No Free Addresses?

Bob Proulx bob at
Mon Dec 13 21:24:53 UTC 2010

My Question: How can I tell why the dhcpd daemon ran out of free
addresses?  Is there a tool that I can use to scan the dhcpd.leases
file and have it report the status of each IP?  There are a lot of
addresses and tracing the file manually is quite tedious.

Here is what happened today: The environment is a school with about
150 or so devices of all sorts.  Some time ago I set up a failover
dhcpd configuration (with some help from the list concerning putting
iPads on their own subnet, thanks to all) and it has been working

Today one of the pair of dhcpd servers died with a hardware problem
leaving the single remaining server for everything.  Things continued
to work fine.  I was very happy with the failover system.  It all
worked great and prevented this from being an emergency.

But after a short time I started to see this in the logs along with
devices not being able to obtain a new IP address.  Devices with an
existing lease were renewing okay.

  Dec 13 12:29:24 ns1 dhcpd: DHCPDISCOVER from 00:26:82:bb:21:c8 via eth0: peer holds all free leases

Obviously the pool wasn't big enough.  I reconfigured things and added
a second pool with 256 addresses and that got things going.  But I
think the pool *should* have been big enough already.  By my count of
active machines I should still have 120 free addresses even with the
half size pool available to the single failed-over server.  With both
up there should be 250 free addresses.  Something is consuming IPs.
Where did they go?


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