DHCP Server not sending offers!

Fri Jul 18 09:30:28 UTC 2014

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
------------------------------------------------------------
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* chef il faut des hommes!L'habit ne fait pas le moine, mais lorsqu'on te
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