DHCP Server not sending offers!
Daniel Hoffmann
daniel.hoffmann at kabelsat-bergen.de
Fri Jul 18 11:08:59 UTC 2014
Yes, Eugène,
depending on your system environment, you can find in the system log
files (e.g. /var/log/messages), if your dhcpd server sends some offers.
I was a little bit confused about these two lines from your tcpdump output:
*DHCP:DISCOVER*
*RQ:10.242.40.18
*After a DISCOVER, you should see an OFFER, after a request, there
should be an ACK or NAK. Some months ago, I saw an implementation with
an older software release, there clients did not get any ACK'S anymore...
I'm sure, that you can find the reason within the logs, or NAK's.
Best regards,
Daniel
Am 18.07.2014 12:29, schrieb Eugène Ngontang:
> @Daniel, do think it's possible to see missing offers log messages?
> And how can I get them? Thanks.
>
> Eugène NG
>
>
> 2014-07-18 12:25 GMT+02:00 Eugène Ngontang <sympavali at gmail.com
> <mailto:sympavali at gmail.com>>:
>
> Yes, the dhcp server is in the same sunet as clients. If it was in
> the same subnet the clients could normaly nerver communicate and
> get IP addresses from the server.
>
> In the server log file I just see discovers and request from
> client. I can't see anything about the missing offers.
>
> Note that again that the first discovers when the server just
> starts get an offer, and at a certain time, the discovers don't
> get disciver anymore. And when I restart the dhcpd service, it
> start sending offers again.
>
> The above means sometime the server curls, but I don't and can't
> know while.
>
> Thank you.
>
> Regards,
> Eugène NG
>
>
> 2014-07-18 12:08 GMT+02:00 Daniel Hoffmann
> <daniel.hoffmann at kabelsat-bergen.de
> <mailto:daniel.hoffmann at kabelsat-bergen.de>>:
>
> Greetings Eugène,
>
> is the dhcp server within the same ip subnet like the clients
> ? What does the dhcp server log file tell you about the
> missing offers ?
>
> Best regards,
> Daniel
>
> Am 18.07.2014 11:30, schrieb Eugène Ngontang:
>> Hi have got an issue with my DHCP server that I can not
>> locate the origin.
>>
>> In fact I have a group of linux hosts with a dhcp server on
>> which I made a reservation, configured to assign IP addresses
>> to hosts staticaly (fixed address), with lease time of 6 hours.
>>
>> The problem is that at least one time per day, all hosts stop
>> getting addresses from the server, while the dhcpd daemon is
>> still running.
>>
>> I have check, and noticed that the hosts do not longer
>> receive DHCPOFFERs from the server, when they send a
>> DHCHPDISCOVER.
>>
>> With tcpdump on the server I can see request from clients,
>> and the server just ignores them. I've try cleaning the dchpd
>> leases file, but it doesn't fix the issue, but when I restart
>> the service, all things turn fine.
>>
>> What I would like to, is know what can the server be doing at
>> this special time when a client want its IP address to be
>> released? I've searched in several forums, and nobody seems
>> to be able to answer me, since it seems to be a programming
>> issue.
>>
>> How can I get a technical documentation of dhcpd? Is it
>> possible to understand when and why a server can ignore
>> DHCPREQUEST?
>>
>> Do someone here has already got this issue?
>>
>> What I've done temporarely, is to set a crontab to restart
>> the dhc service each day at 6:03, 12:03, and 18:03.
>>
>> Here is an extract of tcpdump on the server :
>>
>> *tcpdump: listening on eth0, link-type EN10MB (Ethernet),
>> capture size 1500 bytes*
>> *2014-05-04 12:56:07.419712 00:01:80:7d:db:14 > Broadcast,
>> ethertype IPv4 (0x0800), length 346: (tos 0x0, ttl 128, id 0,
>> offse*
>> *t 0, flags [none], proto: UDP (17), length: 328)
>> 0.0.0.0.bootpc > 255.255.255.255.bootps: [udp sum ok]
>> BOOTP/DHCP, Request fr*
>> *om 00:01:80:7d:db:14, length: 300, xid:0xc768345, secs:3,
>> flags: [none] (0x0000)*
>> * Client Ethernet Address: 00:01:80:7d:db:14*
>> * Vendor-rfc1048:*
>> * DHCP:DISCOVER*
>> * RQ:10.242.40.18*
>> * HN:"FR-LYS-LX004"*
>> *PR:SM+BR+TZ+T121+DN+NS+HN+YD+YS+NTP+MTU+T119+DG*
>> * 0x0000: 4500 0148 0000 0000 8011 39a6 0000 0000*
>> * 0x0010: ffff ffff 0044 0043 0134 f634 0101 0600*
>> * 0x0020: 0c76 8345 0003 0000 0000 0000 0000 0000*
>> * 0x0030: 0000 0000 0000 0000 0001 807d db14 0000*
>> * 0x0040: 0000 0000 0000 0000 0000 0000 0000 0000*
>> * 0x0050: 0000 0000 0000 0000 0000 0000 0000 0000*
>> * 0x0060: 0000 0000 0000 0000 0000 0000 0000 0000*
>> * 0x0070: 0000 0000 0000 0000 0000 0000 0000 0000*
>> * 0x0080: 0000 0000 0000 0000 0000 0000 0000 0000*
>> * 0x0090: 0000 0000 0000 0000 0000 0000 0000 0000*
>> * 0x00a0: 0000 0000 0000 0000 0000 0000 0000 0000*
>> * 0x00b0: 0000 0000 0000 0000 0000 0000 0000 0000*
>> * 0x00c0: 0000 0000 0000 0000 0000 0000 0000 0000*
>> * 0x00d0: 0000 0000 0000 0000 0000 0000 0000 0000*
>> * 0x00e0: 0000 0000 0000 0000 0000 0000 0000 0000*
>> * 0x00f0: 0000 0000 0000 0000 0000 0000 0000 0000*
>> * 0x0100: 0000 0000 0000 0000 6382 5363 3501 0132*
>> * 0x0110: 040a f228 120c 0c46 522d 4c59 532d 4c58*
>> * 0x0120: 3030 3437 0d01 1c02 790f 060c 2829 2a1a*
>> * 0x0130: 7703 ff00 0000 0000 0000 0000 0000 0000*
>> * 0x0140: 0000 0000 0000 0000 9c57 4f09*
>>
>> I have pasted here above the dump just for one host, the rest
>> is the same and only the MAC address differs.
>>
>> Below is an extract of a client system log file :
>>
>> * Apr 30 03:04:47 00-01-80-7e-38-fd dhclient[653]:
>> DHCPDISCOVER on eth0*
>> *to 255.255.255.255 port 67 interval 6 (xid=0x1e903fe)*
>> *Apr 30 03:04:53 00-01-80-7e-38-fd dhclient[653]:
>> DHCPDISCOVER on eth0*
>> *to 255.255.255.255 port 67 interval 8 (xid=0x1e903fe)*
>> *Apr 30 03:05:01 00-01-80-7e-38-fd dhclient[653]:
>> DHCPDISCOVER on eth0*
>> *to 255.255.255.255 port 67 interval 10 (xid=0x1e903fe)*
>> *Apr 30 03:05:11 00-01-80-7e-38-fd dhclient[653]:
>> DHCPDISCOVER on eth0*
>> *to 255.255.255.255 port 67 interval 16 (xid=0x1e903fe)*
>> *Apr 30 03:05:27 00-01-80-7e-38-fd dhclient[653]:
>> DHCPDISCOVER on eth0*
>> *to 255.255.255.255 port 67 interval 18 (xid=0x1e903fe)*
>> *Apr 30 03:05:45 00-01-80-7e-38-fd dhclient[653]:
>> DHCPDISCOVER on eth0*
>> *to 255.255.255.255 port 67 interval 3 (xid=0x1e903fe)*
>> *Apr 30 03:05:48 00-01-80-7e-38-fd dhclient[653]: No
>> DHCPOFFERS received.*
>> *Apr 30 03:05:48 00-01-80-7e-38-fd dhclient[653]: No working
>> leases in*
>> *persistent database - sleeping.*
>>
>>
>> Please can you help to idendify where the problem comes from?
>>
>> I thank you so much for your attention.
>>
>> Best regards,
>> Eugène NG
>> --
>> ngonta_e at epitech.net <mailto:ngonta_e at epitech.net>
>> sympavali at gmail.com <mailto:sympavali at gmail.com>
>> ------------------------------------------------------------
>> /*Aux hommes il faut un chef, et au*//* chef il faut des hommes!
>> L'habit ne fait pas le moine, mais lorsqu'on te voit on te juge!
>> */
>>
>>
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>
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> ngonta_e at epitech.net <mailto:ngonta_e at epitech.net>
> sympavali at gmail.com <mailto:sympavali at gmail.com>
> ------------------------------------------------------------
> /*Aux hommes il faut un chef, et au*//* chef il faut des hommes!
> L'habit ne fait pas le moine, mais lorsqu'on te voit on te juge!
> */
>
>
>
>
> --
> ngonta_e at epitech.net <mailto:ngonta_e at epitech.net>
> sympavali at gmail.com <mailto:sympavali at gmail.com>
> ------------------------------------------------------------
> /*Aux hommes il faut un chef, et au*//* chef il faut des hommes!
> L'habit ne fait pas le moine, mais lorsqu'on te voit on te juge!
> */
>
>
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--
Kabel + Satellit Bergen
Kommunikationstechnik GmbH
Tilzower Weg 32
18528 Bergen auf Rügen
Telefon: 038 38 - 25 04 80
Fax: 038 38 - 20 91 36
Geschäftsführer: Hans-Peter Malze , Rolf Hoffmann
HRB 7582 Stralsund
Finanzamt Stralsund
St.-Nr. 082 / 112 / 01461
USt. ID: DE 134877127
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