dhcp migration issues

Thu Sep 3 15:52:44 UTC 2009

Shawn Holland wrote:
> On Thu, 2009-09-03 at 08:31 -0500, Terry L. Inzauro wrote:
>> List,
>>
>> I've recently migrated off a DHCP appliance to ISC DHCPD and for the most part, there were no issues.  It has been a week
>> since the migration and now I'm seeing some messages like this.
>>
>>
>>
>> 2009-09-03T08:22:00-05:00 <local7.err> dhcpd.server.local dhcpd: Reclaiming abandoned lease 60.164.174.176.
>>
>> 2009-09-03T08:22:00-05:00 <local7.info> dhcpd.server.local dhcpd: DHCPDISCOVER from 00:04:5a:6e:02:86 via 60.164.174.163
>>
>> 2009-09-03T08:22:00-05:00 <local7.info> dhcpd.server.local dhcpd: DHCPOFFER on 60.164.174.176 to 00:04:5a:6e:02:86 via
>> 60.164.174.163
>>
>> 2009-09-03T08:22:00-05:00 <local7.info> dhcpd.server.local dhcpd: DHCPREQUEST for 60.164.174.176 (172.16.1.2)from
>> 00:04:5a:6e:02:86 via 60.164.174.163
>>
>> 2009-09-03T08:22:00-05:00 <local7.info> dhcpd.server.local dhcpd: DHCPACK on 60.164.174.176 to 00:04:5a:6e:02:86 via
>> 60.164.174.163
>>
>> 2009-09-03T08:22:02-05:00 <local7.err> dhcpd.server.local dhcpd: Abandoning IP address 60.164.174.176: declined.
>>
>> 2009-09-03T08:22:02-05:00 <local7.info> dhcpd.server.local dhcpd: DHCPDECLINE of 60.160.174.176 from 00:04:5a:6e:02:86 via
>> 60.160.174.163: not found
>>
>>
>> furthermore, my leases files is riddled with this garbage:
>> grep 60.164.174.173 /var/lib/dhcp3/dhcpd.leases | wc -l
>>
>>
>> lease 60.164.174.176 {
>>   starts 4 2009/09/03 12:52:03;
>>   ends 6 2009/10/03 22:52:03;
>>   cltt 4 2009/09/03 12:52:03;
>>   binding state active;
>>   next binding state free;
>>   hardware ethernet 00:04:5a:6e:02:86;
>>   uid "\001\000\004Zn\002\206";
>> }
>> lease 60.164.174.176 {
>>   starts 4 2009/09/03 12:52:03;
>>   ends 4 2009/09/03 12:52:05;
>>   tstp 4 2009/09/03 12:52:05;
>>   cltt 4 2009/09/03 12:52:03;
>>   binding state abandoned;
>>   next binding state free;
>> }
>>
>>
>> Now, if I were a gambling man, I'd say there are clients that still have leases from the previous dhcp server, but the new
>> DHCP server doesn't know anything about them and tries to assign an address thats currently in use.  I've tried pinging the
>> addresses to no avail(clients may be firewalled) and the router that connects them can't send an arping.
>>
>> Where/How do I begin resolving this issue?
>>
> 
> I don't know much about abandoned leases, but I'm sure you'll get a lot
> of responses..
> 
> But you can try to arping the addresses if you are on the same network.
> It works like ping but uses an arp packet, this will work even if the
> end user has a firewall.
> 

The host is not on the same physical net and my routers do not forward arps.

Note: Other clients on this network/vlan are working fine.

The client (00:04:5a:6e:02:86) is connected via relay-agent.  I noticed there were three IP's that correspond to the MAC of
00:04:5a:6e:02:86 on the routers interface that is connected to that particular vlan.  After removing the MAC entries on the
routers interface, the errors went away and the 3 IP's that were once listed as 'abandoned' disappeared from dhcpd.leases
(they must have got reused as per the man page).

Currently this is happening:
either the client never receives the DHCPOFFER or the client is silently disregarding the DHCPOFFER as the following entries
are repeating.

tcpdump:

2009-09-03T10:43:41-05:00 <local7.info> dhcpd.server.local dhcpd: DHCPDISCOVER from 00:04:5a:6e:02:86 via 60.1
64.174.163
2009-09-03T10:43:41-05:00 <local7.info> dhcpd.server.local dhcpd: DHCPOFFER on 05.164.174.176 to 00:04:5a:6e:0
2:86 via 05.164.174.163

dhcpdump of the packets:

---------------------------------------------------------------------------

  TIME: 2009-09-03 10:45:29.596
    IP: 172.16.1.6 (0:c:db:e1:3b:0) > 172.16.1.2 (0:16:3e:5d:e9:1e)
    OP: 1 (BOOTPREQUEST)
 HTYPE: 1 (Ethernet)
  HLEN: 6
  HOPS: 1
   XID: 0000566d
  SECS: 0
 FLAGS: 0
CIADDR: 0.0.0.0
YIADDR: 0.0.0.0
SIADDR: 0.0.0.0
GIADDR: 60.164.174.163
CHADDR: 00:04:5a:6e:02:86:00:00:00:00:00:00:00:00:00:00
 SNAME: .
 FNAME: .
OPTION:  53 (  1) DHCP message type         1 (DHCPDISCOVER)
OPTION:  61 (  7) Client-identifier         01:00:04:5a:6e:02:86
OPTION:  55 (  6) Parameter Request List      1 (Subnet mask)
                                              3 (Routers)
                                              6 (DNS server)
                                             15 (Domainname)
                                             28 (Broadcast address)
                                             54 (Server identifier)

---------------------------------------------------------------------------
  TIME: 2009-09-03 10:45:29.596
    IP: 172.16.1.2 (0:16:3e:5d:e9:1e) > 60.164.174.163 (0:b:cd:d4:65:ae)
    OP: 2 (BOOTPREPLY)
 HTYPE: 1 (Ethernet)
  HLEN: 6
  HOPS: 1
   XID: 0000566d
  SECS: 0
 FLAGS: 0
CIADDR: 0.0.0.0
YIADDR: 60.164.174.176
SIADDR: 0.0.0.0
GIADDR: 60.164.174.163
CHADDR: 00:04:5a:6e:02:86:00:00:00:00:00:00:00:00:00:00
 SNAME: .
 FNAME: .
OPTION:  53 (  1) DHCP message type         2 (DHCPOFFER)
OPTION:  54 (  4) Server identifier         172.16.1.2
OPTION:  51 (  4) IP address leasetime      2628000 (4w2d10h)
OPTION:   1 (  4) Subnet mask               255.255.255.224
OPTION:   3 (  4) Routers                   60.164.174.161
OPTION:   6 (  8) DNS server                62.22.208.249,62.22.208.250
---------------------------------------------------------------------------