Leases based on MAC addresses

Randall C Grimshaw rgrimsha at
Sun Feb 8 20:44:16 UTC 2009

If a client always gets the same IP based on MAC address... that is a static lease. You must reserve the IP address for that system or you risk duplicates... so it can no longer be part of a dynamic pool. What you are looking for is a registration system that builds a configuration file. Minimally it sounds like you want something to scan your leases and update your configuration as dynamic addresses transition to static.

From: dhcp-users-bounces at [dhcp-users-bounces at] On Behalf Of Elliot Finley [lists at]
Sent: Sunday, February 08, 2009 1:52 PM
To: Glenn Satchell; Users of ISC DHCP
Subject: Re: Leases based on MAC addresses

Glenn Satchell wrote:
>> is there any way in the newest version of ISC-DHCP to have MAC based
>> leases rather than UID based leases?
>> If not, is there anyone willing to code this into the official release
>> for $$$?
>> If not, can anyone point me to the right place in the code to hack this
>> in myself?
> It's already there and has been for many years. Use a host statement
> with a hardware ethernet statement to match against, eg in the
> minimalist form:
> host host_label {
>       hardware ethernet aa:bb:cc:dd:ee:ff;
>       fixed-address;
> }
> The host statement will automatically pick up options, such as
> routers, from the corresponding subnet declaration.

      I'm talking about dynamic leases here.  I have customers that will
get a different IP when they update their systems because their UID will
change.  If the leases were based on their MAC instead, then their IP
would remain the same.

      So the question still remains:  How to have dynamic leases based
on MAC addresses?

Any takers?

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