Заметил что иногда произвольно удаляется все содержимое файла /etc/sysconfig/iptables. Даже если не запущены виртуальные машины, а просто работает демон libvirtd. Сопоставив время изменения этого файла с логами заметил там следующее:
Jul 24 11:11:44 server libvirtd: 11:11:44.406: error : remoteDispatchAuthPolkit:3810 : Policy kit denied action org.libvirt.unix.manage from pid 12936, uid 500, result: 256
Jul 24 11:17:42 server libvirtd: 11:17:42.097: warning : qemudDispatchSignalEvent:392 : Shutting down on signal 15
Jul 24 11:18:20 server libvirtd: Could not find keytab file: /etc/libvirt/krb5.tab: No such file or directory
Jul 24 11:18:20 server libvirtd: 11:18:20.290: error : virRunWithHook:933 : internal error '/sbin/iptables --table filter --delete INPUT --in-interface virbr0 --protocol udp --destination-port 69 --jump ACCEPT' exited with non-zero status 1 and signal 0: iptables: Bad rule (does a matching rule exist in that chain?).#012
Jul 24 11:18:20 server kernel: lo: Disabled Privacy Extensions
Jul 24 11:18:21 server libvirtd: 11:18:21.974: error : remoteDispatchAuthPolkit:3810 : Policy kit denied action org.libvirt.unix.manage from pid 12936, uid 500, result: 256
Jul 24 11:19:26 server libvirtd: 11:19:26.969: error : remoteDispatchAuthPolkit:3810 : Policy kit denied action org.libvirt.unix.manage from pid 12936, uid 500, result: 256
Jul 24 11:21:01 server libvirtd: 11:21:01.426: error : virLibConnError:450 : this function is not supported by the connection driver: virConnectNumOfInterfaces
Jul 24 11:21:01 server libvirtd: 11:21:01.609: error : qemudDomainGetVcpus:6353 : Requested operation is not valid: cannot list vcpu pinning for an inactive domain
Jul 24 11:21:01 server libvirtd: 11:21:01.633: error : qemudDomainGetVcpus:6353 : Requested operation is not valid: cannot list vcpu pinning for an inactive domain
Jul 24 11:21:01 server libvirtd: 11:21:01.643: error : qemudDomainGetVcpus:6353 : Requested operation is not valid: cannot list vcpu pinning for an inactive domain
Jul 24 11:21:25 server libvirtd: 11:21:25.259: error : remoteDispatchAuthPolkit:3810 : Policy kit denied action org.libvirt.unix.manage from pid 22705, uid 500, result: 256
Jul 24 11:22:27 server libvirtd: 11:22:27.155: error : virLibConnError:450 : this function is not supported by the connection driver: virConnectNumOfInterfaces
Jul 24 11:22:27 server libvirtd: 11:22:27.307: error : qemudDomainGetVcpus:6353 : Requested operation is not valid: cannot list vcpu pinning for an inactive domain
Jul 24 11:22:27 server libvirtd: 11:22:27.317: error : qemuDomainGetJobInfo:12057 : Requested operation is not valid: domain is not running
Jul 24 11:22:27 server libvirtd: 11:22:27.346: error : qemudDomainGetVcpus:6353 : Requested operation is not valid: cannot list vcpu pinning for an inactive domain
Jul 24 11:22:27 server libvirtd: 11:22:27.353: error : qemuDomainGetJobInfo:12057 : Requested operation is not valid: domain is not running
Jul 24 11:22:27 server libvirtd: 11:22:27.372: error : qemudDomainGetVcpus:6353 : Requested operation is not valid: cannot list vcpu pinning for an inactive domain
Jul 24 11:22:27 server libvirtd: 11:22:27.378: error : qemuDomainGetJobInfo:12057 : Requested operation is not valid: domain is not running