BOOTP from dynamic client and no dynamic leases

Bill Moseley moseley at
Thu Nov 8 20:21:42 UTC 2007

On Thu, Nov 08, 2007 at 09:45:49AM -0800, David W. Hankins wrote:
> Long story short, it would be my suggestion to give the bootp client
> (the "old mac") a fixed-address in a matching host {} statement.  You
> can also do dynamic bootp, but it's black magic I personally prefer to
> avoid.


I'm still a little unclear on the syntax of dhcpd.conf -- confused how
class and group work, I guess.

The class {} block applies its settings when the "match" happens,
correct?  So if I can identify clients by, say, the vendor string I
can make settings apply.  Is that correct?

Likewise, I can use group {} to group settings together that are used
on different MAC addresses.

What I'm not clear on is what happens when more than one match.

Could I do:

class {
    match for i386 vendor vendor string
    # common settings for i386

class {
    match on newer mac's vendor string
    # common settings for these macs

group {
    # common settings for these clients

    host ltsp1 { hardware ethernet ... }
    host ltsp2 { hardware ethernet ... }

And maybe also using fixed addresses for those two hosts, as you

Can I mix class and group like that?  What happens if something that matches in the
group (by MAC)  also matches in one of the class blocks?

It's handy to do the dynamic addresses, of course -- plug-n-play would
be nice to not have to know all the MAC addresses ahead of time.


Bill Moseley
moseley at

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