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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-10) exists of draft-ietf-sidr-pfx-validate-01 ** Obsolete normative reference: RFC 2385 (Obsoleted by RFC 5925) ** Downref: Normative reference to an Informational RFC: RFC 4808 ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126) ** Obsolete normative reference: RFC 5246 (Obsoleted by RFC 8446) == Outdated reference: A later version (-09) exists of draft-ietf-sidr-repos-struct-08 Summary: 5 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group R. Bush 3 Internet-Draft Internet Initiative Japan 4 Intended status: Standards Track R. Austein 5 Expires: February 14, 2012 Dragon Research Labs 6 August 13, 2011 8 The RPKI/Router Protocol 9 draft-ietf-sidr-rpki-rtr-16 11 Abstract 13 In order to formally validate the origin ASs of BGP announcements, 14 routers need a simple but reliable mechanism to receive RPKI 15 [I-D.ietf-sidr-arch] prefix origin data from a trusted cache. This 16 document describes a protocol to deliver validated prefix origin data 17 to routers. 19 Requirements Language 21 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 22 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 23 document are to be interpreted as described in [RFC2119]. 25 Status of this Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at http://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on February 14, 2012. 42 Copyright Notice 44 Copyright (c) 2011 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 Simplified BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 2. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 61 3. Deployment Structure . . . . . . . . . . . . . . . . . . . . . 4 62 4. Operational Overview . . . . . . . . . . . . . . . . . . . . . 4 63 5. Protocol Data Units (PDUs) . . . . . . . . . . . . . . . . . . 5 64 5.1. Serial Notify . . . . . . . . . . . . . . . . . . . . . . 6 65 5.2. Serial Query . . . . . . . . . . . . . . . . . . . . . . . 6 66 5.3. Reset Query . . . . . . . . . . . . . . . . . . . . . . . 7 67 5.4. Cache Response . . . . . . . . . . . . . . . . . . . . . . 7 68 5.5. IPv4 Prefix . . . . . . . . . . . . . . . . . . . . . . . 8 69 5.6. IPv6 Prefix . . . . . . . . . . . . . . . . . . . . . . . 9 70 5.7. End of Data . . . . . . . . . . . . . . . . . . . . . . . 9 71 5.8. Cache Reset . . . . . . . . . . . . . . . . . . . . . . . 10 72 5.9. Error Report . . . . . . . . . . . . . . . . . . . . . . . 10 73 5.10. Fields of a PDU . . . . . . . . . . . . . . . . . . . . . 11 74 6. Protocol Sequences . . . . . . . . . . . . . . . . . . . . . . 13 75 6.1. Start or Restart . . . . . . . . . . . . . . . . . . . . . 13 76 6.2. Typical Exchange . . . . . . . . . . . . . . . . . . . . . 14 77 6.3. No Incremental Update Available . . . . . . . . . . . . . 14 78 6.4. Cache has No Data Available . . . . . . . . . . . . . . . 15 79 7. Transport . . . . . . . . . . . . . . . . . . . . . . . . . . 15 80 7.1. SSH Transport . . . . . . . . . . . . . . . . . . . . . . 16 81 7.2. TLS Transport . . . . . . . . . . . . . . . . . . . . . . 17 82 7.3. TCP MD5 Transport . . . . . . . . . . . . . . . . . . . . 17 83 7.4. TCP-AO Transport . . . . . . . . . . . . . . . . . . . . . 18 84 8. Router-Cache Set-Up . . . . . . . . . . . . . . . . . . . . . 18 85 9. Deployment Scenarios . . . . . . . . . . . . . . . . . . . . . 19 86 10. Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . 20 87 11. Security Considerations . . . . . . . . . . . . . . . . . . . 21 88 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 89 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23 90 14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23 91 14.1. Normative References . . . . . . . . . . . . . . . . . . . 23 92 14.2. Informative References . . . . . . . . . . . . . . . . . . 24 93 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24 95 1. Introduction 97 In order to formally validate the origin ASs of BGP announcements, 98 routers need a simple but reliable mechanism to receive RPKI 99 [I-D.ietf-sidr-arch] formally validated prefix origin data from a 100 trusted cache. This document describes a protocol to deliver 101 validated prefix origin data to routers. 103 Section 3 describes the deployment structure and Section 4 then 104 presents an operational overview. The binary payloads of the 105 protocol are formally described in Section 5, and the expected PDU 106 sequences are described in Section 6. The transport protocol options 107 are described in Section 7. Section 8 details how routers and caches 108 are configured to connect and authenticate. Section 9 describes 109 likely deployment scenarios. The traditional security and IANA 110 considerations end the document. 112 The protocol is extensible to support new PDUs with new semantics 113 when and as needed, as indicated by deployment experience. PDUs are 114 versioned should deployment experience call for change. 116 2. Glossary 118 The following terms are used with special meaning: 120 Global RPKI: The authoritative data of the RPKI are published in a 121 distributed set of servers at the IANA, RIRs, NIRs, and ISPs, see 122 [I-D.ietf-sidr-repos-struct]. 124 Cache: A coalesced copy of the RPKI which is periodically fetched/ 125 refreshed directly or indirectly from the global RPKI using the 126 [RFC5781] protocol/tools. Relying party update software such as 127 rcynic is used to gather and validate the distributed data of the 128 RPKI into a cache. Trusting this cache further is a matter 129 between the provider of the cache and a relying party. 131 Serial Number: A 32-bit monotonically increasing ordinal which wraps 132 from 2^32-1 to 0. It denotes the logical version of a cache. A 133 cache increments the value by one when it successfully updates its 134 data from a parent cache or from primary RPKI data. As a cache is 135 receiving, new incoming data and implicit deletes are marked with 136 the new serial but MUST NOT be sent until the fetch is complete. 137 A serial number is not commensurate between caches, nor need it be 138 maintained across resets of the cache server. See [RFC1982] on 139 DNS Serial Number Arithmetic for too much detail on serial number 140 arithmetic. 142 Nonce: When a cache server is started, it generates a nonce to 143 identify the instance of the cache and to bind it to the sequence 144 of Serial Numbers that cache instance will generate. This allows 145 the router to restart a failed session knowing that the Serial 146 Number it is using is commensurate with that of the cache. 148 3. Deployment Structure 150 Deployment of the RPKI to reach routers has a three level structure 151 as follows: 153 Global RPKI: The authoritative data of the RPKI are published in a 154 distributed set of servers, RPKI publication repositories, e.g. 155 the IANA, RIRs, NIRs, and ISPs, see [I-D.ietf-sidr-repos-struct]. 157 Local Caches: A local set of one or more collected and verified 158 caches. A relying party, e.g. router or other client, MUST have a 159 trust relationship with, and a trusted transport channel to, any 160 authoritative cache(s) it uses. 162 Routers: A router fetches data from a local cache using the protocol 163 described in this document. It is said to be a client of the 164 cache. There MAY be mechanisms for the router to assure itself of 165 the authenticity of the cache and to authenticate itself to the 166 cache. 168 4. Operational Overview 170 A router establishes and keeps open a connection to one or more 171 caches with which it has client/server relationships. It is 172 configured with a semi-ordered list of caches, and establishes a 173 connection to the most preferred cache, or set of caches, which 174 accept the connections. 176 The router MUST choose the most preferred, by configuration, cache or 177 set of caches so that the operator may control load on their caches 178 and the Global RPKI. 180 Periodically, the router sends to the cache the serial number of the 181 highest numbered data it has received from that cache, i.e. the 182 router's current serial number. When a router establishes a new 183 connection to a cache, or wishes to reset a current relationship, it 184 sends a Reset Query. 186 The Cache responds with all data records which have serial numbers 187 greater than that in the router's query. This may be the null set, 188 in which case the End of Data PDU is still sent. Note that 'greater' 189 must take wrap-around into account, see [RFC1982]. 191 When the router has received all data records from the cache, it sets 192 its current serial number to that of the serial number in the End of 193 Data PDU. 195 When the cache updates its database, it sends a Notify message to 196 every currently connected router. This is a hint that now would be a 197 good time for the router to poll for an update, but is only a hint. 198 The protocol requires the router to poll for updates periodically in 199 any case. 201 Strictly speaking, a router could track a cache simply by asking for 202 a complete data set every time it updates, but this would be very 203 inefficient. The serial number based incremental update mechanism 204 allows an efficient transfer of just the data records which have 205 changed since last update. As with any update protocol based on 206 incremental transfers, the router must be prepared to fall back to a 207 full transfer if for any reason the cache is unable to provide the 208 necessary incremental data. Unlike some incremental transfer 209 protocols, this protocol requires the router to make an explicit 210 request to start the fallback process; this is deliberate, as the 211 cache has no way of knowing whether the router has also established 212 sessions with other caches that may be able to provide better 213 service. 215 As a cache server must evaluate certificates and ROAs which are time 216 dependent, servers' clocks MUST be correct to a tolerance of 217 approximately an hour. 219 5. Protocol Data Units (PDUs) 221 The exchanges between the cache and the router are sequences of 222 exchanges of the following PDUs according to the rules described in 223 Section 6. 225 5.1. Serial Notify 227 The cache notifies the router that the cache has new data. 229 The Cache Nonce reassures the router that the serial numbers are 230 commensurate, i.e. the cache session has not been changed. 232 Serial Notify is only message that the cache can send that is not in 233 response to a message from the router. 235 0 8 16 24 31 236 .-------------------------------------------. 237 | Protocol | PDU | | 238 | Version | Type | Cache Nonce | 239 | 0 | 0 | | 240 +-------------------------------------------+ 241 | | 242 | Length=12 | 243 | | 244 +-------------------------------------------+ 245 | | 246 | Serial Number | 247 | | 248 `-------------------------------------------' 250 5.2. Serial Query 252 Serial Query: The router sends Serial Query to ask the cache for all 253 payload PDUs which have serial numbers higher than the serial number 254 in the Serial Query. 256 The cache replies to this query with a Cache Response PDU 257 (Section 5.4) if the cache has a record of the changes since the 258 serial number specified by the router. If there have been no changes 259 since the router last queried, the cache responds with an End Of Data 260 PDU. If the cache does not have the data needed to update the 261 router, perhaps because its records do not go back to the Serial 262 Number in the Serial Query, then it responds with a Cache Reset PDU 263 (Section 5.8). 265 The Cache Nonce tells the cache what instance the router expects to 266 ensure that the serial numbers are commensurate, i.e. the cache 267 session has not been changed. 269 0 8 16 24 31 270 .-------------------------------------------. 271 | Protocol | PDU | | 272 | Version | Type | Cache Nonce | 273 | 0 | 1 | | 274 +-------------------------------------------+ 275 | | 276 | Length=12 | 277 | | 278 +-------------------------------------------+ 279 | | 280 | Serial Number | 281 | | 282 `-------------------------------------------' 284 5.3. Reset Query 286 Reset Query: The router tells the cache that it wants to receive the 287 total active, current, non-withdrawn, database. The cache responds 288 with a Cache Response PDU (Section 5.4). 290 0 8 16 24 31 291 .-------------------------------------------. 292 | Protocol | PDU | | 293 | Version | Type | reserved = zero | 294 | 0 | 2 | | 295 +-------------------------------------------+ 296 | | 297 | Length=8 | 298 | | 299 `-------------------------------------------' 301 5.4. Cache Response 303 Cache Response: The cache responds with zero or more payload PDUs. 304 When replying to a Serial Query request (Section 5.2), the cache 305 sends the set of all data records it has with serial numbers greater 306 than that sent by the client router. When replying to a Reset Query, 307 the cache sends the set of all data records it has; in this case the 308 withdraw/announce field in the payload PDUs MUST have the value 1 309 (announce). 311 In response to a Reset Query, the new value of Cache Nonce tells the 312 router the instance of the cache session for future confirmation. In 313 response to a Serial Query, the Cache Nonce being the same reassures 314 the router that the serial numbers are commensurate, i.e. the cache 315 session has not changed. 317 0 8 16 24 31 318 .-------------------------------------------. 319 | Protocol | PDU | | 320 | Version | Type | Cache Nonce | 321 | 0 | 3 | | 322 +-------------------------------------------+ 323 | | 324 | Length=8 | 325 | | 326 `-------------------------------------------' 328 5.5. IPv4 Prefix 330 0 8 16 24 31 331 .-------------------------------------------. 332 | Protocol | PDU | | 333 | Version | Type | reserved = zero | 334 | 0 | 4 | | 335 +-------------------------------------------+ 336 | | 337 | Length=20 | 338 | | 339 +-------------------------------------------+ 340 | | Prefix | Max | | 341 | Flags | Length | Length | zero | 342 | | 0..32 | 0..32 | | 343 +-------------------------------------------+ 344 | | 345 | IPv4 Prefix | 346 | | 347 +-------------------------------------------+ 348 | | 349 | Autonomous System Number | 350 | | 351 `-------------------------------------------' 353 The lowest order bit of the Flags field is 1 for an announcement and 354 0 for a withdrawal. 356 In the RPKI, nothing prevents a signing certificate from issuing two 357 identical ROAs, and nothing prohibits the existence of two identical 358 route: or route6: objects in the IRR. In this case there would be no 359 semantic difference between the objects, merely a process redundancy. 361 In the RPKI, there is also an actual need for what might appear to a 362 router as identical IPvX PDUs. This can occur when an upstream 363 certificate is being reissued or there is an address ownership 364 transfer up the validation chain. The ROA would be identical in the 365 router sense, i.e. have the same {prefix, len, max-len, asn}, but a 366 different validation path in the RPKI. This is important to the 367 RPKI, but not to the router. 369 The cache server MUST ensure that it has told the router client to 370 have one and only one IPvX PDU for a unique {prefix, len, max-len, 371 asn} at any one point in time. Should the router client receive an 372 IPvX PDU with a {prefix, len, max-len, asn} identical to one it 373 already has active, it SHOULD raise a Duplicate Announcement Received 374 error. 376 5.6. IPv6 Prefix 378 0 8 16 24 31 379 .-------------------------------------------. 380 | Protocol | PDU | | 381 | Version | Type | reserved = zero | 382 | 0 | 6 | | 383 +-------------------------------------------+ 384 | | 385 | Length=32 | 386 | | 387 +-------------------------------------------+ 388 | | Prefix | Max | | 389 | Flags | Length | Length | zero | 390 | | 0..128 | 0..128 | | 391 +-------------------------------------------+ 392 | | 393 +--- ---+ 394 | | 395 +--- IPv6 Prefix ---+ 396 | | 397 +--- ---+ 398 | | 399 +-------------------------------------------+ 400 | | 401 | Autonomous System Number | 402 | | 403 `-------------------------------------------' 405 5.7. End of Data 407 End of Data: Cache tells router it has no more data for the request. 409 The Cache Nonce MUST be the same as that of the corresponding Cache 410 Response which began the, possibly null, sequence of data PDUs. 412 0 8 16 24 31 413 .-------------------------------------------. 414 | Protocol | PDU | | 415 | Version | Type | Cache Nonce | 416 | 0 | 7 | | 417 +-------------------------------------------+ 418 | | 419 | Length=12 | 420 | | 421 +-------------------------------------------+ 422 | | 423 | Serial Number | 424 | | 425 `-------------------------------------------' 427 5.8. Cache Reset 429 The cache may respond to a Serial Query informing the router that the 430 cache cannot provide an incremental update starting from the serial 431 number specified by the router. The router must decide whether to 432 issue a Reset Query or switch to a different cache. 434 0 8 16 24 31 435 .-------------------------------------------. 436 | Protocol | PDU | | 437 | Version | Type | reserved = zero | 438 | 0 | 8 | | 439 +-------------------------------------------+ 440 | | 441 | Length=8 | 442 | | 443 `-------------------------------------------' 445 5.9. Error Report 447 This PDU is used by either party to report an error to the other. 449 Error reports are only sent as responses to other PDUs. 451 The Error Code is described in Section 10. 453 If the error is not associated with any particular PDU, the Erroneous 454 PDU field MUST be empty and the Length of Encapsulated PDU field MUST 455 be zero. 457 An Error Report PDU MUST NOT be sent for an Error Report PDU. 459 If the error is associated with a PDU of excessive, or possibly 460 corrupt, length, the Erroneous PDU field MAY be truncated. 462 The diagnostic text is optional, if not present the Length of Error 463 Text field SHOULD be zero. If error text is present, it SHOULD be a 464 string in US-ASCII, for maximum portability; if non-US-ASCII 465 characters are absolutely required, the error text MUST use UTF-8 466 encoding. 468 0 8 16 24 31 469 .-------------------------------------------. 470 | Protocol | PDU | | 471 | Version | Type | Error Code | 472 | 0 | 10 | | 473 +-------------------------------------------+ 474 | | 475 | Length | 476 | | 477 +-------------------------------------------+ 478 | | 479 | Length of Encapsulated PDU | 480 | | 481 +-------------------------------------------+ 482 | | 483 ~ Copy of Erroneous PDU ~ 484 | | 485 +-------------------------------------------+ 486 | | 487 | Length of Error Text | 488 | | 489 +-------------------------------------------+ 490 | | 491 | Arbitrary Text | 492 | of | 493 ~ Error Diagnostic Message ~ 494 | | 495 `-------------------------------------------' 497 5.10. Fields of a PDU 499 PDUs contain the following data elements: 501 Protocol Version: An ordinal, currently 0, denoting the version of 502 this protocol. 504 PDU Type: An ordinal, denoting the type of the PDU, e.g. IPv4 505 Prefix, etc. 507 Serial Number: The serial number of the RPKI Cache when this ROA was 508 received from the cache's up-stream cache server or gathered from 509 the global RPKI. A cache increments its serial number when 510 completing an rigorously validated update from a parent cache, for 511 example via rcynic. See [RFC1982] on DNS Serial Number Arithmetic 512 for too much detail on serial number arithmetic. 514 Cache Nonce: When a cache server is started, it generates a nonce to 515 identify the instance of the cache and to bind it to the sequence 516 of Serial Numbers that cache instance will generate. This allows 517 the router to restart a failed session knowing that the Serial 518 Number it is using is commensurate with that of the cache. If, at 519 any time, either the router or the cache finds the value of the 520 nonces they hold disagree, they MUST completely drop the session 521 and the router MUST flush all data learned from that cache. 523 The nonce might be a pseudo-random, a monotonically increasing 524 value if the cache has reliable storage, etc. An implementation 525 which uses a fine granularity of time for the Serial Number might 526 never change the Cache Nonce. 528 Length: A 32 bit ordinal which has as its value the count of the 529 bytes in the entire PDU, including the eight bytes of header which 530 end with the length field. 532 Flags: The lowest order bit of the Flags field is 1 for an 533 announcement and 0 for a withdrawal, whether this PDU announces a 534 new right to announce the prefix or withdraws a previously 535 announced right. A withdraw effectively deletes one previously 536 announced IPvX Prefix PDU with the exact same Prefix, Length, Max- 537 Len, and ASN. 539 Prefix Length: An ordinal denoting the shortest prefix allowed for 540 the prefix. 542 Max Length: An ordinal denoting the longest prefix allowed by the 543 prefix. This MUST NOT be less than the Prefix Length element. 545 Prefix: The IPv4 or IPv6 prefix of the ROA. 547 Autonomous System Number: ASN allowed to announce this prefix, a 32 548 bit ordinal. 550 Zero: Fields shown as zero or reserved MUST be zero. The value of 551 such a field MUST be ignored on receipt. 553 6. Protocol Sequences 555 The sequences of PDU transmissions fall into three conversations as 556 follows: 558 6.1. Start or Restart 560 Cache Router 561 ~ ~ 562 | <----- Reset Query -------- | R requests data (or Serial Query) 563 | | 564 | ----- Cache Response -----> | C confirms request 565 | ------- IPvX Prefix ------> | C sends zero or more 566 | ------- IPvX Prefix ------> | IPv4 and IPv6 Prefix 567 | ------- IPvX Prefix ------> | Payload PDUs 568 | ------ End of Data ------> | C sends End of Data 569 | | and sends new serial 570 ~ ~ 572 When a transport session is first established, the router MAY send a 573 Reset Query and the cache responds with a data sequence of all data 574 it contains. 576 Alternatively, if the router has significant unexpired data from a 577 broken session with the same cache, it MAY start with a Serial Query 578 containing the Cache Nonce from the previous session to ensure the 579 serial numbers are commensurate. 581 This Reset Query sequence is also used when the router receives a 582 Cache Reset, chooses a new cache, or fears that it has otherwise lost 583 its way. 585 To limit the length of time a cache must keep the data necessary to 586 generate incremental updates, a router MUST send either a Serial 587 Query or a Reset Query no less frequently than once an hour. This 588 also acts as a keep alive at the application layer. 590 As the cache MAY not keep updates for little more than one hour, the 591 router MUST have a polling interval of no greater than once an hour. 593 6.2. Typical Exchange 595 Cache Router 596 ~ ~ 597 | -------- Notify ----------> | (optional) 598 | | 599 | <----- Serial Query ------- | R requests data 600 | | 601 | ----- Cache Response -----> | C confirms request 602 | ------- IPvX Prefix ------> | C sends zero or more 603 | ------- IPvX Prefix ------> | IPv4 and IPv6 Prefix 604 | ------- IPvX Prefix ------> | Payload PDUs 605 | ------ End of Data ------> | C sends End of Data 606 | | and sends new serial 607 ~ ~ 609 The cache server SHOULD send a notify PDU with its current serial 610 number when the cache's serial changes, with the expectation that the 611 router MAY then issue a serial query earlier than it otherwise might. 612 This is analogous to DNS NOTIFY in [RFC1996]. The cache MUST rate 613 limit Serial Notifies to no more frequently than one per minute. 615 When the transport layer is up and either a timer has gone off in the 616 router, or the cache has sent a Notify, the router queries for new 617 data by sending a Serial Query, and the cache sends all data newer 618 than the serial in the Serial Query. 620 To limit the length of time a cache must keep old withdraws, a router 621 MUST send either a Serial Query or a Reset Query no less frequently 622 than once an hour. 624 6.3. No Incremental Update Available 626 Cache Router 627 ~ ~ 628 | <----- Serial Query ------ | R requests data 629 | ------- Cache Reset ------> | C cannot supply update 630 | | from specified serial 631 | <------ Reset Query ------- | R requests new data 632 | ----- Cache Response -----> | C confirms request 633 | ------- IPvX Prefix ------> | C sends zero or more 634 | ------- IPvX Prefix ------> | IPv4 and IPv6 Prefix 635 | ------- IPvX Prefix ------> | Payload PDUs 636 | ------ End of Data ------> | C sends End of Data 637 | | and sends new serial 638 ~ ~ 640 The cache may respond to a Serial Query with a Cache Reset, informing 641 the router that the cache cannot supply an incremental update from 642 the serial number specified by the router. This might be because the 643 cache has lost state, or because the router has waited too long 644 between polls and the cache has cleaned up old data that it no longer 645 believes it needs, or because the cache has run out of storage space 646 and had to expire some old data early. Regardless of how this state 647 arose, the cache replies with a Cache Reset to tell the router that 648 it cannot honor the request. When a router receives this, the router 649 SHOULD attempt to connect to any more preferred caches in its cache 650 list. If there are no more preferred caches it MUST issue a Reset 651 Query and get an entire new load from the cache. 653 6.4. Cache has No Data Available 655 Cache Router 656 ~ ~ 657 | <----- Serial Query ------ | R requests data 658 | ---- Error Report PDU ----> | C No Data Available 659 ~ ~ 661 Cache Router 662 ~ ~ 663 | <----- Reset Query ------- | R requests data 664 | ---- Error Report PDU ----> | C No Data Available 665 ~ ~ 667 The cache may respond to either a Serial Query or a Reset Query 668 informing the router that the cache cannot supply any update at all. 669 The most likely cause is that the cache has lost state, perhaps due 670 to a restart, and has not yet recovered. While it is possible that a 671 cache might go into such a state without dropping any of its active 672 sessions, a router is more likely to see this behavior when it 673 initially connects and issues a Reset Query while the cache is still 674 rebuilding its database. 676 When a router receives this kind of error, the router SHOULD attempt 677 to connect to any other caches in its cache list, in preference 678 order. If no other caches are available, the router MUST issue 679 periodic Reset Queries until it gets a new usable load from the 680 cache. 682 7. Transport 684 The transport layer session between a router and a cache carries the 685 binary Protocol Data Units (PDUs) in a persistent session. 687 To prevent cache spoofing and DoS attacks by illegitimate routers, it 688 is highly desirable that the router and the cache are authenticated 689 to each other. Integrity protection for payloads is also desirable 690 to protect against monkey in the middle attacks. Unfortunately, 691 there is no protocol to do so on all currently used platforms. 692 Therefore, as of this document, there is no mandatory to implement 693 transport which provides authentication and integrity protection. 695 To reduce exposure to dropped but non-terminated sessions, both 696 caches and routers SHOULD enable keep alives when available in the 697 chosen transport protocol. 699 It is expected that, when TCP-AO [RFC5925]is available on all 700 platforms deployed by operators, it will become the mandatory to 701 implement transport. 703 Caches and routers MUST implement unprotected transport over TCP 704 using a port, RPKI-Rtr, to be assigned, see Section 12. Operators 705 SHOULD use procedural means, ACLs, ... to reduce the exposure to 706 authentication issues. 708 If available to the operator, caches and routers SHOULD use one of 709 the following more protected protocols. 711 Caches and routers SHOULD use TCP AO transport [RFC5925] over the 712 RPKI-Rtr port. 714 Caches and routers MAY use SSH transport [RFC4252] using using a the 715 normal SSH port. For an example, see Section 7.1. 717 Caches and routers MAY use TCP MD5 transport [RFC2385] using the 718 RPKI-Rtr port. 720 Caches and routers MAY use IPsec transport [RFC4301] using the RPKI- 721 Rtr port. 723 Caches and routers MAY use TLS transport [RFC5246] using using a 724 port, RPKI-Rtr TLS, to be assigned, see Section 12. 726 7.1. SSH Transport 728 To run over SSH, the client router first establishes an SSH transport 729 connection using the SSH transport protocol, and the client and 730 server exchange keys for message integrity and encryption. The 731 client then invokes the "ssh-userauth" service to authenticate the 732 application, as described in the SSH authentication protocol RFC 4252 733 [RFC4252]. Once the application has been successfully authenticated, 734 the client invokes the "ssh-connection" service, also known as the 735 SSH connection protocol. 737 After the ssh-connection service is established, the client opens a 738 channel of type "session", which results in an SSH session. 740 Once the SSH session has been established, the application invokes 741 the application transport as an SSH subsystem called "rpki-rtr". 742 Subsystem support is a feature of SSH version 2 (SSHv2) and is not 743 included in SSHv1. Running this protocol as an SSH subsystem avoids 744 the need for the application to recognize shell prompts or skip over 745 extraneous information, such as a system message that is sent at 746 shell start-up. 748 It is assumed that the router and cache have exchanged keys out of 749 band by some reasonably secured means. 751 Cache servers supporting SSH transport MUST accept RSA and DSA 752 authentication, and SHOULD accept ECDSA authentication. User 753 authentication MUST be supported; host authentication MAY be 754 supported. Implementations MAY support password authentication. 755 Client routers SHOULD verify the public key of the cache, to avoid 756 monkey-in-the-middle attacks. 758 7.2. TLS Transport 760 Client routers using TLS transport MUST use client-side certificates 761 for authentication. While in principle any type of certificate and 762 certificate authority may be used, in general cache operators will 763 generally wish to create their own small-scale CA and issue 764 certificates to each authorized router. This simplifies credential 765 roll-over; any unrevoked, unexpired certificate from the proper CA 766 may be used. If such certificates are used, the CN field [RFC5280] 767 MUST be used to denote the router's identity. 769 Clients SHOULD verify the cache's certificate as well, to avoid 770 monkey-in-the-middle attacks. 772 7.3. TCP MD5 Transport 774 If TCP-MD5 is used, implementations MUST support key lengths of at 775 least 80 printable ASCII bytes, per section 4.5 of [RFC2385]. 776 Implementations MUST also support hexadecimal sequences of at least 777 32 characters, i.e., 128 bits. 779 Key rollover with TCP-MD5 is problematic. Cache servers SHOULD 780 support [RFC4808]. 782 7.4. TCP-AO Transport 784 Implementations MUST support key lengths of at least 80 printable 785 ASCII bytes. Implementations MUST also support hexadecimal sequences 786 of at least 32 characters, i.e., 128 bits. MAC lengths of at least 787 96 bits MUST be supported, per section 5.3 of [RFC5925]. 789 The cryptographic algorithms and associcated parameters described in 790 [RFC5926] MUST be supported. 792 8. Router-Cache Set-Up 794 A cache has the public authentication data for each router it is 795 configured to support. 797 A router may be configured to peer with a selection of caches, and a 798 cache may be configured to support a selection of routers. Each must 799 have the name of, and authentication data for, each peer. In 800 addition, in a router, this list has a non-unique preference value 801 for each server in order of preference. This preference merely 802 denotes proximity, not trust, preferred belief, etc. The client 803 router attempts to establish a session with each potential serving 804 cache in preference order, and then starts to load data from the most 805 preferred cache to which it can connect and authenticate. The 806 router's list of caches has the following elements: 808 Preference: An ordinal denoting the router's preference to connect 809 to that cache, the lower the value the more preferred. 811 Name: The IP Address or fully qualified domain name of the cache. 813 Key: Any needed public key of the cache. 815 MyKey: Any needed private key or certificate of this client. 817 Due to the distributed nature of the RPKI, caches simply can not be 818 rigorously synchronous. A client may hold data from multiple caches, 819 but MUST keep the data marked as to source, as later updates MUST 820 affect the correct data. 822 Just as there may be more than one covering ROA from a single cache, 823 there may be multiple covering ROAs from multiple caches. The 824 results are as described in [I-D.ietf-sidr-pfx-validate]. 826 If data from multiple caches are held, implementations MUST NOT 827 distinguish between data sources when performing validation. 829 When a more preferred cache becomes available, if resources allow, it 830 would be prudent for the client to start fetching from that cache. 832 The client SHOULD attempt to maintain at least one set of data, 833 regardless of whether it has chosen a different cache or established 834 a new connection to the previous cache. 836 A client MAY drop the data from a particular cache when it is fully 837 in synch with one or more other caches. 839 A client SHOULD delete the data from a cache when it has been unable 840 to refresh from that cache for a configurable timer value. The 841 default for that value is twice the polling period for that cache. 843 If a client loses connectivity to a cache it is using, or otherwise 844 decides to switch to a new cache, it SHOULD retain the data from the 845 previous cache until it has a full set of data from one or more other 846 caches. Note that this may already be true at the point of 847 connection loss if the client has connections to more than one cache. 849 9. Deployment Scenarios 851 For illustration, we present three likely deployment scenarios. 853 Small End Site: The small multi-homed end site may wish to outsource 854 the RPKI cache to one or more of their upstream ISPs. They would 855 exchange authentication material with the ISP using some out of 856 band mechanism, and their router(s) would connect to one or more 857 up-streams' caches. The ISPs would likely deploy caches intended 858 for customer use separately from the caches with which their own 859 BGP speakers peer. 861 Large End Site: A larger multi-homed end site might run one or more 862 caches, arranging them in a hierarchy of client caches, each 863 fetching from a serving cache which is closer to the global RPKI. 864 They might configure fall-back peerings to up-stream ISP caches. 866 ISP Backbone: A large ISP would likely have one or more redundant 867 caches in each major PoP, and these caches would fetch from each 868 other in an ISP-dependent topology so as not to place undue load 869 on the global RPKI publication infrastructure. 871 Experience with large DNS cache deployments has shown that complex 872 topologies are ill-advised as it is easy to make errors in the graph, 873 e.g. not maintaining a loop-free condition. 875 Of course, these are illustrations and there are other possible 876 deployment strategies. It is expected that minimizing load on the 877 global RPKI servers will be a major consideration. 879 To keep load on global RPKI services from unnecessary peaks, it is 880 recommended that primary caches which load from the distributed 881 global RPKI not do so all at the same times, e.g. on the hour. 882 Choose a random time, perhaps the ISP's AS number modulo 60 and 883 jitter the inter-fetch timing. 885 10. Error Codes 887 This section contains a preliminary list of error codes. The authors 888 expect additions to this section during development of the initial 889 implementations. Errors which are considered fatal SHOULD cause the 890 session to be dropped. 892 0: Corrupt Data (fatal): The receiver believes the received PDU to 893 be corrupt in a manner not specified by other error codes. 895 1: Internal Error (fatal): The party reporting the error experienced 896 some kind of internal error unrelated to protocol operation (ran 897 out of memory, a coding assertion failed, et cetera). 899 2: No Data Available: The cache believes itself to be in good 900 working order, but is unable to answer either a Serial Query or a 901 Reset Query because it has no useful data available at this time. 902 This is likely to be a temporary error, and most likely indicates 903 that the cache has not yet completed pulling down an initial 904 current data set from the global RPKI system after some kind of 905 event that invalidated whatever data it might have previously held 906 (reboot, network partition, et cetera). 908 3: Invalid Request (fatal): The cache server believes the client's 909 request to be invalid. 911 4: Unsupported Protocol Version (fatal): The Protocol Version is not 912 known by the receiver of the PDU. 914 5: Unsupported PDU Type (fatal): The PDU Type is not known by the 915 receiver of the PDU. 917 6: Withdrawal of Unknown Record (fatal): The received PDU has Flag=0 918 but a record for the Prefix/PrefixLength/MaxLength triple does not 919 exist in the receiver's database. 921 7: Duplicate Announcement Received (fatal): The received PDU has an 922 identical {prefix, len, max-len, asn} tuple as a PDU which is 923 still active in the router. 925 11. Security Considerations 927 As this document describes a security protocol, many aspects of 928 security interest are described in the relevant sections. This 929 section points out issues which may not be obvious in other sections. 931 Cache Validation: In order for a collection of caches as described 932 in Section 9 to guarantee a consistent view, they need to be given 933 consistent trust anchors to use in their internal validation 934 process. Distribution of a consistent trust anchor is assumed to 935 be out of band. 937 Cache Peer Identification: The router initiates a transport session 938 to a cache, which it identifies by either IP address or fully 939 qualified domain name. Be aware that a DNS or address spoofing 940 attack could make the correct cache unreachable. No session would 941 be established, as the authorization keys would not match. 943 Transport Security: The RPKI relies on object, not server or 944 transport, trust. I.e. the IANA root trust anchor is distributed 945 to all caches through some out of band means, and can then be used 946 by each cache to validate certificates and ROAs all the way down 947 the tree. The inter-cache relationships are based on this object 948 security model, hence the inter-cache transport can be lightly 949 protected. 951 But this protocol document assumes that the routers can not do the 952 validation cryptography. Hence the last link, from cache to 953 router, is secured by server authentication and transport level 954 security. This is dangerous, as server authentication and 955 transport have very different threat models than object security. 957 So the strength of the trust relationship and the transport 958 between the router(s) and the cache(s) are critical. You're 959 betting your routing on this. 961 While we can not say the cache must be on the same LAN, if only 962 due to the issue of an enterprise wanting to off-load the cache 963 task to their upstream ISP(s), locality, trust, and control are 964 very critical issues here. The cache(s) really SHOULD be as 965 close, in the sense of controlled and protected (against DDoS, 966 MITM) transport, to the router(s) as possible. It also SHOULD be 967 topologically close so that a minimum of validated routing data 968 are needed to bootstrap a router's access to a cache. 970 The identity of the cache server MUST be verified and 971 authenticated by the router client, and vice versa, before any 972 data are exchanged. 974 12. IANA Considerations 976 This document requests the IANA to assign 'well known' TCP Port 977 Numbers to the RPKI-Router Protocol for the following, see Section 7: 979 RPKI-Rtr 980 RPKI-Rtr TLS 982 This document requests the IANA to create a registry for tuples of 983 Protocol Version / PDU Type, each of which may range from 0 to 255. 984 The name of the registry should be rpki-rtr-pdu. The policy for 985 adding to the registry is RFC Required per [RFC5226], either 986 standards track or experimental. The initial entries should be as 987 follows: 989 Protocol 990 Version PDU Type 991 -------- ------------------- 992 0 0 - Serial Notify 993 0 1 - Serial Query 994 0 2 - Reset Query 995 0 3 - Cache Response 996 0 4 - IPv4 Prefix 997 0 6 - IPv6 Prefix 998 0 7 - End of Data 999 0 8 - Cache Reset 1000 0 10 - Error Report 1001 0 255 - Reserved 1003 This document requests the IANA to create a registry for Error Codes 1004 0 to 255. The name of the registry should be rpki-rtr-error. The 1005 policy for adding to the registry is Expert Review per [RFC5226], 1006 where the responsible IESG area director should appoint the Expert 1007 Reviewer. The initial entries should be as follows: 1009 0 - Corrupt Data 1010 1 - Internal Error 1011 2 - No Data Available 1012 3 - Invalid Request 1013 4 - Unsupported Protocol Version 1014 5 - Unsupported PDU Type 1015 6 - Withdrawal of Unknown Record 1016 7 - Duplicate Announcement Received 1017 255 - Reserved 1019 This document requests the IANA to add an SSH Connection Protocol 1020 Subsystem Name, as defined in [RFC4250], of 'rpki-rtr'. 1022 13. Acknowledgments 1024 The authors wish to thank Steve Bellovin, Rex Fernando, Paul Hoffman, 1025 Russ Housley, Pradosh Mohapatra, Keyur Patel, Sandy Murphy, Robert 1026 Raszuk, John Scudder, Ruediger Volk, and David Ward. Particular 1027 thanks go to Hannes Gredler for showing us the dangers of unnecessary 1028 fields. 1030 14. References 1032 14.1. Normative References 1034 [I-D.ietf-sidr-pfx-validate] 1035 Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R. 1036 Austein, "BGP Prefix Origin Validation", 1037 draft-ietf-sidr-pfx-validate-01 (work in progress), 1038 February 2011. 1040 [RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982, 1041 August 1996. 1043 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1044 Requirement Levels", BCP 14, RFC 2119, March 1997. 1046 [RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5 1047 Signature Option", RFC 2385, August 1998. 1049 [RFC4250] Lehtinen, S. and C. Lonvick, "The Secure Shell (SSH) 1050 Protocol Assigned Numbers", RFC 4250, January 2006. 1052 [RFC4252] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) 1053 Authentication Protocol", RFC 4252, January 2006. 1055 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 1056 Internet Protocol", RFC 4301, December 2005. 1058 [RFC4808] Bellovin, S., "Key Change Strategies for TCP-MD5", 1059 RFC 4808, March 2007. 1061 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 1062 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 1063 May 2008. 1065 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 1066 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 1068 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 1069 Housley, R., and W. Polk, "Internet X.509 Public Key 1070 Infrastructure Certificate and Certificate Revocation List 1071 (CRL) Profile", RFC 5280, May 2008. 1073 [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP 1074 Authentication Option", RFC 5925, June 2010. 1076 [RFC5926] Lebovitz, G. and E. Rescorla, "Cryptographic Algorithms 1077 for the TCP Authentication Option (TCP-AO)", RFC 5926, 1078 June 2010. 1080 14.2. Informative References 1082 [I-D.ietf-sidr-arch] 1083 Lepinski, M. and S. Kent, "An Infrastructure to Support 1084 Secure Internet Routing", draft-ietf-sidr-arch-13 (work in 1085 progress), May 2011. 1087 [I-D.ietf-sidr-repos-struct] 1088 Huston, G., Loomans, R., and G. Michaelson, "A Profile for 1089 Resource Certificate Repository Structure", 1090 draft-ietf-sidr-repos-struct-08 (work in progress), 1091 June 2011. 1093 [RFC1996] Vixie, P., "A Mechanism for Prompt Notification of Zone 1094 Changes (DNS NOTIFY)", RFC 1996, August 1996. 1096 [RFC5781] Weiler, S., Ward, D., and R. Housley, "The rsync URI 1097 Scheme", RFC 5781, February 2010. 1099 Authors' Addresses 1101 Randy Bush 1102 Internet Initiative Japan 1103 5147 Crystal Springs 1104 Bainbridge Island, Washington 98110 1105 US 1107 Phone: +1 206 780 0431 x1 1108 Email: randy@psg.com 1110 Rob Austein 1111 Dragon Research Labs 1113 Email: sra@hactrn.net