Behavior Engineering for Hindrance W. Haddad
Avoidance (behave) Ericsson
Internet-Draft August 26, 2009
Intended status: Informational
Expires: February 27, 2010
A Note on NAT64 Interaction with Mobile IPv6
draft-haddad-behave-nat64-mobility-harmful-00
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Abstract
This memo discusses potential NAT64 technology repercussions for
mobile nodes using Mobile IPv6 stack.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 4
3. NAT64 Incompatibility with Mobile IPv6 . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.1. Normative References . . . . . . . . . . . . . . . . . . . 9
6.2. Informative References . . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
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1. Introduction
NAT64 technology described in [I-D.ietf-behave-v6v4-xlate-stateful],
enables rapid IPv4 network conversion to a pure IPv6 stack while
keeping possible the contact with the remaining IPv4 networks. It
follows that nodes attached to a NAT64-powered network operate with
an IPv6 stack only.
This memo aims to highlight potential NAT64 repercussions for mobile
nodes using Mobile IPv6 ([I-D.ietf-mext-rfc3775bis]) and operating
from behind a NAT64.
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2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
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3. NAT64 Incompatibility with Mobile IPv6
It is interesting to start this section by mentioning that NAT
technology in general has had from its infancy the rare feature of
being incompatible with the Internet. Hence, the described new
incompatibility should not come as a surprise!
NAT64 mechanism relies on DNS64 technology described in
[I-D.ietf-behave-dns64] to provide the querying host with a synthetic
DNS response in which, the queried FQDN is locally translated to an
IPv6 address using the v6 prefix assigned to the NAT64 v6 interface.
By inserting the translated IPv6 address in the synthetic DNS
response, the querying node is tempted to believe that the
destination is also using an IPv6 stack which in turn, enables
establishing a session between the two nodes.
As NAT64 technology may have the potential of becoming widely
deployed, we are tempted to study its behavior in the presence of a
v6 mobility dimension. For this purpose, we assume that a mobile
node (MN) configured with an IPv6 home address (HoA) leaves its
NAT64-powered home network and attaches to a foreign NAT64-powered
network where it configures a new IPv6 address, i.e., care-of address
(CoA). In the following, we look into two scenarios which require
using MIPv6 either to establish a new session or to try to switch the
data packets exchange to the optimal path via using MIPv6 route
optimization (RO) mode.
In a first scenario, we consider that before detaching from its home
network, the MN has established a session with a corresponding node
(CN) which is attached to an IPv4 network. However, due to the NAT64
presence in the home network, the MN believes that it is talking with
an IPv6-enabled CN and hence, it decides upon attaching to the new
NAT64-powered foreign network, to run MIPv6 return routability (RR)
procedure with the CN by sending first a home test init (HoTI)
message via its home agent. It is clear that such message will be
discarded either by a "more" intelligent NAT64 (i.e., in which case
it may be followed by an ICMP message sent to the MN) or by the CN.
In both cases, the MN will correctly realize at some point that the
RR procedure cannot succeed. Consequently, there is no harm
inflicted to the MN and more importantly, no data packet loss since
the MN will keep using MIPv6 bidirectional tunneling (BT) mode.
However, the situation becomes problematic when we consider another
scenario in which, the MN decides to establish a session with the
same CN from the foreign NAT64-powered network. In such case, the MN
will first obtain a synthetic DNS reply which presents the CN as
being an IPv6-enabled node. Based on that, the MN may either try to
create a binding at the CN by running first the RR procedure which
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will ultimately fail (i.e., for the same reasons as in the first
scenario) or more likely, will initiate the session with the CN by
using the BT mode then switching to the RO mode. In this case, the
MN tunnels first its data packets to its HA without having them being
intercepted by the foreign NAT64. However, after reaching the HA,
the data packets will most likely be dropped at some point. This is
due to the presence of the foreign NAT64 IPv6 prefix in the CN's IPv6
address.
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4. Security Considerations
This memo describes scenarios where a NAT64 can inflict harm to a
mobile node visiting the associated network.
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5. Acknowledgements
Thanks to Francis Dupont and Joel Halpern for reviewing the document
at an early stage.
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6. References
6.1. Normative References
[I-D.ietf-mext-rfc3775bis]
Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", draft-ietf-mext-rfc3775bis-04 (work in
progress), July 2009.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
6.2. Informative References
[I-D.ietf-behave-dns64]
Bagnulo, M., Sullivan, A., Matthews, P., and I. Beijnum,
"DNS64: DNS extensions for Network Address Translation
from IPv6 Clients to IPv4 Servers",
draft-ietf-behave-dns64-00 (work in progress), July 2009.
[I-D.ietf-behave-v6v4-xlate-stateful]
Bagnulo, M., Matthews, P., and I. Beijnum, "NAT64: Network
Address and Protocol Translation from IPv6 Clients to IPv4
Servers", draft-ietf-behave-v6v4-xlate-stateful-01 (work
in progress), July 2009.
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Author's Address
Wassim Haddad
Ericsson
6210 Spine Road
Boulder, CO 80301
US
Phone: +303 473 6963
Email: Wassim.Haddad@ericsson.com
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