[clug] IPv6 for home (now aluminium foil hats)

Scott Ferguson scott.ferguson.clug at gmail.com
Sun Jan 1 01:19:25 MST 2012

On 01/01/12 18:15, Francis James Whittle wrote:
> On Sun, 2012-01-01 at 16:25 +1100, Scott Ferguson wrote:

> I use Avahi almost exclusively for local DNS.

If I could figure out how to make Avahi play nicely with DHCP so the PXE
server still worked... I guess there's probably a "man" thingie I should
squint at.

> It would be interesting to know if multicast DNS is any good at large
> numbers (let's say 10000 or so) of hosts...

Or find a way of hardcoding the IP addresses - which is not hard, PXE
boot, check for tag file, if not exist write /etc/network/interfaces ,
assign incremented ip, add ip to dns table, write tag file, reboot.
Either way it's unlikely to be something you can run on WRT (not enough
RAM). But then there should be lots of alternatives to WRT in the next
couple of years - re-purposed Kindles/FondleSlabs/Nokias..

> Sadly the only way I would have of testing this would be to boot up
> a large number of virtual machines, and I'd probably run into memory 
> usage problems even if I had a series of images that did nothing but 
> boot up and launch an mdns responder....

Depends how many NICs per device - you could also (maybe) use timed
changes of /etc/hosts and reset hostname - that way one device (P or V)
could have many identities :-/

>>> For example, I could just plug up to around 2^64 devices into my
>>>  network and... well I wouldn't be able to power them all, but
>>> you see how that's 32 times the ENTIRE ipv4 address space,

According to the infallible Wikipedia:-
"The standard size of a subnet in IPv6 is 264 addresses, the square of
the size of the entire IPv4 address space"

So you're not exaggerating.

>>> and I still shouldn't have run in any major configuration 
>>> problems (Except the problem of where to put so much stuff, and 
>>> how to power it).  After that point I have another 255 networks 
>>> of the same size to plug stuff into, because my ISP handed me an 
>>> unreasonably large block of addresses.  Seriously, what could I 
>>> possibly need a /56 subnet for?
>> Interesting - unfortunately my brain refuses to do big math 
>> today.... like projected population size and uniquely identifiable 
>> network connected devices.
>> Is it possible that the IPV6 address pool is large enough for 
>> mandatory hard-coded addresses in devices instead of SA[*1]?
> I worry about the routability of mandatory hard coded addresses....

I'm sure those that propose tracking everyone everywhere have got a
solution for that (10 minute ping times).

A future scenario might be that devices are designed to be inactive
unless activated by an authorised system at POS - after suitable ID and
authorisation has been produced. So IPs are linked to owner with the
ability for registrants (companies) to transfer the ownership, and a
central authority to revoke them (deactivating the networking ability).
With that scenario routablity would be considered irrelevant.
>> Perhaps I just haven't considered the number of possible discrete 
>> networked devices of the future...?
> It's physically improbable to ever have that many things.  I'm 
> talking about individuals filling up their /64.

Now that my hangover fades I don't think it is physically improbable in
the longer term. If you had a lot of disposable devices with hardcoded
IPs (in a similar manner to MACs). eg. grain of rice sized RFID devices
for military,security, clothing,food, medical devices etc. Some of those
could wind up occupying addresses on your network (in which case you
could substitute "you" for "home").

Filling the device/node side could be your (apparently) smart meter,
your vehicles, your portable devices, and anything you purchase that is
network-able. Sounds implausible until I consider how likely a wireless
gateway in most homes might be - which then increases the number of
cheap RFID tagged devices that could be brought into the home network.

We've already got IBM building systems to track food from farm to
checkout - the consumer gets that information real-time, the rest of the
interested data users have to wait.
How long before some genius decides your shopping preferences, eating
habits, garbage statistics, etc is marketable.

Anyway, this aluminium hat is getting hot, and I really don't want to
test it's ability to attract lightning during this storm :-)



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