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    dhcp issues 2 ip addresses to same computer on same subnet

    Scheduled Pinned Locked Moved DHCP and DNS
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    • C
      cd @johnpoz
      last edited by cd

      @johnpoz Same Mac

      Here is full mac

      from PFSENSE dhcp lease page:

      192.168.40.14 b8:27:eb:d8:3c:ff pi2 2024/02/10 09:22:17 2024/02/10 11:22:17
      192.168.40.13 b8:27:eb:d8:3c:ff pi2

      Yes, the pi has wifi also. but the mac address for both ips identical. I would think that should be impossible.

      I see in your example, eth0 and wlan0 have different macs.

      S johnpozJ 2 Replies Last reply Reply Quote 0
      • S
        serbus @cd
        last edited by serbus

        @cd

        Hello!

        Do you have both connman and dhcpd (dhclient) running?

        I have seen quite a few installs get hit with this lately...

        John

        Lex parsimoniae

        C 1 Reply Last reply Reply Quote 0
        • johnpozJ
          johnpoz LAYER 8 Global Moderator @cd
          last edited by johnpoz

          @cd said in dhcp issues 2 ip addresses to same computer on same subnet:

          but the mac address for both ips identical

          Something odd there.. Yes the 2 different interfaces should have slightly different macs.. I have seen for example just the last number being off by 1.. That is quite common.

          But the same?

          Did you change the mac of one of them.. Did you setup a bridge or something on the device?

          Could you post the output of ifconfig from your pi? Like I did

          An intelligent man is sometimes forced to be drunk to spend time with his fools
          If you get confused: Listen to the Music Play
          Please don't Chat/PM me for help, unless mod related
          SG-4860 24.11 | Lab VMs 2.8, 24.11

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          • C
            cd @serbus
            last edited by

            @serbus I don't know what conman is. Can you clarify?

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            • C
              cd @johnpoz
              last edited by

              @johnpoz 192.168.20.2 00:0f:60:04:53:15 pi2 2024/02/10 10:37:35 2024/02/10 12:37:35

              Notice this lease was very short lived. What i just did to get this was to disconnect pi from switch and plug wifi in.

              FYI, wifi subnet is 192.168.20.X Switch is 192.168.40.x from before

              I also notice that the dchp lease page take forever to update

              I have had issues for a long time with intermittent failure to reach machines on the network. On my tablet for example, to reach my 3d printer, i disconnect and reconnect wifi to get to machine. That works often.
              I have 3 printers on the 20 network. At any one time, i can reach printer A and not reach printer B over wifi.

              I have tried replacing the wifi ap, no help.

              But now this is wired issue. Confusing.

              C 1 Reply Last reply Reply Quote 0
              • C
                cd @cd
                last edited by

                @johnpoz

                Ok,

                here is ifconfig from pi, accessed with only wifi
                connected:

                eth0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
                inet 192.168.40.13 netmask 255.255.255.0 broadcast 192.168.40.255
                inet6 fe80::ba27:ebff:fed8:3cff prefixlen 64 scopeid 0x20<link>
                ether b8:27:eb:d8:3c:ff txqueuelen 1000 (Ethernet)
                RX packets 1041539 bytes 76256137 (72.7 MiB)
                RX errors 0 dropped 0 overruns 0 frame 0
                TX packets 92664 bytes 15160845 (14.4 MiB)
                TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

                lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
                inet 127.0.0.1 netmask 255.0.0.0
                inet6 ::1 prefixlen 128 scopeid 0x10<host>
                loop txqueuelen 1000 (Local Loopback)
                RX packets 11 bytes 1605 (1.5 KiB)
                RX errors 0 dropped 0 overruns 0 frame 0
                TX packets 11 bytes 1605 (1.5 KiB)
                TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

                wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
                inet 192.168.20.2 netmask 255.255.255.0 broadcast 192.168.20.255
                inet6 fe80::1ead:69a5:2035:d36f prefixlen 64 scopeid 0x20<link>
                ether 00:0f:60:04:53:15 txqueuelen 1000 (Ethernet)
                RX packets 1024 bytes 103044 (100.6 KiB)
                RX errors 0 dropped 0 overruns 0 frame 0
                TX packets 89 bytes 13712 (13.3 KiB)
                TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

                johnpozJ 1 Reply Last reply Reply Quote 0
                • johnpozJ
                  johnpoz LAYER 8 Global Moderator @cd
                  last edited by johnpoz

                  @cd well your macs are not the same there..

                  ether b8:27:eb:d8:3c:ff

                  ether 00:0f:60:04:53:15

                  00:0d:60
                  Lifetron Co.,Ltd

                  hmmm - is that some 3rd party wifi dongle or something?

                  edit:
                  Is that data from your lease table - just an OLD expired lease?

                  An intelligent man is sometimes forced to be drunk to spend time with his fools
                  If you get confused: Listen to the Music Play
                  Please don't Chat/PM me for help, unless mod related
                  SG-4860 24.11 | Lab VMs 2.8, 24.11

                  C 1 Reply Last reply Reply Quote 0
                  • S
                    serbus @cd
                    last edited by

                    @cd

                    @cd

                    Connman is a network manager that will get dhcp addresses for interfaces. Sometimes, you can end up with 2 different network managers getting dhcp addresses for the same interface.

                    The syslog file on the client should tell the tale. Grep it for each ip and see which manager is requesting the address.

                        link/ether 42:58:0d:4f:e9:01 brd ff:ff:ff:ff:ff:ff
                        altname enp0s18
                        inet 10.12.12.21/24 brd 10.12.12.255 scope global dynamic ens18
                           valid_lft 691123sec preferred_lft 691123sec
                        inet 10.12.12.28/24 brd 10.12.12.255 scope global secondary ens18
                           valid_lft forever preferred_lft forever
                    
                    
                    Feb 10 09:46:50 debian dhclient[407]: DHCPREQUEST for 10.12.12.21 on ens18 to 255.255.255.255 port 67
                    Feb 10 09:46:50 debian dhclient[407]: DHCPACK of 10.12.12.21 from 10.12.12.1
                    
                    
                    Feb 10 09:46:53 debian connmand[370]: ens18 {add} address 10.12.12.28/24 label ens18 family 2
                    
                    

                    John

                    Lex parsimoniae

                    C 1 Reply Last reply Reply Quote 0
                    • C
                      cd @serbus
                      last edited by cd

                      @serbus Ok,

                      I notice avahi. Could that be the issue?

                      Feb 10 10:22:45 pi2 dhcpcd[567]: eth0: adding route to 192.168.40.0/24
                      Feb 10 10:22:45 pi2 dhcpcd[567]: eth0: adding default route via 192.168.40.1
                      Feb 10 10:37:16 pi2 avahi-daemon[343]: Withdrawing address record for 192.168.40.2 on eth0.
                      Feb 10 10:37:16 pi2 dhcpcd[567]: eth0: deleting route to 192.168.40.0/24
                      Feb 10 10:37:16 pi2 dhcpcd[567]: eth0: deleting default route via 192.168.40.1
                      Feb 10 10:37:35 pi2 dhcpcd[567]: wlan0: rebinding lease of 192.168.20.11
                      Feb 10 10:37:35 pi2 dhcpcd[567]: wlan0: offered 192.168.20.2 from 192.168.20.1
                      Feb 10 10:37:35 pi2 dhcpcd[567]: wlan0: probing address 192.168.20.2/24
                      Feb 10 10:37:39 pi2 dhcpcd[567]: wlan0: leased 192.168.20.2 for 7200 seconds
                      Feb 10 10:37:39 pi2 dhcpcd[567]: wlan0: adding route to 192.168.20.0/24
                      Feb 10 10:37:39 pi2 dhcpcd[567]: wlan0: adding default route via 192.168.20.1
                      Feb 10 10:37:39 pi2 avahi-daemon[343]: Joining mDNS multicast group on interface wlan0.IPv4 with address 192.168.20.2.
                      Feb 10 10:37:39 pi2 avahi-daemon[343]: Registering new address record for 192.168.20.2 on wlan0.IPv4.
                      Feb 10 11:01:41 pi2 dhclient[336]: DHCPREQUEST for 192.168.40.13 on eth0 to 192.168.40.1 port 67

                      When i greped syslog, did not see conman in there.

                      S 1 Reply Last reply Reply Quote 0
                      • C
                        cd @johnpoz
                        last edited by cd

                        @johnpoz

                        UPDATE: Rebooting pi got rid of the eth0 address on pi below:

                        eth0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
                        ether b8:27:eb:d8:3c:ff txqueuelen 1000 (Ethernet)
                        RX packets 0 bytes 0 (0.0 B)
                        RX errors 0 dropped 0 overruns 0 frame 0
                        TX packets 0 bytes 0 (0.0 B)
                        TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

                        lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
                        inet 127.0.0.1 netmask 255.0.0.0
                        inet6 ::1 prefixlen 128 scopeid 0x10<host>
                        loop txqueuelen 1000 (Local Loopback)
                        RX packets 10 bytes 1552 (1.5 KiB)
                        RX errors 0 dropped 0 overruns 0 frame 0
                        TX packets 10 bytes 1552 (1.5 KiB)
                        TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

                        wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
                        inet 192.168.20.3 netmask 255.255.255.0 broadcast 192.168.20.255
                        inet6 fe80::1ead:69a5:2035:d36f prefixlen 64 scopeid 0x20<link>
                        ether 00:0f:60:04:53:15 txqueuelen 1000 (Ethernet)
                        RX packets 141 bytes 16931 (16.5 KiB)
                        RX errors 0 dropped 1 overruns 0 frame 0
                        TX packets 66 bytes 11381 (11.1 KiB)
                        TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

                        I am logged into pi from wifi
                        No cable connected to it.
                        So seems pi thinks it has 2 addresses now but
                        pfsense says only the one i am wifiing into it with.

                        I just noticed avahi entries in syslog, but pfsense has that service disabled.

                        FYI, i really don't know if i even need avahi, not sure i understand.

                        This is the dhcp table from pfsense.

                        192.168.20.2	00:0f:60:04:53:15	pi2		2024/02/10 11:37:39	2024/02/10 13:37:39
                        

                        Ok, this is ifconfig from pi, right now.

                        eth0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
                        inet 192.168.40.13 netmask 255.255.255.0 broadcast 192.168.40.255
                        inet6 fe80::ba27:ebff:fed8:3cff prefixlen 64 scopeid 0x20<link>
                        ether b8:27:eb:d8:3c:ff txqueuelen 1000 (Ethernet)
                        RX packets 1041539 bytes 76256137 (72.7 MiB)
                        RX errors 0 dropped 0 overruns 0 frame 0
                        TX packets 92664 bytes 15160845 (14.4 MiB)
                        TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

                        lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
                        inet 127.0.0.1 netmask 255.0.0.0
                        inet6 ::1 prefixlen 128 scopeid 0x10<host>
                        loop txqueuelen 1000 (Local Loopback)
                        RX packets 11 bytes 1605 (1.5 KiB)
                        RX errors 0 dropped 0 overruns 0 frame 0
                        TX packets 11 bytes 1605 (1.5 KiB)
                        TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

                        wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
                        inet 192.168.20.2 netmask 255.255.255.0 broadcast 192.168.20.255
                        inet6 fe80::1ead:69a5:2035:d36f prefixlen 64 scopeid 0x20<link>
                        ether 00:0f:60:04:53:15 txqueuelen 1000 (Ethernet)
                        RX packets 10340 bytes 859067 (838.9 KiB)
                        RX errors 0 dropped 0 overruns 0 frame 0
                        TX packets 8458 bytes 8131289 (7.7 MiB)
                        TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

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                        • S
                          serbus @cd
                          last edited by

                          @cd

                          Using your example of 2 ips on the same wired mac...

                          192.168.40.14 b8:27:eb:d8:3c:ff pi2 2024/02/10 09:22:17 2024/02/10 11:22:17
                          192.168.40.13 b8:27:eb:d8:3c:ff pi2
                          

                          ...you could try something like...

                          grep -E '192.168.40.14|192.168.40.13' /var/log/syslog*
                          

                          ...to see who grabbed them and when.

                          John

                          Lex parsimoniae

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                          • C
                            cd
                            last edited by

                            ok,
                            I notice for another device, (merc)
                            the PFSENSE is giving out 2 addresses.

                            192.168.20.205	b8:27:eb:da:04:e2	merc		n/a	n/a   That is the static address, and is correct.
                            
                            192.168.20.7	34:7d:e4:4f:ba:b8	merc		2024/02/10 11:50:42	2024/02/10 13:50:42  That is dyamically allocated.  and goes away immediately.
                            

                            Merc is a rpi with only wifi access.

                            from dhcp log on pfsense:

                            Feb 10 11:50:42 kea-dhcp4 90601 INFO [kea-dhcp4.leases.0x19d9d3616d00] DHCP4_LEASE_ALLOC [hwtype=1 34:7d:e4:4f:ba:b8], cid=[01:34:7d:e4:4f:ba:b8], tid=0x6ef47ffc: lease 192.168.20.7 has been allocated for 7200 seconds

                            Why would it do this if it already has a static address set?

                            johnpozJ 1 Reply Last reply Reply Quote 0
                            • johnpozJ
                              johnpoz LAYER 8 Global Moderator @cd
                              last edited by

                              @cd said in dhcp issues 2 ip addresses to same computer on same subnet:

                              Why would it do this if it already has a static address set?

                              Don't use kea yet, would be my suggestion

                              https://docs.netgate.com/pfsense/en/latest/releases/2-7-1.html#rn-2-7-1-kea

                              Many features have yet to be implemented.. It is "preview" of what is to come..

                              An intelligent man is sometimes forced to be drunk to spend time with his fools
                              If you get confused: Listen to the Music Play
                              Please don't Chat/PM me for help, unless mod related
                              SG-4860 24.11 | Lab VMs 2.8, 24.11

                              1 Reply Last reply Reply Quote 0
                              • JKnottJ
                                JKnott @cd
                                last edited by

                                @cd said in dhcp issues 2 ip addresses to same computer on same subnet:

                                Is that a problem switch?

                                Yes, though it may depend on the firmware version. I believe @johnpoz can advise better.

                                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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