Unknown client alerts and clients not getting IP addresses

Simon Hobson dhcp1 at thehobsons.co.uk
Tue Aug 23 07:29:22 UTC 2016

"Fleming, Tony" <t.fleming at tcu.edu> wrote:

> Background:
>                 We create a host record for each device that connects to our network
>                 Over the years our dhcpd.conf file has grown due to little purging (yeah – I know we should be purging the data)
> Symptom:
>                 Suddenly today, we began getting reports users are unable to get an IP address.
>                 The clients vary from iphones, to OS X and PC laptops
>                                 The issue doesn’t seem to be OS or hardware dependent
>                 My logs are alerting:
>                                 dhcpd: DHCPDISCOVER FROM xx:xx:xx:xx:xx:xx via x.x.x.x: uknown client
> In my dhcpd file there is a “host” record for each device – so I am scratching my head to why the device isn’t getting an IP address.
>                 Not all devices are having trouble getting IP leases
> Workaround:
>                 We have removed the directive in dhcpd.conf to “deny unknown clients”
>                 Now all of our devices are getting IP addresses.

Post your config - not all of it ;-)
But when you trim it, be very very careful that you don't alter the structure at all.
Include a problem client - both it's config and the log entries for it.

More information about the dhcp-users mailing list