DHCP Server not sending offers!

Fri Jul 18 10:29:49 UTC 2014

@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>:

> 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>:
>
>  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
>> 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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>
>
>
> --
> ngonta_e at epitech.net
> 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
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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