet. That is what I am not sure about. How to do that?

        Really the router daemon should have its head out in the subnet before the firewall, servicing all of the multicast requests. But you probably would not want that on the WAN interface.

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        • M
          mrsunfire
          last edited by

          Thats the same I care about. Don‘t know if my solution is good or not. Right now it seens that there is nothing routet to WAN.

          Netgate 6100 MAX

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          • IsaacFLI
            IsaacFL @jimp
            last edited by

            @jimp I know it has been a bit of time, but I have found one specific type of traffic, that maybe should be allowed in the default ruleset.

            I am seeing traffic with a source address of :: (unspecified address) with a multicast to ff02::2.

            Observing on Wireshark, what I am seeing is the network device is sending a multicast asking "who is the router" using the :: address as the source. If I create a easy pass rule in pfsense, I see the router respond with a router announcement. Otherwise it is default blocked and no response from router. The router does periodically give router announcements on its own.

            I only see one device with this behavior, (Samsung TV) so not sure if this is something not normal, but it seems like it may be legal behavior.

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            • IsaacFLI
              IsaacFL @IsaacFL
              last edited by

              @jimp I forgot to mention this is an ICMPv6 packet.

              0_1534181983305_router.PNG

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              • M
                mrsunfire
                last edited by

                I can confirm this. My Samsung TV is doing the same think. If you block it, it doesn't use IPv6.

                Netgate 6100 MAX

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                • IsaacFLI
                  IsaacFL @mrsunfire
                  last edited by

                  I had kind of ignored it for a while, assuming it was a Samsung peculiarity. But I checked the RFC 4861 - Neighbor Discovery in IPv6.

                  Par 4.1 Router Solicitation Message Format

                  IP Fields:

                    Source Address
                                   An IP address assigned to the sending interface, or
                                   the unspecified address if no address is assigned
                                   to the sending interface.
                  
                    Destination Address
                                   Typically the all-routers multicast address.
                  
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                  • IsaacFLI
                    IsaacFL @IsaacFL
                    last edited by

                    After further checking I can confirm that Windows 10 does the same thing.

                    On power up, first thing it does is send icmpv6 multicast, from source address [::] to [ff02::2] (All routers on the local network segment). After that it uses its link local address as source for multicast.

                    So it is not just the Samsung.

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                    • jimpJ
                      jimp Rebel Alliance Developer Netgate
                      last edited by

                      Yeah reading through that RFC it does appear to need one more rule to allow from that.

                      I've got a commit coming that should fix it up in 2.4.4.

                      https://redmine.pfsense.org/issues/8791

                      You could make a manual and more specific rule to pass it than allowing any source, though:

                      0_1534423796308_Selection_047.jpg

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                      • JKnottJ
                        JKnott @IsaacFL
                        last edited by

                        @isaacfl said in In a firewall rule, what is included in "LAN net" for IPv6?:

                        I am seeing traffic with a source address of :: (unspecified address) with a multicast to ff02::2.

                        That sort of packet shouldn't even be passed by pfSense, as it's intended to be for the local link only. Check the hop limit and you'll likely find it's 255. This value is used to ensure a packet has not passed through a router, as it would have been decremented from 0 and routers are supposed to discard any packet that has a hop limit of 0. And, a source address of :: or unspecified can never be a destination address, as it's only used by a device that doesn't yet know it's own address. So, you're looking at a packet that's intended to be used on the local network only and pfSense should not attempt to forward it.

                        PfSense running on Qotom mini PC
                        i5 CPU, 4 GB memory, 32 GB SSD & 4 Intel Gb Ethernet ports.
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                        • JKnottJ
                          JKnott @jimp
                          last edited by

                          @jimp said in In a firewall rule, what is included in "LAN net" for IPv6?:

                          I've got a commit coming that should fix it up in 2.4.4.

                          Why should a router or neighbour discovery ever be passed by psSense or any other router? Those are link local only functions. I'd seriously question that passes those off the local net.

                          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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                          • jimpJ
                            jimp Rebel Alliance Developer Netgate @JKnott
                            last edited by

                            @jknott said in In a firewall rule, what is included in "LAN net" for IPv6?:

                            Why should a router or neighbour discovery ever be passed by psSense or any other router? Those are link local only functions. I'd seriously question that passes those off the local net.

                            They need to be able to hit the firewall itself so the firewall can answer neighbor/router discovery queries from these clients. It's multicast so it's all local, won't leave its segment, but still valid for the firewall to pass.

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                            • JKnottJ
                              JKnott
                              last edited by

                              I know why they're needed. However, I've been running IPv6 for over 8 years and this has never been an issue. I'll have to fire up Wireshark and try monitoring what happens with another computer.

                              BTW, I have a Samsung Blu-ray player that no longer connects to the Internet at all. They did something absolutely brilliant. When connecting to the Internet, one of the first things the player does is try to connect to a certain web site. Can't reach the site, no connection and it stops there. However, since that was set up, that site, along with many others, switched to https, which this player cannot handle. As I said, brilliant!

                              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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                              • jimpJ
                                jimp Rebel Alliance Developer Netgate @JKnott
                                last edited by

                                @jknott said in In a firewall rule, what is included in "LAN net" for IPv6?:

                                I know why they're needed. However, I've been running IPv6 for over 8 years and this has never been an issue. I'll have to fire up Wireshark and try monitoring what happens with another computer.

                                I've been running it for years as well without seeing this, but that doesn't make it invalid. It's valid per the RFC and certain (rare?) devices behave this way. There isn't a compelling reason to not allow the traffic. It won't be routed, it's only hitting the local segment.

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                                • IsaacFLI
                                  IsaacFL @jimp
                                  last edited by

                                  @jimp said in In a firewall rule, what is included in "LAN net" for IPv6?:

                                  @jknott said in In a firewall rule, what is included in "LAN net" for IPv6?:

                                  I know why they're needed. However, I've been running IPv6 for over 8 years and this has never been an issue. I'll have to fire up Wireshark and try monitoring what happens with another computer.

                                  I've been running it for years as well without seeing this, but that doesn't make it invalid. It's valid per the RFC and certain (rare?) devices behave this way. There isn't a compelling reason to not allow the traffic. It won't be routed, it's only hitting the local segment.

                                  If you have been running dual stack then some ipv6 errors have been masked by falling back to IPv4.

                                  In my mind I should only have to define a “pass” rule to allow traffic from one subnet to another.

                                  The issue is that these rules are needed for services in the router to perform link local functions that are required by ipv6.

                                  In this case the default rules are not there to allow the router internally to implement NDP on the local net so I am manually having to create pass rules to get them into the router.

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                                  • JKnottJ
                                    JKnott @JKnott
                                    last edited by

                                    @jknott said in In a firewall rule, what is included in "LAN net" for IPv6?:

                                    I'll have to fire up Wireshark and try monitoring what happens with another computer.

                                    I just did, with another computer running Linux. The first 3 packets were:
                                    Neighbour solicitation for it's own link local address from ::, for duplicate address check (DAD)
                                    Router solicitation, with link local address as source
                                    Router advertisement from router to link local address.

                                    My question is why are those devices not doing a DAD to ensure they can use their address, as is required by the specs. Once a device passes DAD for it's link local address, it's free to use it, as shown in my test.
                                    If a device is not doing DAD, it's defective.

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

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                                    • JKnottJ
                                      JKnott @IsaacFL
                                      last edited by

                                      @isaacfl said in In a firewall rule, what is included in "LAN net" for IPv6?:

                                      If you have been running dual stack then some ipv6 errors have been masked by falling back to IPv4.

                                      What sort of errors? I just ran Wireshark filtering on the computer MAC address and ICMP6. No IPv4 involved at all. Incidentally, I've been running a browser add-in called "ShowIP" that shows the web site address, for years. If there was a problem, I'd have noticed it.

                                      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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                                      • jimpJ
                                        jimp Rebel Alliance Developer Netgate @JKnott
                                        last edited by

                                        @jknott Your tests aren't going to tell us anything meaningful about how someone else's device behaves or should behave. Only how yours behave, which is not relevant to this discussion.

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                                        • JKnottJ
                                          JKnott @jimp
                                          last edited by

                                          @jimp said in In a firewall rule, what is included in "LAN net" for IPv6?:

                                          Your tests aren't going to tell us anything meaningful about how someone else's device behaves or should behave. Only how yours behave, which is not relevant to this discussion.

                                          If a device doesn't do DAD, it's defective. Those other people should be running Wireshark to see exactly what's happening. Packet Capture can also be used, but it's not as useful as Wireshark.

                                          I'm just getting set up to test a W10 computer, to see what happens with it.

                                          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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                                          • JKnottJ
                                            JKnott @JKnott
                                            last edited by

                                            @jknott said in In a firewall rule, what is included in "LAN net" for IPv6?:

                                            I'm just getting set up to test a W10 computer, to see what happens with it.

                                            I just tried with W10 and got the exact same sequence as with Linux. Both do DAD and then continue with the link local address. What does that other device do, as shown by Wireshark or Packet Capture? If it's trying to do a RS without having run DAD first, it's defective and has no business being on a network. If it has run DAD, then it should be doing the RS with the link local address as source.

                                            If this is a problem with that other device, then pfSense shouldn't be changed to fix the problem. The problem should be sent back to the company that made the device.

                                            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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