[Dnsmasq-discuss] DHCPv6 with dnsmasq for automated deployments

Pali Rohár pali.rohar at gmail.com
Fri May 25 13:59:42 BST 2018


On Friday 25 May 2018 14:07:34 Oliver Freyermuth wrote:
> Dear dnsmasqers,
> 
> I fear the following is a design issue of DHCPv6, but I wonder if there's a way to overcome it with dnsmasq... 
> 
> When automatically deploying machines via PXE / network installer, there's usually first a DHCPv6 client running in the installer,
> and afterwards (when the machine is installed) the "real" DHCPv6 client running on the machine. 
> Naturally, both will usually have different client DUIDs... 
> 
> Using dnsmasq's functionality to perform DHCPv6 address assignment based on MAC address,
> this works fine for the first client, but the second DHCPv6 client will not get an address until the old lease is expired. 
> 
> In general, I feel this is the correct behaviour, but it's of course rather inconvenient when deploying machines automatically - 
> they will retrieve an IPv6 address with the network installer, and then not get one after the first reboot. 
> Also, when reinstalling them, they will not get an address in the installer if the lease from their "old life" is still valid. 
> 
> Does somebody have a good solution for this? 
> Is there something like "id:*" for IPv4 implemented for the IPv6 world (i.e. something like "duid:*")? 
> 
> Cheers and all the best,
> 	Oliver

Hi Oliver!

dnsmasq for DHCPv6 stores in lease file IAID, not DUID. But assignment
of address is done either by DUID or MAC address.

I think you hit some problem affected by the way how is IPv6 address
assigned according to DUID, IAID, MAC address and status of lease file.

2 years ago I tried to discuss with Simon about possibility to assign
one address to more DHCP requests identified by MAC address and one of
needed thing was probably extension of lease file (to include also MAC
address and DUID) and handling of requests which already have address
assigned in lease file. Apparently until now Simon has not response
about it and I gave up trying to ping him again...

http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2016q1/010404.html

-- 
Pali Rohár
pali.rohar at gmail.com



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