Mobile IPv6 Bootstrapping in Split Scenario
draft-ietf-mip6-bootstrapping-split-07
The information below is for an old version of the document that is already published as an RFC.
Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 5026.
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Authors | James Kempf , Gerardo Giaretta , Vijay Devarapalli | ||
Last updated | 2015-10-14 (Latest revision 2007-07-25) | ||
RFC stream | Internet Engineering Task Force (IETF) | ||
Intended RFC status | Proposed Standard | ||
Formats | |||
Reviews | |||
Additional resources | Mailing list discussion | ||
Stream | WG state | (None) | |
Document shepherd | (None) | ||
IESG | IESG state | Became RFC 5026 (Proposed Standard) | |
Action Holders |
(None)
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Consensus boilerplate | Unknown | ||
Telechat date | (None) | ||
Responsible AD | Jari Arkko | ||
Send notices to | (None) |
draft-ietf-mip6-bootstrapping-split-07
> AAA request (FQDN, HoA) <--------------> DNS update <-----------> AAA answer (FQDN, HoA) <--------------> BA (DNS update option) <----------------------- Notice that, even in this last case, the Home Agent is always required to perform a DNS update for the reverse entry, since this is always performed in the DNS server of the MSP. This is not depicted in the figure above. 8. Option and Attribute Format 8.1. DNS Update mobility option 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Option Type | Option Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Status |R| Reserved | MN identity (FQDN) ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Giaretta, Ed., et al. Expires January 23, 2008 [Page 17] Internet-Draft MIP6 Bootstrapping in split scenario July 2007 Option Type DNS-UPDATE-TYPE to be defined by IANA Option Length 8-bit unsigned integer indicating the length of the option excluding the type and length fields Status 8-bit unsigned integer indicating the result of the dynamic DNS update procedure. This field MUST be set to 0 and ignored by the receiver when the DNS Update mobility option is included in a Binding Update message. When the DNS Update mobility option is included in the Binding Acknowledgement message, values of the Status field less than 128 indicate that the dynamic DNS update was performed successfully by the Home Agent. Values greater than or equal to 128 indicate that the dynamic DNS update was not completed by the HA. The following Status values are currently defined: 0 DNS update performed 128 Reason unspecified 129 Administratively prohibited 130 DNS Update Failed R flag If set the Mobile Node is requesting the HA to remove the DNS entry identified by the FQDN specified in this option and the HoA of the Mobile Node. If not set, the Mobile Node is requesting the HA to create or update a DNS entry with its HoA and the FQDN specified in the option Reserved MUST be set to 0 MN identity The identity of the Mobile Node in FQDN format to be used by the Home Agent to send a Dynamic DNS update. It is a variable length field Giaretta, Ed., et al. Expires January 23, 2008 [Page 18] Internet-Draft MIP6 Bootstrapping in split scenario July 2007 8.2. MIP6_HOME_PREFIX attribute The MIP6_HOME_PREFIX attribute is carried in IKEv2 Configuration Payload messages. This attribute is used to convey the home prefix from which the Mobile Node auto-configures its home address. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |R| Attribute Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix Lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Home Prefix | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix Length | +-+-+-+-+-+-+-+-+ Reserved (1 bit) This bit MUST be set to zero and MUST be ignored on receipt Attribute Type (15 bits) A unique identifier for the MIP6_HOME_PREFIX attribute. To be assigned by IANA Length (2 octets) Length in octets of Value field (Home Prefix, Prefix Lifetime and Prefix Length). This can be 0 or 21 Prefix Lifetime (4 octets) The lifetime of the Home Prefix Home Prefix (16 octets) The prefix of the home link through which the Mobile Node may auto-configure its Home Address Giaretta, Ed., et al. Expires January 23, 2008 [Page 19] Internet-Draft MIP6 Bootstrapping in split scenario July 2007 Prefix Length (1 octet) The length in bits of the home prefix specified in the field Home Prefix When the MIP6_HOME_PREFIX attribute is included by the Mobile Node in the CFG_REQUEST payload, the value of the Length field is 0. When the MIP6_HOME_PREFIX attribute is included in the CFG_REPLY payload by the Home Agent, the value of the Length field is 21 and the attribute contains also the home prefix information. 9. Security Considerations 9.1. HA Address Discovery Use of DNS for address discovery carries certain security risks. DNS transactions in the Internet are typically done without any authentication of the DNS server by the client or of the client by the server. There are two risks involved: 1. A legitimate client obtains a bogus Home Agent address from a bogus DNS server. This is sometimes called a "pharming" attack, 2. An attacking client obtains a legitimate Home Agent address from a legitimate server. The risk in Case 1 is mitigated because the Mobile Node is required to conduct an IKE transaction with the Home Agent prior to performing a Binding Update to establish Mobile IPv6 service. According to the IKEv2 specification [5], the responder must present the initiator with a valid certificate containing the responder's public key, and the responder to initiator IKE_AUTH message must be protected with an authenticator calculated using the public key in the certificate. Thus, an attacker would have to set up both a bogus DNS server and a bogus Home Agent, and provision the Home Agent with a certificate that a victim Mobile Node could verify. If the Mobile Node can detect that the certificate is not trustworthy, the attack will be foiled when the Mobile Node attempts to set up the IKE SA. The risk in Case 2 is limited for a single Mobile Node to Home Agent transaction if the attacker does not possess proper credentials to authenticate with the Home Agent. The IKE SA establishment will fail when the attacking Mobile Node attempts to authenticate itself with the Home Agent. Regardless of whether the Home Agent utilizes EAP or host-side certificates to authenticate the Mobile Node, the authentication will fail unless the Mobile Node has valid credentials. Giaretta, Ed., et al. Expires January 23, 2008 [Page 20] Internet-Draft MIP6 Bootstrapping in split scenario July 2007 Another risk exists in Case 2 because the attacker may be attempting to propagate a DoS attack on the Home Agent. In that case, the attacker obtains the Home Agent address from the DNS, then propagates the address to a network of attacking hosts that bombard the Home Agent with traffic. This attack is not unique to the bootstrapping solution, however, it is actually a risk that any Mobile IPv6 Home Agent installation faces. In fact, the risk is faced by any service in the Internet that distributes a unicast globally routable address to clients. Since Mobile IPv6 requires that the Mobile Node communicate through a globally routable unicast address of a Home Agent, it is possible that the Home Agent address could be propagated to an attacker by various means (theft of the Mobile Node, malware installed on the Mobile Node, evil intent of the Mobile Node owner him/herself, etc.) even if the home address is manually configured on the Mobile Node. Consequently, every Mobile IPv6 Home Agent installation will likely be required to mount anti-DoS measures. Such measures include overprovisioning of links to and from Home Agents and of Home Agent processing capacity, vigilant monitoring of traffic on the Home Agent networks to detect when traffic volume increases abnormally indicating a possible DoS attack, and hot spares that can quickly be switched on in the event an attack is mounted on an operating collection of Home Agents. DoS attacks of moderate intensity should be foiled during the IKEv2 transaction. IKEv2 implementations are expected to generate their cookies without any saved state, and to time out cookie generation parameters frequently, with the timeout value increasing if a DoS attack is suspected. This should prevent state depletion attacks, and should assure continued service to legitimate clients until the practical limits on the network bandwidth and processing capacity of the Home Agent network are reached. Explicit security measures between the DNS server and host, such DNSSEC [19] or TSIG/TKEY [20] [21] can mitigate the risk of 1) and 2), but these security measures are not widely deployed on end nodes. These security measures are not sufficient to protect the Home Agent address against DoS attack, however, because a node having a legitimate security association with the DNS server could nevertheless intentionally or inadvertently cause the Home Agent address to become the target of DoS. Finally notice that assignment of an home agent from the serving network access provider's (local home agent) or a home agent from a nearby network (nearby home agent) may set up the potential to compromise a mobile node's location privacy. A home address anchored at such home agent contains some information about the topological location of the mobile node. Consequently, a mobile node requiring location privacy should not disclose this home address to nodes that are not authorized to learn the mobile node's location, e.g., by Giaretta, Ed., et al. Expires January 23, 2008 [Page 21] Internet-Draft MIP6 Bootstrapping in split scenario July 2007 updating DNS with the new home address. Security considerations for discovering HA using DHCP are covered in [22]. 9.2. Home Address Assignment through IKEv2 Mobile IPv6 bootstrapping assigns the home address through the IKEv2 transaction. The Mobile Node can either choose to request an address, similar to DHCP, or the Mobile Node can request a prefix on the home link then auto-configure an address. RFC 3775 [1] requires that a Home Agent check authorization of a home address received during a Binding Update. Therefore, the home agent MUST authorize each home address allocation and use. This authorization is based on linking the mobile node identity used in the IKEv2 authentication process and the home address. Home agents MUST implement at least the following two modes of authorization: o Configured home address(es) for each mobile node. In this mode, the home agent or infrastructure nodes behind it know what addresses a specific mobile node is authorized to use. The mobile node is allowed to request these addresses, or if the mobile node requests any home address, these addresses are returned to it. o First-come-first-served (FCFS). In this mode, the home agent maintains a pool of "used" addresses, and allows mobile nodes to request any address, as long as it is not used by another mobile node. Addresses MUST be marked as used for at least as long as the binding exists, and are associated with the identity of the mobile node that made the allocation. In addition, the home agent MUST ensure that the requested address is not the authorized address of any other mobile node, if both FCFS and configured modes use the same address space. 9.3. SA Establishment Using EAP Through IKEv2 Security considerations for authentication of the IKE transaction using EAP are covered in [3] . 9.4. Back End Security Between the HA and AAA Server Some deployments of Mobile IPv6 bootstrapping may use an AAA server to handle authorization for mobility service. This process has its own security requirements, but the back end protocol for Home Agent Giaretta, Ed., et al. Expires January 23, 2008 [Page 22] Internet-Draft MIP6 Bootstrapping in split scenario July 2007 to AAA server interface is not covered in this draft. Please see [16] for a discussion of this interface. 9.5. Dynamic DNS Update If a Home Agent performs dynamic DNS update on behalf of the Mobile Node directly with the DNS server, the Home Agent MUST have a security association of some type with the DNS server. The security association MAY be established either using DNSSEC [19] or TSIG/TKEY [20][21]. A security association is REQUIRED even if the DNS server is in the same administrative domain as the Home Agent. The security association SHOULD be separate from the security associations used for other purposes, such as AAA. In the case where the Mobility Service Provider is different from the Mobility Service Authorizer, the network administrators may want to limit the number of cross-administrative domain security associations. If the Mobile Node's FQDN is in the Mobility Service Authorizer's domain, since a security association for AAA signaling involved in mobility service authorization is required in any case, the Home Agent can send the Mobile Node's FQDN to the AAA server under the HA-AAA server security association, and the AAA server can perform the update. In that case, a security association is required between the AAA server and DNS server for the dynamic DNS update. See [16] for a deeper discussion of the Home Agent to AAA server interface. Regardless of whether the AAA server or Home Agent performs DNS update, the authorization of the Mobile Node to update a FQDN MUST be checked prior to the performance of the update. It is an implementation issue as to how authorization is determined. However, in order to allow this authorization step, the Mobile Node MUST use a FQDN as the IDi in IKE_AUTH step of the IKEv2 exchange. The FQDN MUST be the same as the FQDN that will be provided by the Mobile Node in the DNS Update Option. In case EAP over IKEv2 is used to set-up the IPsec SA, the Home Agent gets authorization information about the Mobile Node's FQDN via the AAA back end communication performed during IKEv2 exchange. The outcome of this step will give the Home Agent the necessary information to authorize the DNS update request of the Mobile Node. See [16] for details about the communication between the AAA server and the Home Agent needed to perform the authorization. In case certificates are used in IKEv2, the authorization information about the FQDN for DNS update MUST be present in the certificate provided by the Mobile Node. Since the IKEv2 specification does not include a required certificate type, it is not possible to specify Giaretta, Ed., et al. Expires January 23, 2008 [Page 23] Internet-Draft MIP6 Bootstrapping in split scenario July 2007 precisely how the Mobile Node's FQDN should appear in the certificate. However, as an example, if the certificate type is "X.509 Certificate - Signature" (one of the recommended types) then the FQDN may appear in the subjectAltName attribute extension [23]. 10. IANA Considerations This document defines a new Mobility Option and a new IKEv2 Configuration Attribute Type. The following values should be assigned: o from "Mobility Option" namespace ([1]): DNS-UPDATE-TYPE (Section 8.1) o from "IKEv2 Configuration Payload Attribute Types" namespace ([5]): MIP6_HOME_PREFIX attribute (Section 8.2) o from "IKEv2 Notify Payload Error Types" namespace ([5]): USE_ASSIGNED_HoA error type (Section 5.3.2) 11. Contributors This contribution is a joint effort of the bootstrapping solution design team of the MIP6 WG. The contributors include Basavaraj Patil, Alpesh Patel, Jari Arkko, James Kempf, Yoshihiro Ohba, Gopal Dommety, Alper Yegin, Junghoon Jee, Vijay Devarapalli, Kuntal Chowdury, Julien Bournelle. The design team members can be reached at: Gerardo Giaretta gerardog@qualcomm.com Basavaraj Patil basavaraj.patil@nokia.com Alpesh Patel alpesh@cisco.com Jari Arkko jari.arkko@kolumbus.fi James Kempf kempf@docomolabs-usa.com Yoshihiro Ohba yohba@tari.toshiba.com Gopal Dommety gdommety@cisco.com Giaretta, Ed., et al. Expires January 23, 2008 [Page 24] Internet-Draft MIP6 Bootstrapping in split scenario July 2007 Alper Yegin alper.yegin@samsung.com Vijay Devarapalli vijay.devarapalli@azairenet.com Kuntal Chowdury kchowdury@starentnetworks.com Junghoon Jee jhjee@etri.re.kr Julien Bournelle julien.bournelle@gmail.com 12. Acknowledgements The authors would like to thank Rafa Lopez, Francis Dupont, Jari Arkko, Kilian Weniger, Vidya Narayanan, Ryuji Wakikawa, Michael Ye for their valuable comments. 13. References 13.1. Normative References [1] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [3] Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with IKEv2 and the Revised IPsec Architecture", RFC 4877, April 2007. [4] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for specifying the location of services (DNS SRV)", RFC 2782, February 2000. [5] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", RFC 4306, December 2005. [6] Vixie, P., Thomson, S., Rekhter, Y., and J. Bound, "Dynamic Updates in the Domain Name System (DNS UPDATE)", RFC 2136, April 1997. 13.2. Informative References [7] Patel, A. and G. Giaretta, "Problem Statement for bootstrapping Mobile IPv6 (MIPv6)", RFC 4640, September 2006. Giaretta, Ed., et al. Expires January 23, 2008 [Page 25] Internet-Draft MIP6 Bootstrapping in split scenario July 2007 [8] Manner, J. and M. Kojo, "Mobility Related Terminology", RFC 3753, June 2004. [9] Adams, C., Farrell, S., Kause, T., and T. Mononen, "Internet X.509 Public Key Infrastructure Certificate Management Protocol (CMP)", RFC 4210, September 2005. [10] Korver, B., "The Internet IP Security PKI Profile of IKEv1/ ISAKMP, IKEv2, and PKIX", draft-ietf-pki4ipsec-ikecert-profile-12 (work in progress), February 2007. [11] Narten, T., "Neighbor Discovery for IP version 6 (IPv6)", draft-ietf-ipv6-2461bis-11 (work in progress), March 2007. [12] Aura, T., "Cryptographically Generated Addresses (CGA)", RFC 3972, March 2005. [13] Narten, T. and R. Draves, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", RFC 3041, January 2001. [14] Droms, R., "DNS Configuration options for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3646, December 2003. [15] Chowdhury, K. and A. Yegin, "MIP6-bootstrapping for the Integrated Scenario", draft-ietf-mip6-bootstrapping-integrated-dhc-04 (work in progress), June 2007. [16] Giaretta, G., "AAA Goals for Mobile IPv6", draft-ietf-mip6-aaa-ha-goals-03 (work in progress), September 2006. [17] Chowdhury, K., "RADIUS Mobile IPv6 Support", draft-ietf-mip6-radius-02 (work in progress), March 2007. [18] Bournelle, J., "Diameter Mobile IPv6: HA <-> HAAA Support", draft-ietf-dime-mip6-split-02 (work in progress), May 2007. [19] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "DNS Security Introduction and Requirements", RFC 4033, March 2005. [20] Vixie, P., Gudmundsson, O., Eastlake, D., and B. Wellington, "Secret Key Transaction Authentication for DNS (TSIG)", RFC 2845, May 2000. Giaretta, Ed., et al. Expires January 23, 2008 [Page 26] Internet-Draft MIP6 Bootstrapping in split scenario July 2007 [21] Eastlake, D., "Secret Key Establishment for DNS (TKEY RR)", RFC 2930, September 2000. [22] Jang, H., "DHCP Option for Home Information Discovery in MIPv6", draft-ietf-mip6-hiopt-05 (work in progress), June 2007. [23] Housley, R., Polk, W., Ford, W., and D. Solo, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 3280, April 2002. Authors' Addresses Gerardo Giaretta Qualcomm Email: gerardog@qualcomm.com James Kempf DoCoMo Labs USA 181 Metro Drive San Jose, CA 95110 USA Email: kempf@docomolabs-usa.com Vijay Devarapalli Azaire Networks 3121 Jay Street Santa Clara, CA 95054 USA Email: vijay.devarapalli@azairenet.com Giaretta, Ed., et al. Expires January 23, 2008 [Page 27] Internet-Draft MIP6 Bootstrapping in split scenario July 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Giaretta, Ed., et al. Expires January 23, 2008 [Page 28]