Lost network connection

[Mouglou]

Hi everybody,

I've a problem with my dhcp server.
It runs on CentOS 5.6.
This is the dhcpd.conf file:

authoritative;
ddns-update-style none;
deny declines;
deny bootp;

option domain-name "mydomain.domain";
option domain-name-servers IP;
option routers IP;
option time-offset -18000;
#option ntp-servers IP;

subnet IP netmask MASK {

range IP START IP END ;
default-lease-time 86400;
max-lease-time 172800;
}

I've some computers which runing Windows who lost network connection for many seconds when the lease end.
I don't know why and how to resolve this problem?

Somebody have an idea?

Thanks
Mouglou

[Lazydog]

Nothing jumps out as being wrong.
What do the log files on the windows systems say?
What do the DHCP server logs say?

[Mouglou]

Hi Robert,

On windows computers, the log says:
"Dchp" error with id 1003, and the specifications is: The semaphore timeout period has expired

On my dhcp server, i've this:

Jun 14 09:45:11 bsi-fw dhcpd: DHCPREQUEST for IP from 00:23:ae:8a:b9:f4 (computer-name) via eth2
Jun 14 09:45:11 bsi-fw dhcpd: DHCPACK on IP to 00:23:ae:8a:b9:f4 (computer-name) via eth2

And I've this informations which is write fifteen just for today...

Thanks for your help!

[Mouglou]

Do you have an idea with these informations?

Mouglou

[Lazydog]

Not sure I have not seen this before. Not sure why you have deny in your dhcp config file. I don't use them here you might want to remove them.

[Mouglou]

I have this deny for this reasons:

deny declines:
The DHCPDECLINE message can be sent by a DHCP client to indicate that it does not consider the lease
offered by the server to be valid. By issuing many DHCPDECLINE messages, a malicious client can exhaust the
DHCP server’s pool of IP addresses, causing the DHCP server to forget old address allocations

deny bootp:
The bootp option tells dhcpd to respond to BOOTP queries. If support for this simpler protocol is not needed,
it should be disabled to remove attack vectors against the DHCP server.

You think it can come from here?
Cause my problem still here... And I don't know what to do...

Mouglou

[Lazydog]

Give it a go, whats the most that could happen?

[Mouglou]

I don't know exactly but it's prevention

I will try without these settings

[Lazydog]

This is the point. You should understand everything you do in your configuration file so that when problem arise you would have a good idea what might be causing the problem. What works for someone on the internet might not work for you and to just blindly follow their setup isn't the best of ideas.

A prefect example is the thread in the coffee lounge about having fun with your system. Those are examples of not knowing what they do and simply trying them out will hurt your system.