dhcpd "forgets" leases that it offered

Mon Sep 24 12:29:26 UTC 2012

Hello list

first of all thanks for the recent tips you gave us to fix our dhcp
patch. We did as people on the list said and the server does not crash
anymore. Seems that we did not check for zero-pointers in the patch code.
But now we still have the problem that the server seems to "forget"
leases it just offered. The strange thing is that this seems to happen
only to units made by a certain manufactor. We checked the logs a lot
but could only see this problem with MAC addresses from Landis+Gyr.
The first problem is that the server ACKs to an IP (@02:49:31) but when
the client tries to relase this lease the server say "lease not found"
(@02:53:57)
The other problem is that the server ACKs to IPs that were NOT requested
by the client. @08:22:58 the clients requests for 100.100.171.204 but
the servers ACKs for 100.100.175.167

Again only one manufactor seems to have this problems. We have no
influence on the devices from this manufactor, we have to take them as
they are.
Would it be possible that a "bad" dhcp implementation on those clients
could lead to such problems with the server?

Thanks for any ideas

tobi

Lease time = 86400 (1 day)
Problem #1:
Sometimes the server doesn't know the lease any more (e.g. 4 minutes in 
this example see Sep 24 02:49:31 & Sep 24 02:53:57).

Problem #2:
Gives ACKs to not requested IPs (Sep 24 08:22:58)

Both problems happen only on certain clients where mac starts with 
00:0f:93 (Landis+Gyr).

root at dhcp1:~# zcat /var/log/dhcpd/dhcpd.log-20120924.gz | grep 
"00:0f:93:00:12:94"
Sep 23 08:20:32 dhcp1 dhcpd: DHCPDISCOVER from 00:0f:93:00:12:94 via 
172.24.0.1
Sep 23 08:20:33 dhcp1 dhcpd: DHCPOFFER on 100.100.169.106 to 
00:0f:93:00:12:94 via 172.24.0.1
Sep 23 08:20:33 dhcp1 dhcpd: DHCPREQUEST for 100.100.169.106 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1
Sep 23 08:20:33 dhcp1 dhcpd: DHCPACK on 100.100.169.106 to 
00:0f:93:00:12:94 via 172.24.0.1
Sep 23 21:59:16 dhcp1 dhcpd: DHCPDISCOVER from 00:0f:93:00:12:94 via 
172.24.0.1
Sep 23 21:59:17 dhcp1 dhcpd: DHCPOFFER on 100.100.169.106 to 
00:0f:93:00:12:94 via 172.24.0.1
Sep 23 21:59:17 dhcp1 dhcpd: DHCPREQUEST for 100.100.169.106 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1
Sep 23 21:59:17 dhcp1 dhcpd: DHCPACK on 100.100.169.106 to 
00:0f:93:00:12:94 via 172.24.0.1
Sep 24 02:49:30 dhcp1 dhcpd: DHCPDISCOVER from 00:0f:93:00:12:94 via 
172.24.0.1
Sep 24 02:49:31 dhcp1 dhcpd: DHCPOFFER on 100.100.169.106 to 
00:0f:93:00:12:94 via 172.24.0.1
Sep 24 02:49:31 dhcp1 dhcpd: DHCPREQUEST for 100.100.169.106 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1
*Sep 24 02:49:31 dhcp1 dhcpd: DHCPACK on 100.100.169.106 to 
00:0f:93:00:12:94 via 172.24.0.1*
Sep 24 02:53:37 dhcp1 dhcpd: DHCPDISCOVER from 00:0f:93:00:12:94 via 
172.24.0.1
Sep 24 02:53:39 dhcp1 dhcpd: DHCPDISCOVER from 00:0f:93:00:12:94 via 
172.24.0.1
Sep 24 02:53:40 dhcp1 dhcpd: DHCPOFFER on 100.100.175.167 to 
00:0f:93:00:12:94 via 172.24.0.1
Sep 24 02:53:40 dhcp1 dhcpd: DHCPREQUEST for 100.100.175.167 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1: unknown lease 
100.100.175.167.
Sep 24 02:53:41 dhcp1 dhcpd: DHCPREQUEST for 100.100.175.167 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1: unknown lease 
100.100.175.167.
Sep 24 02:53:43 dhcp1 dhcpd: DHCPREQUEST for 100.100.175.167 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1: unknown lease 
100.100.175.167.
Sep 24 02:53:45 dhcp1 dhcpd: DHCPREQUEST for 100.100.175.167 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1: unknown lease 
100.100.175.167.
Sep 24 02:53:49 dhcp1 dhcpd: DHCPREQUEST for 100.100.175.167 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1: unknown lease 
100.100.175.167.
Sep 24 02:53:53 dhcp1 dhcpd: DHCPREQUEST for 100.100.175.167 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1: unknown lease 
100.100.175.167.
*Sep 24 02:53:57 dhcp1 dhcpd: DHCPRELEASE of 100.100.169.106 from 
00:0f:93:00:12:94 via 172.24.0.1 (not found)*
Sep 24 02:53:57 dhcp1 dhcpd: DHCPDISCOVER from 00:0f:93:00:12:94 via 
172.24.0.1
Sep 24 02:53:57 dhcp1 dhcpd: DHCPOFFER on 100.100.175.167 to 
00:0f:93:00:12:94 via 172.24.0.1
Sep 24 02:53:57 dhcp1 dhcpd: DHCPREQUEST for 100.100.175.167 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1
Sep 24 02:53:57 dhcp1 dhcpd: DHCPACK on 100.100.175.167 to 
00:0f:93:00:12:94 via 172.24.0.1

root at dhcp1:~# cat /var/log/dhcpd/dhcpd.log | grep "00:0f:93:00:12:94"
Sep 24 08:18:38 dhcp1 dhcpd: DHCPDISCOVER from 00:0f:93:00:12:94 via 
172.24.0.1
Sep 24 08:18:39 dhcp1 dhcpd: DHCPOFFER on 100.100.175.167 to 
00:0f:93:00:12:94 via 172.24.0.1
Sep 24 08:18:39 dhcp1 dhcpd: DHCPREQUEST for 100.100.175.167 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1
Sep 24 08:18:39 dhcp1 dhcpd: DHCPACK on 100.100.175.167 to 
00:0f:93:00:12:94 via 172.24.0.1
Sep 24 08:22:45 dhcp1 dhcpd: DHCPDISCOVER from 00:0f:93:00:12:94 via 
172.24.0.1
Sep 24 08:22:47 dhcp1 dhcpd: DHCPDISCOVER from 00:0f:93:00:12:94 via 
172.24.0.1
Sep 24 08:22:48 dhcp1 dhcpd: DHCPOFFER on 100.100.171.204 to 
00:0f:93:00:12:94 via 172.24.0.1
Sep 24 08:22:48 dhcp1 dhcpd: DHCPREQUEST for 100.100.171.204 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1: unknown lease 
100.100.171.204.
Sep 24 08:22:49 dhcp1 dhcpd: DHCPREQUEST for 100.100.171.204 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1: unknown lease 
100.100.171.204.
Sep 24 08:22:51 dhcp1 dhcpd: DHCPREQUEST for 100.100.171.204 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1: unknown lease 
100.100.171.204.
Sep 24 08:22:54 dhcp1 dhcpd: DHCPREQUEST for 100.100.171.204 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1: unknown lease 
100.100.171.204.
*Sep 24 08:22:58 dhcp1 dhcpd: DHCPREQUEST for 100.100.171.204 
(100.100.149.70) from 00:0f:93:00:12:94 via 172.24.0.1
Sep 24 08:22:58 dhcp1 dhcpd: DHCPACK on 100.100.175.167 to 
00:0f:93:00:12:94 via 172.24.0.1*

-- 
Freundliche Grüsse

Datapark AG
Tobias Szyndler
Hubstrasse 101
CH-9500 Wil SG

Tel. +41 71 560 60 95
szyndler at datapark.ch <mailto:szyndler at datapark.ch>
www.datapark.ch <http://www.datapark.ch>

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