force to only accept hardware address as dhcp-client-identifier

John Hascall john at
Tue Jan 29 15:50:03 UTC 2008

Unless they have recently changed their minds,
despite numerous requests, ISC refuses to add such
an option because it is contrary to the RFC standards
documents.  However, this comes up on the list every
few months, so if you are not afraid to get your hands
a little dirty and modify the code yuorself, if you
look back through the list archives, you can find several
patches to do this.

We have been running our dhcpd like this for years.


> Hello,
> the isc dhcp server identifies dhcp clients by the
> dhcp-client-identifier they send. this can be different
> for each client depending on the dhcp-client config:
> - host-name
> - vendor-code
> - some string
> - ...
> - hw-address
> if no dhcp-client-identifier is sent by the client, the server uses the
> hardware address as identifier.
> we have the problem, that we are serving thousands of clients, and
> different clients with coincidently the same hostname could be
> configurated to send their hostname as identifier. So we get the
> duplicate-hostname-problem and we cannot force all users to configurate
> their dhcp-clients in a certain (some users don't even know which
> dhcp-client they are using)
> is there a way to force/configure the dhcp-server, so that it only
> chooses hardware address of the client as valid identifier no matter
> what other dhcp-client-identifier the client is sending?
> thanks and best regards
> tarik gasmi

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