DHCP Server Offline.

Ean Kingston ean at hedron.org
Fri Jul 15 14:17:58 GMT 2005

On July 15, 2005 10:11 am, Stephan Weaver wrote:
> Hello folks,
> I have a Stand Alone FreeBSD Firewall / Nat / Dhcp Server.
> Everything seems to work fine, up until this morning.
> Users seem to complain they could not get on the network anymore.
> Further investigation revealed the dhcp server could not be contacted.
> Further more, only some of the users were online.
> I am guessing that these clients who were online had an ip address from the
> dhcp server at a previous time and the lease didnt expire as yet.
> And users who were not online, the lease expired and attempted to contact
> the dhcp server and failed.
> I Would appreciate any help or suggestions.

Set the lease expire time to at least 5 days (7 to 10 is better) and the 
renewal time to between 4 and 12 hours.

Then setup a dhcp monitoring process that will alert you if it fails to get an 
address or renewal.

Make sure you have more addresses available than you ever expect to give out. 
I go with 50% more. I've known some admins that want at least double.

> Like what to do in the future incase this happens again.

Setup 2 dhcp servers on the network. If one fails, the other will hopefully 
continue to serve addresses. Monitor this one as well.

> I Would like to find out what had happened.

Start reading logs. 

> The last thing that i had done to the server was setup, configure and
> install 'ntop';
> dont know if this would cause a problem.
> Thank you in advance.
> Stephan Weaver
> P.S. Please reply to my Directly at @
> stephanweaver at hotmail.com

Ean Kingston

E-Mail: ean AT hedron DOT org
URL: http://www.hedron.org/
I am currently looking for work. If you need competent system/network 
administration please feel free to contact me directly.

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