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 Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on February 27, 2010. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Haddad Expires February 27, 2010 [Page 1] Internet-Draft NAT64 Mobility August 2009 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 Haddad Expires February 27, 2010 [Page 2] Internet-Draft NAT64 Mobility August 2009 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. Haddad Expires February 27, 2010 [Page 3] Internet-Draft NAT64 Mobility August 2009 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]. Haddad Expires February 27, 2010 [Page 4] Internet-Draft NAT64 Mobility August 2009 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 Haddad Expires February 27, 2010 [Page 5] Internet-Draft NAT64 Mobility August 2009 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. Haddad Expires February 27, 2010 [Page 6] Internet-Draft NAT64 Mobility August 2009 4. Security Considerations This memo describes scenarios where a NAT64 can inflict harm to a mobile node visiting the associated network. Haddad Expires February 27, 2010 [Page 7] Internet-Draft NAT64 Mobility August 2009 5. Acknowledgements Thanks to Francis Dupont and Joel Halpern for reviewing the document at an early stage. Haddad Expires February 27, 2010 [Page 8] Internet-Draft NAT64 Mobility August 2009 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. Haddad Expires February 27, 2010 [Page 9] Internet-Draft NAT64 Mobility August 2009 Author's Address Wassim Haddad Ericsson 6210 Spine Road Boulder, CO 80301 US Phone: +303 473 6963 Email: Wassim.Haddad@ericsson.com Haddad Expires February 27, 2010 [Page 10]