Re-write the UID as the MAC

Randall C Grimshaw rgrimsha at
Fri Feb 13 14:07:19 UTC 2009

This looks clever, but many people use the actual client identifier - even if only to stop idle RAS allocations from consuming their pools.


-----Original Message-----
From: dhcp-users-bounces at [mailto:dhcp-users-bounces at] On Behalf Of Glenn Satchell
Sent: Thursday, February 12, 2009 8:21 PM
To: dhcp-users at
Subject: Re: Re-write the UID as the MAC

>Date: Thu, 12 Feb 2009 15:59:13 +0000
>To: Users of ISC DHCP <dhcp-users at>
>From: Simon Hobson <dhcp1 at>
>Subject: Re: Re-write the UID as the MAC
>X-BeenThere: dhcp-users at
>Drew Weaver wrote:
>>Is there a reliable way via the configuration file to use the MAC 
>>address as the UID? Since there doesn't appear to be enough support 
>>for having an option to use the MAC as the key. I'm wondering if it 
>>is possible to somehow just rewrite the UID as the MAC address of a 
>No, it's often requested, been on the roadmap, but not implemented yet.
>Simon Hobson

This is from the dhcp-options man page:

     option dhcp-client-identifier string;

       This option can be used to specify a DHCP client  identif-
       ier in a host declaration, so that dhcpd can find the host
       record by matching against the client identifier.

I haven't tried this, but what about setting it, eg:

  option dhcp-client-identifier hardware;

Maybe try it and see?

Glenn Satchell     mailto:glenn.satchell at | It's a dog  eat dog
Uniq Advances Pty Ltd | world, and by golly,
PO Box 70 Paddington NSW Australia 2021              | we better make sure
tel:0409-458-580  tel:02-9380-6360  fax:02-9380-6416 | we're the dog.

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