[Kea-users] dnsmasq-style address allocation

[Sten Carlsen]

One thing that is unclear to me is whether the randomness or the predictability of the address reallocation is more important?

The chosen solution should reflect that choice. My reading of the original posting indicated to me that the reallocation of the same address was the main thing here - I might very well be wrong in that reading.


Thanks

Sten

> On 10 Aug 2024, at 17.26, Darren Ankney <darren.ankney at gmail.com> wrote:
> 
> Hi WIllhelm,
> 
> You might try combining the random allocater with "lease affinity"
> with a long "hold-reclaimed-time".  This should offer similar
> functionality:
> 
> random: https://kea.readthedocs.io/en/kea-2.6.1/arm/dhcp4-srv.html#random-allocator
> lease affinity:
> https://kea.readthedocs.io/en/kea-2.6.1/arm/lease-expiration.html#configuring-lease-affinity
> 
> Thank you,
> Darren Ankney
> 
> On Fri, Aug 9, 2024 at 4:32 AM Wilhelm Schuster <lists+kea at rot13.io> wrote:
>> 
>> Hi list,
>> 
>> I'm evaluating switching from OpenWRT to VyOS on my main home network
>> router setup. VyOS integrates kea as DHCPv4 server whereas OpenWRT
>> relies on dnsmasq.
>> 
>> dnsmasq implements an interesting address allocation strategy which I
>> like quite a bit. Here is how its manpage describes it [1]:
>> 
>>     Dnsmasq is designed to choose IP addresses for DHCP clients using a
>>     hash of the client's MAC address. This normally allows a client's
>>     address to remain stable long-term, even if the client sometimes
>>     allows its DHCP lease to expire. In this default mode IP addresses
>>     are distributed pseudo-randomly over the entire available address
>>     range.
>> 
>> Here is a link to the source code: [2]
>> 
>> I'm a fan of that strategy as it keeps host addresses somewhat stable
>> even after leases have expired. I've scoured the kea manual, but was
>> unable to find a suitable strategy: the random allocator does not appear
>> to use the client MAC address (from a brief look at the kea source). If
>> there is no built-in way to mimic the allocation strategy, is there the
>> possibility to implement a custom allocator as a plugin or hook, or does
>> that require forking the codebase?
>> 
>> [1]: https://man.archlinux.org/man/dnsmasq.8#dhcp-sequential-ip
>> [2]:
>> https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=blob;f=src/dhcp.c;h=b65facd8707b03919d6f78afd2ea8dd25078e5e9;hb=HEAD#l790
>> 
>> Cheers, Wilhelm.
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