How can I configure a DHCP server to assign addresses based on the OS that is running

Simon Hobson dhcp1 at
Fri May 21 22:25:36 UTC 2010

Marc Chamberlin wrote:

>If indeed the dhcpd server is this restrictive about what is allowed 
>when assigning fixed addresses, within host declarations, then IMHO 
>it is a serious oversight on the designers part! Thoughts, ideas?

You could try bottom posting, or at least trimming what you quote - 
just a suggestion ...

You have to realise how long ago these decisions were made, and at 
the time this was more than enough for almost all users - it was 
certainly a big step up from the likes of BOOTP which was still 
common back then. As with many things, there's an element of "we 
wouldn't start from here" but people never the way things would turn 
out more than a decade later.

There are a couple of things that come to mind.

1) The latest versions now support reserved leases - you have to edit 
the leases file, but once set, a lease is permanently tied to a 
client. This gives you a fixed address but all the stuff that goes 
with a normal lease lifecycle. It gets round the issues with host 
statements and fixed addresses bypassing this.
If you want to manually assign addresses, it's possible to add a 
skeleton reserved lease in advance of adding a device to the network, 
and it will pick up the assigned address.

2) It's been talked about, but IIRC not implemented, to allow the 
admin to override the primary key selection. Ie, you could override 
the default of "pick first value (client-id, hardware)". You could 
probably cook something up to include the vendor class were this in 
AFAIK, it's still in the "would like to do - anyone want to sponsor 
it" category.

Simon Hobson

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