Cleanup leases?

Simon Hobson dhcp1 at
Tue Sep 26 20:32:21 UTC 2006

B. Cook wrote:

>  >> I have a /25 defined for about 64+ laptops, and for low public usage
>>>  here at the library..
>>>  today I have started to receive the 'no free leases' entry in the logs..
>  >> I am going in and removing leases that ended about 20+ days ago..

If a lease ended 20+ days ago then it should be available for re-use.

>  >> How can I keep this file cleaned up so that people that need leases will
>  >> get them back from people that are no longer using them?

As someone else has already pointed out, this is automatic. The last 
state of a lease (when it changes to free) is kept so that the same 
address can be offered to a client should it return in the future - 
but these addresses ARE available to be offered to another client if 

># Public Network
>subnet netmask {
>default-lease-time 1800;
>max-lease-time 1800;
>option domain-name "public.adriance";
>option domain-name-servers;
>#option domain-name-servers;
>option routers;
>This is what I am using.
>and this is my global section:
># $Id: dhcpd.conf,v 1.89 2006/09/22 15:48:56 root Exp root $
>always-reply-rfc1048 true;
>ddns-update-style none;
>ddns-updates off;
>deny bootp;
>deny declines;
>deny duplicates;
>log-facility local7;
>one-lease-per-client on;
>ping-check true;

You've clipped that a bit too harshly - according to this you don't 
have any ranges to lease so you would get "no free leases" :-)

>I don't understand how I saw leases in there from July.. and Aug.. and

Old leases kept as already mentioned.

Two other thoughts come to mind :

1) Do you have any form of conditional access configured - eg pools 
restricted to known/unknown hosts or specific classes ? If so then I 
would look again at those. If a client is not permitted a lease from 
any pool then you will get "no free leases" even though there are 
plenty available - it's just that there aren't any that the client is 
allowed to use.

2) Are you using failover, and if so, what version server ? I believe 
in some of the older versions there are bugs that can result in 
leases not making the transition to free state - hence the addresses 
never become available to re-lease to another client. This should be 
obvious though, what state are the leases you are/have already 
deleted from the leases file ?

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