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    Question about WAN IP not matching Gateway IP

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    • bmeeksB
      bmeeks @The Party of Hell No
      last edited by bmeeks

      @The-Party-of-Hell-No said in Question about WAN IP not matching Gateway IP:

      @viragomann the first five digits match

      If you don't post enough information here (including the provided subnet mask), no one can answer your question.

      However, you can use a subnet calculator tool such as this one: https://www.calculator.net/ip-subnet-calculator.html to test things and answer your question.

      Or this one: https://www.subnet-calculator.com/

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      • T
        The Party of Hell No @The Party of Hell No
        last edited by

        @The-Party-of-Hell-No
        Subnet mask IPv4 255.255.254.0

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        • bmeeksB
          bmeeks @The Party of Hell No
          last edited by bmeeks

          @The-Party-of-Hell-No said in Question about WAN IP not matching Gateway IP:

          @The-Party-of-Hell-No
          Subnet mask IPv4 255.255.254.0

          That will be the same as a /23 CIDR mask. It's likely the gateway is in the same subnet as the IP you provided. Would be quite incorrect if the ISP provided a gateway that is not in the same subnet.

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          • E
            enthu19 @The Party of Hell No
            last edited by enthu19

            @The-Party-of-Hell-No
            Usable Host IP Range: xx.xxx.106.1 - xx,xxx.107.254

            106.1 fall within the same subnet /23

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            • V
              viragomann @The Party of Hell No
              last edited by

              @The-Party-of-Hell-No
              So they are within the same subnet. It goes from x.x.106.0 to x.x.107.255.

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              • bmeeksB
                bmeeks
                last edited by

                @viragomann is correct. x.x.106.0 is the network, x.x.107.255 is the broadcast address, and assignable address space ranges from x.x.106.1 to x.x.107.254 (for a /23 subnet mask, or 255.255.254.0)

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                • T
                  The Party of Hell No
                  last edited by

                  Thank you for the info and the link to the calculator. So for my Dynamic DNS Status - NO-IP which is set to 107.26, do I need to correct it to the gateway 106.1?

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                  • bmeeksB
                    bmeeks @The Party of Hell No
                    last edited by bmeeks

                    @The-Party-of-Hell-No said in Question about WAN IP not matching Gateway IP:

                    Thank you for the info and the link to the calculator. So for my Dynamic DNS Status - NO-IP which is set to 107.26, do I need to correct it to the gateway 106.1?

                    No, your Dynamic DNS should register your actual assigned WAN public IP address. The gateway is out of the picture for that. The gateway is simply the IP address where your firewall sends any traffic that does not match an IP range assigned to local firewall interfaces.

                    If you are new to networking, this may help clear some things up: https://www.cbtnuggets.com/blog/technology/networking/what-is-default-gateway.

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                    • T
                      The Party of Hell No @bmeeks
                      last edited by

                      @bmeeks
                      So in my simple minded explanation the WAN public IP address is the outward (Public) IP for the modem/router - incoming. The gateway is the internal (Private) IP the firewall uses sending any traffic that does not match an IP range assigned to local firewall interfaces - outgoing?

                      They do not need to match, but must belong in the same subnet.

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                      • bmeeksB
                        bmeeks @The Party of Hell No
                        last edited by bmeeks

                        @The-Party-of-Hell-No said in Question about WAN IP not matching Gateway IP:

                        @bmeeks
                        So in my simple minded explanation the WAN public IP address is the outward (Public) IP for the modem/router - incoming. The gateway is the internal (Private) IP the firewall uses sending any traffic that does not match an IP range assigned to local firewall interfaces - outgoing?

                        They do not need to match, but must belong in the same subnet.

                        The gateway is not necessarily "private", but it is the IP address where your firewall will send any traffic that is not local to a network defined on the firewall (local means IP ranges specified for your firewall interfaces).

                        Think of the default gateway on the WAN as the Post Office. That's where you send all of your outbound mail. The Post Office takes it from there and physically gets the mail to the destination. You simply provide a destination address and a return address. The Post Office decides which truck route to put the mail on so that it eventually reaches the intended recipient. Same analogy for network traffic. A packet leaving your firewall WAN interface directed at the default gateway IP contains a destination IP address and a "return address" which is the firewall's WAN IP. The default gateway handles getting the packet to the correct destination and also routing any returned packets back to you.

                        Every network will have a gateway. That's where packets are sent when the destination IP is not local within the network's subnet. There are gateways and a default gateway. In a large network it is possible for a router to have a table of many gateway IPs representing "known routes" to particular subnets. But there will always be a default gateway which will get any packets whose destination IP range is unknown to the router (meaning the destination IP is not local nor does the router have any defined gateway matching that subnet).

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                        • T
                          The Party of Hell No @bmeeks
                          last edited by

                          @bmeeks
                          Thank you sir! You have educated me, and I am a better person for it. Your analogy of the Post Office is excellent.

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