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Checking references for intended status: Experimental ---------------------------------------------------------------------------- ** Obsolete normative reference: RFC 5201 (Obsoleted by RFC 7401) ** Obsolete normative reference: RFC 5202 (Obsoleted by RFC 7402) ** Obsolete normative reference: RFC 5203 (Obsoleted by RFC 8003) ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126) ** Obsolete normative reference: RFC 5245 (Obsoleted by RFC 8445, RFC 8839) == Outdated reference: A later version (-12) exists of draft-ietf-hip-cert-03 -- Obsolete informational reference (is this intentional?): RFC 5389 (Obsoleted by RFC 8489) -- Obsolete informational reference (is this intentional?): RFC 5766 (Obsoleted by RFC 8656) Summary: 6 errors (**), 0 flaws (~~), 9 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 HIP Working Group A. Keranen 3 Internet-Draft J. Melen 4 Intended status: Experimental Ericsson 5 Expires: March 19, 2011 September 15, 2010 7 Native NAT Traversal Mode for the Host Identity Protocol 8 draft-ietf-hip-native-nat-traversal-00 10 Abstract 12 This document specifies a new Network Address Translator (NAT) 13 traversal mode for the Host Identity Protocol (HIP). The new mode is 14 based on the Interactive Connectivity Establishment (ICE) methodology 15 and UDP encapsulation of data and signaling traffic. The main 16 difference from the previously specified modes is the use of HIP 17 messages for all NAT traversal procedures. 19 Status of this Memo 21 This Internet-Draft is submitted to IETF in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF), its areas, and its working groups. Note that 26 other groups may also distribute working documents as Internet- 27 Drafts. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 The list of current Internet-Drafts can be accessed at 35 http://www.ietf.org/ietf/1id-abstracts.txt. 37 The list of Internet-Draft Shadow Directories can be accessed at 38 http://www.ietf.org/shadow.html. 40 This Internet-Draft will expire on March 19, 2011. 42 Copyright Notice 44 Copyright (c) 2010 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (http://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 61 3. Protocol Description . . . . . . . . . . . . . . . . . . . . . 4 62 3.1. Relay Registration . . . . . . . . . . . . . . . . . . . . 4 63 3.2. Registration Authentication . . . . . . . . . . . . . . . 4 64 3.3. Forwarding Rules and Permissions . . . . . . . . . . . . . 5 65 3.4. Relaying UDP Encapsulated Data and Control Packets . . . . 6 66 3.5. Candidate Gathering . . . . . . . . . . . . . . . . . . . 6 67 3.6. Base Exchange via HIP Relay Server . . . . . . . . . . . . 7 68 3.7. Native NAT Traversal Mode Negotiation . . . . . . . . . . 7 69 3.8. Connectivity Check Pacing Negotiation . . . . . . . . . . 7 70 3.9. Connectivity Checks . . . . . . . . . . . . . . . . . . . 7 71 3.10. NAT Keepalives . . . . . . . . . . . . . . . . . . . . . . 8 72 3.11. Handling Conflicting SPI Values . . . . . . . . . . . . . 8 73 4. Packet Formats . . . . . . . . . . . . . . . . . . . . . . . . 9 74 4.1. RELAYED_ADDRESS and MAPPED_ADDRESS Parameters . . . . . . 9 75 4.2. PEER_PERMISSION Parameter . . . . . . . . . . . . . . . . 10 76 4.3. HIP Connectivity Check Packets . . . . . . . . . . . . . . 11 77 5. Security Considerations . . . . . . . . . . . . . . . . . . . 12 78 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 79 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 80 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 81 8.1. Normative References . . . . . . . . . . . . . . . . . . . 13 82 8.2. Informative References . . . . . . . . . . . . . . . . . . 14 83 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 85 1. Introduction 87 The Host Identity Protocol (HIP) [RFC5201] is specified to run 88 directly on top of IPv4 or IPv6. However, many middleboxes found in 89 the Internet, such as NATs and firewalls, often allow only UDP or TCP 90 traffic to pass [RFC5207]. Also, especially NATs usually require the 91 host behind a NAT to create a forwarding state in the NAT before 92 other hosts outside of the NAT can contact the host behind the NAT. 93 To overcome this problem, different methods, commonly referred to as 94 NAT traversal techniques, have been developed. 96 Two NAT traversal techniques for HIP are specified in [RFC5770]. One 97 of them uses only UDP encapsulation, while the other uses also the 98 Interactive Connectivity Establishment (ICE) [RFC5245] protocol, 99 which in turn uses Session Traversal Utilities for NAT (STUN) 100 [RFC5389] and Traversal Using Relays around NAT (TURN) [RFC5766] 101 protocols to achieve a reliable NAT traversal solution. 103 The benefit of using ICE and STUN/TURN is that one can re-use the NAT 104 traversal infrastructure already available in the Internet, such as 105 STUN and TURN servers. Also, some middleboxes may be STUN-aware and 106 could be able to do something "smart" when they see STUN being used 107 for NAT traversal. However, implementing a full ICE/STUN/TURN 108 protocol stack results in a considerable amount of effort and code 109 which could be avoided by re-using and extending HIP messages and 110 state machines for the same purpose. Thus, this document specifies a 111 new NAT traversal mode that uses HIP messages instead of STUN for the 112 connectivity checks, keepalives, and data relaying. 114 2. Terminology 116 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 117 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 118 document are to be interpreted as described in RFC 2119 [RFC2119]. 120 This document uses the same terminology as [RFC5770] and the 121 following: 123 HIP data relay: 124 A host that forwards HIP data packets, such as Encapsulating 125 Security Payload (ESP) [RFC5202], between two hosts. 127 Registered host: 128 A host that has registered for a relaying service with a HIP data 129 relay. 131 3. Protocol Description 133 This section describes the normative behavior of the protocol 134 extension. Most of the procedures are similar to what is defined in 135 [RFC5770] but with different, or additional, parameter types and 136 values. In addition, a new type of relaying server, HIP data relay, 137 is specified. 139 3.1. Relay Registration 141 Relay registration procedure for HIP signaling is identical to the 142 one specified in Section 4.1 of [RFC5770]. However, a host MAY also 143 register for UDP encapsulated ESP relaying using Registration Type 144 RELAY_UDP_ESP (value [TBD by IANA: 3]). 146 If the HIP relay server supports relaying of UDP encapsulated ESP, 147 the host is allowed to register for data relaying service (see 148 Section 3.2), and the relay has relaying resources (free port 149 numbers, bandwidth, etc.) available, the relay opens a UDP port on 150 one of its addresses and signals the address and port to the 151 registering host using the RELAYED_ADDRESS parameter (see Section 4.1 152 for details). If the relay would accept the data relaying request 153 but does not have enough resources to provide data relaying service, 154 it MUST reject the request with Failure Type [TBD by IANA: 2] 155 (Insufficient resources). 157 The registered host MUST maintain an active HIP association with the 158 data relay as long as it requires the data relaying service. When 159 the HIP association is closed (or times out), or the registration 160 lifetime passes without the registered host refreshing the 161 registration, the data relay MUST stop relaying packets for that host 162 and close the corresponding UDP port (unless other registered hosts 163 are still using it). 165 The data relay MAY use the same relayed address and port for multiple 166 registered hosts, but since this can cause problems with stateful 167 firewalls (see Section 5) it is NOT RECOMMENDED. 169 3.2. Registration Authentication 171 If the HIP data relay knows the Host Identities (HIs) of all the 172 hosts that are allowed to use the relaying service, it SHOULD reject 173 registrations from unknown hosts. However, since it may be 174 unfeasible to pre-configure the relay with all the HIs, the relay 175 SHOULD also support HIP certificates [I-D.ietf-hip-cert] to allow for 176 certificate based authentication. 178 When a host wants to register with a HIP data relay, it SHOULD check 179 if it has a suitable certificate for authenticating with the relay. 180 How the suitability is determined and how the certificates are 181 obtained is out of scope for this document. If the host has one or 182 more suitable certificates, the host SHOULD include them (or just the 183 most suitable one) in a CERT parameter to the HIP packet along with 184 the REG_REQUEST parameter. If the host does not have any suitable 185 certificates, it SHOULD send the registration request without the 186 CERT parameter to test whether the relay accepts the request based on 187 the host's identity. 189 When a relay receives a HIP packet with a REG_REQUEST parameter, and 190 it requires authentication for at least one of the Registration Types 191 listed in the REG_REQUEST parameter, it MUST first check whether the 192 HI of the registering host is in the allowed list for all the 193 Registration Types in the REG_REQUEST parameter. If the host is in 194 the allowed list (or the relay does not require any authentication), 195 the relay MUST proceed with the registration. 197 If the host was not in the allowed list and the relay requires the 198 host to authenticate, the relay MUST check whether the packet also 199 contains a CERT parameter. If the packet does not contain a CERT 200 parameter, the server MUST reject the registrations requiring 201 authentication with Failure Type 0 (Registration requires additional 202 credentials) [RFC5203]. If the certificate is valid and accepted 203 (issued for the registering host and signed by a trusted issuer), the 204 relay MUST proceed with the registration. If the certificate in the 205 parameter is not accepted, the relay MUST reject the corresponding 206 registrations with Failure Type [TBD by IANA: 3] (Invalid 207 certificate). 209 3.3. Forwarding Rules and Permissions 211 The HIP data relay uses a similar permission model as a TURN server: 212 before any ESP data packets sent by a peer are forwarded, a 213 permission MUST be set for the peer's address. The permissions also 214 install a forwarding rule, similar to TURN's channels, based on the 215 Security Parameter Index (SPI) values in the ESP packets. 217 Permissions are not required for the connectivity checks, but if a 218 relayed address is selected to be used for data, the registered host 219 MUST send an UPDATE message [RFC5201] with a PEER_PERMISSION 220 parameter (see Section 4.2) with the address of the peer and the 221 outbound and inbound SPI values the host is using with this peer. 223 When a data relay receives an UPDATE with a PEER_PERMISSION 224 parameter, it MUST check if the sender of the UPDATE is registered 225 for data relaying service, and drop the UPDATE if the host was not 226 registered. If the host was registered, the relay checks if there is 227 a permission with matching information (address, protocol, port and 228 SPI values). If there is no such permission, a new permission MUST 229 be created and its lifetime MUST be set to 5 minutes. If an 230 identical permission already existed, it MUST be refreshed by setting 231 the lifetime to 5 minutes. A registered host SHOULD refresh 232 permissions roughly 1 minute before the expiration if the permission 233 is still needed. 235 3.4. Relaying UDP Encapsulated Data and Control Packets 237 When a HIP data relay accepts to relay UDP encapsulated data, it 238 opens a UDP port (relayed address) for this purpose as described in 239 Section 3.1. If the data relay receives a UDP encapsulated HIP 240 control packet on that port, it MUST forward the packet to the 241 registered host and add a RELAY_FROM parameter to the packet as if 242 the data relay was acting as a HIP relay server [RFC5770]. 244 When a host wants to send a HIP control packet (such as a 245 connectivity check packet) to a peer via the data relay, it MUST add 246 a RELAY_TO parameter containing the peer's address to the packet and 247 send it to the data relay's address. The data relay MUST send the 248 packet to the peer's address from the relayed address. 250 If the data relay receives a UDP packet that is not a HIP control 251 packet to the relayed address, it MUST check whether there is a 252 permission set for the peer the packet is coming from (i.e., the 253 sender's address and SPI value matches to an installed permission), 254 and if there is, it MUST forward the packet to the registered host 255 that created the permission. Packets without a permission MUST be 256 dropped silently. 258 When a host wants to send a UDP encapsulated ESP packet to a peer via 259 the data relay, it MUST have an active permission at the data relay 260 for the peer with the outbound SPI value it is using. The host MUST 261 send the UDP encapsulated ESP packet to the data relay's address. 263 When the data relay receives a UDP encapsulated ESP packet from a 264 registered host, it MUST check whether there exists a permission for 265 that outbound SPI value. If such permission exists, the packet MUST 266 be forwarded to the address that was registered for the SPI value. 267 If no permission exists, the packet is dropped. 269 3.5. Candidate Gathering 271 A host needs to gather a set of address candidates before starting 272 the connectivity checks. One server reflexive candidate can be 273 discovered during the registration with the HIP relay server from the 274 REG_FROM parameter. 276 If a host has more than one network interface, additional server 277 reflexive candidates can be discovered by sending registration 278 requests with Registration Type CANDIDATE_DISCOVERY (value [TBD by 279 IANA: 4]) from each of the interfaces to a HIP relay server. When a 280 HIP relay server receives a registration request with 281 CANDIDATE_DISCOVERY type, it MUST add a REG_FROM parameter, 282 containing the same information as if this was a relay registration, 283 to the response. This request type SHOULD NOT create any state at 284 the HIP relay server. 286 It is RECOMMENDED that the host also obtains a relayed candidate from 287 a HIP data relay as described in Section 3.1. 289 Gathering of candidates MAY also be performed like specified in 290 Section 4.2 of [RFC5770] if STUN and TURN servers are available, or 291 if the host has just a single interface and there are no TURN or HIP 292 data relay servers available. 294 3.6. Base Exchange via HIP Relay Server 296 The Base Exchange is performed as described in Section 4.5 of 297 [RFC5770], except that "ICE candidates" are replaced by the 298 candidates gathered using procedures described in Section 3.5 300 3.7. Native NAT Traversal Mode Negotiation 302 A host implementing this specification SHOULD signal the support for 303 the native HIP NAT traversal mode by adding ICE-HIP-UDP NAT traversal 304 mode (value [TBD by IANA: 3]) in the NAT_TRAVERSAL_MODE [RFC5770] 305 parameter. If this mode is supported by both endpoints, and is the 306 most preferred mode out of the all supported modes, further NAT 307 traversal procedures are performed as specified in this document. 308 Note that the results of the previously described methods, candidate 309 gathering and HIP data relay registration with HIP messages, can be 310 used also with the ICE-STUN-UDP NAT traversal mode. 312 3.8. Connectivity Check Pacing Negotiation 314 Since the NAT traversal mode specified in this document utilizes 315 connectivity checks, the check pacing negotiation MUST be performed 316 as specified in Section 4.4 of [RFC5770]. New connectivity check 317 transactions MUST NOT be started faster than once every Ta (the value 318 negotiated with the TRANSACTION_PACING parameter). 320 3.9. Connectivity Checks 322 The connectivity checks are performed as described in Section 4.6 of 323 [RFC5770] but instead of STUN packets, the connectivity checks are 324 HIP UPDATE packets. See Section 4.3 for parameter details. 326 As defined in [RFC5770], both hosts MUST form a priority ordered 327 checklist and start check transactions every Ta milliseconds as long 328 as the checks are running and there are candidate pairs whose tests 329 have not started. The retransmission timeout (RTO) for the 330 connectivity check UPDATE packets MUST be calculated as defined in 331 Section 4.6 of [RFC5770]. 333 All connectivity check request packets MUST contain a 334 CANDIDATE_PRIORITY parameter (see Section 4.3) with the priority 335 value that would be assigned to a peer reflexive candidate if one was 336 learned from this check. The UPDATE packets that acknowledge a 337 connectivity check requests MUST be sent from the same address that 338 received the check and to the same address where the check was 339 received from. 341 The acknowledgment UPDATE packets MUST contain a MAPPED_ADDRESS 342 parameter with the port, protocol, and IP address of the address 343 where the connectivity check request was received from. 345 After a working candidate pair, or pairs, have been discovered, the 346 controlling host MUST conclude the checks by nominating the highest 347 priority candidate pair for use. The pair MUST be nominated by 348 sending an ESP packet on the selected pair. If the controlling host 349 does not have any data to send, it SHOULD send an ICMP echo request 350 using the nominated pair to signal to the controlled host that it can 351 stop checks and start using the nominated pair. 353 If the connectivity checks failed the hosts SHOULD notify each other 354 about the failure with a CONNECTIVITY_CHECKS_FAILED NOTIFY packet 355 [RFC5770]. 357 3.10. NAT Keepalives 359 To keep the NAT bindings towards the HIP relay server and the HIP 360 data relay alive, if a registered host has not sent any data or 361 control messages to the relay for 15 seconds, it MUST send a HIP 362 NOTIFY packet to the relay. Likewise, if the host has not sent any 363 data to a host it has security association and has run connectivity 364 checks with, it MUST send either a HIP NOTIFY packet or an ICMP echo 365 request using the same locators as the security association is using. 367 3.11. Handling Conflicting SPI Values 369 Since the HIP data relay determines from the SPI value to which peer 370 an ESP packet should be forwarded, the outbound SPI values need to be 371 unique for each relayed address registration. Thus, if a registered 372 host detects that a peer would use an SPI value that is already used 373 with another peer via the relay, it MUST NOT select the relayed 374 address for use. The host MAY restart the base exchange to avoid a 375 conflict or it MAY refrain from using the relayed candidate for the 376 connectivity checks. 378 Since the SPI space is 32 bits and the SPI values should be random, 379 the probability for a conflicting SPI value is fairly small. 380 However, a host with many peers MAY decrease the odds of a conflict 381 by registering more than one relayed address using different local 382 addresses. 384 4. Packet Formats 386 The following subsections define the parameter and packet encodings 387 for the new HIP parameters used for NAT traversal. UDP encapsulation 388 of the HIP and ESP packets and format of the other required 389 parameters is specified in Section 5 of [RFC5770]. 391 4.1. RELAYED_ADDRESS and MAPPED_ADDRESS Parameters 393 The format of the RELAYED_ADDRESS and MAPPED_ADDRESS parameters 394 (Figure 1) is identical to REG_FROM, RELAY_FROM and RELAY_TO 395 parameters. This document specifies only use of UDP relaying and 396 thus only protocol 17 is allowed. However, future documents may 397 specify support for other protocols. 399 0 1 2 3 400 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 1 401 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 402 | Type | Length | 403 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 404 | Port | Protocol | Reserved | 405 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 406 | | 407 | Address | 408 | | 409 | | 410 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 412 Type [TBD by IANA; 413 RELAYED_ADDRESS: 4650 414 MAPPED_ADDRESS: 4660] 415 Length 20 416 Port the UDP port number 417 Protocol IANA assigned, Internet Protocol number (17 for UDP) 418 Reserved reserved for future use; zero when sent, ignored 419 when received 420 Address an IPv6 address or an IPv4 address in "IPv4-Mapped 421 IPv6 address" format 423 Figure 1: Format of the RELAYED_ADDRESS and MAPPED_ADDRESS Parameters 425 4.2. PEER_PERMISSION Parameter 427 The format of the PEER_PERMISSION parameter is shown in Figure 2. 428 The parameter is used for setting up and refreshing forwarding rules 429 and permissions at the data relay for data packets. The parameter 430 contains one or more sets of Port, Protocol, Address, Outbound SPI, 431 and Inbound SPI values. One set defines a rule for one peer address. 433 0 1 2 3 434 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 1 435 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 436 | Type | Length | 437 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 438 | Port | Protocol | Reserved | 439 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 440 | | 441 | Address | 442 | | 443 | | 444 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 445 | OSPI | 446 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 447 | ISPI | 448 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 449 | | 450 | ... | 451 | | 452 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 454 Type [TBD by IANA; 4680] 455 Length length in octets, excluding Type and Length 456 Port the transport layer (UDP) port number 457 Protocol IANA assigned, Internet Protocol number (17 for UDP) 458 Reserved reserved for future use; zero when sent, ignored 459 when received 460 Address an IPv6 address, or an IPv4 address in "IPv4-Mapped 461 IPv6 address" format, of the peer 462 OSPI the outbound SPI value the registered host is using for 463 the peer with the Address and Port 464 ISPI the inbound SPI value the registered host is using for 465 the peer with the Address and Port 467 Figure 2: Format of the PEER_PERMISSION Parameter 469 4.3. HIP Connectivity Check Packets 471 The connectivity request messages are HIP UPDATE packets with 472 CANDIDATE_PRIORITY parameter (Figure 3). Response UPDATE packets 473 contain a MAPPED_ADDRESS parameter (Figure 1). 475 0 1 2 3 476 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 1 477 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 478 | Type | Length | 479 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 480 | Priority | 481 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 483 Type [TBD by IANA; 4700] 484 Length 4 485 Priority the priority of a peer reflexive candidate 487 Figure 3: Format of the CANDIDATE_PRIORITY Parameter 489 5. Security Considerations 491 Same security considerations as with [RFC5770] apply also to this NAT 492 traversal mode. 494 If the data relay uses the same relayed address and port for multiple 495 registered hosts, it appears to all the peers, and their firewalls, 496 that all the registered hosts using the relay are at the same 497 address. Thus, a stateful firewall may allow packets pass from hosts 498 that would not normally be able to send packets to a peer behind the 499 firewall. Therefore, a HIP data relay SHOULD NOT re-use the port 500 numbers. If port numbers need to be re-used, the relay SHOULD have a 501 sufficiently large pool of port numbers and select ports from the 502 pool randomly to decrease the chances of a registered host obtaining 503 the same address that a certain other host is using. 505 6. Acknowledgements 507 This document re-uses many of the ideas proposed in various earlier 508 HIP NAT traversal related drafts by Miika Komu, Simon Schuetz, Martin 509 Stiemerling, Pekka Nikander, Marcelo Bagnulo, Vivien Schmitt, Abhinav 510 Pathak, Lars Eggert, Thomas Henderson, Hannes Tschofenig, and Philip 511 Matthews. 513 7. IANA Considerations 515 This section is to be interpreted according to [RFC5226]. 517 This document updates the IANA Registry for HIP Parameter Types 518 [RFC5201] by assigning new HIP Parameter Type values for the new HIP 519 Parameters: RELAYED_ADDRESS, MAPPED_ADDRESS (defined in Section 4.1), 520 and PEER_PERMISSION (defined in Section 4.2). 522 This document also updates the IANA Registry for HIP NAT traversal 523 modes [RFC5770] by assigning value for the NAT traversal mode ICE- 524 HIP-UDP (defined in Section 3.7). 526 This document defines additional registration types for the HIP 527 Registration Extension [RFC5203] that allow registering with a HIP 528 relay server for ESP relaying service: RELAY_UDP_ESP (defined in 529 Section 3.1); and performing server reflexive candidate discovery: 530 CANDIDATE_DISCOVERY (defined in Section 3.5). 532 The IANA Registry for HIP Registration Failure Types is updated with 533 new Failure Types "Insufficient resources" (defined in Section 3.1) 534 and "Invalid certificate" (defined in Section 3.2). 536 8. References 538 8.1. Normative References 540 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 541 Requirement Levels", BCP 14, RFC 2119, March 1997. 543 [RFC5201] Moskowitz, R., Nikander, P., Jokela, P., and T. Henderson, 544 "Host Identity Protocol", RFC 5201, April 2008. 546 [RFC5202] Jokela, P., Moskowitz, R., and P. Nikander, "Using the 547 Encapsulating Security Payload (ESP) Transport Format with 548 the Host Identity Protocol (HIP)", RFC 5202, April 2008. 550 [RFC5203] Laganier, J., Koponen, T., and L. Eggert, "Host Identity 551 Protocol (HIP) Registration Extension", RFC 5203, 552 April 2008. 554 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 555 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 556 May 2008. 558 [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment 559 (ICE): A Protocol for Network Address Translator (NAT) 560 Traversal for Offer/Answer Protocols", RFC 5245, 561 April 2010. 563 [RFC5770] Komu, M., Henderson, T., Tschofenig, H., Melen, J., and A. 564 Keranen, "Basic Host Identity Protocol (HIP) Extensions 565 for Traversal of Network Address Translators", RFC 5770, 566 April 2010. 568 [I-D.ietf-hip-cert] 569 Heer, T. and S. Varjonen, "HIP Certificates", 570 draft-ietf-hip-cert-03 (work in progress), April 2010. 572 8.2. Informative References 574 [RFC5207] Stiemerling, M., Quittek, J., and L. Eggert, "NAT and 575 Firewall Traversal Issues of Host Identity Protocol (HIP) 576 Communication", RFC 5207, April 2008. 578 [RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing, 579 "Session Traversal Utilities for NAT (STUN)", RFC 5389, 580 October 2008. 582 [RFC5766] Mahy, R., Matthews, P., and J. Rosenberg, "Traversal Using 583 Relays around NAT (TURN): Relay Extensions to Session 584 Traversal Utilities for NAT (STUN)", RFC 5766, April 2010. 586 Authors' Addresses 588 Ari Keranen 589 Ericsson 590 Hirsalantie 11 591 02420 Jorvas 592 Finland 594 Email: Ari.Keranen@ericsson.com 596 Jan Melen 597 Ericsson 598 Hirsalantie 11 599 02420 Jorvas 600 Finland 602 Email: Jan.Melen@ericsson.com