[Dnsmasq-discuss] IPv6 addresses are (almost) immediately deprecated

[Graham Leggett]

On 22 Sep 2023, at 20:27, Geert Stappers <stappers at stappers.nl> wrote:

>> I have a dnsmasq config on a development machine that looks like this:
>> 
>> dhcp-range=fd33:xxxx:xxxx:1::, ra-only, 24h
>> 
>> The intention is for this development machine to announce to anyone
>> directly connected that the development machine exists, and can be
>> connected to. No routing, no DNS, only “I exist”.
>> 
>> This almost works. On MacOS I’m getting an IP address allocated on
>> the expected interface, but almost immediately the address is declared
>> “deprecated”.
> 
> Why?

I was today-years-old when I learned there was such a thing as a deprecated IPv6 address. I am as confused as you are :)

>> This causes MacOS to ignore the direct connection and to route packets
>> to the router, which in turn has no idea what to do with the packets
>> and (correctly) drops them.
>> 
>> How do I get dnsmasq to tell anyone who cares that the IPv6 addresses
>> are valid and not deprecated?
> 
> I would start with only two computers: One being dnsmasq doing radvd,
> the other one being told "you exist".

I am somewhat limited in the hardware I have available to me.

The development machine is currently running in virtualbox. Virtualbox local only networks appear to ignore IPv6 on the host, there is talk of setting /etc/vbox/networks.conf but this does not appear to work. Ignoring this side-quest for now.

Virtualbox bridging the development machine directly to the network works - but the IPv6 addresses are deprecated soon after being assigned, and so stop working after a short while.

The end goal is ease of use - deploy the development machine and off you go, but this seems to be weirdly difficult. Does anyone know what would trigger a deprecated IPv6 address to be created, and how to make it stop?

Regards,
Graham
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