DHCP "static" assignments

Gregory Sloop gregs at sloop.net
Wed Aug 7 22:01:49 UTC 2013



RR> On Aug 7, 2013, at 2:12 PM, Gregory Sloop wrote:

>> CB> On Aug 7, 2013, at 1:39 PM, Gregory Sloop <gregs at sloop.net> wrote:
>> 
>>>> Here's the effect I want...
>>>> 
>>>> I want the DHCP server to hand out specific IP's to specific MAC
>>>> addresses, [as defined in the host record.]
>>>> 
>>>> They're static DHCP assignments, not static IP clients.
>>>> ---
>>>> i.e. I want 10.0.0.10 to get assigned *via the DHCP server* to the
>>>> host with MAC Address aa:bb:cc:dd:ee:ff
>>>> 
>>>> Also, I'm assigning via DHCP addresses from 10.0.0.1-10.0.0.20 to
>>>> anyone who asks via DHCP.
>>>> 
>>>> The way I do it now, is assign pools as follows
>>>> 
>>>> 10.0.0.1-10.0.0.9 && set "allow unknown-hosts"
>>>> 10.0.0.10 && set "deny unknown-hosts"
>>>> 10.0.0.11-10.0.0.20 && set "allow unknown-hosts"
>>>> 
>>>> AND create a host entry for 10.0.0.10 like so:
>>>> 
>>>> host somehost {
>>>>       hardware ethernet aa:bb:cc:dd:ee:ff;
>>>>       fixed-address 10.0.0.10;
>>>>       }
>>>> 
>>>> I *think* I have to include the relevant IP in a pool. (In this case
>>>> 10.0.0.10)  [If there's no pool with 10.0.0.10 in it, the DHCP server
>>>> won't hand out an IP for 10.0.0.10, no matter what host record there
>>>> is, will it?]
>> 
>> CB> Yes it will. You do not need a pool surrounding your reserved address.
>> 
>> CB> Something like this should work:
>> 
>> CB> host somehost {
>> CB>         hardware ethernet aa:bb:cc:dd:ee:ff;
>> CB>         fixed-address 10.0.0.10;
>> CB> }
>> 
>> CB> subnet 10.0.0.0 netmask 255.255.255.0 {
>> CB>         <options>
>> CB>         pool {
>> CB>                 range 10.0.0.1 10.0.0.9;
>> CB>                 range 10.0.0.11 10.0.0.20;
>> CB>         }
>> CB> }
>> 
>> Wow, I guess I really *was* holding it wrong, eh!? :)
>> Thanks all for the help!
>> 
>> [I still wish I could just define the whole pool as 1-20 and then the
>> host def would reserve it, but I'll live, I suppose. :) ]

RR> This wish, or its intent, has been expressed many times on this
RR> list.  The answer is always to use reserved leases.  But there's
RR> no way to reserve a lease using the configuration file.  It can
RR> only be done dynamically omshell/omapi (as mentioned in your
RR> original message)

So, let me ask this in regards to omapi/omshell.

I saw threads that said you could *reserve* the lease indefinitely,
but there were no commands that would mark it as free again - or
remove the reservation.

Is that still true, and if not, what are the commands to reserve and
release the reservation via omshell?

[I'm having a hard enough time just getting omshell to set the partner
down state, so I'm not feeling frisky and confident to do lots more
daunting tasks! :) ]



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