idnits 2.17.1 draft-ietf-sidr-rpki-rtr-14.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The abstract seems to contain references ([I-D.ietf-sidr-arch]), which it shouldn't. Please replace those with straight textual mentions of the documents in question. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (July 10, 2011) is 4671 days in the past. Is this intentional? 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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-10) exists of draft-ietf-sidr-pfx-validate-01 ** Obsolete normative reference: RFC 2385 (Obsoleted by RFC 5925) ** Downref: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reference: RFC 5226 (Obsoleted by RFC 8126) ** Obsolete normative reference: RFC 5246 (Obsoleted by RFC 8446) == Outdated reference: A later version (-09) exists of draft-ietf-sidr-repos-struct-08 Summary: 5 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--).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: January 11, 2012 ISC 6 July 10, 2011 8 The RPKI/Router Protocol 9 draft-ietf-sidr-rpki-rtr-14 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 January 11, 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 . . . . . . . . . . . . . . . . . . . . . 17 84 8. Router-Cache Set-Up . . . . . . . . . . . . . . . . . . . . . 18 85 9. Deployment Scenarios . . . . . . . . . . . . . . . . . . . . . 19 86 10. Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . 20 87 11. Security Considerations . . . . . . . . . . . . . . . . . . . 20 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 0 8 16 24 31 233 .-------------------------------------------. 234 | Protocol | PDU | | 235 | Version | Type | Cache Nonce | 236 | 0 | 0 | | 237 +-------------------------------------------+ 238 | | 239 | Length=12 | 240 | | 241 +-------------------------------------------+ 242 | | 243 | Serial Number | 244 | | 245 `-------------------------------------------' 247 5.2. Serial Query 249 Serial Query: The router sends Serial Query to ask the cache for all 250 payload PDUs which have serial numbers higher than the serial number 251 in the Serial Query. 253 The cache replies to this query with a Cache Response PDU 254 (Section 5.4) if the cache has a record of the changes since the 255 serial number specified by the router. If there have been no changes 256 since the router last queried, the cache responds with an End Of Data 257 PDU. If the cache does not have the data needed to update the 258 router, perhaps because its records do not go back to the Serial 259 Number in the Serial Query, then it responds with a Cache Reset PDU 260 (Section 5.8). 262 The Cache Nonce tells the cache what instance the router expects to 263 ensure that the serial numbers are commensurate, i.e. the cache 264 session has not been changed. 266 0 8 16 24 31 267 .-------------------------------------------. 268 | Protocol | PDU | | 269 | Version | Type | Cache Nonce | 270 | 0 | 1 | | 271 +-------------------------------------------+ 272 | | 273 | Length=12 | 274 | | 275 +-------------------------------------------+ 276 | | 277 | Serial Number | 278 | | 279 `-------------------------------------------' 281 5.3. Reset Query 283 Reset Query: The router tells the cache that it wants to receive the 284 total active, current, non-withdrawn, database. The cache responds 285 with a Cache Response PDU (Section 5.4). 287 0 8 16 24 31 288 .-------------------------------------------. 289 | Protocol | PDU | | 290 | Version | Type | reserved = zero | 291 | 0 | 2 | | 292 +-------------------------------------------+ 293 | | 294 | Length=8 | 295 | | 296 `-------------------------------------------' 298 5.4. Cache Response 300 Cache Response: The cache responds with zero or more payload PDUs. 301 When replying to a Serial Query request (Section 5.2), the cache 302 sends the set of all data records it has with serial numbers greater 303 than that sent by the client router. When replying to a Reset Query, 304 the cache sends the set of all data records it has; in this case the 305 withdraw/announce field in the payload PDUs MUST have the value 1 306 (announce). 308 In response to a Reset Query, the new value of Cache Nonce tells the 309 router the instance of the cache session for future confirmation. In 310 response to a Serial Query, the Cache Nonce being the same reassures 311 the router that the serial numbers are commensurate, i.e. the cache 312 session has not changed. 314 0 8 16 24 31 315 .-------------------------------------------. 316 | Protocol | PDU | | 317 | Version | Type | Cache Nonce | 318 | 0 | 3 | | 319 +-------------------------------------------+ 320 | | 321 | Length=8 | 322 | | 323 `-------------------------------------------' 325 5.5. IPv4 Prefix 327 0 8 16 24 31 328 .-------------------------------------------. 329 | Protocol | PDU | | 330 | Version | Type | reserved = zero | 331 | 0 | 4 | | 332 +-------------------------------------------+ 333 | | 334 | Length=20 | 335 | | 336 +-------------------------------------------+ 337 | | Prefix | Max | | 338 | Flags | Length | Length | zero | 339 | | 0..32 | 0..32 | | 340 +-------------------------------------------+ 341 | | 342 | IPv4 Prefix | 343 | | 344 +-------------------------------------------+ 345 | | 346 | Autonomous System Number | 347 | | 348 `-------------------------------------------' 350 The lowest order bit of the Flags field is 1 for an announcement and 351 0 for a withdrawal. 353 In the RPKI, nothing prevents a signing certificate from issuing two 354 identical ROAs, and nothing prohibits the existence of two identical 355 route: or route6: objects in the IRR. In this case there would be no 356 semantic difference between the objects, merely a process redundancy. 358 In the RPKI, there is also an actual need for what might appear to a 359 router as identical IPvX PDUs. This can occur when an upstream 360 certificate is being reissued or there is an address ownership 361 transfer up the validation chain. The ROA would be identical in the 362 router sense, i.e. have the same {prefix, len, max-len, asn}, but a 363 different validation path in the RPKI. This is important to the 364 RPKI, but not to the router. 366 The cache server MUST ensure that it has told the router client to 367 have one and only one IPvX PDU for a unique {prefix, len, max-len, 368 asn} at any one point in time. Should the router client receive an 369 IPvX PDU with a {prefix, len, max-len, asn} identical to one it 370 already has active, it SHOULD raise a Duplicate Announcement Received 371 error. 373 5.6. IPv6 Prefix 375 0 8 16 24 31 376 .-------------------------------------------. 377 | Protocol | PDU | | 378 | Version | Type | reserved = zero | 379 | 0 | 6 | | 380 +-------------------------------------------+ 381 | | 382 | Length=32 | 383 | | 384 +-------------------------------------------+ 385 | | Prefix | Max | | 386 | Flags | Length | Length | zero | 387 | | 0..128 | 0..128 | | 388 +-------------------------------------------+ 389 | | 390 +--- ---+ 391 | | 392 +--- IPv6 Prefix ---+ 393 | | 394 +--- ---+ 395 | | 396 +-------------------------------------------+ 397 | | 398 | Autonomous System Number | 399 | | 400 `-------------------------------------------' 402 5.7. End of Data 404 End of Data: Cache tells router it has no more data for the request. 406 The Cache Nonce MUST be the same as that of the corresponding Cache 407 Response which began the, possibly null, sequence of data PDUs. 409 0 8 16 24 31 410 .-------------------------------------------. 411 | Protocol | PDU | | 412 | Version | Type | Cache Nonce | 413 | 0 | 7 | | 414 +-------------------------------------------+ 415 | | 416 | Length=12 | 417 | | 418 +-------------------------------------------+ 419 | | 420 | Serial Number | 421 | | 422 `-------------------------------------------' 424 5.8. Cache Reset 426 The cache may respond to a Serial Query informing the router that the 427 cache cannot provide an incremental update starting from the serial 428 number specified by the router. The router must decide whether to 429 issue a Reset Query or switch to a different cache. 431 0 8 16 24 31 432 .-------------------------------------------. 433 | Protocol | PDU | | 434 | Version | Type | reserved = zero | 435 | 0 | 8 | | 436 +-------------------------------------------+ 437 | | 438 | Length=8 | 439 | | 440 `-------------------------------------------' 442 5.9. Error Report 444 This PDU is used by either party to report an error to the other. 446 The Error Code is described in Section 10. 448 If the error is not associated with any particular PDU, the Erroneous 449 PDU field MUST be empty and the Length of Encapsulated PDU field MUST 450 be zero. 452 An Error Report PDU MUST NOT be sent for an Error Report PDU. 454 If the error is associated with a PDU of excessive, or possibly 455 corrupt, length, the Erroneous PDU field MAY be truncated. 457 The diagnostic text is optional, if not present the Length of Error 458 Text field SHOULD be zero. If error text is present, it SHOULD be a 459 string in US-ASCII, for maximum portability; if non-US-ASCII 460 characters are absolutely required, the error text MUST use UTF-8 461 encoding. 463 0 8 16 24 31 464 .-------------------------------------------. 465 | Protocol | PDU | | 466 | Version | Type | Error Code | 467 | 0 | 10 | | 468 +-------------------------------------------+ 469 | | 470 | Length | 471 | | 472 +-------------------------------------------+ 473 | | 474 | Length of Encapsulated PDU | 475 | | 476 +-------------------------------------------+ 477 | | 478 ~ Copy of Erroneous PDU ~ 479 | | 480 +-------------------------------------------+ 481 | | 482 | Length of Error Text | 483 | | 484 +-------------------------------------------+ 485 | | 486 | Arbitrary Text | 487 | of | 488 ~ Error Diagnostic Message ~ 489 | | 490 `-------------------------------------------' 492 5.10. Fields of a PDU 494 PDUs contain the following data elements: 496 Protocol Version: An ordinal, currently 0, denoting the version of 497 this protocol. 499 PDU Type: An ordinal, denoting the type of the PDU, e.g. IPv4 500 Prefix, etc. 502 Serial Number: The serial number of the RPKI Cache when this ROA was 503 received from the cache's up-stream cache server or gathered from 504 the global RPKI. A cache increments its serial number when 505 completing an rigorously validated update from a parent cache, for 506 example via rcynic. See [RFC1982] on DNS Serial Number Arithmetic 507 for too much detail on serial number arithmetic. 509 Cache Nonce: When a cache server is started, it generates a nonce to 510 identify the instance of the cache and to bind it to the sequence 511 of Serial Numbers that cache instance will generate. This allows 512 the router to restart a failed session knowing that the Serial 513 Number it is using is commensurate with that of the cache. If, at 514 any time, either the router or the cache finds the value of the 515 nonces they hold disagree, they MUST completely drop the session 516 and the router MUST flush all data learned from that cache. 518 The nonce might be a pseudo-random, a monotonically increasing 519 value if the cache has reliable storage, etc. An implementation 520 which uses a fine granularity of time for the Serial Number might 521 never change the Cache Nonce. 523 Length: A 32 bit ordinal which has as its value the count of the 524 bytes in the entire PDU, including the eight bytes of header which 525 end with the length field. 527 Flags: The lowest order bit of the Flags field is 1 for an 528 announcement and 0 for a withdrawal, whether this PDU announces a 529 new right to announce the prefix or withdraws a previously 530 announced right. A withdraw effectively deletes one previously 531 announced IPvX Prefix PDU with the exact same Prefix, Length, Max- 532 Len, and ASN. 534 Prefix Length: An ordinal denoting the shortest prefix allowed for 535 the prefix. 537 Max Length: An ordinal denoting the longest prefix allowed by the 538 prefix. This MUST NOT be less than the Prefix Length element. 540 Prefix: The IPv4 or IPv6 prefix of the ROA. 542 Autonomous System Number: ASN allowed to announce this prefix, a 32 543 bit ordinal. 545 Zero: Fields shown as zero or reserved MUST be zero. The value of 546 such a field MUST be ignored on receipt. 548 6. Protocol Sequences 550 The sequences of PDU transmissions fall into three conversations as 551 follows: 553 6.1. Start or Restart 555 Cache Router 556 ~ ~ 557 | <----- Reset Query -------- | R requests data (or Serial Query) 558 | | 559 | ----- Cache Response -----> | C confirms request 560 | ------- IPvX Prefix ------> | C sends zero or more 561 | ------- IPvX Prefix ------> | IPv4 and IPv6 Prefix 562 | ------- IPvX Prefix ------> | Payload PDUs 563 | ------ End of Data ------> | C sends End of Data 564 | | and sends new serial 565 ~ ~ 567 When a transport session is first established, the router MAY send a 568 Reset Query and the cache responds with a data sequence of all data 569 it contains. 571 Alternatively, if the router has significant unexpired data from a 572 broken session with the same cache, it MAY start with a Serial Query 573 containing the Cache Nonce from the previous session to ensure the 574 serial numbers are commensurate. 576 This Reset Query sequence is also used when the router receives a 577 Cache Reset, chooses a new cache, or fears that it has otherwise lost 578 its way. 580 To limit the length of time a cache must keep the data necessary to 581 generate incremental updates, a router MUST send either a Serial 582 Query or a Reset Query no less frequently than once an hour. This 583 also acts as a keep alive at the application layer. 585 As the cache MAY not keep updates for little more than one hour, the 586 router MUST have a polling interval of no greater than once an hour. 588 6.2. Typical Exchange 590 Cache Router 591 ~ ~ 592 | -------- Notify ----------> | (optional) 593 | | 594 | <----- Serial Query ------- | R requests data 595 | | 596 | ----- Cache Response -----> | C confirms request 597 | ------- IPvX Prefix ------> | C sends zero or more 598 | ------- IPvX Prefix ------> | IPv4 and IPv6 Prefix 599 | ------- IPvX Prefix ------> | Payload PDUs 600 | ------ End of Data ------> | C sends End of Data 601 | | and sends new serial 602 ~ ~ 604 The cache server SHOULD send a notify PDU with its current serial 605 number when the cache's serial changes, with the expectation that the 606 router MAY then issue a serial query earlier than it otherwise might. 607 This is analogous to DNS NOTIFY in [RFC1996]. The cache MUST rate 608 limit Serial Notifies to no more frequently than one per minute. 610 When the transport layer is up and either a timer has gone off in the 611 router, or the cache has sent a Notify, the router queries for new 612 data by sending a Serial Query, and the cache sends all data newer 613 than the serial in the Serial Query. 615 To limit the length of time a cache must keep old withdraws, a router 616 MUST send either a Serial Query or a Reset Query no less frequently 617 than once an hour. 619 6.3. No Incremental Update Available 621 Cache Router 622 ~ ~ 623 | <----- Serial Query ------ | R requests data 624 | ------- Cache Reset ------> | C cannot supply update 625 | | from specified serial 626 | <------ Reset Query ------- | R requests new data 627 | ----- Cache Response -----> | C confirms request 628 | ------- IPvX Prefix ------> | C sends zero or more 629 | ------- IPvX Prefix ------> | IPv4 and IPv6 Prefix 630 | ------- IPvX Prefix ------> | Payload PDUs 631 | ------ End of Data ------> | C sends End of Data 632 | | and sends new serial 633 ~ ~ 635 The cache may respond to a Serial Query with a Cache Reset, informing 636 the router that the cache cannot supply an incremental update from 637 the serial number specified by the router. This might be because the 638 cache has lost state, or because the router has waited too long 639 between polls and the cache has cleaned up old data that it no longer 640 believes it needs, or because the cache has run out of storage space 641 and had to expire some old data early. Regardless of how this state 642 arose, the cache replies with a Cache Reset to tell the router that 643 it cannot honor the request. When a router receives this, the router 644 SHOULD attempt to connect to any more preferred caches in its cache 645 list. If there are no more preferred caches it MUST issue a Reset 646 Query and get an entire new load from the cache. 648 6.4. Cache has No Data Available 650 Cache Router 651 ~ ~ 652 | <----- Serial Query ------ | R requests data 653 | ---- Error Report PDU ----> | C cannot supply update 654 ~ ~ 656 Cache Router 657 ~ ~ 658 | <----- Reset Query ------- | R requests data 659 | ---- Error Report PDU ----> | C cannot supply update 660 ~ ~ 662 The cache may respond to either a Serial Query or a Reset Query 663 informing the router that the cache cannot supply any update at all. 664 The most likely cause is that the cache has lost state, perhaps due 665 to a restart, and has not yet recovered. While it is possible that a 666 cache might go into such a state without dropping any of its active 667 sessions, a router is more likely to see this behavior when it 668 initially connects and issues a Reset Query while the cache is still 669 rebuilding its database. 671 When a router receives this kind of error, the router SHOULD attempt 672 to connect to any other caches in its cache list, in preference 673 order. If no other caches are available, the router MUST issue 674 periodic Reset Queries until it gets a new usable load from the 675 cache. 677 7. Transport 679 The transport layer session between a router and a cache carries the 680 binary Protocol Data Units (PDUs) in a persistent session. 682 To prevent cache spoofing and DoS attacks by illegitimate routers, it 683 is highly desirable that the router and the cache are authenticated 684 to each other. Integrity protection for payloads is also desirable 685 to protect against monkey in the middle attacks. Unfortunately, 686 there is no protocol to do so on all currently used platforms. 687 Therefore, as of this document, there is no mandatory to implement 688 transport which provides authentication and integrity protection. 690 It is expected that, when TCP-AO [RFC5925]is available on all 691 platforms deployed by operators, it will become the mandatory to 692 implement transport. 694 Caches and routers MUST implement unprotected transport over TCP 695 using a port, RPKI-Rtr, to be assigned, see Section 12. Operators 696 SHOULD use procedural means, ACLs, ... to reduce the exposure to 697 authentication issues. 699 If available to the operator, caches and routers SHOULD use one of 700 the following more protected protocols. 702 Caches and routers SHOULD use TCP AO transport [RFC5925] over the 703 RPKI-Rtr port. 705 Caches and routers MAY use SSH transport [RFC4252] using using a the 706 normal SSH port. For an example, see Section 7.1. 708 Caches and routers MAY use TCP MD5 transport [RFC2385] using the 709 RPKI-Rtr port. 711 Caches and routers MAY use IPsec transport [RFC4301] using the RPKI- 712 Rtr port. 714 Caches and routers MAY use TLS transport [RFC5246] using using a 715 port, RPKI-Rtr TLS, to be assigned, see Section 12. 717 7.1. SSH Transport 719 To run over SSH, the client router first establishes an SSH transport 720 connection using the SSH transport protocol, and the client and 721 server exchange keys for message integrity and encryption. The 722 client then invokes the "ssh-userauth" service to authenticate the 723 application, as described in the SSH authentication protocol RFC 4252 724 [RFC4252]. Once the application has been successfully authenticated, 725 the client invokes the "ssh-connection" service, also known as the 726 SSH connection protocol. 728 After the ssh-connection service is established, the client opens a 729 channel of type "session", which results in an SSH session. 731 Once the SSH session has been established, the application invokes 732 the application transport as an SSH subsystem called "rpki-rtr". 733 Subsystem support is a feature of SSH version 2 (SSHv2) and is not 734 included in SSHv1. Running this protocol as an SSH subsystem avoids 735 the need for the application to recognize shell prompts or skip over 736 extraneous information, such as a system message that is sent at 737 shell start-up. 739 It is assumed that the router and cache have exchanged keys out of 740 band by some reasonably secured means. 742 Cache servers supporting SSH transport MUST accept RSA and DSA 743 authentication, and SHOULD accept ECDSA authentication. User 744 authentication MUST be supported; host authentication MAY be 745 supported. Implementations MAY support password authentication. 746 Client routers SHOULD verify the public key of the cache, to avoid 747 monkey-in-the-middle attacks. 749 7.2. TLS Transport 751 Client routers using TLS transport MUST use client-side certificates 752 for authentication. While in principle any type of certificate and 753 certificate authority may be used, in general cache operators will 754 generally wish to create their own small-scale CA and issue 755 certificates to each authorized router. This simplifies credential 756 roll-over; any unrevoked, unexpired certificate from the proper CA 757 may be used. If such certificates are used, the CN field [RFC5280] 758 MUST be used to denote the router's identity. 760 Clients SHOULD verify the cache's certificate as well, to avoid 761 monkey-in-the-middle attacks. 763 7.3. TCP MD5 Transport 765 If TCP-MD5 is used, implementations MUST support key lengths of at 766 least 80 printable ASCII bytes, per section 4.5 of [RFC2385]. 767 Implementations MUST also support hexadecimal sequences of at least 768 32 characters, i.e., 128 bits. 770 Key rollover with TCP-MD5 is problematic. Cache servers SHOULD 771 support [RFC4808]. 773 7.4. TCP-AO Transport 775 Implementations MUST support key lengths of at least 80 printable 776 ASCII bytes. Implementations MUST also support hexadecimal sequences 777 of at least 32 characters, i.e., 128 bits. MAC lengths of at least 778 96 bits MUST be supported, per section 5.3 of [RFC5925]. 780 The cryptographic algorithms and associcated parameters described in 781 [RFC5926] MUST be supported. 783 8. Router-Cache Set-Up 785 A cache has the public authentication data for each router it is 786 configured to support. 788 A router may be configured to peer with a selection of caches, and a 789 cache may be configured to support a selection of routers. Each must 790 have the name of, and authentication data for, each peer. In 791 addition, in a router, this list has a non-unique preference value 792 for each server in order of preference. This preference merely 793 denotes proximity, not trust, preferred belief, etc. The client 794 router attempts to establish a session with each potential serving 795 cache in preference order, and then starts to load data from the most 796 preferred cache to which it can connect and authenticate. The 797 router's list of caches has the following elements: 799 Preference: An ordinal denoting the router's preference to connect 800 to that cache, the lower the value the more preferred. 802 Name: The IP Address or fully qualified domain name of the cache. 804 Key: Any needed public key of the cache. 806 MyKey: Any needed private key or certificate of this client. 808 Due to the distributed nature of the RPKI, caches simply can not be 809 rigorously synchronous. A client may hold data from multiple caches, 810 but MUST keep the data marked as to source, as later updates MUST 811 affect the correct data. 813 Just as there may be more than one covering ROA from a single cache, 814 there may be multiple covering ROAs from multiple caches. The 815 results are as described in [I-D.ietf-sidr-pfx-validate]. 817 If data from multiple caches are held, implementations MUST NOT 818 distinguish between data sources when performing validation. 820 When a more preferred cache becomes available, if resources allow, it 821 would be prudent for the client to start fetching from that cache. 823 The client SHOULD attempt to maintain at least one set of data, 824 regardless of whether it has chosen a different cache or established 825 a new connection to the previous cache. 827 A client MAY drop the data from a particular cache when it is fully 828 in synch with one or more other caches. 830 A client SHOULD delete the data from a cache when it has been unable 831 to refresh from that cache for a configurable timer value. The 832 default for that value is twice the polling period for that cache. 834 If a client loses connectivity to a cache it is using, or otherwise 835 decides to switch to a new cache, it SHOULD retain the data from the 836 previous cache until it has a full set of data from one or more other 837 caches. Note that this may already be true at the point of 838 connection loss if the client has connections to more than one cache. 840 9. Deployment Scenarios 842 For illustration, we present three likely deployment scenarios. 844 Small End Site: The small multi-homed end site may wish to outsource 845 the RPKI cache to one or more of their upstream ISPs. They would 846 exchange authentication material with the ISP using some out of 847 band mechanism, and their router(s) would connect to one or more 848 up-streams' caches. The ISPs would likely deploy caches intended 849 for customer use separately from the caches with which their own 850 BGP speakers peer. 852 Large End Site: A larger multi-homed end site might run one or more 853 caches, arranging them in a hierarchy of client caches, each 854 fetching from a serving cache which is closer to the global RPKI. 855 They might configure fall-back peerings to up-stream ISP caches. 857 ISP Backbone: A large ISP would likely have one or more redundant 858 caches in each major PoP, and these caches would fetch from each 859 other in an ISP-dependent topology so as not to place undue load 860 on the global RPKI publication infrastructure. 862 Experience with large DNS cache deployments has shown that complex 863 topologies are ill-advised as it is easy to make errors in the graph, 864 e.g. not maintaining a loop-free condition. 866 Of course, these are illustrations and there are other possible 867 deployment strategies. It is expected that minimizing load on the 868 global RPKI servers will be a major consideration. 870 To keep load on global RPKI services from unnecessary peaks, it is 871 recommended that primary caches which load from the distributed 872 global RPKI not do so all at the same times, e.g. on the hour. 873 Choose a random time, perhaps the ISP's AS number modulo 60 and 874 jitter the inter-fetch timing. 876 10. Error Codes 878 This section contains a preliminary list of error codes. The authors 879 expect additions to this section during development of the initial 880 implementations. Errors which are considered fatal SHOULD cause the 881 session to be dropped. 883 0: Corrupt Data (fatal): The receiver believes the received PDU to 884 be corrupt in a manner not specified by other error codes. 886 1: Internal Error (fatal): The party reporting the error experienced 887 some kind of internal error unrelated to protocol operation (ran 888 out of memory, a coding assertion failed, et cetera). 890 2: No Data Available: The cache believes itself to be in good 891 working order, but is unable to answer either a Serial Query or a 892 Reset Query because it has no useful data available at this time. 893 This is likely to be a temporary error, and most likely indicates 894 that the cache has not yet completed pulling down an initial 895 current data set from the global RPKI system after some kind of 896 event that invalidated whatever data it might have previously held 897 (reboot, network partition, et cetera). 899 3: Invalid Request (fatal): The cache server believes the client's 900 request to be invalid. 902 4: Unsupported Protocol Version (fatal): The Protocol Version is not 903 known by the receiver of the PDU. 905 5: Unsupported PDU Type (fatal): The PDU Type is not known by the 906 receiver of the PDU. 908 6: Withdrawal of Unknown Record (fatal): The received PDU has Flag=0 909 but a record for the Prefix/PrefixLength/MaxLength triple does not 910 exist in the receiver's database. 912 7: Duplicate Announcement Received (fatal): The received PDU has an 913 identical {prefix, len, max-len, asn} tuple as a PDU which is 914 still active in the router. 916 11. Security Considerations 918 As this document describes a security protocol, many aspects of 919 security interest are described in the relevant sections. This 920 section points out issues which may not be obvious in other sections. 922 Cache Validation: In order for a collection of caches as described 923 in Section 9 to guarantee a consistent view, they need to be given 924 consistent trust anchors to use in their internal validation 925 process. Distribution of a consistent trust anchor is assumed to 926 be out of band. 928 Cache Peer Identification: The router initiates a transport session 929 to a cache, which it identifies by either IP address or fully 930 qualified domain name. Be aware that a DNS or address spoofing 931 attack could make the correct cache unreachable. No session would 932 be established, as the authorization keys would not match. 934 Transport Security: The RPKI relies on object, not server or 935 transport, trust. I.e. the IANA root trust anchor is distributed 936 to all caches through some out of band means, and can then be used 937 by each cache to validate certificates and ROAs all the way down 938 the tree. The inter-cache relationships are based on this object 939 security model, hence the inter-cache transport can be lightly 940 protected. 942 But this protocol document assumes that the routers can not do the 943 validation cryptography. Hence the last link, from cache to 944 router, is secured by server authentication and transport level 945 security. This is dangerous, as server authentication and 946 transport have very different threat models than object security. 948 So the strength of the trust relationship and the transport 949 between the router(s) and the cache(s) are critical. You're 950 betting your routing on this. 952 While we can not say the cache must be on the same LAN, if only 953 due to the issue of an enterprise wanting to off-load the cache 954 task to their upstream ISP(s), locality, trust, and control are 955 very critical issues here. The cache(s) really SHOULD be as 956 close, in the sense of controlled and protected (against DDoS, 957 MITM) transport, to the router(s) as possible. It also SHOULD be 958 topologically close so that a minimum of validated routing data 959 are needed to bootstrap a router's access to a cache. 961 The identity of the cache server MUST be verified and 962 authenticated by the router client, and vice versa, before any 963 data are exchanged. 965 12. IANA Considerations 967 This document requests the IANA to assign TCP Port Numbers to the 968 RPKI-Router Protocol for the following, see Section 7: 970 RPKI-Rtr 971 RPKI-Rtr TLS 973 This document requests the IANA to create a registry for tuples of 974 Protocol Version / PDU Type, each of which may range from 0 to 255. 975 The name of the registry should be rpki-rtr-pdu. The policy for 976 adding to the registry is RFC Required per [RFC5226], either 977 standards track or experimental. The initial entries should be as 978 follows: 980 Protocol 981 Version PDU Type 982 -------- ------------------- 983 0 0 - Serial Notify 984 0 1 - Serial Query 985 0 2 - Reset Query 986 0 3 - Cache Response 987 0 4 - IPv4 Prefix 988 0 6 - IPv6 Prefix 989 0 7 - End of Data 990 0 8 - Cache Reset 991 0 10 - Error Report 992 0 255 - Reserved 994 This document requests the IANA to create a registry for Error Codes 995 0 to 255. The name of the registry should be rpki-rtr-error. The 996 policy for adding to the registry is Expert Review per [RFC5226], 997 where the responsible IESG area director should appoint the Expert 998 Reviewer. The initial entries should be as follows: 1000 0 - Corrupt Data 1001 1 - Internal Error 1002 2 - No Data Available 1003 3 - Invalid Request 1004 4 - Unsupported Protocol Version 1005 5 - Unsupported PDU Type 1006 6 - Withdrawal of Unknown Record 1007 7 - Duplicate Announcement Received 1008 255 - Reserved 1010 This document requests the IANA to add an SSH Connection Protocol 1011 Subsystem Name, as defined in [RFC4250], of 'rpki-rtr'. 1013 13. Acknowledgments 1015 The authors wish to thank Steve Bellovin, Rex Fernando, Russ Housley, 1016 Pradosh Mohapatra, Keyur Patel, Sandy Murphy, Robert Raszuk, John 1017 Scudder, Ruediger Volk, and David Ward. Particular thanks go to 1018 Hannes Gredler for showing us the dangers of unnecessary fields. 1020 14. References 1022 14.1. Normative References 1024 [I-D.ietf-sidr-pfx-validate] 1025 Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R. 1026 Austein, "BGP Prefix Origin Validation", 1027 draft-ietf-sidr-pfx-validate-01 (work in progress), 1028 February 2011. 1030 [RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982, 1031 August 1996. 1033 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1034 Requirement Levels", BCP 14, RFC 2119, March 1997. 1036 [RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5 1037 Signature Option", RFC 2385, August 1998. 1039 [RFC4250] Lehtinen, S. and C. Lonvick, "The Secure Shell (SSH) 1040 Protocol Assigned Numbers", RFC 4250, January 2006. 1042 [RFC4252] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) 1043 Authentication Protocol", RFC 4252, January 2006. 1045 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 1046 Internet Protocol", RFC 4301, December 2005. 1048 [RFC4808] Bellovin, S., "Key Change Strategies for TCP-MD5", 1049 RFC 4808, March 2007. 1051 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 1052 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 1053 May 2008. 1055 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 1056 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 1058 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 1059 Housley, R., and W. Polk, "Internet X.509 Public Key 1060 Infrastructure Certificate and Certificate Revocation List 1061 (CRL) Profile", RFC 5280, May 2008. 1063 [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP 1064 Authentication Option", RFC 5925, June 2010. 1066 [RFC5926] Lebovitz, G. and E. Rescorla, "Cryptographic Algorithms 1067 for the TCP Authentication Option (TCP-AO)", RFC 5926, 1068 June 2010. 1070 14.2. Informative References 1072 [I-D.ietf-sidr-arch] 1073 Lepinski, M. and S. Kent, "An Infrastructure to Support 1074 Secure Internet Routing", draft-ietf-sidr-arch-13 (work in 1075 progress), May 2011. 1077 [I-D.ietf-sidr-repos-struct] 1078 Huston, G., Loomans, R., and G. Michaelson, "A Profile for 1079 Resource Certificate Repository Structure", 1080 draft-ietf-sidr-repos-struct-08 (work in progress), 1081 June 2011. 1083 [RFC1996] Vixie, P., "A Mechanism for Prompt Notification of Zone 1084 Changes (DNS NOTIFY)", RFC 1996, August 1996. 1086 [RFC5781] Weiler, S., Ward, D., and R. Housley, "The rsync URI 1087 Scheme", RFC 5781, February 2010. 1089 Authors' Addresses 1091 Randy Bush 1092 Internet Initiative Japan 1093 5147 Crystal Springs 1094 Bainbridge Island, Washington 98110 1095 US 1097 Phone: +1 206 780 0431 x1 1098 Email: randy@psg.com 1099 Rob Austein 1100 Internet Systems Consortium 1101 950 Charter Street 1102 Redwood City, CA 94063 1103 USA 1105 Email: sra@isc.org