Multiple Provisioning Domain Architecture
draft-ietf-mif-mpvd-arch-05
The information below is for an old version of the document.
Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 7556.
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Author | Dmitry Anipko | ||
Last updated | 2014-09-17 (Latest revision 2014-09-15) | ||
Replaces | draft-anipko-mif-mpvd-arch | ||
RFC stream | Internet Engineering Task Force (IETF) | ||
Formats | |||
Reviews |
GENART Telechat review
(of
-10)
by Francis Dupont
Ready w/issues
GENART Last Call review
(of
-09)
by Francis Dupont
Ready w/issues
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Additional resources | Mailing list discussion | ||
Stream | WG state | WG Document | |
Document shepherd | DENG Hui | ||
IESG | IESG state | Became RFC 7556 (Informational) | |
Consensus boilerplate | Unknown | ||
Telechat date | (None) | ||
Responsible AD | (None) | ||
Send notices to | (None) |
draft-ietf-mif-mpvd-arch-05
5.2.3.1.1. Connection-oriented APIs For connection-oriented APIs, when the initial incoming packet is received, the packet PvD is remembered for the established connection and used for handling of outgoing traffic for that connection. While typically, connection-oriented APIs use a connection-oriented transport protocol, such as TCP, it is possible to have a connection- oriented API that uses a generally connectionless transport protocol, such as UDP. For APIs/protocols that support multiple IP traffic flows associated with a single transport API connection object (for example, multi path TCP), the processing rules may be adjusted accordingly. 5.2.3.1.2. Connectionless APIs For connectionless APIs, the host should provide an API that PvD- aware applications can use to query the PvD associated with the packet. For outgoing traffic on this transport API object, the OS should use the selected outgoing PvDs, determined as described above. 5.2.4. Enforcement of Security Policies By themselves, PvDs do not define, and cannot be used for communication of, security policies. When implemented in a network, this architecture provides the host with information about connected networks. The actual behavior of the host then depends on the host's policies (provisioned through mechanisms out of scope of this document), applied taking received PvD information into account. In some scenarios, e.g. a VPN, such policies could require the host to use only a particular VPN PvD for some / all of the application's traffic (VPN 'disable split tunneling' also known as 'force tunneling' behavior), or apply such restrictions only to selected applications and allow the simultaneous use of the VPN PvD together with the other connected PvDs by the other or all applications (VPN 'split tunneling' behavior). 5.3. Connectivity Tests Although some PvDs may appear as valid candidates for PvD selection (e.g. good link quality, consistent connection parameters, etc.), they may provide limited or no connectivity to the desired network or the Internet. For example, some PvDs provide limited IP connectivity (e.g., scoped to the link or to the access network), but require the node to authenticate through a web portal to get full access to the Internet. This may be more likely to happen for PvDs which are not trusted by a given PvD-aware node. An attempt to use such a PvD may lead to limited network connectivity or application connection failures. To prevent the latter, a PvD- aware node may perform a connectivity test for the PvD before using it to serve application network connection requests. In current implementations, some nodes already implement this e.g., by trying to Anipko Expires March 17, 2015 [Page 16] Internet-Draft MPVD architecture September 2014 reach a dedicated web server (see [RFC6419]). Section 5.2 describes how a PvD-aware node shall maintain and use multiple PvDs separately. The PvD-aware node shall perform a connectivity test and, only after validation of the PvD, consider using it to serve application connections requests. Ongoing connectivity tests are also required, since during the IP session, the end-to-end connectivity could be disrupted for various reasons (e.g. L2 problems, IP QoS issues); hence, a connectivity monitoring function is needed to check the connectivity status and remove the PvD from the set of usable PvDs if necessary. There may be cases where a connectivity test for PvD selection may not be appropriate and should be complemented, or replaced, by PvD selection based on other factors. For example, this could be realized by leveraging some 3GPP and IEEE mechanisms, which would allow the exposure of some PvD characteristics to the node (e.g. 3GPP Access Network Discovery and Selection Function (ANDSF) [TS23.402], IEEE 802.11u [IEEE802.11u]/ANQP). 5.4. Relationship to Interface Management and Connection Managers Current devices, such as mobile handsets make use of proprietary mechanisms and custom applications to manage connectivity in environments with multiple interfaces and multiple sets of network configuration. These mechanisms or applications are commonly known as connection managers [RFC6419]. Connection managers sometimes rely on policy servers to allow a node that is connected to multiple networks to perform network selection. They can also make use of routing guidance from the network (e.g. 3GPP ANDSF [TS23.402]). Although connection managers solve some connectivity problems, they rarely address network selection problems in a comprehensive manner. With proprietary solutions, it is challenging to present coherent behavior to the end user of the device, as different platforms present different behaviors even when connected to the same network, with the same type of interface, and for the same purpose. The architecture described in this document should improve the hosts behavior by providing the hosts with tools and guidance to make informed network selection decisions. 6. PvD support in APIs For all levels of PvD support in APIs described in this chapter, it is expected that the notifications about changes in the set of available PvDs are exposed as part of the API surface. 6.1. Basic Anipko Expires March 17, 2015 [Page 17] Internet-Draft MPVD architecture September 2014 Applications are not PvD-aware in any manner and only submit connection requests. The node performs PvD selection implicitly, without any application participation, based purely on node-specific administrative policies and / or choices made by the user from a user interface provided by the operating environment, not by the application. As an example, PvD selection can be done at the name service lookup step by using the relevant configuration elements, such as those described in [RFC6731]. As another example, PvD selection could be made based on application identity or type (i.e., a node could always use a particular PvD for a VOIP application). 6.2. Intermediate Applications indirectly participate in PvD selection by specifying hard requirements and soft preferences. As an example, a real time communication application intending to use the connection for the exchange of real time audio / video data may indicate a preference or a requirement for connection quality, which could affect PvD selection (different PvDs could correspond to Internet connections with different loss rates and latencies). Another example is the connection of an infrequently executed background activity, which checks for application updates and performs large downloads when updates are available. For such connections, a cheaper or zero cost PvD may be preferable, even if such a connection has a higher relative loss rate or lower bandwidth. The node performs PvD selection based on applications' inputs and policies and / or user preferences. Some / all properties of the resultant PvD may be exposed to applications. 6.3. Advanced PvDs are directly exposed to applications for enumeration and selection. Node polices and / or user choices may still override the applications' preferences and limit which PvD(s) can be enumerated and / or used by the application, irrespective of any preferences which the application may have specified. Depending on the implementation, such restrictions (imposed by node policy and / or user choice) may or may not be visible to the application. 7. PvD Trust for PvD-Aware Node 7.1. Untrusted PvDs Implicit and explicit PvDs for which no trust relationship exists are considered untrusted. Only PvDs which meet the requirements in Section 7.2 are trusted; any other PvD is untrusted. Anipko Expires March 17, 2015 [Page 18] Internet-Draft MPVD architecture September 2014 In order to avoid the various forms of misinformation that could occur when PvDs are untrusted, nodes that implement PvD separation cannot assume that two explicit PvDs with the same identifier are actually the same PvD. A node that makes this assumption will be vulnerable to attacks where, for example, an open Wifi hotspot might assert that it was part of another PvD and thereby attempt to draw traffic intended for that PvD onto its own network. Since implicit PvD identifiers are synthesized by the node, this issue cannot arise with implicit PvDs. Mechanisms exist (for example, [RFC6731]) whereby a PvD can provide configuration information that asserts special knowledge about the reachability of resources through that PvD. Such assertions cannot be validated unless the node has a trust relationship with the PvD; therefore, assertions of this type must be ignored by nodes that receive them from untrusted PvDs. Failure to ignore such assertions could result in traffic being diverted from legitimate destinations to spoofed destinations. 7.2. Trusted PvDs Trusted PvDs are PvDs for which two conditions apply: First, a trust relationship must exist between the node that is using the PvD configuration and the source that provided that configuration; this is the authorization portion of the trust relationship. Second, there must be some way to validate the trust relationship. This is the authentication portion of the trust relationship. Two mechanisms for validating the trust relationship are defined. It shall be possible to validate the trust relationship for all advertised elements of a trusted PvD, irrespective of whether the PvD elements are communicated as a whole, e.g., in a single DHCP option, or separately, e.g., in supplementary RA options. The feasibility of mechanisms to implement a trust relationship for all PvD elements will be determined in the respective companion design documents. 7.2.1. Authenticated PvDs One way to validate the trust relationship between a node and the source of a PvD is through the combination of cryptographic authentication and an identifier configured on the node. In some cases, the two could be the same; for example, if authentication is by a shared secret, the secret would have to be associated with the PvD identifier. Without a PvD Identifier / shared key tuple, authentication would be impossible, and hence authentication and authorization are combined. Anipko Expires March 17, 2015 [Page 19] Internet-Draft MPVD architecture September 2014 However, if authentication is done using a public key mechanism such as a TLS certificate or DANE, authentication by itself is not enough since theoretically any PvD could be authenticated in this way. In addition to authentication, the node would need configuration to trust the identifier being authenticated. Validating the authenticated PvD name against a list of PvD names configured as trusted on the node would constitute the authorization step in this case. 7.2.2. PvDs Trusted by Attachment In some cases, a trust relationship may be validated by some means other than those described in Section 7.2.1 simply by virtue of the connection through which the PvD was obtained. For instance, a handset connected to a mobile network may know through the mobile network infrastructure that it is connected to a trusted PvD. Whatever mechanism was used to validate that connection constitutes the authentication portion of the PvD trust relationship. Presumably, such a handset would be configured from the factory (or else through mobile operator or user preference settings) to trust the PvD, and this would constitute the authorization portion of this type of trust relationship. 8. Contributors The following individuals contributed to this document (listed in no specific order): Alper Yegin (alper.yegin@yegin.org), Aaron Yi Ding (yding@cs.helsinki.fi), Zhen Cao (caozhenpku@gmail.com), Dapeng Liu (liudapeng@chinamobile.com), Dave Thaler (dthaler@microsoft.com), Dmitry Anipko (dmitry.anipko@microsoft.com), Hui Deng (denghui@chinamobile.com), Jouni Korhonen (jouni.nospam@gmail.com), Juan Carlos Zuniga (JuanCarlos.Zuniga@InterDigital.com), Konstantinos Pentikousis (k.pentikousis@huawei.com), Marc Blanchet (marc.blanchet@viagenie.ca), Margaret Wasserman (margaretw42@gmail.com), Pierrick Seite (pierrick.seite@orange.com), Suresh Krishnan (suresh.krishnan@ericsson.com), Teemu Savolainen (teemu.savolainen@nokia.com), Ted Lemon (ted.lemon@nominum.com) and Tim Chown (tjc@ecs.soton.ac.uk). 9. Acknowledgments The authors would like to thank (in no specific order) Ian Farrer, Marcus Stenberg and Mikael Abrahamsson for their review and comments. 10. IANA Considerations This memo does not include any IANA requests. 11. Security Considerations There are at least three different forms of attacks that can be performed using configuration sources that support multiple provisioning domains. Anipko Expires March 17, 2015 [Page 20] Internet-Draft MPVD architecture September 2014 Tampering with provided configuration information: An attacker may attempt to modify information provided inside the PvD container option. These attacks can easily be prevented by using message integrity features provided by the underlying protocol used to carry the configuration information. E.g. SEND [RFC3971] would detect any form of tampering with the RA contents and the DHCPv6 [RFC3315] AUTH option that would detect any form of tampering with the DHCPv6 message contents. This attack can also be performed by a compromised configuration source by modifying information inside a specific PvD, in which case the mitigations proposed in the next subsection may be helpful. Rogue configuration source: A compromised configuration source, such as a router or a DHCPv6 server, may advertise information about PvDs that it is not authorized to advertise. e.g. A coffee shop WLAN may advertise configuration information purporting to be from an enterprise and may try to attract enterprise related traffic. The only real way to prevent this is is for the PvD related configuration container to contain embedded authentication and authorization information from the owner of the PvD. This provides the client with a way of detecting the attack by verifying the authentication and authorization information provided inside the PvD container option, after verifying its trust of the PvD owner (e.g. a certificate with a well-known / common trust anchor). Replay attacks: A compromised configuration source or an on-link attacker may try to capture advertised configuration information and replay it on a different link, or at a future point in time. This can be avoided by including a replay protection mechanism such as a timestamp or a nonce inside the PvD container to ensure the validity of the provided information. 12. References 12.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 12.2. Informative References [I-D.bhandari-dhc-class-based-prefix] Systems, C., Halwasia, G., Gundavelli, S., Deng, H., Thiebaut, L., Korhonen, J. and I. Farrer, "DHCPv6 class based prefix", Internet-Draft draft-bhandari-dhc-class- based-prefix-05, July 2013. [I-D.korhonen-dmm-prefix-properties] Korhonen, J., Patil, B., Gundavelli, S., Seite, P. and D. Liu, "IPv6 Prefix Mobility Management Properties", Internet-Draft draft-korhonen-dmm-prefix-properties-03, October 2012. Anipko Expires March 17, 2015 [Page 21] Internet-Draft MPVD architecture September 2014 [IEEE802.11u] IEEE, "IEEE Standard 802.11u-2011 (Amendment 9: Interworking with External Networks)", 2011. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. [RFC3971] Arkko, J., Kempf, J., Zill, B. and P. Nikander, "SEcure Neighbor Discovery (SEND)", RFC 3971, March 2005. [RFC4861] Narten, T., Nordmark, E., Simpson, W. and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, September 2007. [RFC5739] Eronen, P., Laganier, J. and C. Madson, "IPv6 Configuration in Internet Key Exchange Protocol Version 2 (IKEv2)", RFC 5739, February 2010. [RFC5996] Kaufman, C., Hoffman, P., Nir, Y. and P. Eronen, "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC 5996, September 2010. [RFC6182] Ford, A., Raiciu, C., Handley, M., Barre, S. and J. Iyengar, "Architectural Guidelines for Multipath TCP Development", RFC 6182, March 2011. [RFC6418] Blanchet, M. and P. Seite, "Multiple Interfaces and Provisioning Domains Problem Statement", RFC 6418, November 2011. [RFC6419] Wasserman, M. and P. Seite, "Current Practices for Multiple-Interface Hosts", RFC 6419, November 2011. [RFC6555] Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with Dual-Stack Hosts", RFC 6555, April 2012. [RFC6724] Thaler, D., Draves, R., Matsumoto, A. and T. Chown, "Default Address Selection for Internet Protocol Version 6 (IPv6)", RFC 6724, September 2012. [RFC6731] Savolainen, T., Kato, J. and T. Lemon, "Improved Recursive DNS Server Selection for Multi-Interfaced Nodes", RFC 6731, December 2012. [RFC7078] Matsumoto, A., Fujisaki, T. and T. Chown, "Distributing Address Selection Policy Using DHCPv6", RFC 7078, January 2014. [TS23.402] 3GPP, "3GPP TS 23.402; Architecture enhancements for non- 3GPP accesses; release 12", . Anipko Expires March 17, 2015 [Page 22] Internet-Draft MPVD architecture September 2014 Author's Address Dmitry Anipko, editor Microsoft Corporation One Microsoft Way Redmond, WA 98052 USA Phone: +1 425 703 7070 Email: dmitry.anipko@microsoft.com Anipko Expires March 17, 2015 [Page 23]