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Checking references for intended status: Informational ---------------------------------------------------------------------------- -- Obsolete informational reference (is this intentional?): RFC 5201 (Obsoleted by RFC 7401) -- Obsolete informational reference (is this intentional?): RFC 4843 (Obsoleted by RFC 7343) Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 9 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group T. Henderson 3 Internet-Draft The Boeing Company 4 Intended status: Informational P. Nikander 5 Expires: December 30, 2008 Ericsson Research NomadicLab 6 M. Komu 7 Helsinki Institute for Information 8 Technology 9 June 28, 2008 11 Using the Host Identity Protocol with Legacy Applications 12 draft-ietf-hip-applications-03 14 Status of this Memo 16 By submitting this Internet-Draft, each author represents that any 17 applicable patent or other IPR claims of which he or she is aware 18 have been or will be disclosed, and any of which he or she becomes 19 aware will be disclosed, in accordance with Section 6 of BCP 79. 21 Internet-Drafts are working documents of the Internet Engineering 22 Task Force (IETF), its areas, and its working groups. Note that 23 other groups may also distribute working documents as Internet- 24 Drafts. 26 Internet-Drafts are draft documents valid for a maximum of six months 27 and may be updated, replaced, or obsoleted by other documents at any 28 time. It is inappropriate to use Internet-Drafts as reference 29 material or to cite them other than as "work in progress." 31 The list of current Internet-Drafts can be accessed at 32 http://www.ietf.org/ietf/1id-abstracts.txt. 34 The list of Internet-Draft Shadow Directories can be accessed at 35 http://www.ietf.org/shadow.html. 37 This Internet-Draft will expire on December 30, 2008. 39 Abstract 41 This document is an informative overview of how legacy applications 42 can be made to work with the Host Identity Protocol (HIP). HIP 43 proposes to add a cryptographic name space for network stack names. 44 From an application viewpoint, HIP-enabled systems support a new 45 address family of host identifiers, but it may be a long time until 46 such HIP-aware applications are widely deployed even if host systems 47 are upgraded. This informational document discusses implementation 48 and Application Programming Interface (API) issues relating to using 49 HIP in situations in which the system is HIP-aware but the 50 applications are not, and is intended to aid implementors and early 51 adopters in thinking about and locally solving systems issues 52 regarding the incremental deployment of HIP. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 57 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 58 3. Enabling HIP transparently within the system . . . . . . . . . 6 59 3.1. Applying HIP to cases in which IP addresses are used . . . 6 60 3.2. Interposing a HIP-aware agent in the DNS resolution . . . 7 61 3.3. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 8 62 4. Users Invoking HIP with a Legacy Application . . . . . . . . . 10 63 4.1. Connecting to a HIT or LSI . . . . . . . . . . . . . . . . 10 64 4.2. Using a modified DNS name . . . . . . . . . . . . . . . . 10 65 4.3. Other techniques . . . . . . . . . . . . . . . . . . . . . 11 66 5. Local address management . . . . . . . . . . . . . . . . . . . 12 67 6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 68 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 69 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 70 9. Informative References . . . . . . . . . . . . . . . . . . . . 18 71 Appendix A. Changes from previous versions . . . . . . . . . . . 19 72 A.1. From version-01 to version-02 . . . . . . . . . . . . . . 19 73 A.2. From version-02 to version-03 (current) . . . . . . . . . 20 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21 75 Intellectual Property and Copyright Statements . . . . . . . . . . 22 77 1. Introduction 79 The Host Identity Protocol (HIP) [RFC5201] is an experimental effort 80 in the IETF and IRTF to study a new public-key-based name space for 81 use as host identifiers in Internet protocols. Fully deployed, the 82 HIP architecture would permit applications and users to explicitly 83 request the system to send packets to another host by expressing a 84 location-independent unique name of a peer host when the system call 85 to connect or send packets is performed. However, there will be a 86 transition period during which systems become HIP-enabled but 87 applications are not. This informational document does not propose 88 normative specification or even suggest that different HIP 89 implementations use more uniform methods for legacy application 90 support, but is intended instead to aid implementors and early 91 adopters in thinking about and solving systems issues regarding the 92 incremental deployment of HIP. 94 When applications and systems are both HIP-aware, the coordination 95 between the application and the system can be straightforward. For 96 example, using the terminology of the widely used sockets Application 97 Programming Interface (API), the application can issue a system call 98 to send packets to another host by naming it explicitly, and the 99 system can perform the necessary name-to-address mapping to assign 100 appropriate routable addresses to the packets. To enable this, a new 101 address family for hosts could be defined, and additional API 102 extensions could be defined (such as allowing IP addresses to be 103 passed in the system call, along with the host name, as hints of 104 where to initially try to reach the host). 106 This document does not define a native HIP API such as described 107 above. Rather, this document is concerned with the scenario in which 108 the application is not HIP-aware and a traditional IP-address-based 109 API is used by the application. 111 The discussion so far assumes that applications are written directly 112 to a sockets API. However, many applications are built on top of 113 middleware that exports a higher-level API to the application. In 114 this case, for the purpose of this document, we refer to the 115 combination of the middleware and the middleware- based application 116 as an overall application, or client of the sockets API. 118 When HIP is enabled on a system, but the applications are not HIP- 119 aware, there are a few basic possibilities to use HIP, each of which 120 may or may not be supported by a given HIP implementation. We report 121 here on techniques that have been used or considered by experimental 122 HIP implementations. We organize the discussion around the policy 123 chosen to use or expose HIP to the applications. The first option is 124 that users are completely unaware of HIP, or are unable to control 125 whether or not HIP is invoked, but rather the system chooses to 126 enable HIP for some or all sessions based on policy. The second 127 option is that the user makes a decision to try to use HIP by 128 conveying this information somehow within the constraints of the 129 unmodified application. We discuss both of these use cases in detail 130 below. 132 HIP was designed to work with unmodified applications, to ease 133 incremental deployment. For instance, the HIT is the same size as 134 the IPv6 address, and the design thinking was that, during initial 135 experiments and transition periods, the HITs could substitute in data 136 structures where IPv6 addresses were expected. However, to a varying 137 degree depending on the mechanism employed, such use of HIP can alter 138 the semantics of what is considered to be an IP address by 139 applications. Applications use IP addresses as short-lived local 140 handles, long-lived application associations, callbacks, referrals, 141 and identity comparisons. The transition techniques described below 142 have implications on these different uses of IP addresses by legacy 143 applications, and we will try to clarify these implications in the 144 below discussions. 146 2. Terminology 148 Callback: The application at one end retrieves the IP address of 149 the peer and uses that to later communicate "back" to the peer. 150 An example is the FTP PORT command. 152 Host Identity: An abstract concept applied to a computing platform. 154 Host Identifier (HI): A public key of an asymmetric key pair used as 155 a name for a Host Identity. More details are available in 156 [RFC5201]. 158 Host Identity Tag (HIT): A 128-bit quantity composed with the hash 159 of a Host Identity. More details are available in [RFC4843] and 160 [RFC5201]. 162 Local Scope Identifier (LSI): A 32- or 128-bit quantity locally 163 representing the Host Identity at the IPv4 or IPv6 API. 165 Referral: In an application with more than two parties, party B 166 takes the IP address of party A and passes that to party C. After 167 this party C uses the IP address to communicate with A. 169 Resolver: The system function used by applications to resolve domain 170 names to IP addresses. 172 Short-lived local handle: The IP addresses is never retained by the 173 application. The only usage is for the application to pass it 174 from the DNS APIs (e.g., getaddrinfo()) and the API to the 175 protocol stack (e.g., connect() or sendto()). 177 Long-lived application associations: The IP address is retained by 178 the application for several instances of communication. 180 3. Enabling HIP transparently within the system 182 When both users and applications are unaware of HIP, but the host 183 administrator chooses to use HIP between hosts, a few options are 184 possible. The first basic option is to perform a mapping of the 185 application-provided IP address to a host identifier within the 186 stack. The second option, if DNS is used, is to interpose a local 187 agent in the DNS resolution process and to return to the application 188 a HIT or a locally scoped handle, formatted like an IP address. 190 3.1. Applying HIP to cases in which IP addresses are used 192 Consider the case in which an application issues a "connect(ip)" 193 system call to set the default destination to a system named by 194 address "ip", but for which the host administrator would like to 195 enable HIP to protect the communications. The user or application 196 intends for the system to communicate with the host reachable at that 197 IP address. The decision to invoke HIP must be done on the basis of 198 host policy. For example, when an IPsec-based implementation of HIP 199 is being used, a policy may be entered into the security policy 200 database that mandates to use or to try HIP based on a match on the 201 source or destination IP address, port numbers, or other factors. 202 The mapping of IP address to host identifier may be implemented by 203 modifying the host operating system or by wrapping the existing 204 sockets API, such as in the TESLA approach [paper.tesla]. 206 There are a number of ways that HIP could be configured by the host 207 administrator in such a scenario. 209 Manual configuration: 211 Pre-existing SAs may be available due to previous administrative 212 action, or a binding between an IP address and a HIT could be 213 stored in a configuration file or database. 215 Opportunistically: 217 The system could send an I1 to the Responder with an empty value 218 for Responder HIT. 220 Using DNS to map IP addresses to HIs: 222 If the responder has host identifiers registered in the forward 223 DNS zone and has a PTR record in the reverse zone, the Initiator 224 could perform a reverse+forward lookup to learn the HIT associated 225 with the address. Although the approach should work under normal 226 circumstances, it has not been tested to verify that there are no 227 recursion or bootstrapping issues, particularly if HIP is used to 228 secure the connection to the DNS servers. Discussion of the 229 security implications of the use or absence of DNSSEC is deferred 230 to the security considerations section. 232 Using HIP in the above fashion can cause additional setup delays 233 compared to using plain IP. For opportunistic mode, a host must wait 234 to learn whether the peer is HIP-capable, although the delays may be 235 mitigated in some implementations by sending initial packets (e.g., 236 TCP SYN) in parallel to the HIP I1 packet and waiting some time to 237 receive a HIP R1 before processing a TCP SYN/ACK. Note that there 238 presently does not exist specification for how to invoke such 239 connections in parallel. Resolution latencies may also be incurred 240 when using DNS in the above fashion. 242 A possible way to reduce latencies noted above, in the case that the 243 application uses DNS, would be for the system to opportunistically 244 query for HIP records in parallel to other DNS resource records, and 245 to temporarily cache the HITs returned with a DNS lookup, indexed by 246 the IP addresses returned in the same entry, and pass the IP 247 addresses up to the application as usual. If an application connects 248 to one of those IP addresses within a short time after the lookup, 249 the host should initiate a base exchange using the cached HITs. The 250 benefit is that this removes the uncertainty/delay associated with 251 opportunistic HIP, because the DNS record suggests that the peer is 252 HIP-capable. 254 3.2. Interposing a HIP-aware agent in the DNS resolution 256 In the previous section, it was noted that a HIP-unaware application 257 might typically use the DNS to fetch IP addresses prior to invoking 258 socket calls. A HIP-enabled system might make use of DNS to 259 transparently fetch host identifiers for such domain names prior to 260 the onset of communication. 262 A system with a local DNS agent could alternately return a Local 263 Scope Identifier (LSI) or HIT rather than an IP address, if HIP 264 information is available in the DNS or other directory that binds a 265 particular domain name to a host identifier, and otherwise to return 266 an IP address as usual. The system can then maintain a mapping 267 between LSI and host identifier and perform the appropriate 268 conversion at the system call interface or below. The application 269 uses the LSI or HIT as it would an IP address. This technique has 270 been used in overlay networking experiments such as the Internet 271 Indirection Infrastructure (i3) and by at least one HIP 272 implementation. 274 In the case when resolvers can return multiple destination 275 identifiers for an application, it may be configured that some of the 276 identifiers can be HIP-based identifiers, and the rest can be IPv4 or 277 IPv6 addresses. The system resolver may return HIP-based identifiers 278 in front of the list of identifiers when the underlying system and 279 policies support HIP. An application processing the identifiers 280 sequentially will then first try a HIP-based connection and only then 281 other non-HIP based connections. However, certain applications may 282 launch the connections in parallel. In such a case, the non-HIP 283 connections may succeed before HIP connections. Based on local 284 system policies, a system may disallow such behaviour and return only 285 HIP-based identifiers when they are found from DNS. 287 If the application obtains LSIs or HITs that it treats as IP 288 addresses, a few potential hazards arise. First, applications that 289 perform referrals may pass the LSI to another system that has no 290 system context to resolve the LSI back to a host identifier or an IP 291 address. Note that these are the same type of applications that will 292 likely break if used over certain types of network address 293 translators (NATs). Second, applications may cache the results of 294 DNS queries for a long time, and it may be hard for a HIP system to 295 determine when to perform garbage collection on the LSI bindings. 296 However, when using HITs, the security of using the HITs for identity 297 comparison may be stronger than in the case of using IP addresses. 298 Finally, applications may generate log files, and administrators or 299 other consumers of these log files may become confused to find LSIs 300 or HITs instead of IP addresses. Therefore, it is recommended that 301 the HIP software logs the HITs, LSIs (if applicable), and FQDN- 302 related information so that administrators can correlate other logs 303 with HIP identifiers. 305 It may be possible for an LSI or HIT to be routable or resolvable, 306 either directly or through an overlay, in which case it would be 307 preferable for applications to handle such names instead of IP 308 addresses. However, such networks are out of scope of this document. 310 3.3. Discussion 312 Solutions preserving the use of IP addresses in the applications have 313 the benefit of better support for applications that use IP addresses 314 for long-lived application associations, callbacks, and referrals, 315 although it should be noted that applications are discouraged from 316 using IP addresses in this manner due to the frequent presence of 317 NATs [RFC1958]. However, they have weaker security properties than 318 the approaches outlined in Section 3.2 and Section 4, because the 319 binding between host identifier and address is weak and not visible 320 to the application or user. In fact, the semantics of the 321 application's "connect(ip)" call may be interpreted as "connect me to 322 the system reachable at IP address ip" but perhaps no stronger 323 semantics than that. HIP can be used in this case to provide perfect 324 forward secrecy and authentication, but not to strongly authenticate 325 the peer at the onset of communications. 327 Using IP addresses at the application layer may not provide the full 328 potential benefits of HIP mobility support. It allows for mobility 329 if the system is able to readdress long-lived, connected sockets upon 330 a HIP readdress event. However, as in current systems, mobility will 331 break in the connectionless case, when an application caches the IP 332 address and repeatedly calls sendto(), or in the case of TCP when the 333 system later opens additional sockets to the same destination. 335 Section 4.1.6 of the base HIP protocol specification [RFC5201] states 336 that implementations that learn of HIT-to-IP address bindings through 337 the use of HIP opportunistic mode must not enforce those bindings on 338 later communications sessions. This implies that when IP addresses 339 are used by the applications, systems that attempt to 340 opportunistically set up HIP must not assume that later sessions to 341 the same address will communicate with the same host. 343 The legacy application is unaware of HIP and therefore cannot notify 344 the user when the application uses HIP. However, the operating 345 system can notify the user of the usage of HIP through a user agent. 346 Further, it is possible for the user agent to name the network 347 application that caused a HIP-related event. This way, the user is 348 aware when he or she is using HIP even though the legacy network 349 application is not. Based on usability tests from initial 350 deployments, displaying the HITs and LSIs should be avoided in user 351 interfaces. Instead, traditional security measures (lock pictures, 352 colored address bars) should be used where possible. 354 One drawback to spoofing the DNS resolution is that some 355 applications, or selected instances of an application, actually may 356 want to fetch IP addresses (e.g., diagnostic applications such as 357 ping). One way to provide finer granularity on whether the resolver 358 returns an IP address or an LSI is to have the user form a modified 359 domain name when he or she wants to invoke HIP. This leads us to 360 consider, in the next section, use cases for which the end user 361 explicitly and selectively chooses to enable HIP. 363 4. Users Invoking HIP with a Legacy Application 365 The previous section described approaches for configuring HIP for 366 legacy applications that did not necessarily involve the user. 367 However, there may be cases in which a legacy application user wants 368 to use HIP for a given application instance by signaling to the HIP- 369 enabled system in some way. If the application user interface or 370 configuration file accepts IP addresses, there may be an opportunity 371 to provide a HIT or an LSI in its place. Furthermore, if the 372 application uses DNS, a user may provide a specially crafted domain 373 name to signal to the resolver to fetch HIP records and to signal to 374 the system to use HIP. We describe both of these approaches below. 376 4.1. Connecting to a HIT or LSI 378 Section 3.2 above describes the use of HITs or LSIs as spoofed return 379 values of the DNS resolution process. A similar approach that is 380 more explicit is to configure the application to connect directly to 381 a HIT (e.g., "connect(HIT)" as a socket call). This scenario has 382 stronger security semantics, because the application is asking the 383 system to send packets specifically to the named peer system. HITs 384 have been defined as Overlay Routable Cryptographic Hash Identifiers 385 (ORCHIDs) such that they cannot be confused with routable IP 386 addresses; see [RFC4843]. 388 This approach also has a few challenges. Using HITs can be more 389 cumbersome for human users (due to the flat HIT name space) than 390 using either IPv6 addresses or domain names. Another challenge with 391 this approach is in actually finding the IP addresses to use, based 392 on the HIT. Some type of HIT resolution service would be needed in 393 this case. A third challenge of this approach is in supporting 394 callbacks and referrals to possibly non-HIP-aware hosts. However, 395 since most communications in this case would likely be to other HIP- 396 aware hosts (else the initial HIP associations would fail to 397 establish), the resulting referral problem may be that the peer host 398 supports HIP but is not able to perform HIT resolution for some 399 reason. 401 4.2. Using a modified DNS name 403 Specifically, if the application requests to resolve "HIP- 404 www.example.com" (or some similar prefix string), then the system 405 returns an LSI, while if the application requests to resolve 406 "www.example.com", IP address(es) are returned as usual. The use of 407 a prefix rather than suffix is recommended, and the use of a string 408 delimiter that is not a dot (".") is also recommended, to reduce the 409 likelihood that such modified DNS names are mistakenly treated as 410 names rooted at a new top-level domain. Limits of domain name length 411 or label length (255 or 63, respectively) should be considered when 412 prepending any prefixes. 414 4.3. Other techniques 416 Alternatives to using a modified DNS name that have been experimented 417 with include the following. Command-line tools or tools with a 418 graphical user interface (GUI) can be provided by the system to allow 419 a user to set the policy on which applications use HIP. Another 420 common technique, for dynamically linked applications, is to 421 dynamically link the application to a modified library that wraps the 422 system calls and interposes HIP layer communications on them; this 423 can be invoked by the user by running commands through a special 424 shell, for example. 426 5. Local address management 428 The previous two sections focused mainly on controlling client 429 behavior (HIP initiator). We must also consider the behavior for 430 servers. Typically, a server binds to a wildcard IP address and 431 well-known port. In the case of HIP use with legacy server 432 implementations, there are again a few options. The system may be 433 configured manually to always, optionally (depending on the client 434 behavior), or never use HIP with a particular service, as a matter of 435 policy, when the server specifies a wildcard (IP) address. 437 When a system API call such as getaddrinfo [RFC3493] is used for 438 resolving local addresses, it may also return HITs or LSIs, if the 439 system has assigned HITs or LSIs to internal virtual interfaces 440 (common in many HIP implementations). The application may use such 441 identifiers as addresses in subsequent socket calls. 443 Some applications may try to bind a socket to a specific local 444 address, or may implement server-side access control lists based on 445 socket calls such as getsockname() and getpeername() in the C-based 446 socket APIs. If the local address specified is an IP address, again, 447 the underlying system may be configured to still use HIP. If the 448 local address specified is a HIT (Section 4), the system should 449 enforce that connections to the local application can only arrive to 450 the specified HIT. If a system has many HITs, an application that 451 binds to a single HIT cannot accept connections to the other HITs in 452 the system. 454 When a host has multiple HIs and the socket behavior does not 455 prescribe the use of any particular HI as a local identifier, it is a 456 matter of local policy as to how to select a HI to serve as a local 457 identifier. However, systems that bind to a wildcard may face 458 problems when multiple HITs or LSIs are defined. These problems are 459 not specific to HIP per se, but are also encountered in non-HIP 460 multihoming scenarios with applications not designed for multihoming. 462 As an example, consider a client application that sends an UDP 463 datagram to a server that is bound to a wildcard. The server 464 application receives the packet using recvfrom() and sends a response 465 using sendto(). The problem here is that sendto() may actually use a 466 different server HIT than the client assumes. The client will drop 467 the response packet when the client implements access control on the 468 UDP socket (e.g. using connect()). 470 Reimplementing the server application using the sendmsg() and 471 recvmsg() to support multihoming (particularly considering the 472 ancillary data) would be the ultimate solution to this problem, but 473 with legacy applications is not an option. As a workaround, we make 474 suggestion for servers providing UDP-based services with non- 475 multihoming capable services. Such servers should announce only the 476 HIT or public key that matches to the default outgoing HIT of the 477 host to avoid such problems. 479 Finally, some applications may create a connection to a local HIT. 480 In such a case, the local system may use NULL encryption to avoid 481 unnecessary encryption overhead, and may be otherwise more permissive 482 than usual such as excluding authentication, Diffie-Hellman exchange, 483 and puzzle. 485 6. Security Considerations 487 In this section we discuss the security of the system in general 488 terms, outlining some of the security properties. However, this 489 section is not intended to provide a complete risk analysis. Such an 490 analysis would, in any case, be dependent on the actual application 491 using HIP, and is therefore considered out of scope. 493 The scenarios outlined above differ considerably in their security 494 properties. When the DNS is used, there are further differences 495 related to whether DNSSEC [RFC4033] is used or not, and whether the 496 DNS zones are considered trustworthy enough. Here we mean that there 497 should exist a delegation chain to whatever trust anchors are 498 available in the respective trees, and the DNS zone administrators in 499 charge of the netblock should be trusted to put in the right 500 information. 502 When IP addresses are used by applications to name the peer system, 503 the security properties depend on the configuration method. With 504 manual configuration, the security of the system is comparable to a 505 non-HIP system with similar IPsec policies. The security semantics 506 of an initial opportunistic key exchange are roughly equal to non- 507 secured IP; the exchange is vulnerable to man-in-the-middle attacks. 508 However, the system is less vulnerable to connection hijacking 509 attacks. If the DNS is used, if both zones are secured (or the HITs 510 are stored in the reverse DNS record) and the client trusts the 511 DNSSEC signatures, the system may provide a fairly high security 512 level. However, much depends on the details of the implementation, 513 the security and administrative practices used when signing the DNS 514 zones, and other factors. 516 Using the forward DNS to map a domain name into an LSI is a case that 517 is closest to the most typical use scenarios today. If DNSSEC is 518 used, the result is fairly similar to the current use of certificates 519 with TLS. If DNSSEC is not used, the result is fairly similar to the 520 current use of plain IP, with the additional protection of data 521 integrity, confidentiality, and prevention of connection hijacking 522 that opportunistic HIP provides. If DNSSEC is used, data integrity 523 and data origin authentication services are added to the normal DNS 524 query protocol, thereby providing more certainty that the desired 525 host is being contacted, if the DNS records themselves are 526 trustworthy. 528 If the application is basing its operations on HITs, the connections 529 become automatically secured due to the implicit channel bindings in 530 HIP. That is, when the application makes a connect(HIT) system call, 531 the resulting packets will either be sent to a node possessing the 532 corresponding private key or the security association will fail to be 533 established. 535 When the system provides (spoofs) LSIs or HITs instead of IP 536 addresses as the result of name resolution, the resultant fields may 537 inadvertently show up in user interfaces and system logs, which may 538 cause operational concerns for some network administrators. 539 Therefore, it is recommended that the HIP software logs the HITs, 540 LSIs (if applicable), and FQDN-related information so that 541 administrators can correlate other logs with HIP identifiers. 543 7. IANA Considerations 545 This document has no actions for IANA. 547 8. Acknowledgments 549 Jeff Ahrenholz, Gonzalo Camarillo, Alberto Garcia, Teemu Koponen, 550 Julien Laganier, and Jukka Ylitalo have provided comments on 551 different versions of this draft. Erik Nordmark provided the 552 taxonomy of how applications use IP addresses in a previously expired 553 Internet Draft. The document received substantial and useful 554 comments during the review phase from David Black, Pekka Savola, Lars 555 Eggert, and Peter Koch. 557 9. Informative References 559 [RFC5201] Moskowitz, R., Nikander, P., Jokela, P., and T. Henderson, 560 "Host Identity Protocol", RFC 5201, April 2008. 562 [RFC4843] Nikander, P., Laganier, J., and F. Dupont, "An IPv6 Prefix 563 for Overlay Routable Cryptographic Hash Identifiers 564 (ORCHID)", RFC 4843, April 2007. 566 [paper.tesla] 567 Salz, J., Balakrishnan, H., and A. Snoeren, "TESLA: A 568 Transparent, Extensible Session-Layer Architecture for 569 End-to-end Network Services", Proceedings of USENIX 570 Symposium on Internet Technologies and Systems (USITS), 571 pages 211-224, March 2003. 573 [RFC1958] Carpenter, B., "Architectural Principles of the Internet", 574 RFC 1958, June 1996. 576 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 577 Rose, "DNS Security Introduction and Requirements", 578 RFC 4033, March 2005. 580 [RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W. 581 Stevens, "Basic Socket Interface Extensions for IPv6", 582 RFC 3493, February 2003. 584 Appendix A. Changes from previous versions 586 This section is to be removed by the RFC Editor before publication. 587 It summarizes resolution of issues raised in the following reviews: 588 (1) IESG last call, (2) Gen-ART review, and (3) DNS directorate 589 review. Mobility and secdir reviews did not result in actionable 590 comments. 592 A.1. From version-01 to version-02 594 Better clarity in the abstract and introduction about the goal of the 595 draft; namely, that it is informational to help implementors and 596 early adopters think about and solve deployment issues (comment from 597 Pekka Savola). 599 Delete the second paragraph of 3 about the general applicability of 600 replacing IP addresses with LSIs and HITs at the socket layer. 601 (comment from Pekka Savola). 603 Delete comments in Section 3.2 on routable LSIs, as this is seen to 604 be out of scope and potentially controversial or incomplete (comment 605 from David Black). 607 Delete reference to Erik Nordmark's shim6 application referral draft, 608 since it is a dead draft (comment from David Black). Instead, Erik 609 is cited in the acknowledgments section for providing the taxonomy of 610 IP address usage scenarios. 612 Clarify (and reference the base spec) in Sec. 3.1 that use of the 613 opportunistic mode requires that systems not enforce that the 614 HIT-to-IP address bindings learned will pertain to subsequent 615 sessions to that IP address. 617 Section 3.2 drew comments from several reviewers. First, David Black 618 raised the issue that spoofing IP addresses with HITs or LSIs raises 619 risks that it may turn up in log records; this has been noted in the 620 text. The section on using a DNS suffix to signal the preferred use 621 of HIP was objected to by members of the DNS directorate and others 622 (including the co-author Pekka Nikander), due to concern that queries 623 to a new TLD might leak out. The current draft instead recommends a 624 DNS prefix instead of suffix, due to a suggestion by Thomas Narten. 626 In section 3.1, clarify recursion issues that may arise when doing 627 reverse+forward lookup of HIP records from DNS (comment from Pekka 628 Savola). 630 Clarify more specifically in security considerations section the 631 DNSSEC trust assumptions or security considerations (outline of text 632 provided by Pekka Savola, and similar comment raised by Peter Koch). 634 Clarified in security considerations section that IP address spoofing 635 could cause some operational difficulties if they unexpectedly show 636 up in log files or UIs (comment from David Black). 638 Clarified in Sec. 3.1 that opportunistic and DNS techniques can incur 639 additional latency when compared to plain IP (comment from Lars 640 Eggert) 642 Added third option to Section 3.2 for using DNS (transparently 643 fetching HIP resource records when doing other RR queries), suggested 644 by Lars Eggert and also by Olaf Kolkman. 646 Incorporated last-call comments from Miika Komu, which were all 647 handled in Section 3.4: i) clarify multihoming issue for servers with 648 multiple HITs, when receiving UDP, ii) clarify a problem that might 649 arise for applications that do parallel connect, and iii) suggest 650 that loopback HIP connections could use a NULL encryption. 652 Removed expired references and updated active references. 654 Incorporated additional review comments from Miika Komu, and some 655 suggested replacement text, and added him as a co-author. 657 A.2. From version-02 to version-03 (current) 659 DNSSEC clarifications added based on dns-dir review from Peter Koch 661 Editing pass through document. Organizationally, everything except 662 security considerations was in one section. The existing text of 663 Sections 3.1 through 3.3 was moved to new Sections 3 and 4, the 664 previous text of section 3.4 has been moved to section 5, and the 665 previous Section 4 (security considerations) is now Section 6. 666 Performed further wordsmithing and cleanup. 668 Authors' Addresses 670 Thomas Henderson 671 The Boeing Company 672 P.O. Box 3707 673 Seattle, WA 674 USA 676 Email: thomas.r.henderson@boeing.com 678 Pekka Nikander 679 Ericsson Research NomadicLab 680 JORVAS FIN-02420 681 FINLAND 683 Phone: +358 9 299 1 684 Email: pekka.nikander@nomadiclab.com 686 Miika Komu 687 Helsinki Institute for Information Technology 688 Metsaenneidonkuja 4 689 Helsinki FIN-02420 690 FINLAND 692 Phone: +358503841531 693 Email: miika@iki.fi 695 Full Copyright Statement 697 Copyright (C) The IETF Trust (2008). 699 This document is subject to the rights, licenses and restrictions 700 contained in BCP 78, and except as set forth therein, the authors 701 retain all their rights. 703 This document and the information contained herein are provided on an 704 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 705 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 706 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 707 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 708 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 709 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 711 Intellectual Property 713 The IETF takes no position regarding the validity or scope of any 714 Intellectual Property Rights or other rights that might be claimed to 715 pertain to the implementation or use of the technology described in 716 this document or the extent to which any license under such rights 717 might or might not be available; nor does it represent that it has 718 made any independent effort to identify any such rights. 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