Subject: Re: Proposed Resolution of Issues [1-37]

From: "Gunter Van de Velde (gvandeve)" <[email-masked]>
Date: Fri, 21 Oct 2005 21:47:57 +0200

At 09:33 2/09/2005 +0100, Tim Chown wrote:

Issue 24 - so what text will you use?
:)

In the background Elwyn worked with us on this aspect. The

text to replace Ch4.4 is below. We feel that text looks more balanced
now.

This replacement text will be in the NAP-02 draft.

<snip>

4.4.  Privacy and Topology Hiding
using IPv6

Partial host privacy is achieved in IPv6 using pseudo-random
privacy

addresses [RFC 3041] which are generated as required, so
that a

session can use an address that is valid only for a limited
time.

Exactly as with IPv4 NAT, this only allows such a session to
be

traced back to the subnet that originates it, but not
immediately to

the actual host.

Due to the large IPv6 address space available there is
plenty of

freedom to randomize subnet allocations.  By doing
this, it is

possible to reduce the correlation between a subnet and its
location.

When doing both subnet and IID randomization [RFC 3041] a
casual

snooper won't be able to deduce much about the networks
topology.

The obtaining of a single address will tell the snooper very
little

about other addresses.  This is different from IPv4
where address

space limitations cause this to be not true.  In most
usage cases

this concept should be sufficient for address privacy and
topology

hiding.

In the case where a network administrator wishes to fully
conceal the

internal IPv6 topology, and the majority of its host
computer

addresses, a possible option is to run all internal traffic
using

Unique Local Addresses (ULA) since such packets can by
definition

never exit the site.  For hosts that do in fact need to
generate

external traffic, by using multiple IPv6 addresses (ULAs and
one or

more global addresses), it will be possible to hide and mask
some or

all of the internal network.  As discussed in Section
3.1, there are

multiple parts to the IPv6 address, and different techniques
to

manage privacy for each.

There are two possible scenarios for the extreme situation
when a

network manager also wishes to fully conceal the internal
IPv6

topology.

o  One could use explicit host routes and remove the
correlation

between location and IPv6 address.
This solution does however

show severe scalability issues.

o  The other technology to fully hide the internal
topology would be

to use a tunneling mechanism.  Mobile
IPv6 without route

optimization is one example.  In this
example the public facing

addresses are indirected via an edge Home
Agent (HA).  This

indirection method truly masks the
internal topology as all nodes

with global access appear to share a
common subnet.  The downside

of using this method is that it makes
usage of middleware like a

Home Agent (HA).

<end snip>

Brgds,

G/