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    Dual WAN DHCP Issues

    Scheduled Pinned Locked Moved General pfSense Questions
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    • P Offline
      pfsense_user1 @stephenw10
      last edited by pfsense_user1

      @stephenw10 The dhclient logs only show activity for WAN1, not WAN2.

      I ran a packet capture on WAN2 and this is what I got. I ran the capture after doing a modem reboot.

      16:52:56.503025 IP 0.0.0.0.68 > 255.255.255.255.67: UDP, length 300
      16:53:04.561132 IP 0.0.0.0.68 > 255.255.255.255.67: UDP, length 300
      16:53:05.503615 IP 0.0.0.0.68 > 255.255.255.255.67: UDP, length 300
      16:53:07.504406 IP 0.0.0.0.68 > 255.255.255.255.67: UDP, length 300
      16:53:12.507199 IP 0.0.0.0.68 > 255.255.255.255.67: UDP, length 300
      16:53:22.507780 IP 0.0.0.0.68 > 255.255.255.255.67: UDP, length 300
      16:53:33.589897 IP 0.0.0.0.68 > 255.255.255.255.67: UDP, length 300
      16:53:35.121168 IP 192.168.0.1 > 224.0.0.22: igmp
      16:53:35.845608 IP 192.168.0.1 > 224.0.0.22: igmp
      16:53:38.310160 IP 192.168.0.1 > 224.0.0.22: igmp
      16:53:38.525158 IP 192.168.0.1 > 224.0.0.22: igmp
      16:53:45.505022 IP 0.0.0.0.68 > 255.255.255.255.67: UDP, length 300
      16:53:45.506322 IP 192.168.100.1.67 > 192.168.100.10.68: UDP, length 300
      16:53:53.505188 IP 0.0.0.0.68 > 255.255.255.255.67: UDP, length 300
      16:53:53.506328 IP 192.168.100.1.67 > 192.168.100.10.68: UDP, length 300
      16:54:05.731285 ARP, Request who-has 192.168.100.10 tell 192.168.100.10, length 28
      16:54:07.178225 ARP, Request who-has 192.168.100.1 tell 192.168.100.10, length 28
      16:54:07.179570 ARP, Reply 192.168.100.1 is-at <MAC removed>, length 46
      16:54:07.179622 IP 192.168.100.10 > 192.168.100.1: ICMP echo request, id 11720, seq 0, length 64
      16:54:07.180623 IP 192.168.100.1 > 192.168.100.10: ICMP echo reply, id 11720, seq 0, length 64
      16:54:20.253659 IP 192.168.100.10 > 192.168.100.1: ICMP echo request, id 12980, seq 0, length 9
      16:54:20.255227 IP 192.168.100.1 > 192.168.100.10: ICMP echo reply, id 12980, seq 0, length 9
      16:54:20.761851 IP 192.168.100.10 > 192.168.100.1: ICMP echo request, id 12980, seq 1, length 9
      16:54:20.763220 IP 192.168.100.1 > 192.168.100.10: ICMP echo reply, id 12980, seq 1, length 9
      16:54:21.777608 ARP, Request who-has 192.168.100.1 tell 192.168.100.10, length 28
      16:54:21.778419 ARP, Reply 192.168.100.1 is-at <MAC removed>, length 46
      16:54:21.778477 IP 192.168.100.10 > 192.168.100.1: ICMP echo request, id 12980, seq 2, length 9
      16:54:21.779491 IP 192.168.100.1 > 192.168.100.10: ICMP echo reply, id 12980, seq 2, length 9
      ...
      16:54:39.519584 ARP, Request who-has 72.X.X.X tell 72.X.X.X, length 46
      ...

      8800b106-0a08-440a-a4b5-1e2b3c3d5537-image.png
      e3a815f4-4d48-4b32-8e64-edf35ea15395-image.png

      5b70e2cd-e52e-43f3-a55a-b5523644bd71-image.png

      The interface appears to be on a public subnet, but it doesn't get an address. After doing a reboot of the pfSense, it got IP 192.168.100.10. I rebooted the modem after that, and it got IP 192.168.100.1. I still have the "reject leases from" set to "192.168.100.1,192.168.100.10".

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      • stephenw10S Offline
        stephenw10 Netgate Administrator
        last edited by

        Right so it definitely pulled a lease. There should be something shown in the dhcp log when that happened.

        But the pcap shows the dhcp response was from 192.168.100.1 so it should have rejected that offer. Again I'd expect to see something logged.

        P 1 Reply Last reply Reply Quote 0
        • chpalmerC Offline
          chpalmer
          last edited by

          Are both connections from the same ISP?

          Triggering snowflakes one by one..
          Intel(R) Core(TM) i5-4590T CPU @ 2.00GHz on an M400 WG box.

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          • P Offline
            pfsense_user1 @chpalmer
            last edited by

            @chpalmer No they are separate ISPs

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            • stephenw10S Offline
              stephenw10 Netgate Administrator
              last edited by

              On a 2100 the WAN has a different MAC so shouldn't be a problem. That can be an issue on the 7100.

              But, yes, maybe requires a different client identifier?

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              • P Offline
                pfsense_user1 @stephenw10
                last edited by

                @stephenw10 First modem reboot:
                6e7eb75b-8cae-49e6-a007-cb3cc3ac5c19-image.png
                3d561ce0-cdd7-43e3-b884-2c5cde03c6be-image.png

                Before the second modem reboot, I added in "WAN2" to the hostname field:
                db005a36-264f-4798-b34c-c9bed4e958a5-image.png

                Second reboot:
                94005a08-853a-465b-937d-e3a5484d48c2-image.png
                edca9957-9d59-42d3-8377-61fa524cf9d4-image.png

                I also did a pfSense reboot when on the line with the ISP, and they said that they don't see the modem and router bridging.

                chpalmerC GertjanG 2 Replies Last reply Reply Quote 0
                • chpalmerC Offline
                  chpalmer @pfsense_user1
                  last edited by

                  @pfsense_user1 Have you tried rebooting everything but keeping the first modem offline to see if there is some kind of issue with both modems having the same management address?

                  Shouldn't but trying to rule certain things out.

                  Triggering snowflakes one by one..
                  Intel(R) Core(TM) i5-4590T CPU @ 2.00GHz on an M400 WG box.

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                  • GertjanG Online
                    Gertjan @pfsense_user1
                    last edited by Gertjan

                    @pfsense_user1

                    The 'dhclient', the DHCPv4 client on your (a) WAN does it can do t get a lease.
                    It's start with a PRENIT.
                    Then, as it 'recalls' the last WAN IPv4 it had, it emits multiple (every second) DHCPREQUEST to validate this 'last recently used IPv4.
                    No answer came back.
                    Ok, the dhclient will go for an all new lease : it start to send (broadcast) DHCPDISCOVER's, so any available (existing) DHCP server(s) can now answer on this request.
                    No asnwer, so a incremental delay is used, and the DHCPDISCOVER is repeated.
                    Up until delay number '12'.
                    Still no answer. Silence.
                    Suddenly, some one replied : 192.168.100.1 (and yeah, it took 27m:42s-26m:47s = close to seconds for this device to answer. This 192.168.100.1 was also rebooting, which will explain the absence all this time ?
                    Anyway, still no dies, as you've instructed that you don't want to use "192.168.100.1" as a DHCP server.

                    At this moment, dhcp6c also kicks in (same physical WAN interface ? Another one ?) and this DHCP client receives answer right away, like within milliseconds.

                    At 27m:28your dhclient (IPv4) (the same client as the process ID 4488 is the same) continues to send DHCPDISCOVERS, and 192.168.1.100 replies straight away, and dhclient doesn't what his answer (lease proposition). It tells you that "No DHCPOFFERS received" - it will try to re use (probably previous) 192.168.100.10 lease .... and from that momenon on, no more message from "4488"

                    But wait, another dhclient process start talking (logging) now : 13778. It signals a TIMEOUT ... where did this dhclient process 13778 came from ? I didn't saw the startup logged.

                    And another one : 14629, which did has success, as it says "Starting add_new_address()" which makes me think it got a lease (next line says 192.168.100.10 !)

                    Now things becomes even more complex : 14629 - 15890 - 16830 -17302 - 18101, for me, these are all different process IDs. Incredible. A nice dentition of a real mess.

                    Questions :
                    Who is 192.168.100.1 ? a local modem ? Router ?
                    You don't want to get a lease from this device, why ?
                    I can't see what other device (DHCP server) (from where ?) is actually answering.

                    Before rebooting : the old way :
                    Power down (for pfSense : cleanly, with the GUI !!) everything.
                    Now power up WAN circuit "1"
                    and WAN circuit "2"
                    and wait a minute or so for everything to boot.
                    Then, power up pfSense.

                    Another thing to try : get two simple small witches.
                    Between each ISP WAN device and the related pfSense, place a switch. One for each WAN. I know, this seems stupid, il less optimal, but can help. because, if the WAN ISP senses that it's LAN gets triggered (as pfSense wakes up and activates its/a WAN) it will reboot, creating some sort of loop of 'restarts'.

                    The final, best solution would be : as this is a typical situation where the ISP device isn't really fool proof, and needs 'hand holding' and random manual intervention at random times, express your ultimate consumers right : pick a better one. This time you know that 'speed' and 'price' are not the most important selection criteria. It's overall stability and easy of access.
                    And yes, I know, sometimes, you have not always a choice.

                    No "help me" PM's please. Use the forum, the community will thank you.
                    Edit : and where are the logs ??

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                    • stephenw10S Offline
                      stephenw10 Netgate Administrator
                      last edited by

                      Ah OK, you can see it's trying to use old lease data after failing to get a new lease. Look for /var/db/dhclient.leases.mvneta1.666. That file should show all the recent leases and it;s tryign the most recent one.

                      Either remove the 192.168.100.1 leases from there or just remove that file entirely.

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                      • P Offline
                        pfsense_user1 @stephenw10
                        last edited by

                        @stephenw10 I renamed the "/var/db/dhclient.leases.mvneta1.666" file then did a few modem reboots. It correctly rejects 192.168.100.1, but it never gets a DHCP address.
                        24c8b82d-5ba2-4186-b44b-7e3e226f7ef4-image.png

                        I swapped modem connections so the WAN2 connection is now running on the WAN port. It gets an IP correctly and I'm online.

                        Is there possibly an issue with the LAN interface config:
                        950c8d73-8f4e-4d96-812e-fa7ed27a4e7f-image.png

                        4b0df646-74d1-45a3-9688-df599b11c6c1-image.png

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                        • stephenw10S Offline
                          stephenw10 Netgate Administrator
                          last edited by stephenw10

                          Ah yes you should have LAN 666 untagged on port 3 in order to use traffic on it directly. So: (3,5t). And if so you should remove port 3 from VLAN1 so it does leave that.

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                          • P Offline
                            pfsense_user1 @stephenw10
                            last edited by

                            @stephenw10 That worked, thanks.

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