Subject: RE: [Mip6] review of draft-ietf-mip6-bootstrapping-split-00.txt

From: "Kilian Weniger" <[email-masked]>
Date: Thu, 6 Oct 2005 11:39:39 +0200

> jak>> The selection of HoA in and of itself doesn't reveal 
> much about the 
> location even at the time of bootstrapping. So I'd like to 
> see this sentence 
> ("Thus...revealed.") dropped.

But the sentence (and the entire paragraph) refers to the scenario
described in the first paragraph, which includes updating DNS (not only
HoA selection)? Anyhow, if this is misleading, I don't have problems
with removing the sentence, but I would like to make clear that the
fixed location refers to the location at the time of bootstrapping and
that it may change after bootstrapping again with a different HA. Can
you agree to the following sentence (and we drop the "Thus..revealed"
sentence, as you suggested)?

   "Second, the mobile 
   node (if using reverse tunneling) will effectively appear to be at 
   a fixed topological location in the mobility service provider's 
   as long as it does not bootstrap again with a different home 
   agent in a different network and request DNS update subsequently."

> interoperability. If we decide in favor of removing, then I 
> think we should 
> save this text and put it into the integrated scenerio draft.

I agree that the potential location privacy issue with local HAs should
be described in the sec cons sections in the integrated scenario draft.
But even if the text about location-dependent HA naming is removed from
the split scenario draft, location-dependent HA discovery may still be
possible to some extent by using country code suffixes (the location is
of course much less accurate). Depending on how strict the requirement
for location privacy is, an issue may still exist. If, for instance, a
user from US is on a business trip in Europe and that user roams to
Vodafone Germany, it may discover an HA for bootstrapping using
"ha1.vodafone.de" or "_mip6._ipv6.vodafone.de". When updating DNS with
the new HoA, that may give a hint that the user is currently in Germany.

And even the provider name itself could include some location
information if it is a small provider which only covers a small
geographical area.

What do others think?

Kilian

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From: "James Kempf" <[email-masked]>
Date: Thu, 6 Oct 2005 10:01:32 -0700

that it may change after bootstrapping again with a different HA.

jak>> The only way an eavesdropper could know, from a DNS-registered home 
address obtained through bootstrapping, that a MN is at a particular 
location is:

1) The eavesdropper has been keeping track of the DNS-registered home 
address in the past and has seen that the newly registered address is 
different,
2) The eavesdropper knows the victim's home MSP, either from previous 
addresses, or from some other way (note: the victim's FQDN doesn't provide 
any information in general about the MSP, because the FQDN is handled by the 
MSA, which might be a separate administrative entity),
2) The eavesdropper knows that the newly registered address belongs to an 
MSP that is not the victim's home MSP and that the current MSP routinely 
uses local home agents,

In addition, the granularity of the information obtained from the home 
address depends on the topological to geographical coverage of the home 
agent. So if the coverage area is, say, the entire Bay Area in California, 
the eavesdropper doesn't get a whole heck of a lot of information about 
where the person is.

jak>> My point is that the eavesdropper needs a lot of additional 
information about the victim and the MSPs that the victim is using before it 
can conclude anything about the location. If you want to put all these 
conditions into the text, I think it would make the description more 
accurate.

Can

   "Second, the mobile

jak>> That seems OK.

jak>> If Vodafone has no local HA service in Germany, then the user will 
always use it's home MSP in the US. So there's no issue.

jak>> We're currently discussing among the authors about what to put in the 
draft regarding local home agent assignment. If there is no text specifying 
how to do it, then I think we don't need to say anything. But I think we do 
need to say something in the integrated scenario draft, because it will be 
possible there.

            jak