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    Introducing Netgate Nexus: Multi-Instance Management at Your Fingertips.

    7100 : spoof MAC ?

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    • S Offline
      sgw @stephenw10
      last edited by

      @stephenw10 Ah, I see.
      On the first appliance (which runs right now) I can see there is that LAGG0 already.
      As I haven't created it myself it was also already rebooted ;-)

      But there is no field for assigning a MAC in the GUI.

      Recreating sounds dangerous: wouldn't I lose connectivity then? I very likely have to do that from remote, so I'd need a safe procedure.

      Bonus question: the resulting config would also work unchanged on the appliance with "physical MAC = spoofed MAC" ?

      thanks!

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      • stephenw10S Offline
        stephenw10 Netgate Administrator
        last edited by stephenw10

        Hmm, so there is no LAGG interface on the standby device?

        lagg0 is in the default config for the 7100. It can be removed to create other configs, multiple WAN MACs for example.
        It is not assigned as an interface by default though and you need to do that to get the MAC spoof field.

        But, yes, adding or removing that means re-configuring the switch and it's VERY easy to loose connectivity if that's how you are connected.

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        • S Offline
          sgw @stephenw10
          last edited by

          @stephenw10 said in 7100 : spoof MAC ?:

          Hmm, so there is no LAGG interface on the standby device?

          That one is offline right now. It's the same config as the online device ->

          lagg0 is in the default config for the 7100. It can be removed to create other configs, multiple WAN MACs for example.
          It is not assigned as an interface by default though and you need to do that to get the MAC spoof field.

          But, yes, adding or removing that means re-configuring the switch and it's VERY easy to loose connectivity if that's how you are connected.

          It is visible as "Available network port", but not yet assigned on the active device (in interfaces_assign.php).

          I won't try that now, I could try it on the 2nd device in a maintenance window (plus the spoofing part).

          I wouldn't remove the Interface LAGG0, I would only add an "Interface Assignment" to then be able to spoof the MAC there. Right?

          I think I know my way, I have to make that appointment with the local admin guy first.

          thanks

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          • stephenw10S Offline
            stephenw10 Netgate Administrator
            last edited by

            Yes exactly, you need to assign lagg0 as an interface so you can set it's properties in the gui. Then enable the assigned interface and set the MAC there. No need to set anything else on the interface.

            Screenshot from 2026-05-19 15-04-10.png

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            • S Offline
              sgw @stephenw10
              last edited by

              @stephenw10 great, thanks.
              We maybe try that in about 1.5 hours from now.

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              • S Offline
                sgw @sgw
                last edited by

                Hmm.
                The spoofing worked. I assigned etc then we had to powercycle the box to get it online again.

                After that the displayed MAC was the spoofed one. Looked OK.

                BUT the fiber-router (or whatever that is) didn't "see" the pfSense interface connected.
                We had the admin of the provider on the phone, he ran diagnostics, we rebooted and replugged that router without getting it online.

                We had electrical link, but he didn't see the MAC arp-wise (I assume).

                Plugging back to the original appliance (without spoofing) worked immediately.

                The provider-admin asks upstream .. he is only the tech for the reseller, or so.

                I wonder: could the fact that it's a LAGG be a problem? I think of stuff like LACP, STP or whatever is different from a plain access interface.

                I am just wondering what's the difference from the view of that fiber-box.

                I'll keep you posted. Maybe I hear something tomorrow.

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                • stephenw10S Offline
                  stephenw10 Netgate Administrator
                  last edited by

                  The spoofed MAC definitely shows up for me. The upstream router shows it in its ARP table or a pcap.

                  The LAGG and VLAN shouldn't make any difference. None of that layer 2 stuff exists beyond the switch.

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                  • S Offline
                    sgw @stephenw10
                    last edited by

                    @stephenw10

                    You talk of the internal switch?
                    There is no switch between the 7100 and the fiber-appliance.

                    Thanks for clarifying. It was just a wild guess while I was listing the possible differences between plugging in the 2 7100-appliances.

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                    • stephenw10S Offline
                      stephenw10 Netgate Administrator
                      last edited by

                      Yes the internal switch. The upstream devices shouldn't see any of the LAGG or VLAN specific packets.

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                      • S Offline
                        sgw @stephenw10
                        last edited by

                        @stephenw10 thank you. Even more of a mystery.
                        I am curious what the upstream support replies.
                        I don't expect much ...

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                        • stephenw10S Offline
                          stephenw10 Netgate Administrator
                          last edited by

                          Really the only significant difference would be the overhead the tagging adds meaning the path MTU might be slightly lower. But that would be identical between the two 7100s. And it wouldn't prevent connecting entirely.

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                          • S Offline
                            sgw @stephenw10
                            last edited by sgw

                            I have a theory ... we might test that on friday or tuesday.

                            Maybe on appliance 2 the assigned order of the interfaces got mixed up?

                            I am not 100% sure if that is possible, the config.xml was restored so that should be identical.

                            What I think of: the local admin plugs the cable for WAN2 into ETH2 on App1 and things work (I just make up an example).

                            So we'd assume ETH2 on Appliance2 should also be assigned to WAN2 (and use its configured static IP etc). The admin just plugs the cable FROM App1:ETH2 TO App2:ETH2 ...

                            If that's not the case and for some reason WAN2 points to ETH3 on Appliance2 (because of whatever ... timings at bootup?) this would result in the logged behavior: ETH2 plugged in would show the spoofed MAC, but no configured IP.

                            The theory maybe lacks a bit .. but could that be the case?

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                            • stephenw10S Offline
                              stephenw10 Netgate Administrator
                              last edited by

                              What might be happening is the switch config is different. That doesn't get synced so it's possible you have the VLAN assigned to a different port on the secondary node. It's unlikely though if you restored a config onto the secondary from the primary when creating it.
                              But it's easy enough to compare the switch config on each node.

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                              • S Offline
                                sgw @stephenw10
                                last edited by

                                @stephenw10

                                Yes, the internal switch config on Appliance was missing the configs for the additional WAN-interfaces.

                                The MAC-spoofing might not be needed at all, a test with a random laptop came online on that upstream fiber gateway without problems (with some random MAC).

                                Now with the correct VLANs etc on the internal switch the plugging works perfectly (we can plug between the 2 appliances and connectivity is up immediately).

                                thanks!

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                                • stephenw10S Offline
                                  stephenw10 Netgate Administrator
                                  last edited by

                                  Nice. Good result! 👍

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                                  • S Offline
                                    sgw @stephenw10
                                    last edited by

                                    @stephenw10 said in 7100 : spoof MAC ?:

                                    Nice. Good result! 👍

                                    It's an honor to hear this from you, thanks ;-)

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