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Network Working Group                                       T. HendersonRequest for Comments: 5338                            The Boeing CompanyCategory: Informational                                      P. Nikander                                            Ericsson Research NomadicLab                                                                 M. Komu                           Helsinki Institute for Information Technology                                                          September 2008Using the Host Identity Protocol with Legacy ApplicationsStatus of This Memo   This memo provides information for the Internet community.  It does   not specify an Internet standard of any kind.  Distribution of this   memo is unlimited.Abstract   This document is an informative overview of how legacy applications   can be made to work with the Host Identity Protocol (HIP).  HIP   proposes to add a cryptographic name space for network stack names.   From an application viewpoint, HIP-enabled systems support a new   address family of host identifiers, but it may be a long time until   such HIP-aware applications are widely deployed even if host systems   are upgraded.  This informational document discusses implementation   and Application Programming Interface (API) issues relating to using   HIP in situations in which the system is HIP-aware but the   applications are not, and is intended to aid implementors and early   adopters in thinking about and locally solving systems issues   regarding the incremental deployment of HIP.Henderson, et al.            Informational                      [Page 1]

RFC 5338           Using HIP with Legacy Applications     September 2008Table of Contents1. Introduction ....................................................22. Terminology .....................................................33. Enabling HIP Transparently within the System ....................43.1. Applying HIP to Cases in Which IP Addresses Are Used .......43.2. Interposing a HIP-Aware Agent in the DNS Resolution ........63.3. Discussion .................................................74. Users Invoking HIP with a Legacy Application ....................84.1. Connecting to a HIT or LSI .................................84.2. Using a Modified DNS Name ..................................94.3. Other Techniques ...........................................95. Local Address Management ........................................96. Security Considerations ........................................117. Acknowledgments ................................................128. Informative References .........................................121.  Introduction   The Host Identity Protocol (HIP) [RFC5201] is an experimental effort   in the IETF and IRTF to study a new public-key-based name space for   use as host identifiers in Internet protocols.  Fully deployed, the   HIP architecture would permit applications and users to explicitly   request the system to send packets to another host by expressing a   location-independent unique name of a peer host when the system call   to connect or send packets is performed.  However, there will be a   transition period during which systems become HIP-enabled but   applications are not.  This informational document does not propose   normative specification or even suggest that different HIP   implementations use more uniform methods for legacy application   support, but is intended instead to aid implementors and early   adopters in thinking about and solving systems issues regarding the   incremental deployment of HIP.   When applications and systems are both HIP-aware, the coordination   between the application and the system can be straightforward.  For   example, using the terminology of the widely used sockets Application   Programming Interface (API), the application can issue a system call   to send packets to another host by naming it explicitly, and the   system can perform the necessary name-to-address mapping to assign   appropriate routable addresses to the packets.  To enable this, a new   address family for hosts could be defined, and additional API   extensions could be defined (such as allowing IP addresses to be   passed in the system call, along with the host name, as hints of   where to initially try to reach the host).Henderson, et al.            Informational                      [Page 2]

RFC 5338           Using HIP with Legacy Applications     September 2008   This document does not define a native HIP API such as described   above.  Rather, this document is concerned with the scenario in which   the application is not HIP-aware and a traditional IP-address-based   API is used by the application.   The discussion so far assumes that applications are written directly   to a sockets API.  However, many applications are built on top of   middleware that exports a higher-level API to the application.  In   this case, for the purpose of this document, we refer to the   combination of the middleware and the middleware-based application as   an overall application, or client of the sockets API.   When HIP is enabled on a system, but the applications are not HIP-   aware, there are a few basic possibilities to use HIP, each of which   may or may not be supported by a given HIP implementation.  We report   here on techniques that have been used or considered by experimental   HIP implementations.  We organize the discussion around the policy   chosen to use or expose HIP to the applications.  The first option is   that users are completely unaware of HIP, or are unable to control   whether or not HIP is invoked, but rather the system chooses to   enable HIP for some or all sessions based on policy.  The second   option is that the user makes a decision to try to use HIP by   conveying this information somehow within the constraints of the   unmodified application.  We discuss both of these use cases in detail   below.   HIP was designed to work with unmodified applications, to ease   incremental deployment.  For instance, the HIT is the same size as   the IPv6 address, and the design thinking was that, during initial   experiments and transition periods, the HITs could substitute in data   structures where IPv6 addresses were expected.  However, to a varying   degree depending on the mechanism employed, such use of HIP can alter   the semantics of what is considered to be an IP address by   applications.  Applications use IP addresses as short-lived local   handles, long-lived application associations, callbacks, referrals,   and identity comparisons [APP-REF].  The transition techniques   described below have implications on these different uses of IP   addresses by legacy applications, and we will try to clarify these   implications in the below discussions.2.  Terminology   Callback:   The application at one end retrieves the IP address of      the peer and uses that to later communicate "back" to the peer.      An example is the FTP PORT command.   Host Identity:  An abstract concept applied to a computing platform.Henderson, et al.            Informational                      [Page 3]

RFC 5338           Using HIP with Legacy Applications     September 2008   Host Identifier (HI):  A public key of an asymmetric key pair used as      a name for a Host Identity.  More details are available in      [RFC5201].   Host Identity Tag (HIT):  A 128-bit quantity composed with the hash      of a Host Identity.  More details are available in [RFC4843] and      [RFC5201].   Local Scope Identifier (LSI):  A 32- or 128-bit quantity locally      representing the Host Identity at the IPv4 or IPv6 API.   Long-lived application associations:  The IP address is retained by      the application for several instances of communication.   Referral:   In an application with more than two parties, party B      takes the IP address of party A and passes that to party C.  After      this, party C uses the IP address to communicate with A.   Resolver:  The system function used by applications to resolve domain      names to IP addresses.   Short-lived local handle:  The IP addresses is never retained by the      application.  The only usage is for the application to pass it      from the DNS APIs (e.g., getaddrinfo()) and the API to the      protocol stack (e.g., connect() or sendto()).3.  Enabling HIP Transparently within the System   When both users and applications are unaware of HIP, but the host   administrator chooses to use HIP between hosts, a few options are   possible.  The first basic option is to perform a mapping of the   application-provided IP address to a host identifier within the   stack.  The second option, if DNS is used, is to interpose a local   agent in the DNS resolution process and to return to the application   a HIT or a locally scoped handle, formatted like an IP address.3.1.  Applying HIP to Cases in Which IP Addresses Are Used   Consider the case in which an application issues a "connect(ip)"   system call to set the default destination to a system named by   address "ip", but for which the host administrator would like to   enable HIP to protect the communications.  The user or application   intends for the system to communicate with the host reachable at that   IP address.  The decision to invoke HIP must be done on the basis of   host policy.  For example, when an IPsec-based implementation of HIP   is being used, a policy may be entered into the security policy   database that mandates to use or to try HIP based on a match on the   source or destination IP address, port numbers, or other factors.Henderson, et al.            Informational                      [Page 4]

RFC 5338           Using HIP with Legacy Applications     September 2008   The mapping of IP address to host identifier may be implemented by   modifying the host operating system or by wrapping the existing   sockets API, such as in the TESLA approach [TESLA].   There are a number of ways that HIP could be configured by the host   administrator in such a scenario.   Manual configuration:      Pre-existing Security Associations (SAs) may be available due to      previous administrative action, or a binding between an IP address      and a HIT could be stored in a configuration file or database.   Opportunistically:      The system could send an I1 to the Responder with an empty value      for Responder HIT.   Using DNS to map IP addresses to HIs:      If the Responder has host identifiers registered in the forward      DNS zone and has a PTR record in the reverse zone, the Initiator      could perform a reverse+forward lookup to learn the HIT associated      with the address.  Although the approach should work under normal      circumstances, it has not been tested to verify that there are no      recursion or bootstrapping issues, particularly if HIP is used to      secure the connection to the DNS servers.  Discussion of the      security implications of the use or absence of DNS Security      (DNSSEC) is deferred to the Security Considerations section.   Using HIP in the above fashion can cause additional setup delays   compared to using plain IP.  For opportunistic mode, a host must wait   to learn whether the peer is HIP-capable, although the delays may be   mitigated in some implementations by sending initial packets (e.g.,   TCP SYN) in parallel to the HIP I1 packet and waiting some time to   receive a HIP R1 before processing a TCP SYN/ACK.  Note that there   presently does not exist specification for how to invoke such   connections in parallel.  Resolution latencies may also be incurred   when using DNS in the above fashion.   A possible way to reduce the above-noted latencies, in the case that   the application uses DNS, would be for the system to   opportunistically query for HIP records in parallel to other DNS   resource records, and to temporarily cache the HITs returned with a   DNS lookup, indexed by the IP addresses returned in the same entry,   and pass the IP addresses up to the application as usual.  If an   application connects to one of those IP addresses within a short time   after the lookup, the host should initiate a base exchange using theHenderson, et al.            Informational                      [Page 5]

RFC 5338           Using HIP with Legacy Applications     September 2008   cached HITs.  The benefit is that this removes the uncertainty/delay   associated with opportunistic HIP, because the DNS record suggests   that the peer is HIP-capable.3.2.  Interposing a HIP-Aware Agent in the DNS Resolution   In the previous section, it was noted that a HIP-unaware application   might typically use the DNS to fetch IP addresses prior to invoking   socket calls.  A HIP-enabled system might make use of DNS to   transparently fetch host identifiers for such domain names prior to   the onset of communication.   A system with a local DNS agent could alternately return a Local   Scope Identifier (LSI) or HIT rather than an IP address, if HIP   information is available in the DNS or other directory that binds a   particular domain name to a host identifier, and otherwise to return   an IP address as usual.  The system can then maintain a mapping   between LSI and host identifier and perform the appropriate   conversion at the system call interface or below.  The application   uses the LSI or HIT as it would an IP address.  This technique has   been used in overlay networking experiments such as the Internet   Indirection Infrastructure (i3) and by at least one HIP   implementation.   In the case when resolvers can return multiple destination   identifiers for an application, it may be configured that some of the   identifiers can be HIP-based identifiers, and the rest can be IPv4 or   IPv6 addresses.  The system resolver may return HIP-based identifiers   in front of the list of identifiers when the underlying system and   policies support HIP.  An application processing the identifiers   sequentially will then first try a HIP-based connection and only then   other non-HIP based connections.  However, certain applications may   launch the connections in parallel.  In such a case, the non-HIP   connections may succeed before HIP connections.  Based on local   system policies, a system may disallow such behavior and return only   HIP-based identifiers when they are found from DNS.   If the application obtains LSIs or HITs that it treats as IP   addresses, a few potential hazards arise.  First, applications that   perform referrals may pass the LSI to another system that has no   system context to resolve the LSI back to a host identifier or an IP   address.  Note that these are the same type of applications that will   likely break if used over certain types of network address   translators (NATs).  Second, applications may cache the results of   DNS queries for a long time, and it may be hard for a HIP system to   determine when to perform garbage collection on the LSI bindings.   However, when using HITs, the security of using the HITs for identity   comparison may be stronger than in the case of using IP addresses.Henderson, et al.            Informational                      [Page 6]

RFC 5338           Using HIP with Legacy Applications     September 2008   Finally, applications may generate log files, and administrators or   other consumers of these log files may become confused to find LSIs   or HITs instead of IP addresses.  Therefore, it is recommended that   the HIP software logs the HITs, LSIs (if applicable), corresponding   IP addresses, and Fully Qualified Domain Name (FQDN)-related   information so that administrators can correlate other logs with HIP   identifiers.   It may be possible for an LSI or HIT to be routable or resolvable,   either directly or through an overlay, in which case it would be   preferable for applications to handle such names instead of IP   addresses.  However, such networks are out of scope of this document.3.3.  Discussion   Solutions preserving the use of IP addresses in the applications have   the benefit of better support for applications that use IP addresses   for long-lived application associations, callbacks, and referrals,   although it should be noted that applications are discouraged from   using IP addresses in this manner due to the frequent presence of   NATs [RFC1958].  However, they have weaker security properties than   the approaches outlined inSection 3.2 andSection 4, because the   binding between host identifier and address is weak and not visible   to the application or user.  In fact, the semantics of the   application's "connect(ip)" call may be interpreted as "connect me to   the system reachable at IP address ip" but perhaps no stronger   semantics than that.  HIP can be used in this case to provide perfect   forward secrecy and authentication, but not to strongly authenticate   the peer at the onset of communications.   Using IP addresses at the application layer may not provide the full   potential benefits of HIP mobility support.  It allows for mobility   if the system is able to readdress long-lived, connected sockets upon   a HIP readdress event.  However, as in current systems, mobility will   break in the connectionless case, when an application caches the IP   address and repeatedly calls sendto(), or in the case of TCP when the   system later opens additional sockets to the same destination.Section 4.1.6 of the base HIP protocol specification [RFC5201] states   that implementations that learn of HIT-to-IP address bindings through   the use of HIP opportunistic mode must not enforce those bindings on   later communications sessions.  This implies that when IP addresses   are used by the applications, systems that attempt to   opportunistically set up HIP must not assume that later sessions to   the same address will communicate with the same host.Henderson, et al.            Informational                      [Page 7]

RFC 5338           Using HIP with Legacy Applications     September 2008   The legacy application is unaware of HIP and therefore cannot notify   the user when the application uses HIP.  However, the operating   system can notify the user of the usage of HIP through a user agent.   Further, it is possible for the user agent to name the network   application that caused a HIP-related event.  This way, the user is   aware when he or she is using HIP even though the legacy network   application is not.  Based on usability tests from initial   deployments, displaying the HITs and LSIs should be avoided in user   interfaces.  Instead, traditional security measures (lock pictures,   colored address bars) should be used where possible.   One drawback to spoofing the DNS resolution is that some   applications, or selected instances of an application, actually may   want to fetch IP addresses (e.g., diagnostic applications such as   ping).  One way to provide finer granularity on whether the resolver   returns an IP address or an LSI is to have the user form a modified   domain name when he or she wants to invoke HIP.  This leads us to   consider, in the next section, use cases for which the end user   explicitly and selectively chooses to enable HIP.4.  Users Invoking HIP with a Legacy Application   The previous section described approaches for configuring HIP for   legacy applications that did not necessarily involve the user.   However, there may be cases in which a legacy application user wants   to use HIP for a given application instance by signaling to the HIP-   enabled system in some way.  If the application user interface or   configuration file accepts IP addresses, there may be an opportunity   to provide a HIT or an LSI in its place.  Furthermore, if the   application uses DNS, a user may provide a specially crafted domain   name to signal to the resolver to fetch HIP records and to signal to   the system to use HIP.  We describe both of these approaches below.4.1.  Connecting to a HIT or LSISection 3.2 above describes the use of HITs or LSIs as spoofed return   values of the DNS resolution process.  A similar approach that is   more explicit is to configure the application to connect directly to   a HIT (e.g., "connect(HIT)" as a socket call).  This scenario has   stronger security semantics, because the application is asking the   system to send packets specifically to the named peer system.  HITs   have been defined as Overlay Routable Cryptographic Hash Identifiers   (ORCHIDs) such that they cannot be confused with routable IP   addresses; see [RFC4843].   This approach also has a few challenges.  Using HITs can be more   cumbersome for human users (due to the flat HIT name space) than   using either IPv6 addresses or domain names.  Another challenge withHenderson, et al.            Informational                      [Page 8]

RFC 5338           Using HIP with Legacy Applications     September 2008   this approach is in actually finding the IP addresses to use, based   on the HIT.  Some type of HIT resolution service would be needed in   this case.  A third challenge of this approach is in supporting   callbacks and referrals to possibly non-HIP-aware hosts.  However,   since most communications in this case would likely be to other HIP-   aware hosts (else the initial HIP associations would fail to   establish), the resulting referral problem may be that the peer host   supports HIP but is not able to perform HIT resolution for some   reason.4.2.  Using a Modified DNS Name   Specifically, if the application requests to resolve "HIP-   www.example.com" (or some similar prefix string), then the system   returns an LSI, while if the application requests to resolve   "www.example.com", IP address(es) are returned as usual.  The use of   a prefix rather than suffix is recommended, and the use of a string   delimiter that is not a dot (".") is also recommended, to reduce the   likelihood that such modified DNS names are mistakenly treated as   names rooted at a new top-level domain.  Limits of domain name length   or label length (255 or 63, respectively) should be considered when   prepending any prefixes.4.3.  Other Techniques   Alternatives to using a modified DNS name that have been experimented   with include the following.  Command-line tools or tools with a   graphical user interface (GUI) can be provided by the system to allow   a user to set the policy on which applications use HIP.  Another   common technique, for dynamically linked applications, is to   dynamically link the application to a modified library that wraps the   system calls and interposes HIP layer communications on them; this   can be invoked by the user by running commands through a special   shell, for example.5.  Local Address Management   The previous two sections focused mainly on controlling client   behavior (HIP initiator).  We must also consider the behavior for   servers.  Typically, a server binds to a wildcard IP address and   well-known port.  In the case of HIP use with legacy server   implementations, there are again a few options.  The system may be   configured manually to always, optionally (depending on the client   behavior), or never use HIP with a particular service, as a matter of   policy, when the server specifies a wildcard (IP) address.Henderson, et al.            Informational                      [Page 9]

RFC 5338           Using HIP with Legacy Applications     September 2008   When a system API call such as getaddrinfo [RFC3493] is used for   resolving local addresses, it may also return HITs or LSIs, if the   system has assigned HITs or LSIs to internal virtual interfaces   (common in many HIP implementations).  The application may use such   identifiers as addresses in subsequent socket calls.   Some applications may try to bind a socket to a specific local   address, or may implement server-side access control lists based on   socket calls such as getsockname() and getpeername() in the C-based   socket APIs.  If the local address specified is an IP address, again,   the underlying system may be configured to still use HIP.  If the   local address specified is a HIT (Section 4), the system should   enforce that connections to the local application can only arrive to   the specified HIT.  If a system has many HIs, an application that   binds to a single HIT cannot accept connections to the other HIs but   the one corresponding to the specified HIT.   When a host has multiple HIs and the socket behavior does not   prescribe the use of any particular HI as a local identifier, it is a   matter of local policy as to how to select a HI to serve as a local   identifier.  However, systems that bind to a wildcard may face   problems when multiple HITs or LSIs are defined.  These problems are   not specific to HIP per se, but are also encountered in non-HIP   multihoming scenarios with applications not designed for multihoming.   As an example, consider a client application that sends a UDP   datagram to a server that is bound to a wildcard.  The server   application receives the packet using recvfrom() and sends a response   using sendto().  The problem here is that sendto() may actually use a   different server HIT than the client assumes.  The client will drop   the response packet when the client implements access control on the   UDP socket (e.g., using connect()).   Reimplementing the server application using the sendmsg() and   recvmsg() to support multihoming (particularly considering the   ancillary data) would be the ultimate solution to this problem, but   with legacy applications is not an option.  As a workaround, we make   suggestion for servers providing UDP-based services with non-   multihoming-capable services.  Such servers should announce only the   HIT or public key that matches to the default outgoing HIT of the   host to avoid such problems.   Finally, some applications may create a connection to a local HIT.   In such a case, the local system may use NULL encryption to avoid   unnecessary encryption overhead, and may be otherwise more permissive   than usual such as excluding authentication, Diffie-Hellman exchange,   and puzzle.Henderson, et al.            Informational                     [Page 10]

RFC 5338           Using HIP with Legacy Applications     September 20086.  Security Considerations   In this section, we discuss the security of the system in general   terms, outlining some of the security properties.  However, this   section is not intended to provide a complete risk analysis.  Such an   analysis would, in any case, be dependent on the actual application   using HIP, and is therefore considered out of scope.   The scenarios outlined above differ considerably in their security   properties.  When the DNS is used, there are further differences   related to whether or not DNSSEC [RFC4033] is used, and whether the   DNS zones are considered trustworthy enough.  Here we mean that there   should exist a delegation chain to whatever trust anchors are   available in the respective trees, and the DNS zone administrators in   charge of the netblock should be trusted to put in the right   information.   When IP addresses are used by applications to name the peer system,   the security properties depend on the configuration method.  With   manual configuration, the security of the system is comparable to a   non-HIP system with similar IPsec policies.  The security semantics   of an initial opportunistic key exchange are roughly equal to non-   secured IP; the exchange is vulnerable to man-in-the-middle attacks.   However, the system is less vulnerable to connection hijacking   attacks.  If the DNS is used, if both zones are secured (or the HITs   are stored in the reverse DNS record) and the client trusts the   DNSSEC signatures, the system may provide a fairly high security   level.  However, much depends on the details of the implementation,   the security and administrative practices used when signing the DNS   zones, and other factors.   Using the forward DNS to map a domain name into an LSI is a case that   is closest to the most typical use scenarios today.  If DNSSEC is   used, the result is fairly similar to the current use of certificates   with Transport Layer Security (TLS).  If DNSSEC is not used, the   result is fairly similar to the current use of plain IP, with the   additional protection of data integrity, confidentiality, and   prevention of connection hijacking that opportunistic HIP provides.   If DNSSEC is used, data integrity and data origin authentication   services are added to the normal DNS query protocol, thereby   providing more certainty that the desired host is being contacted, if   the DNS records themselves are trustworthy.Henderson, et al.            Informational                     [Page 11]

RFC 5338           Using HIP with Legacy Applications     September 2008   If the application is basing its operations on HITs, the connections   become automatically secured due to the implicit channel bindings in   HIP.  That is, when the application makes a connect(HIT) system call,   either the resulting packets will be sent to a node possessing the   corresponding private key or the security association will fail to be   established.   When the system provides (spoofs) LSIs or HITs instead of IP   addresses as the result of name resolution, the resultant fields may   inadvertently show up in user interfaces and system logs, which may   cause operational concerns for some network administrators.   Therefore, it is recommended that the HIP software logs the HITs,   LSIs (if applicable), corresponding IP addresses, and FQDN-related   information so that administrators can correlate other logs with HIP   identifiers.7.  Acknowledgments   Jeff Ahrenholz, Gonzalo Camarillo, Alberto Garcia, Teemu Koponen,   Julien Laganier, and Jukka Ylitalo have provided comments on   different versions of this document.  The document received   substantial and useful comments during the review phase from David   Black, Lars Eggert, Peter Koch, Thomas Narten, and Pekka Savola.8.  Informative References   [RFC5201]  Moskowitz, R., Nikander, P., Jokela, P., Ed., and T.              Henderson, "Host Identity Protocol",RFC 5201, April 2008.   [RFC4843]   Nikander, P., Laganier, J., and F. Dupont, "An IPv6              Prefix for Overlay Routable Cryptographic Hash Identifiers              (ORCHID)",RFC 4843, April 2007.   [TESLA]     Salz, J., Balakrishnan, H., and A. Snoeren, "TESLA:  A              Transparent, Extensible Session-Layer Architecture for              End-to-end Network Services",  Proceedings of USENIX              Symposium on Internet Technologies and Systems (USITS),              pages 211-224, March 2003.   [RFC1958]  Carpenter, B., Ed., "Architectural Principles of the              Internet",RFC 1958, June 1996.   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.              Rose, "DNS Security Introduction and Requirements",RFC4033, March 2005.Henderson, et al.            Informational                     [Page 12]

RFC 5338           Using HIP with Legacy Applications     September 2008   [RFC3493]  Gilligan, R., Thomson, S., Bound, J., McCann, J., and W.              Stevens, "Basic Socket Interface Extensions for IPv6",RFC3493, February 2003.   [APP_REF]  Nordmark, E.,"Shim6 Application Referral Issues", Work in              Progress, July 2005.Authors' Addresses   Thomas Henderson   The Boeing Company   P.O. Box 3707   Seattle, WA   USA   EMail: thomas.r.henderson@boeing.com   Pekka Nikander   Ericsson Research NomadicLab   JORVAS  FIN-02420   FINLAND   Phone: +358 9 299 1   EMail: pekka.nikander@nomadiclab.com   Miika Komu   Helsinki Institute for Information Technology   Metsaenneidonkuja 4   Helsinki  FIN-02420   FINLAND   Phone: +358503841531   EMail: miika@iki.fiHenderson, et al.            Informational                     [Page 13]

RFC 5338           Using HIP with Legacy Applications     September 2008Full Copyright Statement   Copyright (C) The IETF Trust (2008).   This document is subject to the rights, licenses and restrictions   contained inBCP 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 inBCP 78 andBCP 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 athttp://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.Henderson, et al.            Informational                     [Page 14]