[Kea-users] Need help assigning subnets by class with host reservations

Thomas Markwalder tmark at isc.org
Tue Nov 15 11:49:51 UTC 2016


On 11/14/16 5:05 PM, MRob wrote:
>>>> 3. Is using "lease.decline(0)" the best (only) way, at least in this
>>>> hook point, to turn away unknown clients? That's what I've done and
>>>> it works, though the lease is still processed and sent to the
>>>> client, but with what I think is a lease for zero seconds.
>>>
>>>  Declining a lease is intended to be a client initiated action, so I
>>> don't really think this is direction to go.  If you set the
>>> lease4_select next step action to SKIP before returning from your
>>> lease4_select hook:
>>>
>>> "NEXT STEP STATUS: If any callout installed on the "lease4_select"
>>> hook sets the next step action to SKIP, the server will not assign any
>>> lease and the callouts become responsible for the lease assignment. If
>>> the callouts fail to provide a lease, the packet processing will
>>> continue, but client will not get an address."
>>>
>>> If your callout does not then assign a lease using its own decision
>>> making,  the server will generate a NAK to your client.
>>
>> This works much better (though again, would have not needed to bother
>> you if I had been able to find the docs you quote here). Thanks again
>> for all your help, it's working quite nicely now.
>
> Caveat: when a lease is skipped, the server immediately tries again to
> allocate another lease for the client, and does this many more times
> in the same second, so much so that there are nearly 2000 lines of
> logging at maximum verbosity before a NAK is sent. Then it keeps
> trying many times per second for another few seconds.
>
> This seems quite excessive. Shouldn't the server send the NAK and stop
> retrying after a lease is denied? At a minimum, retries should be rate
> limited or limited to X number of retries.

This does not sound like the intended outcome, we'll need to look into
this. An excerpt of your log file would helpful.

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