Is it normal for start time to be later than end time in the leases file?
David Coulthart
davec at columbia.edu
Wed Aug 20 20:43:43 UTC 2008
I'm running a pair of DHCP servers (3.0.4, working to upgrade to
3.1.1) with failover configured. I received a report that a host that
is configured with a fixed address was having trouble obtaining its
lease. It was previously receiving an IP from the dynamic pool for
the same network. The messages in the logs were:
Aug 20 10:12:38 <primary-dhcp-server> dhcpd: [ID 702911 local6.info]
DHCPDISCOVER from <MAC> via <gateway IP>
Aug 20 10:12:38 <primary-dhcp-server> dhcpd: [ID 702911 local6.info]
DHCPOFFER on <fixed-IP> to <MAC> via <gateway IP>
Aug 20 10:12:38 <secondary-dhcp-server> dhcpd: [ID 702911
local6.error] uid lease <dynamic-IP> for client <MAC> is duplicate on
<shared-network>
Aug 20 10:12:38 <secondary-dhcp-server> dhcpd: [ID 702911 local6.info]
DHCPDISCOVER from <MAC> via <gateway IP>
Aug 20 10:12:38 <secondary-dhcp-server> dhcpd: [ID 702911 local6.info]
DHCPOFFER on <fixed-IP> to <MAC> via <gateway IP>
Aug 20 10:12:38 <primary-dhcp-server> dhcpd: [ID 702911 local6.info]
DHCPREQUEST for <fixed-IP> (<secondary-dhcp-server-IP>) from <MAC> via
<gateway IP>
Aug 20 10:12:38 <primary-dhcp-server> dhcpd: [ID 702911 local6.info]
DHCPACK on <fixed-IP> to <MAC> via <gateway IP>
Aug 20 10:12:38 <primary-dhcp-server> dhcpd: [ID 702911 local6.info]
DHCPREQUEST for <fixed-IP> (<secondary-dhcp-server-IP>) from <MAC> via
<gateway IP>
Aug 20 10:12:38 <secondary-dhcp-server> dhcpd: [ID 702911
local6.error] uid lease <dynamic-IP> for client <MAC> is duplicate on
<shared-network>
Aug 20 10:12:38 <secondary-dhcp-server> dhcpd: [ID 702911 local6.info]
DHCPREQUEST for <fixed-IP> (<secondary-dhcp-server-IP>) from <MAC> via
<gateway IP>
Aug 20 10:12:38 <primary-dhcp-server> dhcpd: [ID 702911 local6.info]
DHCPACK on <fixed-IP> to <MAC> via <gateway IP>
Aug 20 10:12:38 <secondary-dhcp-server> dhcpd: [ID 702911 local6.info]
DHCPACK on <fixed-IP> to <MAC> via <gateway IP>
Aug 20 10:12:38 <secondary-dhcp-server> dhcpd: [ID 702911
local6.error] uid lease <dynamic-IP> for client <MAC> is duplicate on
<shared-network>
Aug 20 10:12:38 <secondary-dhcp-server> dhcpd: [ID 702911 local6.info]
DHCPREQUEST for <fixed-IP> (<secondary-dhcp-server-IP>) from <MAC> via
<gateway IP>
Aug 20 10:12:38 <secondary-dhcp-server> dhcpd: [ID 702911 local6.info]
DHCPACK on <fixed-IP> to <MAC> via <gateway IP>
Examining the leases files for the MAC address in question, I found:
On the secondary DHCP server:
lease <dynamic-IP> {
starts 2 2008/08/19 05:35:52;
ends 5 2008/08/15 16:26:53;
tstp 5 2008/08/15 16:26:53;
tsfp 2 2008/08/19 05:35:52;
atsfp 2 2008/08/19 05:35:52;
cltt 5 2008/08/15 16:24:50;
binding state backup;
hardware ethernet <MAC>;
uid "<UID>";
}
lease <dynamic-IP-#2-in-same-shared-network> {
starts 2 2008/08/19 07:51:03;
ends 6 2008/08/16 04:56:25;
tstp 6 2008/08/16 04:56:25;
tsfp 2 2008/08/19 07:51:03;
atsfp 2 2008/08/19 07:51:03;
cltt 5 2008/08/15 16:56:53;
binding state backup;
hardware ethernet <MAC>;
uid "<UID>";
}
On the primary DHCP server:
lease <dynamic-IP> {
starts 2 2008/08/19 05:35:52;
ends 5 2008/08/15 16:26:53;
tstp 2 2008/08/19 05:35:52;
tsfp 2 2008/08/19 05:35:52;
atsfp 2 2008/08/19 05:35:52;
cltt 5 2008/08/15 16:24:50;
binding state backup;
hardware ethernet <MAC>;
uid "<UID>";
}
lease <dynamic-IP-#2-in-same-shared-network> {
starts 2 2008/08/19 07:51:03;
ends 6 2008/08/16 04:56:25;
tstp 2 2008/08/19 07:51:03;
tsfp 2 2008/08/19 07:51:03;
atsfp 2 2008/08/19 07:51:03;
cltt 5 2008/08/15 16:56:53;
binding state backup;
hardware ethernet <MAC>;
uid "<UID>";
}
The part that stymied me was that the date listed for "ends" was
earlier than the date listed for "starts". I cooked up a small perl
script to do a quick check & found that approximately 32,000 out of
81,000 leases exhibited this phenomenon. Is this normal? I fed these
configs & leases files to dhcpd 3.1.1 using the -t & -T options and
didn't receive any warnings.
Thx,
Dave Coulthart
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