possible to lose (a) lease(s) across a reboot?

Brian J. Murrell brian at interlinx.bc.ca
Tue Dec 3 21:44:32 UTC 2013


I have a situation here using dhcpd 4.1.1-34.P1[.el6_4.1] on CentOS 6.4
where I think I'm losing leases across reboots of the server.  Looking
in the syslog for the lease issuance observe:

Dec  3 10:41:04 mgmt1 dhcpd: DHCPDISCOVER from 52:54:00:14:d9:14 via eth0:1 
Dec  3 10:41:05 mgmt1 dhcpd: DHCPOFFER on 10.14.82.106 to 52:54:00:14:d9:14 via eth0:1 
Dec  3 10:41:05 mgmt1 dhcpd: Added new forward map from lotus-14vm14.foo.example.com to 10.14.82.106 
Dec  3 10:41:05 mgmt1 dhcpd: added reverse map from 106.82.14.10.in-addr.arpa. to lotus-14vm14.foo.example.com 
Dec  3 10:41:05 mgmt1 dhcpd: DHCPREQUEST for 10.14.82.106 (192.168.0.253) from 52:54:00:14:d9:14 via eth0:1 
Dec  3 10:41:05 mgmt1 dhcpd: DHCPACK on 10.14.82.106 to 52:54:00:14:d9:14 via eth0:1 

Client acquires a lease and DDNS is updated.  The lease on the client
shows:

lease {
  interface "eth0";
  fixed-address 10.14.82.106;
  option subnet-mask 255.255.248.0;
  option routers 10.14.80.1;
  option dhcp-lease-time 21600;
  option dhcp-message-type 5;
  option domain-name-servers 10.14.80.8,10.14.80.9,10.14.80.6;
  option dhcp-server-identifier 192.168.0.253;
  option domain-name "foo.example.com";
  renew 2 2013/12/03 23:29:22;
  rebind 3 2013/12/04 01:56:04;
  expire 3 2013/12/04 02:41:04;
}

But notice that at a very short time later, the server is rebooted and
at pretty much near the same time, the DDNS records are removed:

Dec  3 12:51:58 mgmt1 dhcpd: Not searching LDAP since ldap-server, ldap-port and ldap-base-dn were not specified in the config file
Dec  3 12:51:58 mgmt1 dhcpd: Internet Systems Consortium DHCP Server 4.1.1-P1
Dec  3 12:51:58 mgmt1 dhcpd: Copyright 2004-2010 Internet Systems Consortium.
Dec  3 12:51:58 mgmt1 dhcpd: All rights reserved.
Dec  3 12:51:58 mgmt1 dhcpd: For info, please visit https://www.isc.org/software/dhcp/
Dec  3 12:51:58 mgmt1 dhcpd: Not searching LDAP since ldap-server, ldap-port and ldap-base-dn were not specified in the config file
Dec  3 12:51:58 mgmt1 dhcpd: Wrote 0 class decls to leases file.
Dec  3 12:51:58 mgmt1 dhcpd: Wrote 0 deleted host decls to leases file.
Dec  3 12:51:58 mgmt1 dhcpd: Wrote 0 new dynamic host decls to leases file.
Dec  3 12:51:58 mgmt1 dhcpd: Wrote 457 leases to leases file.
Dec  3 12:51:58 mgmt1 dhcpd: Multiple interfaces match the same shared network: eth0 eth0:1
Dec  3 12:51:58 mgmt1 dhcpd: Listening on LPF/eth0:1/52:54:00:0f:ce:31/foo
Dec  3 12:51:58 mgmt1 dhcpd: Sending on   LPF/eth0:1/52:54:00:0f:ce:31/foo
Dec  3 12:51:58 mgmt1 dhcpd: Listening on LPF/eth0/52:54:00:0f:ce:31/foo
Dec  3 12:51:58 mgmt1 dhcpd: Sending on   LPF/eth0/52:54:00:0f:ce:31/foo
Dec  3 12:51:58 mgmt1 dhcpd: Sending on   Socket/fallback/fallback-net
Dec  3 12:52:03 mgmt1 named[10699]: client 127.0.0.1#36402: updating zone 'foo.example.com/IN': deleting an RR at lotus-14vm14.foo.example.com A
Dec  3 12:52:03 mgmt1 dhcpd: if lotus-14vm14.foo.example.com IN TXT "0042f38fafbb61232a6de221705cc4f24b" rrset exists and lotus-14vm14.foo.example.com IN A 10.14.82.106 rrset exists delete lotus-14vm14.foo.example.com IN A 10.14.82.106: success.
Dec  3 12:52:03 mgmt1 named[10699]: client 127.0.0.1#54009: updating zone 'foo.example.com/IN': deleting an RR at lotus-14vm14.foo.example.com TXT
Dec  3 12:52:03 mgmt1 dhcpd: if lotus-14vm14.foo.example.com IN A rrset doesn't exist and lotus-14vm14.foo.example.com IN AAAA rrset doesn't exist delete lotus-14vm14.foo.example.com IN TXT "0042f38fafbb61232a6de221705cc4f24b": success.

At that time, there was no lease in the DHCP server's lease file
corresponding to that above MAC address.  But with the following lease
times configured:

         default-lease-time         21600;
         max-lease-time             43200;

That lease should not have been removed only 2h11m after being issued.
The removal is remarkably suspicious in that it's the first thing the
DHCP server does after being restarted.

So did the restart lose a lease?

Cheers,
b.

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