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    CentOS 7 VM on Hyper-V losing DHCP assigned address

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    centos 7 dhcp failed hyper-v chrony
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    • JaredBuschJ
      JaredBusch
      last edited by JaredBusch

      I have many CentOS 7 VMs on Hyper-v and randomly (and rarely) I have this problem.

      The system will be unreachable. I log in to the console and i see it has no IP address. a quick ifdown/ifup and it is back. I assume it is failing to renew?

      Where can I look to try and locate the cause?

      0_1463408752229_upload-0c08ebab-dfc4-417c-af88-11f319747fdf

      1 Reply Last reply Reply Quote 1
      • scottalanmillerS
        scottalanmiller
        last edited by

        In theory, /var/log/messages should hold some clues.

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

          @scottalanmiller said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

          In theory, /var/log/messages should hold some clues.

          but what do i look for is the better question I guess.

          1 Reply Last reply Reply Quote 0
          • dafyreD
            dafyre
            last edited by

            Your DHCP server's logs may also hold some clues if you can narrow down the time frame when the IP address vanishes.

            1 Reply Last reply Reply Quote 0
            • JaredBuschJ
              JaredBusch
              last edited by

              WTF.. the date went south...

              [root@owncloud ~]# grep DHCP /var/log/messages-20160516
May 11 08:49:13 owncloud dhclient[1134]: DHCPREQUEST on eth0 to 10.201.1.7 port 67 (xid=0x2ca58a7d)
May 11 08:49:13 owncloud dhclient[1134]: DHCPACK from 10.201.1.7 (xid=0x2ca58a7d)
May 11 08:49:13 owncloud NetworkManager[804]: <info>  (eth0): DHCPv4 state changed bound -> bound
May 11 18:15:47 owncloud dhclient[1134]: DHCPREQUEST on eth0 to 10.201.1.7 port 67 (xid=0x2ca58a7d)
May 11 18:15:47 owncloud dhclient[1134]: DHCPACK from 10.201.1.7 (xid=0x2ca58a7d)
May 11 18:15:47 owncloud NetworkManager[804]: <info>  (eth0): DHCPv4 state changed bound -> bound
May 12 06:11:42 owncloud dhclient[1134]: DHCPREQUEST on eth0 to 10.201.1.7 port 67 (xid=0x2ca58a7d)
May 12 06:11:42 owncloud dhclient[1134]: DHCPACK from 10.201.1.7 (xid=0x2ca58a7d)
May 12 06:11:42 owncloud NetworkManager[804]: <info>  (eth0): DHCPv4 state changed bound -> bound
May 12 17:00:03 owncloud dhclient[1134]: DHCPREQUEST on eth0 to 10.201.1.7 port 67 (xid=0x2ca58a7d)
May 12 17:00:03 owncloud dhclient[1134]: DHCPACK from 10.201.1.7 (xid=0x2ca58a7d)
May 12 17:00:03 owncloud NetworkManager[804]: <info>  (eth0): DHCPv4 state changed bound -> bound
May 13 02:14:18 owncloud dhclient[1134]: DHCPREQUEST on eth0 to 10.201.1.7 port 67 (xid=0x2ca58a7d)
May 13 02:14:18 owncloud dhclient[1134]: DHCPACK from 10.201.1.7 (xid=0x2ca58a7d)
May 13 02:14:18 owncloud NetworkManager[804]: <info>  (eth0): DHCPv4 state changed bound -> bound
May 22 23:30:53 owncloud NetworkManager[817]: <info>  Activation (eth0) Beginning DHCPv4 transaction (timeout in 45 seconds)
May 22 23:30:54 owncloud dhclient[1146]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 3 (xid=0x18ffd4fe)
May 22 23:30:54 owncloud dhclient[1146]: DHCPREQUEST on eth0 to 255.255.255.255 port 67 (xid=0x18ffd4fe)
May 22 23:30:54 owncloud dhclient[1146]: DHCPOFFER from 10.201.1.7
May 22 23:30:54 owncloud dhclient[1146]: DHCPACK from 10.201.1.7 (xid=0x18ffd4fe)
May 22 23:30:54 owncloud NetworkManager[817]: <info>  (eth0): DHCPv4 state changed unknown -> bound
May 16 16:36:07 owncloud NetworkManager[803]: <info>  Activation (eth0) Beginning DHCPv4 transaction (timeout in 45 seconds)
May 16 16:36:07 owncloud dhclient[1133]: DHCPREQUEST on eth0 to 255.255.255.255 port 67 (xid=0x27078c0b)
May 16 16:36:07 owncloud dhclient[1133]: DHCPACK from 10.201.1.7 (xid=0x27078c0b)
May 16 16:36:07 owncloud NetworkManager[803]: <info>  (eth0): DHCPv4 state changed unknown -> bound
[root@owncloud ~]#
              1 Reply Last reply Reply Quote 0
              • JaredBuschJ
                JaredBusch
                last edited by

                So the ntpd service is not present on this system. but I know I enabled an NTP server during the CentOS 7 setup.

                Anyone know where that setting is? I'm not finding anything with my Google Fu this morning except answers relating to ntpd.

                1 Reply Last reply Reply Quote 0
                • coliverC
                  coliver
                  last edited by

                  It doesn't use ntpd anymore. I think it uses chrony.

                  Make sure you have it set so that the time isn't coming from the hardware, I had that issue with Linux VMs on both VMWare and Hyper-V in the past.

                  JaredBuschJ 1 Reply Last reply Reply Quote 1
                  • scottalanmillerS
                    scottalanmiller
                    last edited by

                    Yeah, chrony is the new replacement.

                    1 Reply Last reply Reply Quote 1
                    • JaredBuschJ
                      JaredBusch @coliver
                      last edited by

                      @coliver said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                      It doesn't use ntpd anymore. I think it uses chrony.

                      Make sure you have it set so that the time isn't coming from the hardware, I had that issue with Linux VMs on both VMWare and Hyper-V in the past.

                      Thanks, Once i knew the right name I had no problem finding the config file.

                      It seems i left a couple public servers in there. But hardware, should only be possibly hit on boot up right?

                      /me goes off to double check Hyper-V settigns.

                      # These servers were defined in the installation:
server 10.201.1.7 iburst
server 10.201.1.1 iburst
server 0.centos.pool.ntp.org iburst
server 3.centos.pool.ntp.org iburst
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).

# Ignore stratum in source selection.
stratumweight 0

# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift

# Enable kernel RTC synchronization.
rtcsync

# In first three updates step the system clock instead of slew
# if the adjustment is larger than 10 seconds.
makestep 10 3

# Allow NTP client access from local network.
#allow 192.168/16

# Listen for commands only on localhost.
bindcmdaddress 127.0.0.1
bindcmdaddress ::1

# Serve time even if not synchronized to any NTP server.
#local stratum 10

keyfile /etc/chrony.keys

# Specify the key used as password for chronyc.
commandkey 1

# Generate command key if missing.
generatecommandkey

# Disable logging of client accesses.
noclientlog

# Send a message to syslog if a clock adjustment is larger than 0.5 seconds.
logchange 0.5


logdir /var/log/chrony
#log measurements statistics tracking
                      coliverC 1 Reply Last reply Reply Quote 0
                      • coliverC
                        coliver @JaredBusch
                        last edited by

                        @JaredBusch said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                        @coliver said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                        It doesn't use ntpd anymore. I think it uses chrony.

                        Make sure you have it set so that the time isn't coming from the hardware, I had that issue with Linux VMs on both VMWare and Hyper-V in the past.

                        Thanks, Once i knew the right name I had no problem finding the config file.

                        It seems i left a couple public servers in there. But hardware, should only be possibly hit on boot up right?

                        /me goes off to double check Hyper-V settigns.

                        # These servers were defined in the installation:
server 10.201.1.7 iburst
server 10.201.1.1 iburst
server 0.centos.pool.ntp.org iburst
server 3.centos.pool.ntp.org iburst
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).

# Ignore stratum in source selection.
stratumweight 0

# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift

# Enable kernel RTC synchronization.
rtcsync

# In first three updates step the system clock instead of slew
# if the adjustment is larger than 10 seconds.
makestep 10 3

# Allow NTP client access from local network.
#allow 192.168/16

# Listen for commands only on localhost.
bindcmdaddress 127.0.0.1
bindcmdaddress ::1

# Serve time even if not synchronized to any NTP server.
#local stratum 10

keyfile /etc/chrony.keys

# Specify the key used as password for chronyc.
commandkey 1

# Generate command key if missing.
generatecommandkey

# Disable logging of client accesses.
noclientlog

# Send a message to syslog if a clock adjustment is larger than 0.5 seconds.
logchange 0.5


logdir /var/log/chrony
#log measurements statistics tracking

                        I'm not sure about that. I know I had to disable it per VM on Hyper-V.

                        JaredBuschJ 1 Reply Last reply Reply Quote 1
                        • JaredBuschJ
                          JaredBusch @coliver
                          last edited by

                          @coliver said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                          I'm not sure about that. I know I had to disable it per VM on Hyper-V.

                          Right, I know that, but i thought it always checks hardware on boot regardless of setting... It is not checked.

                          0_1463410288970_upload-d748086a-2b51-4117-9ece-4f5a79451e03

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

                            @JaredBusch said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                            @coliver said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                            I'm not sure about that. I know I had to disable it per VM on Hyper-V.

                            Right, I know that, but i thought it always checks hardware on boot regardless of setting... It is not checked.

                            0_1463410288970_upload-d748086a-2b51-4117-9ece-4f5a79451e03

                            Good, then maybe that public server was the issue.

                            JaredBuschJ 1 Reply Last reply Reply Quote 1
                            • JaredBuschJ
                              JaredBusch @coliver
                              last edited by

                              @coliver said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                              @JaredBusch said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                              @coliver said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                              I'm not sure about that. I know I had to disable it per VM on Hyper-V.

                              Right, I know that, but i thought it always checks hardware on boot regardless of setting... It is not checked.

                              Good, then maybe that public server was the issue.

                              I hope so. highly annoying

                              1 Reply Last reply Reply Quote 0
                              • JaredBuschJ
                                JaredBusch
                                last edited by

                                Same issue different server.
                                Why is the time so f'd up.
                                I checked the Hyper-V server, it has the correct time.
                                0_1474475697544_upload-b90e69f0-ebe9-49ad-94e2-34880565e42e

                                I checked chrony on the CentOS box, it had public NTP servers. Boom problem.
                                Changed the ntp servers to internal sources and magic.

                                [root@owncloud ~]# grep chrony /var/log/messages
Sep 19 14:14:44 owncloud chronyd[765]: Can't synchronise: no selectable sources
Sep 21 17:02:28 owncloud chronyd[758]: chronyd version 2.1.1 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +DEBUG +ASYNCDNS +IPV6 +SECHASH)
Sep 21 17:02:28 owncloud chronyd[758]: Frequency -25.319 +/- 0.011 ppm read from /var/lib/chrony/drift
Sep 20 14:12:20 owncloud chronyd[758]: Selected source 209.208.79.69
Sep 20 14:12:20 owncloud chronyd[758]: System clock wrong by -96617.583787 seconds, adjustment started
Sep 20 14:12:20 owncloud chronyd[758]: System clock was stepped by -96617.583787 seconds
Sep 20 14:12:21 owncloud chronyd[758]: Selected source 104.238.179.130
Sep 20 19:02:11 owncloud chronyd[758]: Selected source 209.208.79.69
Sep 22 08:35:19 owncloud chronyd[758]: chronyd version 2.1.1 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +DEBUG +ASYNCDNS +IPV6 +SECHASH)
Sep 22 08:35:19 owncloud chronyd[758]: Frequency -25.359 +/- 0.039 ppm read from /var/lib/chrony/drift
Sep 21 11:26:54 owncloud chronyd[758]: Selected source 10.202.1.1
Sep 21 11:26:54 owncloud chronyd[758]: System clock wrong by -76114.165928 seconds, adjustment started
Sep 21 11:26:54 owncloud chronyd[758]: System clock was stepped by -76114.165928 seconds

                                [root@owncloud ~]# date
Wed Sep 21 11:38:02 CDT 2016
[root@owncloud ~]#
                                1 Reply Last reply Reply Quote 0
                                • JaredBuschJ
                                  JaredBusch
                                  last edited by

                                  So the reason I posted to this again.. If you cannot trust ntp.org anymore how are we supposed to handle this.

                                  scottalanmillerS 1 Reply Last reply Reply Quote 1
                                  • scottalanmillerS
                                    scottalanmiller @JaredBusch
                                    last edited by

                                    @JaredBusch said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                                    So the reason I posted to this again.. If you cannot trust ntp.org anymore how are we supposed to handle this.

                                    What did I miss? Why can't we trust NTP.org?

                                    JaredBuschJ coliverC 2 Replies Last reply Reply Quote 0
                                    • JaredBuschJ
                                      JaredBusch @scottalanmiller
                                      last edited by

                                      @scottalanmiller said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                                      @JaredBusch said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                                      So the reason I posted to this again.. If you cannot trust ntp.org anymore how are we supposed to handle this.

                                      What did I miss? Why can't we trust NTP.org?

                                      It pulled the wrong date for the server, which then f'd up the DHCP renew.

                                      1 Reply Last reply Reply Quote 0
                                      • coliverC
                                        coliver @scottalanmiller
                                        last edited by

                                        @scottalanmiller said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                                        @JaredBusch said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                                        So the reason I posted to this again.. If you cannot trust ntp.org anymore how are we supposed to handle this.

                                        What did I miss? Why can't we trust NTP.org?

                                        Crazy time skew with ntp.org and chrony. Never had the issue with the ntpd system. I've had it on some of my new CentOS servers as well. We have a atomic clock on site here but if using ntp,org we get some serious skew.

                                        1 Reply Last reply Reply Quote 1
                                        • scottalanmillerS
                                          scottalanmiller
                                          last edited by

                                          Are we sure that ntp.org was the issue? Is this repeatable?

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

                                            @scottalanmiller said in CentOS 7 VM on Hyper-V losing DHCP assigned address:

                                            Are we sure that ntp.org was the issue? Is this repeatable?

                                            Second time it has caught me. Completely different server. Completely different client.

                                            coliverC 1 Reply Last reply Reply Quote 0
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