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    Help troubleshooting L2TP over IPSEC VPN connections.

    IT Discussion
    ipsec l2tp windows 10 vpn ubnt ubiquiti edgerouter edgerouter lite
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    • JaredBusch
      JaredBusch @Romo last edited by

      @romo said in Help troubleshooting L2TP over IPSEC VPN connections.:

      @JaredBusch @scottalanmiller Any idea?

      Is this user trying to connect from the same IP as another user?

      gjacobse Romo 2 Replies Last reply Reply Quote 1
      • gjacobse
        gjacobse @JaredBusch last edited by

        @jaredbusch said in Help troubleshooting L2TP over IPSEC VPN connections.:

        @romo said in Help troubleshooting L2TP over IPSEC VPN connections.:

        @JaredBusch @scottalanmiller Any idea?

        Is this user trying to connect from the same IP as another user?

        Generally not.. They are remote / home users.

        1 Reply Last reply Reply Quote 0
        • Romo
          Romo @JaredBusch last edited by

          @jaredbusch said in Help troubleshooting L2TP over IPSEC VPN connections.:

          @romo said in Help troubleshooting L2TP over IPSEC VPN connections.:

          @JaredBusch @scottalanmiller Any idea?

          Is this user trying to connect from the same IP as another user?

          No, a single user trying to connect from home. She connected Wednesday without a problem, but Thursday she tries to connect again and it is not possible.

          Logs show

          13[CFG] unable to install policy EDGE_ROUTER_IP/32[udp/l2f] === USER_PUBLIC_IP/32[udp/l2f] out (mark 0/0x00000000) for reqid 35, the same policy for reqid 14 exists
          13[CFG] unable to install policy USER_PUBLIC_IP/32[udp/l2f] === EDGE_ROUTER_IP/32[udp/l2f] in (mark 0/0x00000000) for reqid 35, the same policy for reqid 14 exists
          

          New connection can't be made because a policy with the same details is already present. If we vpn from any place that has a different public ip than the one from her home, we can establish the vpn connection without a problem.

          dbeato 1 Reply Last reply Reply Quote 0
          • dbeato
            dbeato @Romo last edited by

            @romo said in Help troubleshooting L2TP over IPSEC VPN connections.:

            @jaredbusch said in Help troubleshooting L2TP over IPSEC VPN connections.:

            @romo said in Help troubleshooting L2TP over IPSEC VPN connections.:

            @JaredBusch @scottalanmiller Any idea?

            Is this user trying to connect from the same IP as another user?

            No, a single user trying to connect from home. She connected Wednesday without a problem, but Thursday she tries to connect again and it is not possible.

            Logs show

            13[CFG] unable to install policy EDGE_ROUTER_IP/32[udp/l2f] === USER_PUBLIC_IP/32[udp/l2f] out (mark 0/0x00000000) for reqid 35, the same policy for reqid 14 exists
            13[CFG] unable to install policy USER_PUBLIC_IP/32[udp/l2f] === EDGE_ROUTER_IP/32[udp/l2f] in (mark 0/0x00000000) for reqid 35, the same policy for reqid 14 exists
            

            New connection can't be made because a policy with the same details is already present. If we vpn from any place that has a different public ip than the one from her home, we can establish the vpn connection without a problem.

            What VPN client are you using, default to Windows?

            Romo 1 Reply Last reply Reply Quote 0
            • Romo
              Romo @dbeato last edited by

              @dbeato Yes

              dbeato 1 Reply Last reply Reply Quote 0
              • dbeato
                dbeato @Romo last edited by

                @romo said in Help troubleshooting L2TP over IPSEC VPN connections.:

                @dbeato Yes

                Okay, was looking at that error on other OpenVPN clients that had issues on older versions.

                Romo 1 Reply Last reply Reply Quote 0
                • Romo
                  Romo @dbeato last edited by

                  @dbeato said in Help troubleshooting L2TP over IPSEC VPN connections.:

                  @romo said in Help troubleshooting L2TP over IPSEC VPN connections.:

                  @dbeato Yes

                  Okay, was looking at that error on other OpenVPN clients that had issues on older versions.

                  It looks like it is a Strongswan issue, as a temporary fix it should be resolved by manually restarting the IPSec VPN (restart vpn). Unfortunately, during working hours it seems to be too disruptive to use for properly connected users. At least without having tested the effects of the restart for connected users.

                  The strange thing is the connection is acting as if two computers were trying to access the VPN server behind the same NAT when according to the user it is only a single device.

                  1 Reply Last reply Reply Quote 1
                  • Romo
                    Romo last edited by Romo

                    Here is our issue https://wiki.strongswan.org/issues/431, it was fixed 3 years ago when version 5.3 of strongSwan came out.

                    I had not found what strongSwan version we were using, I just assumed we were using something newer. Then I found that our edge router is using strongSwan 5.2.2.

                    Here is our version.

                    Status of IKE charon daemon (strongSwan 5.2.2, Linux 3.10.107-UBNT, mips64):
                      uptime: 3 days, since Aug 06 22:12:40 2018
                      malloc: sbrk 376832, mmap 0, used 295456, free 81376
                      worker threads: 11 of 16 idle, 5/0/0/0 working, job queue: 0/0/0/0, scheduled:
                    

                    From here https://community.ubnt.com/t5/EdgeMAX-Feature-Requests/Upgrade-to-strongswan-5-6-x/idi-p/1507341 we see a change to strongSwan 5.5.x has been accepted don't know when it will be available.

                    strongSwan 5.3 + can now handle identical policies by reusing the same reqid. This allows identical CHILD_SAs to the same host.

                    So that probably means multiple machines behind NAT could also work when the fix is implemented.

                    dbeato 1 Reply Last reply Reply Quote 2
                    • gjacobse
                      gjacobse last edited by

                      jeeze,.. that is a sad state to think that we have nbeen fighting this for that long,...

                      @JaredBusch @scottalanmiller
                      Can a cron be set to restart the ipsec every 24 hours?

                      JaredBusch 1 Reply Last reply Reply Quote 1
                      • dbeato
                        dbeato @Romo last edited by

                        @romo said in Help troubleshooting L2TP over IPSEC VPN connections.:

                        Here is our issue https://wiki.strongswan.org/issues/431, it was fixed 3 years ago when version 5.3 of strongSwan came out.

                        I had not found what strongSwan version we were using, I just assumed we were using something newer. Then I found that our edge router is using strongSwan 5.2.2.

                        Here is our version.

                        Status of IKE charon daemon (strongSwan 5.2.2, Linux 3.10.107-UBNT, mips64):
                          uptime: 3 days, since Aug 06 22:12:40 2018
                          malloc: sbrk 376832, mmap 0, used 295456, free 81376
                          worker threads: 11 of 16 idle, 5/0/0/0 working, job queue: 0/0/0/0, scheduled:
                        

                        From here https://community.ubnt.com/t5/EdgeMAX-Feature-Requests/Upgrade-to-strongswan-5-6-x/idi-p/1507341 we see a change to strongSwan 5.5.x has been accepted don't know when it will be available.

                        strongSwan 5.3 + can now handle identical policies by reusing the same reqid. This allows identical CHILD_SAs to the same host.

                        So that probably means multiple machines behind NAT could also work when the fix is implemented.

                        Yeah, that is what I found and was referring to. I just did not post it here.

                        1 Reply Last reply Reply Quote 0
                        • JaredBusch
                          JaredBusch @gjacobse last edited by

                          @gjacobse said in Help troubleshooting L2TP over IPSEC VPN connections.:

                          jeeze,.. that is a sad state to think that we have nbeen fighting this for that long,...

                          @JaredBusch @scottalanmiller
                          Can a cron be set to restart the ipsec every 24 hours?

                          Yes.

                          1 Reply Last reply Reply Quote 0
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