idnits 2.17.1 draft-ietf-sidr-rpki-rtr-03.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 == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: Serial Number: A 32-bit monotonically increasing ordinal which wraps from 2^32-1 to 0. It denotes the logical version of a cache. A cache increments the value by one when it successfully updates its data from a parent cache or from primary RPKI data. As a cache is receiving, new incoming data, and implicit deletes, are marked with the new serial but MUST not be sent until the fetch is complete. A serial number is not commensurate between caches, nor need it be maintained across resets of the cache server. See [RFC1982] on DNS Serial Number Arithmetic for too much detail on serial number arithmetic. -- The document date (November 19, 2010) is 4900 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) ** Downref: Normative reference to an Informational draft: draft-ietf-sidr-roa-validation (ref. 'I-D.ietf-sidr-roa-validation') ** Downref: Normative reference to an Informational RFC: RFC 5781 == Outdated reference: A later version (-13) exists of draft-ietf-sidr-arch-11 == Outdated reference: A later version (-09) exists of draft-ietf-sidr-repos-struct-06 Summary: 3 errors (**), 0 flaws (~~), 4 warnings (==), 1 comment (--).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 IIJ 4 Intended status: Standards Track R. Austein 5 Expires: May 23, 2011 ISC 6 November 19, 2010 8 The RPKI/Router Protocol 9 draft-ietf-sidr-rpki-rtr-03 11 Abstract 13 In order to formally validate the origin ASes of BGP announcements, 14 routers need a simple but reliable mechanism to receive RPKI 15 [I-D.ietf-sidr-arch] or analogous prefix origin data from a trusted 16 cache. This document describes a protocol to deliver validated 17 prefix origin data to routers over ssh. 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 RFC 2119 [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 May 23, 2011. 42 Copyright Notice 44 Copyright (c) 2010 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (http://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 2. Deployment Structure . . . . . . . . . . . . . . . . . . . . . 3 61 3. Operational Overview . . . . . . . . . . . . . . . . . . . . . 3 62 4. Protocol Data Units (PDUs) . . . . . . . . . . . . . . . . . . 4 63 4.1. Serial Notify . . . . . . . . . . . . . . . . . . . . . . 5 64 4.2. Serial Query . . . . . . . . . . . . . . . . . . . . . . . 5 65 4.3. Reset Query . . . . . . . . . . . . . . . . . . . . . . . 6 66 4.4. Cache Response . . . . . . . . . . . . . . . . . . . . . . 6 67 4.5. IPv4 Prefix . . . . . . . . . . . . . . . . . . . . . . . 7 68 4.6. IPv6 Prefix . . . . . . . . . . . . . . . . . . . . . . . 8 69 4.7. End of Data . . . . . . . . . . . . . . . . . . . . . . . 8 70 4.8. Cache Reset . . . . . . . . . . . . . . . . . . . . . . . 9 71 4.9. Error Report . . . . . . . . . . . . . . . . . . . . . . . 9 72 4.10. Fields of a PDU . . . . . . . . . . . . . . . . . . . . . 10 73 5. Protocol Sequences . . . . . . . . . . . . . . . . . . . . . . 11 74 5.1. Start or Restart . . . . . . . . . . . . . . . . . . . . . 11 75 5.2. Typical Exchange . . . . . . . . . . . . . . . . . . . . . 12 76 5.3. No Incremental Update Available . . . . . . . . . . . . . 13 77 5.4. Cache has No Data Available . . . . . . . . . . . . . . . 13 78 6. SSH Transport . . . . . . . . . . . . . . . . . . . . . . . . 14 79 7. Router-Cache Set-Up . . . . . . . . . . . . . . . . . . . . . 14 80 8. Deployment Scenarios . . . . . . . . . . . . . . . . . . . . . 16 81 9. Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . 16 82 10. Security Considerations . . . . . . . . . . . . . . . . . . . 17 83 11. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 84 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 85 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19 86 14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 87 14.1. Normative References . . . . . . . . . . . . . . . . . . . 19 88 14.2. Informative References . . . . . . . . . . . . . . . . . . 19 89 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20 91 1. Introduction 93 In order to formally validate the origin ASes of BGP announcements, 94 routers need a simple but reliable mechanism to receive RPKI 95 [I-D.ietf-sidr-arch] or analogous formally validated prefix origin 96 data from a trusted cache. This document describes a protocol to 97 deliver validated prefix origin data to routers over ssh. 99 Section 2 describes the deployment structure and Section 3 then 100 presents an operational overview. The binary payloads of the 101 protocol are formally described in Section 4, and the expected PDU 102 sequences are described in Section 5. The transport protocol is 103 described in Section 6. Section 7 details how routers and caches are 104 configured to connect and authenticate. Section 8 describes likely 105 deployment scenarios. The traditional security and IANA 106 considerations end the document. 108 The protocol is extensible to support new PDUs with new semantics 109 when and as needed, as indicated by deployment experience. PDUs are 110 versioned should deployment experience call for change. 112 2. Deployment Structure 114 Deployment of the RPKI to reach routers has a three level structure 115 as follows: 117 Global RPKI: The authoritative data of the RPKI are published in a 118 distributed set of servers, RPKI publication repositories, e.g. 119 the IANA, RIRs, NIRs, and ISPs, see [I-D.ietf-sidr-repos-struct]. 121 Local Caches: A local set of one or more collected and verified non- 122 authoritative caches. A relying party, e.g. router or other 123 client, MUST have a formally authenticated trust relationship 124 with, and a secure transport channel to, any non-authoritative 125 cache(s) it uses. 127 Routers: A router fetches data from a local cache using the protocol 128 described in this document. It is said to be a client of the 129 cache. There are mechanisms for the router to assure itself of 130 the authenticity of the cache and to authenticate itself to the 131 cache. 133 3. Operational Overview 135 A router establishes and keeps open an authenticated connection to a 136 cache with which it has a client/server relationship. It is 137 configured with a semi-ordered list of caches, and establishes a 138 connection to the most preferred cache, or set of caches, which 139 accepts one. 141 Periodically, the router sends to the cache the serial number of the 142 highest numbered data record it has received from that cache, i.e. 143 the router's current serial number. When a router establishes a new 144 connection to a cache, or wishes to reset a current relationship, it 145 sends a Reset Query. 147 The Cache responds with all data records which have serial numbers 148 greater than that in the router's query. This may be the null set, 149 in which case the End of Data PDU is still sent. Note that 'greater' 150 must take wrap-around into account, see [RFC1982]. 152 When the router has received all data records from the cache, it sets 153 its current serial number to that of the serial number in the End of 154 Data PDU. 156 When the cache updates its database, it sends a Notify message to 157 every currently connected router. This is a hint that now would be a 158 good time for the router to poll for an update, but is only a hint. 159 The protocol requires the router to poll for updates periodically in 160 any case. 162 Strictly speaking, a router could track a cache simply by asking for 163 a complete data set every time it updates, but this would be very 164 inefficient. The serial number based incremental update mechanism 165 allows an efficient transfer of just the data records which have 166 changed since last update. As with any update protocol based on 167 incremental transfers, the router must be prepared to fall back to a 168 full transfer if for any reason the cache is unable to provide the 169 necessary incremental data. Unlike some incremental transfer 170 protocols, this protocol requires the router to make an explicit 171 request to start the fallback process; this is deliberate, as the 172 cache has no way of knowing whether the router has also established 173 sessions with other caches that may be able to provide better 174 service. 176 4. Protocol Data Units (PDUs) 178 The exchanges between the cache and the router are sequences of 179 exchanges of the following PDUs according to the rules described in 180 Section 5. 182 4.1. Serial Notify 184 The cache notifies the router that the cache has new data. 186 0 8 16 24 31 187 .-------------------------------------------. 188 | Protocol | PDU | | 189 | Version | Type | reserved = zero | 190 | 0 | 0 | | 191 +-------------------------------------------+ 192 | | 193 | Length=12 | 194 | | 195 +-------------------------------------------+ 196 | | 197 | Serial Number | 198 | | 199 `-------------------------------------------' 201 4.2. Serial Query 203 Serial Query: The router sends Serial Query to ask the cache for all 204 payload PDUs which have serial numbers higher than the serial number 205 in the Serial Query. 207 The cache replies to this query with a Cache Response PDU 208 (Section 4.4) if the cache has a record of the changes since the 209 serial number specified by the router. If there have been no changes 210 since the router last queried, the cache responds with an End Of Data 211 PDU. If the cache does not have the data needed to update the 212 router, perhaps because its records do not go back to the Serial 213 Number in the Serial Query, then it responds with a Cache Reset PDU 214 (Section 4.8). 216 0 8 16 24 31 217 .-------------------------------------------. 218 | Protocol | PDU | | 219 | Version | Type | reserved = zero | 220 | 0 | 1 | | 221 +-------------------------------------------+ 222 | | 223 | Length=12 | 224 | | 225 +-------------------------------------------+ 226 | | 227 | Serial Number | 228 | | 229 `-------------------------------------------' 231 4.3. Reset Query 233 Reset Query: The router tells the cache that it wants to receive the 234 total active, current, non-withdrawn, database. The cache responds 235 with a Cache Response PDU (Section 4.4). 237 0 8 16 24 31 238 .-------------------------------------------. 239 | Protocol | PDU | | 240 | Version | Type | reserved = zero | 241 | 0 | 2 | | 242 +-------------------------------------------+ 243 | | 244 | Length=8 | 245 | | 246 `-------------------------------------------' 248 4.4. Cache Response 250 Cache Response: The cache responds with zero or more payload PDUs. 251 When replying to a Serial Query request (Section 4.2), the cache 252 sends the set of all data records it has with serial numbers greater 253 than that sent by the client router. When replying to a Reset Query, 254 the cache sends the set of all data records it has; in this case the 255 withdraw/announce field in the payload PDUs MUST have the value 1 256 (announce). 258 0 8 16 24 31 259 .-------------------------------------------. 260 | Protocol | PDU | | 261 | Version | Type | reserved = zero | 262 | 0 | 3 | | 263 +-------------------------------------------+ 264 | | 265 | Length=8 | 266 | | 267 `-------------------------------------------' 269 4.5. IPv4 Prefix 271 0 8 16 24 31 272 .-------------------------------------------. 273 | Protocol | PDU | | 274 | Version | Type | reserved = zero | 275 | 0 | 4 | | 276 +-------------------------------------------+ 277 | | 278 | Length=20 | 279 | | 280 +-------------------------------------------+ 281 | | Prefix | Max | | 282 | Flags | Length | Length | zero | 283 | | 0..32 | 0..32 | | 284 +-------------------------------------------+ 285 | | 286 | IPv4 prefix | 287 | | 288 +-------------------------------------------+ 289 | | 290 | Autonomous System Number | 291 | | 292 `-------------------------------------------' 294 Due to the nature of the RPKI and the IRR, there can be multiple 295 identical IPvX PDUs. A router MUST be prepared to receive multiple 296 identical record announcements and MUST NOT consider a record to have 297 been deleted until it has received a corresponding number of 298 withdrawals or a reset is performed Hence the router will likely keep 299 an internal reference count on each IPvX PDU. 301 In the RPKI, nothing prevents a signing certificate from issuing two 302 identical ROAs, and nothing prohibits the existence of two identical 303 route: or route6: objects in the IRR. In this case there would be no 304 semantic difference between the objects, merely a process redundancy. 306 In the RPKI, there is also an actual need for what will appear to the 307 router as identical IPvX PDUs. This occurs when an upstream 308 certificate is being reissued or a site is changing providers, often 309 a 'make and break' situation. The ROA is identical in the router 310 sense, i.e. has the same {prefix, len, max-len, asn}, but has a 311 different validation path in the RPKI. This is important to the 312 RPKI, but not to the router. 314 The lowest order bit of the Flags field is 1 for an announcement and 315 0 for a withdrawal. 317 4.6. IPv6 Prefix 319 0 8 16 24 31 320 .-------------------------------------------. 321 | Protocol | PDU | | 322 | Version | Type | reserved = zero | 323 | 0 | 6 | | 324 +-------------------------------------------+ 325 | | 326 | Length=32 | 327 | | 328 +-------------------------------------------+ 329 | | Prefix | Max | | 330 | Flags | Length | Length | zero | 331 | | 0..32 | 0..128 | | 332 +-------------------------------------------+ 333 | | 334 +--- ---+ 335 | | 336 +--- IPv6 prefix ---+ 337 | | 338 +--- ---+ 339 | | 340 +-------------------------------------------+ 341 | | 342 | Autonomous System Number | 343 | | 344 `-------------------------------------------' 346 4.7. End of Data 348 End of Data: Cache tells router it has no more data for the request. 350 0 8 16 24 31 351 .-------------------------------------------. 352 | Protocol | PDU | | 353 | Version | Type | reserved = zero | 354 | 0 | 7 | | 355 +-------------------------------------------+ 356 | | 357 | Length=12 | 358 | | 359 +-------------------------------------------+ 360 | | 361 | Serial Number | 362 | | 363 `-------------------------------------------' 365 4.8. Cache Reset 367 The cache may respond to a Serial Query informing the router that the 368 cache cannot provide an incremental update starting from the serial 369 number specified by the router. The router must decide whether to 370 issue a Reset Query or switch to a different cache. 372 0 8 16 24 31 373 .-------------------------------------------. 374 | Protocol | PDU | | 375 | Version | Type | reserved = zero | 376 | 0 | 8 | | 377 +-------------------------------------------+ 378 | | 379 | Length=8 | 380 | | 381 `-------------------------------------------' 383 4.9. Error Report 385 This PDU is used by either party to report an error to the other. 387 The Error Number is described in Section 9. 389 If the error is not associated with any particular PDU, the Erroneous 390 PDU field should be empty and the Length of Encapsulated PDU field 391 should be zero. 393 The diagnostic text is optional, if not present the Length of Error 394 Text field should be zero. If error text is present, it SHOULD be a 395 string in US-ASCII, for maximum portability; if non-US-ASCII 396 characters are absolutely required, the error text MUST use UTF-8 397 encoding. 399 0 8 16 24 31 400 .-------------------------------------------. 401 | Protocol | PDU | | 402 | Version | Type | Error Number | 403 | 0 | 10 | | 404 +-------------------------------------------+ 405 | | 406 | Length | 407 | | 408 +-------------------------------------------+ 409 | | 410 | Length of Encapsulated PDU | 411 | | 412 +-------------------------------------------+ 413 | | 414 ~ Copy of Erroneous PDU ~ 415 | | 416 +-------------------------------------------+ 417 | | 418 | Length of Error Text | 419 | | 420 +-------------------------------------------+ 421 | | 422 | Arbitrary Text | 423 | of | 424 ~ Error Diagnostic Message ~ 425 | | 426 `-------------------------------------------' 428 4.10. Fields of a PDU 430 PDUs contain the following data elements: 432 Protocol Version: An ordinal, currently 0, denoting the version of 433 this protocol. 435 Serial Number: The serial number of the RPKI Cache when this ROA was 436 received from the cache's up-stream cache server or gathered from 437 the global RPKI. A cache increments its serial number when 438 completing an rigorously validated update from a parent cache, for 439 example via rcynic. See [RFC1982] on DNS Serial Number Arithmetic 440 for too much detail on serial number arithmetic. 442 Length: A 32 bit ordinal which has as its value the count of the 443 bytes in the entire PDU, including the eight bytes of header which 444 end with the length field. 446 Flags: The lowest order bit of the Flags field is 1 for an 447 announcement and 0 for a withdrawal, whether this PDU announces a 448 new right to announce the prefix or withdraws a previously 449 announced right. A withdraw effectively deletes one previously 450 announced IPvX Prefix PDU with the exact same Prefix, Length, Max- 451 Len, and ASN. 453 Prefix Length: An ordinal denoting the shortest prefix allowed for 454 the prefix. 456 Max Length: An ordinal denoting the longest prefix allowed by the 457 prefix. This MUST NOT be less than the Prefix Length element. 459 Prefix: The IPv4 or IPv6 prefix of the ROA. 461 Autonomous System Number: ASN allowed to announce this prefix, a 32 462 bit ordinal. 464 Zero: Fields shown as zero or reserved MUST be zero. The value of 465 such a field MUST be ignored on receipt. 467 5. Protocol Sequences 469 The sequences of PDU transmissions fall into three conversations as 470 follows: 472 5.1. Start or Restart 474 Cache Router 475 ~ ~ 476 | <----- Reset Query -------- | R requests data 477 | | 478 | ----- Cache Response -----> | C confirms request 479 | ------- IPvX Prefix ------> | C sends zero or more 480 | ------- IPvX Prefix ------> | IPv4 and IPv6 Prefix 481 | ------- IPvX Prefix ------> | Payload PDUs 482 | ------ End of Data ------> | C sends End of Data 483 | | and sends new serial 484 ~ ~ 486 When a transport session is first established, the router sends a 487 Reset Query and the cache responds with a data sequence of all data 488 it contains. 490 This Reset Query sequence is also used when the router receives a 491 Cache Reset, chooses a new cache, or fears that it has otherwise lost 492 its way. 494 To limit the length of time a cache must keep the data necessary to 495 generate incremental updates, a router MUST send either a Serial 496 Query or a Reset Query no less frequently than once an hour. This 497 also acts as a keep alive at the application layer. 499 5.2. Typical Exchange 501 Cache Router 502 ~ ~ 503 | -------- Notify ----------> | (optional) 504 | | 505 | <----- Serial Query ------- | R requests data 506 | | 507 | ----- Cache Response -----> | C confirms request 508 | ------- IPvX Prefix ------> | C sends zero or more 509 | ------- IPvX Prefix ------> | IPv4 and IPv6 Prefix 510 | ------- IPvX Prefix ------> | Payload PDUs 511 | ------ End of Data ------> | C sends End of Data 512 | | and sends new serial 513 ~ ~ 515 The cache server SHOULD send a notify PDU with its current serial 516 number when the cache's serial changes, with the expectation that the 517 router MAY then issue a serial query earlier than it otherwise might. 518 This is analogous to DNS NOTIFY in [RFC1996]. The cache SHOULD rate 519 limit Serial Notifies to no more frequently than one per minute. 521 When the transport layer is up and either a timer has gone off in the 522 router, or the cache has sent a Notify, the router queries for new 523 data by sending a Serial Query, and the cache sends all data newer 524 than the serial in the Serial Query. 526 To limit the length of time a cache must keep old withdraws, a router 527 MUST send either a Serial Query or a Reset Query no less frequently 528 than once an hour. 530 5.3. No Incremental Update Available 532 Cache Router 533 ~ ~ 534 | <----- Serial Query ------ | R requests data 535 | ------- Cache Reset ------> | C cannot supply update 536 | | from specified serial 537 | <------ Reset Query ------- | R requests new data 538 | ----- Cache Response -----> | C confirms request 539 | ------- IPvX Prefix ------> | C sends zero or more 540 | ------- IPvX Prefix ------> | IPv4 and IPv6 Prefix 541 | ------- IPvX Prefix ------> | Payload PDUs 542 | ------ End of Data ------> | C sends End of Data 543 | | and sends new serial 544 ~ ~ 546 The cache may respond to a Serial Query with a Cache Reset, informing 547 the router that the cache cannot supply an incremental update from 548 the serial number specified by the router. This might be because the 549 cache has lost state, or because the router has waited too long 550 between polls and the cache has cleaned up old data that it no longer 551 believes it needs, or because the cache has run out of storage space 552 and had to expire some old data early. Regardless of how this state 553 arose, the cache replies with a Cache Reset to tell the router that 554 it cannot honor the request. When a router receives this, the router 555 SHOULD attempt to connect to any more preferred caches in its cache 556 list. If there are no more preferred caches it MUST issue a Reset 557 Query and get an entire new load from the cache. 559 5.4. Cache has No Data Available 561 Cache Router 562 ~ ~ 563 | <----- Serial Query ------ | R requests data 564 | ---- Error Report PDU ----> | C cannot supply update 565 ~ ~ 567 Cache Router 568 ~ ~ 569 | <----- Reset Query ------- | R requests data 570 | ---- Error Report PDU ----> | C cannot supply update 571 ~ ~ 573 The cache may respond to either a Serial Query or a Reset Query 574 informing the router that the cache cannot supply any update at all. 575 The most likely cause is that the cache has lost state, perhaps due 576 to a restart, and has not yet recovered. While it is possible that a 577 cache might go into such a state without dropping any of its active 578 sessions, a router is more likely to see this behavior when it 579 initially connects and issues a Reset Query while the cache is still 580 rebuilding its database. 582 When a router receives this kind of error, the router SHOULD attempt 583 to connect to any other caches in its cache list, in preference 584 order. If no other caches are available, the router MUST issue 585 periodic Reset Queries until it gets a new usable load from the 586 cache. 588 6. SSH Transport 590 The transport layer session between a router and a cache carries the 591 binary Protocol Data Units (PDUs) in a persistent SSH session. 593 To run over SSH, the client router first establishes an SSH transport 594 connection using the SSH transport protocol, and the client and 595 server exchange keys for message integrity and encryption. The 596 client then invokes the "ssh-userauth" service to authenticate the 597 application, as described in the SSH authentication protocol RFC 4252 598 [RFC4252]. Once the application has been successfully authenticated, 599 the client invokes the "ssh-connection" service, also known as the 600 SSH connection protocol. 602 After the ssh-connection service is established, the client opens a 603 channel of type "session", which results in an SSH session. 605 Once the SSH session has been established, the application invokes 606 the application transport as an SSH subsystem called "rpki-rtr". 607 Subsystem support is a feature of SSH version 2 (SSHv2) and is not 608 included in SSHv1. Running this protocol as an SSH subsystem avoids 609 the need for the application to recognize shell prompts or skip over 610 extraneous information, such as a system message that is sent at 611 shell start-up. 613 It is assumed that the router and cache have exchanged keys out of 614 band by some reasonably secured means. 616 7. Router-Cache Set-Up 618 A cache has the public authentication data for each router it is 619 configured to support. 621 A router may be configured to peer with a selection of caches, and a 622 cache may be configured to support a selection of routers. Each must 623 have the name of, and authentication data for, each peer. In 624 addition, in a router, this list has a non-unique preference value 625 for each server in order of preference. This preference merely 626 denotes proximity, not trust, preferred belief, etc. The client 627 router attempts to establish a session with each potential serving 628 cache in preference order, and then starts to load data from the most 629 preferred cache to which it can connect and authenticate. The 630 router's list of caches has the following elements: 632 Preference: An ordinal denoting the router's preference to connect 633 to that cache, the lower the value the more preferred. 635 Name: The IP Address or fully qualified domain name of the cache. 637 Key: The public ssh key of the cache. 639 MyKey: The private ssh key of this client. 641 Due to the distributed nature of the RPKI, caches simply can not be 642 rigorously synchronous. A client may hold data from multiple caches, 643 but MUST keep the data marked as to source, as later updates MUST 644 affect the correct data. 646 Just as there may be more than one covering ROA from a single cache, 647 there may be multiple covering ROAs from multiple caches. The 648 results are as described in [I-D.ietf-sidr-roa-validation]. 650 If data from multiple caches are held, implementations MUST NOT 651 distinguish between data sources when performing validation. 653 When a more preferred cache becomes available, if resources allow, it 654 would be prudent for the client to start fetching from that cache. 656 The client SHOULD attempt to maintain at least one set of data, 657 regardless of whether it has chosen a different cache or established 658 a new connection to the previous cache. 660 A client MAY drop the data from a particular cache when it is fully 661 in synch with one or more other caches. 663 A client SHOULD delete the data from a cache when it has been unable 664 to refresh from that cache for a configurable timer value. The 665 default for that value is twice the polling period for that cache. 667 If a client loses connectivity to a cache it is using, or otherwise 668 decides to switch to a new cache, it SHOULD retain the data from the 669 previous cache until it has a full set of data from one or more other 670 caches. Note that this may already be true at the point of 671 connection loss if the client has connections to more than one cache. 673 8. Deployment Scenarios 675 For illustration, we present three likely deployment scenarios. 677 Small End Site: The small multi-homed end site may wish to outsource 678 the RPKI cache to one or more of their upstream ISPs. They would 679 exchange authentication material with the ISP using some out of 680 band mechanism, and their router(s) would connect to one or more 681 up-streams' caches. The ISPs would likely deploy caches intended 682 for customer use separately from the caches with which their own 683 BGP speakers peer. 685 Large End Site: A larger multi-homed end site might run one or more 686 caches, arranging them in a hierarchy of client caches, each 687 fetching from a serving cache which is closer to the global RPKI. 688 They might configure fall-back peerings to up-stream ISP caches. 690 ISP Backbone: A large ISP would likely have one or more redundant 691 caches in each major PoP, and these caches would fetch from each 692 other in an ISP-dependent topology so as not to place undue load 693 on the global RPKI publication infrastructure. 695 Experience with large DNS cache deployments has shown that complex 696 topologies are ill-advised as it is easy to make errors in the graph, 697 e.g. not maintaining a loop-free condition. 699 Of course, these are illustrations and there are other possible 700 deployment strategies. It is expected that minimizing load on the 701 global RPKI servers will be a major consideration. 703 To keep load on global RPKI services from unnecessary peaks, it is 704 recommended that primary caches which load from the distributed 705 global RPKI not do so all at the same times, e.g. on the hour. 706 Choose a random time, perhaps the ISP's AS number modulo 60 and 707 jitter the inter-fetch timing. 709 9. Error Codes 711 This section contains a preliminary list of error codes. The authors 712 expect additions to this section during development of the initial 713 implementations. Eventually, these error codes will probably need to 714 reside in an IANA registry. 716 0: Reserved. 718 1: Internal Error: The party reporting the error experienced some 719 kind of internal error unrelated to protocol operation (ran out of 720 memory, a coding assertion failed, et cetera). 722 2: No Data Available: The cache believes itself to be in good 723 working order, but is unable to answer either a Serial Query or a 724 Reset Query because it has no useful data available at this time. 725 This is likely to be a temporary error, and most likely indicates 726 that the cache has not yet completed pulling down an initial 727 current data set from the global RPKI system after some kind of 728 event that invalidated whatever data it might have previously held 729 (reboot, network partition, etcetera). 731 10. Security Considerations 733 As this document describes a security protocol, many aspects of 734 security interest are described in the relevant sections. This 735 section points out issues which may not be obvious in other sections. 737 Cache Validation: In order for a collection of caches as described 738 in Section 8 to guarantee a consistent view, they need to be given 739 consistent trust anchors to use in their internal validation 740 process. Distribution of a consistent trust anchor is assumed to 741 be out of band. 743 Cache Peer Identification: The router initiates an ssh transport 744 session to a cache, which it identifies by either IP address or 745 fully qualified domain name. Be aware that a DNS or address 746 spoofing attack could make the correct cache unreachable. No 747 session would be established, as the authorization keys would not 748 match. 750 Transport Security: The RPKI relies on object, not server or 751 transport, trust. I.e. the IANA root trust anchor is distributed 752 to all caches through some out of band means, and can then be used 753 by each cache to validate certificates and ROAs all the way down 754 the tree. The inter-cache relationships are based on this object 755 security model, hence the inter-cache transport can be lightly 756 protected. 758 But this protocol document assumes that the routers can not do the 759 validation cryptography. Hence the last link, from cache to 760 router, is secured by server authentication and transport level 761 security. This is dangerous, as server authentication and 762 transport have very different threat models than object security. 764 So the strength of the trust relationship and the transport 765 between the router(s) and the cache(s) are critical. You're 766 betting your routing on this. 768 While we can not say the cache must be on the same LAN, if only 769 due to the issue of an enterprise wanting to off-load the cache 770 task to their upstream ISP(s), locality, trust, and control are 771 very critical issues here. The cache(s) really SHOULD be as 772 close, in the sense of controlled and protected (against DDoS, 773 MITM) transport, to the router(s) as possible. It also SHOULD be 774 topologically close so that a minimum of validated routing data 775 are needed to bootstrap a router's access to a cache. 777 11. Glossary 779 The following terms are used with special meaning: 781 Global RPKI: The authoritative data of the RPKI are published in a 782 distributed set of servers at the IANA, RIRs, NIRs, and ISPs, see 783 [I-D.ietf-sidr-repos-struct]. 785 Non-authorative Cache: A coalesced copy of the RPKI which is 786 periodically fetched/refreshed directly or indirectly from the 787 global RPKI using the [RFC5781] protocol/tools 789 Cache: Relying party update sofcware such as rcynic is used to 790 gather and validate the distributed data of the RPKI into a cache. 791 Trusting this cache further is a matter between the provider of 792 the cache and a relying party. 794 Serial Number: A 32-bit monotonically increasing ordinal which wraps 795 from 2^32-1 to 0. It denotes the logical version of a cache. A 796 cache increments the value by one when it successfully updates its 797 data from a parent cache or from primary RPKI data. As a cache is 798 receiving, new incoming data, and implicit deletes, are marked 799 with the new serial but MUST not be sent until the fetch is 800 complete. A serial number is not commensurate between caches, nor 801 need it be maintained across resets of the cache server. See 802 [RFC1982] on DNS Serial Number Arithmetic for too much detail on 803 serial number arithmetic. 805 12. IANA Considerations 807 This document requests the IANA to create a registry for PDU types. 809 This document requests the IANA to create a registry for Error Codes. 811 In addition, a registry for Version Numbers would be needed if new 812 Version Number is defined in a new RFC. 814 Note to RFC Editor: this section may be replaced on publication as an 815 RFC. 817 13. Acknowledgments 819 The authors wish to thank Steve Bellovin, Rex Fernando, Russ Housley, 820 Pradosh Mohapatra, Keyur Patel, Sandy Murphy, Robert Raszuk, John 821 Scudder, Ruediger Volk, and David Ward. Particular thanks go to 822 Hannes Gredler for showing us the dangers of unnecessary fields. 824 14. References 826 14.1. Normative References 828 [I-D.ietf-sidr-roa-validation] 829 Huston, G. and G. Michaelson, "Validation of Route 830 Origination using the Resource Certificate PKI and ROAs", 831 draft-ietf-sidr-roa-validation-10 (work in progress), 832 November 2010. 834 [RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982, 835 August 1996. 837 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 838 Requirement Levels", BCP 14, RFC 2119, March 1997. 840 [RFC4252] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) 841 Authentication Protocol", RFC 4252, January 2006. 843 [RFC5781] Weiler, S., Ward, D., and R. Housley, "The rsync URI 844 Scheme", RFC 5781, February 2010. 846 14.2. Informative References 848 [I-D.ietf-sidr-arch] 849 Lepinski, M. and S. Kent, "An Infrastructure to Support 850 Secure Internet Routing", draft-ietf-sidr-arch-11 (work in 851 progress), September 2010. 853 [I-D.ietf-sidr-repos-struct] 854 Huston, G., Loomans, R., and G. Michaelson, "A Profile for 855 Resource Certificate Repository Structure", 856 draft-ietf-sidr-repos-struct-06 (work in progress), 857 November 2010. 859 [RFC1996] Vixie, P., "A Mechanism for Prompt Notification of Zone 860 Changes (DNS NOTIFY)", RFC 1996, August 1996. 862 Authors' Addresses 864 Randy Bush 865 Internet Initiative Japan, Inc. 866 5147 Crystal Springs 867 Bainbridge Island, Washington 98110 868 US 870 Phone: +1 206 780 0431 x1 871 Email: randy@psg.com 873 Rob Austein 874 Internet Systems Consortium 875 950 Charter Street 876 Redwood City, CA 94063 877 USA 879 Email: sra@isc.org