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

David W. Hankins David_Hankins at
Tue Jan 29 19:50:38 UTC 2008

On Tue, Jan 29, 2008 at 07:07:08PM +0000, Simon Hobson wrote:
> What happened to the proposal to add a config option to control the 
> primary key selection criteria ? Did it make in into any of the 
> current releases, is it still on the 'to do' list, or did it get 
> dropped ?

it got added and dropped two or three times.  it's still on the 'to
do' list.

the current thinking on how to implement this is to provide a way to
over-ride the option value.  this is more generic and may apply more
directly to mixed RFC 4361 environments.  the final code would
ignore an over-ridden option content that was zero length.

> Also, adding the ability to use this value (ie the selected key) as a 
> client selector in host statements would also deal with the "assign 
> address to client by option-82" that comes up fairly regularly.

in the dhcp-4 work, we were trying to figure out how people would want
to describe a host {} statement for a DHCPv6 client.  i'm not sure
we're done with that, but we had to add a way to identify a host
record based upon an arbitrary option contents, so you could get the
MAC address out of a DOCSIS-3.0 vendor class option.

it doesn't currently work for v4, but all that's really necessary is
adding a few lines of code to perform the by-option-contents lookup
somewhere in DHCPv4 message processing.

so that's another, more low hanging fruit, for assignment by option
82 contents (but requires you assign a fixed address for every port
rather than assigning dynamic addresses to switch ports as they come

Ash bugud-gul durbatuluk agh burzum-ishi krimpatul.
Why settle for the lesser evil?
David W. Hankins	"If you don't do it right the first time,
Software Engineer		     you'll just have to do it again."
Internet Systems Consortium, Inc.		-- Jack T. Hankins

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