client refuses to accept offer

Randall C Grimshaw rgrimsha at syr.edu
Wed May 12 12:44:28 UTC 2010


Sounds like the network is suppressing your DHCP, possibly using Cisco DHCP-snooping or similar. This would not be surprising in an enterprise environment where DHCP can be very disruptive. Its use should always be coordinated through your central administration.

Randy

-----Original Message-----
From: dhcp-users-bounces+rgrimsha=syr.edu at lists.isc.org [mailto:dhcp-users-bounces+rgrimsha=syr.edu at lists.isc.org] On Behalf Of anctop
Sent: Wednesday, May 12, 2010 3:18 AM
To: Users of ISC DHCP
Subject: Re: client refuses to accept offer

On 12/05/2010, Glenn Satchell <glenn.satchell at uniq.com.au> wrote:
> Looks like you have the interactions with the other dhcp servers sorted
> out ok then.
>
> Can you run wireshark (or similar) on the client to see what it is
> receiving and sending? It may be that the dhcp offer is not making it to
> the client, or perhaps a dhcp option is missing in the offer? Similarly

On the client side, wireshark shows no traffic to/from the dhcp
server. In the "Protocol" column, those "DHCP" entries have only
"0.0.0.0" as source and "255.255.255.255" as destination.
It appears that the offers from the server cannot reach the client.

> a packet trace on the server to look at the contents of the packets
> (tcpdump, wireshark, snoop, etc).

On the server side, I invoke "tcpdump | grep -i 'dhcp'" for a while, getting :

| tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
| listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
| 15:07:53.503779 IP xxx.bootps > 255.255.255.255.bootpc: BOOTP/DHCP,
Reply, length 300
| 15:07:55.775134 IP xxx.bootps > 255.255.255.255.bootpc: BOOTP/DHCP,
Reply, length 300
| 15:07:56.046481 IP xxx.bootps > 255.255.255.255.bootpc: BOOTP/DHCP,
Reply, length 300
| 15:08:05.127992 IP xxx.bootps > 147.8.108.99.bootpc: BOOTP/DHCP,
Reply, length 300
| 15:08:09.117579 IP xxx.bootps > 147.8.108.99.bootpc: BOOTP/DHCP,
Reply, length 300
| 15:08:17.117256 IP xxx.bootps > 147.8.108.99.bootpc: BOOTP/DHCP,
Reply, length 300

Any conclusion ?

Regards,
anctop


> regards,
> -glenn
>
> On 05/12/10 13:38, anctop wrote:
>> On 12/05/2010, Glenn Satchell<glenn.satchell at uniq.com.au>  wrote:
>>> Have you tried uncommenting authoritative?
>>
>> Yes, but no help.
>>
>>> Be careful if all these dhcp servers operate on the same subnet. The
>>> client may be getting responses from more than just your dhcp server.
>>
>> As far as I know, the other servers reject "unknown" hosts, and my
>> test client is "unknown" to them.
>>
>>> The client may also be sending a dhcpdecline, which you're ignoring.
>>
>> I've tried commenting out "deny declines;", but no help.
>>
>> Regards,
>> anctop
>>
>>
>>> regards,
>>> -glenn
>>>
>>> On 05/12/10 13:13, anctop wrote:
>>>> I'm new to DHCP. My system is Linux 2.6.30.2, connected to a network
>>>> which already has some DHCP server(s) running.
>>>> I have a few static IP addresses in hand which I'm allowed to use, and
>>>> I want to create my own DHCP server.
>>>> I've built and installed dhcp-4.1.1 on my system. As a first step, I
>>>> tried to assign a fixed address for a particular computer. My
>>>> dhcpd.conf is :
>>>>
>>>>> option domain-name "yyy.zzz";
>>>>> option domain-name-servers 147.8.2.2;
>>>>>
>>>>> default-lease-time 3600;
>>>>> max-lease-time 14400;
>>>>>
>>>>> deny unknown-clients;
>>>>> deny bootp;
>>>>> deny declines;
>>>>> deny client-updates;
>>>>> deny leasequery;
>>>>>
>>>>> # authoritative;
>>>>>
>>>>> boot-unknown-clients false;
>>>>>
>>>>> log-facility local1;
>>>>>
>>>>> subnet 147.8.108.0 netmask 255.255.255.0 {
>>>>> }
>>>>>
>>>>> host x099 {
>>>>>     hardware ethernet 00:0C:F1:D1:16:78;
>>>>>     fixed-address 147.8.108.99;
>>>>>     option host-name "x099";
>>>>>     option routers 147.8.96.1;
>>>>>     option subnet-mask 255.255.255.0;
>>>>> }
>>>>
>>>> I start the server on the foreground (dhcpd -4 -d), then connect the
>>>> client (running WinXP SP3) to the network. There're many console
>>>> messages, here are the relevant ones :
>>>>
>>>>> May 12 10:16:27 xxx dhcpd: Internet Systems Consortium DHCP Server
>>>>> 4.1.1
>>>>> May 12 10:16:27 xxx dhcpd: Copyright 2004-2010 Internet Systems
>>>>> Consortium.
>>>>> May 12 10:16:27 xxx dhcpd: All rights reserved.
>>>>> May 12 10:16:27 xxx dhcpd: For info, please visit
>>>>> https://www.isc.org/software/dhcp/
>>>>> May 12 10:16:27 xxx dhcpd: Wrote 0 deleted host decls to leases file.
>>>>> May 12 10:16:27 xxx dhcpd: Wrote 0 new dynamic host decls to leases
>>>>> file.
>>>>> May 12 10:16:27 xxx dhcpd: Wrote 0 leases to leases file.
>>>>> May 12 10:16:27 xxx dhcpd: Listening on
>>>>> LPF/eth0/00:11:2f:53:aa:49/147.8.108.0/24
>>>>> May 12 10:16:27 xxx dhcpd: Sending on
>>>>> LPF/eth0/00:11:2f:53:aa:49/147.8.108.0/24
>>>>> May 12 10:16:27 xxx dhcpd: Sending on   Socket/fallback/fallback-net
>>>>> May 12 10:16:32 xxx dhcpd: DHCPDISCOVER from 00:0c:f1:d1:16:78 via eth0
>>>>> May 12 10:16:32 xxx dhcpd: DHCPOFFER on 147.8.108.99 to
>>>>> 00:0c:f1:d1:16:78
>>>>> via eth0
>>>>> May 12 10:16:35 xxx dhcpd: DHCPDISCOVER from 00:0c:f1:d1:16:78 via eth0
>>>>> May 12 10:16:35 xxx dhcpd: DHCPOFFER on 147.8.108.99 to
>>>>> 00:0c:f1:d1:16:78
>>>>> via eth0
>>>>> May 12 10:16:44 xxx dhcpd: DHCPDISCOVER from 00:0c:f1:d1:16:78 via eth0
>>>>> May 12 10:16:44 xxx dhcpd: DHCPOFFER on 147.8.108.99 to
>>>>> 00:0c:f1:d1:16:78
>>>>> via eth0
>>>>
>>>> It appears that the client does not accept the DHCPOFFER and asks for
>>>> one repeatedly until it gives up. The same problem for other "host"
>>>> declarations.
>>>>
>>>> How can this be fixed ?
>>>>
>>>> Regards,
>>>> anctop
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