PXE and Windows eating up DHCP leases

Question

Hi,
We've got three DHCP servers on three sites, running the ISC DHCP
daemon. We also have Zen for Desktops 7 on all three sites running on
Netware 6.5.
My problem is that when the PC boots, it ends up with two leases - one
for when the PXE runs, and another for when Windows boots! I've attached
an example of what happens, and the leases from the log files of the
server, to show what's happening. In a nutshell, it seems to be related
to the fact that the PXE session doesn't show a UID to the DHCP server,
but Windows does. As a result, DHCPD treats them as two different hosts,
and grants two leases. The only way around this right now is
ridiculously short leases, which results in very chatty workstations and
servers.
I tried the "deny duplicates;" setting in the dhcpd.conf, but that
doesn't seem to have worked. We have just over 50% of the DHCP pool
used, so as a result most PCs work, apart from the last ones on which
start showing 'No free leases' in the log file.
I'm going to upgrade the server to SLES10 soon (it's currently on an
ancient redhat install), but there's nothing in the changelogs relating
to duplicates that I could see, so I don't think it's a version issue.
Can anybody suggest anything to try and alleviate this problem? Is
anybody seeing this?
Regards,
====================== LOG FILES ============================
PXE Boot
========
Oct 27 11:46:08 ernie dhcpd: DHCPDISCOVER from 00:07:e9:f2:d3:13 via
192.168.200.2
Oct 27 11:46:09 ernie dhcpd: DHCPOFFER on 192.168.200.130 to
00:07:e9:f2:d3:13 via 192.168.200.2
Oct 27 11:46:10 ernie dhcpd: DHCPREQUEST for 192.168.200.130
(192.149.238.50) from 00:07:e9:f2:d3:13 via 192.168.200.2
Oct 27 11:46:10 ernie dhcpd: DHCPACK on 192.168.200.130 to
00:07:e9:f2:d3:13 via 192.168.200.2
Oct 27 11:46:10 ernie dhcpd: DHCPREQUEST for 192.168.200.130
(192.149.238.50) from 00:07:e9:f2:d3:13 via 192.168.200.3
Oct 27 11:46:10 ernie dhcpd: DHCPACK on 192.168.200.130 to
00:07:e9:f2:d3:13 via 192.168.200.3
lease 192.168.200.130 {
starts 5 2006/10/27 10:46:10;
ends 5 2006/10/27 10:56:10;
binding state active;
next binding state free;
hardware ethernet 00:07:e9:f2:d3:13;
lease 192.168.200.130 {
starts 5 2006/10/27 10:46:10;
ends 5 2006/10/27 10:56:10;
binding state active;
next binding state free;
hardware ethernet 00:07:e9:f2:d3:13;
Windows Boot
============
Oct 27 11:47:11 ernie dhcpd: DHCPDISCOVER from 00:07:e9:f2:d3:13 via
192.168.200.2
Oct 27 11:47:12 ernie dhcpd: DHCPOFFER on 192.168.200.65 to
00:07:e9:f2:d3:13 (BCUC-6D8215E8EA) via 192.168.200.2
Oct 27 11:47:12 ernie dhcpd: DHCPREQUEST for 192.168.200.65
(192.149.238.50) from 00:07:e9:f2:d3:13 (BCUC-6D8215E8EA) via 192.168.200.2
Oct 27 11:47:12 ernie dhcpd: DHCPACK on 192.168.200.65 to
00:07:e9:f2:d3:13 (BCUC-6D8215E8EA) via 192.168.200.2
Oct 27 11:47:12 ernie dhcpd: DHCPREQUEST for 192.168.200.65
(192.149.238.50) from 00:07:e9:f2:d3:13 (BCUC-6D8215E8EA) via 192.168.200.3
Oct 27 11:47:12 ernie dhcpd: DHCPACK on 192.168.200.65 to
00:07:e9:f2:d3:13 (BCUC-6D8215E8EA) via 192.168.200.3
lease 192.168.200.65 {
starts 5 2006/10/27 10:47:12;
ends 5 2006/10/27 10:57:12;
binding state active;
next binding state free;
hardware ethernet 00:07:e9:f2:d3:13;
uid "\001\000\007\351\362\323\023";
client-hostname "BCUC-6D8215E8EA";
lease 192.168.200.65 {
starts 5 2006/10/27 10:47:12;
ends 5 2006/10/27 10:57:12;
binding state active;
next binding state free;
hardware ethernet 00:07:e9:f2:d3:13;
uid "\001\000\007\351\362\323\023";
client-hostname "BCUC-6D8215E8EA";
David Rickard
ICT Security Officer
david dot [email protected], 01494 522141 Ext: 3531
Information & Communication Technologies
Buckinghamshire Chilterns University College
Queen Alexandra Road, High Wycombe, BUCKS, HP11 2JZ

Answer 1

David Rickard wrote:
> Hi,
>
> We've got three DHCP servers on three sites, running the ISC DHCP
> daemon. We also have Zen for Desktops 7 on all three sites running on
> Netware 6.5.
>
> My problem is that when the PC boots, it ends up with two leases - one
> for when the PXE runs, and another for when Windows boots! I've attached
> an example of what happens, and the leases from the log files of the
> server, to show what's happening. In a nutshell, it seems to be related
> to the fact that the PXE session doesn't show a UID to the DHCP server,
> but Windows does. As a result, DHCPD treats them as two different hosts,
> and grants two leases. The only way around this right now is
> ridiculously short leases, which results in very chatty workstations and
> servers.
>
> I tried the "deny duplicates;" setting in the dhcpd.conf, but that
> doesn't seem to have worked. We have just over 50% of the DHCP pool
> used, so as a result most PCs work, apart from the last ones on which
> start showing 'No free leases' in the log file.
>
> I'm going to upgrade the server to SLES10 soon (it's currently on an
> ancient redhat install), but there's nothing in the changelogs relating
> to duplicates that I could see, so I don't think it's a version issue.
>
> Can anybody suggest anything to try and alleviate this problem? Is
> anybody seeing this?
>
> Regards,
>
>
> ====================== LOG FILES ============================
>
> PXE Boot
> ========
>
> Oct 27 11:46:08 ernie dhcpd: DHCPDISCOVER from 00:07:e9:f2:d3:13 via
> 192.168.200.2
> Oct 27 11:46:09 ernie dhcpd: DHCPOFFER on 192.168.200.130 to
> 00:07:e9:f2:d3:13 via 192.168.200.2
> Oct 27 11:46:10 ernie dhcpd: DHCPREQUEST for 192.168.200.130
> (192.149.238.50) from 00:07:e9:f2:d3:13 via 192.168.200.2
> Oct 27 11:46:10 ernie dhcpd: DHCPACK on 192.168.200.130 to
> 00:07:e9:f2:d3:13 via 192.168.200.2
> Oct 27 11:46:10 ernie dhcpd: DHCPREQUEST for 192.168.200.130
> (192.149.238.50) from 00:07:e9:f2:d3:13 via 192.168.200.3
> Oct 27 11:46:10 ernie dhcpd: DHCPACK on 192.168.200.130 to
> 00:07:e9:f2:d3:13 via 192.168.200.3
>
> lease 192.168.200.130 {
> starts 5 2006/10/27 10:46:10;
> ends 5 2006/10/27 10:56:10;
> binding state active;
> next binding state free;
> hardware ethernet 00:07:e9:f2:d3:13;
> }
> lease 192.168.200.130 {
> starts 5 2006/10/27 10:46:10;
> ends 5 2006/10/27 10:56:10;
> binding state active;
> next binding state free;
> hardware ethernet 00:07:e9:f2:d3:13;
> }
>
> Windows Boot
> ============
>
> Oct 27 11:47:11 ernie dhcpd: DHCPDISCOVER from 00:07:e9:f2:d3:13 via
> 192.168.200.2
> Oct 27 11:47:12 ernie dhcpd: DHCPOFFER on 192.168.200.65 to
> 00:07:e9:f2:d3:13 (BCUC-6D8215E8EA) via 192.168.200.2
> Oct 27 11:47:12 ernie dhcpd: DHCPREQUEST for 192.168.200.65
> (192.149.238.50) from 00:07:e9:f2:d3:13 (BCUC-6D8215E8EA) via 192.168.200.2
> Oct 27 11:47:12 ernie dhcpd: DHCPACK on 192.168.200.65 to
> 00:07:e9:f2:d3:13 (BCUC-6D8215E8EA) via 192.168.200.2
> Oct 27 11:47:12 ernie dhcpd: DHCPREQUEST for 192.168.200.65
> (192.149.238.50) from 00:07:e9:f2:d3:13 (BCUC-6D8215E8EA) via 192.168.200.3
> Oct 27 11:47:12 ernie dhcpd: DHCPACK on 192.168.200.65 to
> 00:07:e9:f2:d3:13 (BCUC-6D8215E8EA) via 192.168.200.3
>
> lease 192.168.200.65 {
> starts 5 2006/10/27 10:47:12;
> ends 5 2006/10/27 10:57:12;
> binding state active;
> next binding state free;
> hardware ethernet 00:07:e9:f2:d3:13;
> uid "\001\000\007\351\362\323\023";
> client-hostname "BCUC-6D8215E8EA";
> }
> lease 192.168.200.65 {
> starts 5 2006/10/27 10:47:12;
> ends 5 2006/10/27 10:57:12;
> binding state active;
> next binding state free;
> hardware ethernet 00:07:e9:f2:d3:13;
> uid "\001\000\007\351\362\323\023";
> client-hostname "BCUC-6D8215E8EA";
> }
>
Hi,
Just following this one up. It's still happening!
I tried using 'deny duplicates' in the dhcpd.conf, and it seemed to work
for a while, but it's still happening; I think we just had a low number
of PCs switched on!
We're on ZfD 7 SP1, Hotfix 3, with the Hotfix 4 PXE files installed
(Hotfix 4 came out about a week after I installed hotfix 3!).
Anyway, it's still happening and driving me to distraction. Of about
140-something hosts, they're using twice as many leases as they should,
so they're back on 10-minute leases, just to recycle them fast enough.
Anybody have any suggestions?!
David Rickard
ICT Security Officer
[email protected], 01494 522141 Ext: 3531
Information & Communication Technologies
Buckinghamshire Chilterns University College
Queen Alexandra Road, High Wycombe, BUCKS, HP11 2JZ