idnits 2.17.1 draft-pmohapat-sidr-pfx-validate-01.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** The document seems to lack a License Notice according IETF Trust Provisions of 28 Dec 2009, Section 6.b.ii or Provisions of 12 Sep 2009 Section 6.b -- however, there's a paragraph with a matching beginning. Boilerplate error? (You're using the IETF Trust Provisions' Section 6.b License Notice from 12 Feb 2009 rather than one of the newer Notices. See https://trustee.ietf.org/license-info/.) 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 : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document seems to contain a disclaimer for pre-RFC5378 work, and may have content which was first submitted before 10 November 2008. The disclaimer is necessary when there are original authors that you have been unable to contact, or if some do not wish to grant the BCP78 rights to the IETF Trust. If you are able to get all authors (current and original) to grant those rights, you can and should remove the disclaimer; otherwise, the disclaimer is needed and you can ignore this comment. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (March 5, 2009) is 5531 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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-13) exists of draft-ietf-sidr-arch-03 ** Downref: Normative reference to an Informational draft: draft-ietf-sidr-arch (ref. 'I-D.ietf-sidr-arch') == Outdated reference: A later version (-12) exists of draft-ietf-sidr-roa-format-03 == Outdated reference: A later version (-06) exists of draft-ymbk-rpki-rtr-protocol-00 Summary: 2 errors (**), 0 flaws (~~), 4 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group P. Mohapatra, Ed. 3 Internet-Draft Cisco Systems 4 Intended status: Standards Track J. Scudder, Ed. 5 Expires: September 6, 2009 Juniper Networks 6 March 5, 2009 8 BGP Prefix Origin Validation 9 draft-pmohapat-sidr-pfx-validate-01 11 Status of this Memo 13 This Internet-Draft is submitted to IETF in full conformance with the 14 provisions of BCP 78 and BCP 79. This document may contain material 15 from IETF Documents or IETF Contributions published or made publicly 16 available before November 10, 2008. The person(s) controlling the 17 copyright in some of this material may not have granted the IETF 18 Trust the right to allow modifications of such material outside the 19 IETF Standards Process. Without obtaining an adequate license from 20 the person(s) controlling the copyright in such materials, this 21 document may not be modified outside the IETF Standards Process, and 22 derivative works of it may not be created outside the IETF Standards 23 Process, except to format it for publication as an RFC or to 24 translate it into languages other than English. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF), its areas, and its working groups. Note that 28 other groups may also distribute working documents as Internet- 29 Drafts. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 The list of current Internet-Drafts can be accessed at 37 http://www.ietf.org/ietf/1id-abstracts.txt. 39 The list of Internet-Draft Shadow Directories can be accessed at 40 http://www.ietf.org/shadow.html. 42 This Internet-Draft will expire on September 6, 2009. 44 Copyright Notice 46 Copyright (c) 2009 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents in effect on the date of 51 publication of this document (http://trustee.ietf.org/license-info). 52 Please review these documents carefully, as they describe your rights 53 and restrictions with respect to this document. 55 Abstract 57 A BGP route associates an address prefix with a set of autonomous 58 systems (AS) that identify the interdomain path the prefix has 59 traversed in the form of BGP announcements. This set is represented 60 as the AS_PATH attribute in BGP and starts with the AS that 61 originated the prefix. To help reduce well-known threats against BGP 62 including prefix hijacking and monkey-in-the-middle attacks, one of 63 the security requirements is the ability to validate the origination 64 AS of BGP routes. More specifically, one needs to validate that the 65 AS number claiming to originate an address prefix (as derived from 66 the AS_PATH attribute of the BGP route) is in fact authorized. This 67 document describes a simple validation mechanism to partially satisfy 68 this requirement. 70 Table of Contents 72 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 73 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5 74 2. Prefix-to-AS Mapping Database . . . . . . . . . . . . . . . . 5 75 3. Changes to the BGP Decision Process . . . . . . . . . . . . . 6 76 3.1. Policy Control . . . . . . . . . . . . . . . . . . . . . . 7 77 4. Route Aggregation . . . . . . . . . . . . . . . . . . . . . . 7 78 5. Interaction with Local Cache . . . . . . . . . . . . . . . . . 7 79 6. Deployment Considerations . . . . . . . . . . . . . . . . . . 7 80 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 8 81 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 82 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 83 10. Security Considerations . . . . . . . . . . . . . . . . . . . 9 84 11. Normative References . . . . . . . . . . . . . . . . . . . . . 9 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 87 1. Introduction 89 A BGP route associates an address prefix with a set of autonomous 90 systems (AS) that identify the interdomain path the prefix has 91 traversed in the form of BGP announcements. This set is represented 92 as the AS_PATH attribute in BGP and starts with the AS that 93 originated the prefix. To help reduce well-known threats against BGP 94 including prefix hijacking and monkey-in-the-middle attacks, one of 95 the security requirements is the ability to validate the origination 96 AS of BGP routes. More specifically, one needs to validate that the 97 AS number claiming to originate an address prefix (as derived from 98 the AS_PATH attribute of the BGP route) is in fact authorized. This 99 document describes a simple validation mechanism to partially satisfy 100 this requirement. 102 The Resource Public Key Infrastructure (RPKI) describes an approach 103 to build a formally verifyable database of IP addresses and AS 104 numbers as resources. The overall architecture of RPKI as defined in 105 [I-D.ietf-sidr-arch] consists of three main components: 107 o A public key infrastructure (PKI) with the necessary certificate 108 objects, 110 o Digitally signed routing objects, 112 o A distributed repository system to hold the objects that would 113 also support periodic retrieval. 115 The RPKI system is based on resource certificates that define 116 extensions to X.509 to represent IP addresses and AS identifiers 117 [RFC3779], thus the name RPKI. Route Origin Authorizations (ROA) 118 [I-D.ietf-sidr-roa-format] are separate digitally signed objects that 119 define associations between ASes and IP address blocks. Finally the 120 repository system is operated in a distributed fashion through the 121 IANA, RIR hierarchy, and ISPs. 123 In order to benefit from the RPKI system, it is envisioned that 124 relying parties either at AS or organization level obtain a local 125 copy of the signed object collection, verify the signatures, and 126 process them. The cache must also be refreshed periodically. The 127 exact access mechanism used to retrieve the local cache is beyond the 128 scope of this document. 130 Once the cache is made local, individual BGP speakers can utilize the 131 processed data to validate BGP announcements. The protocol details 132 to retrieve the processed data from the local cache to the BGP 133 speakers is beyond the scope of this document (refer to 134 [I-D.ymbk-rpki-rtr-protocol] for such a mechanism). This document 135 proposes a simple modification to the BGP decision process that makes 136 use of the processed data from signed objects and validates prefix 137 origination of received BGP UPDATE messages. 139 Note that the complete path attestation against the AS_PATH attribute 140 of a route is outside the scope of this document. 142 Although RPKI provides the context for this draft, it is equally 143 possible to use any other database which is able to map prefixes to 144 their authorized origin ASes. Each distinct database will have its 145 own particular operational and security characteristics; such 146 characteristics are beyond the scope of this document. 148 1.1. Requirements Language 150 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 151 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 152 document are to be interpreted as described in RFC 2119 [RFC2119]. 154 2. Prefix-to-AS Mapping Database 156 The resource certificates and other signed objects (e.g. ROAs) as 157 received from the RPKI repository and stored in the local cache are 158 not in a suitable format to be matched against the prefixes received. 159 Moreover, further processing of the objects is necessary -- e.g. ROA 160 validation is required, which involves checking against the 161 corresponding EE certificate and so on up to configured trust 162 anchors, presumably for the IANA and/or other registries. But a 163 validated and normalized database can be created on the router for 164 efficient lookup purposes. The primary key for this database is a 165 prefix set represented as (IP prefix)/[min. length, max. length]. 166 The value stored against each prefix set is the set of AS numbers 167 that is assigned or sub-allocated the corresponding IP address block. 168 This database can be implemented as a prefix trie structure. 170 Whenever UPDATEs are received from peers, a BGP speaker is expected 171 to perform a lookup in this database for each of the prefixes in the 172 UPDATE message. To aid with better description, we define terms 173 "UPDATE prefix" and "UPDATE origin AS number" to denote the values 174 derived from the received UPDATE message, and "database prefix set" 175 and "database origin AS number set" to mean the values derived from 176 the database lookup. Note that in the presence of overlapping 177 prefixes, the database lookup against the "UPDATE prefix" may yield 178 multiple matches. 180 The following are the different types of results expected from such a 181 lookup operation: 183 o If the "UPDATE prefix" finds no matching or covering prefixes in 184 the database, the lookup result is returned as "not found". Due 185 to incremental deployment model of the RPKI repository, it is 186 expected that a complete registry of all IP address blocks and 187 their AS associations is not available at a given point of time. 189 o If there are "database prefix sets" that cover the "UPDATE 190 prefix", and one of them has the "UPDATE origin AS number" in the 191 "database origin AS number sets", then the lookup result is 192 returned as "valid". 194 o If there are "database prefix sets" which cover the "UPDATE 195 prefix", but none of them has the "UPDATE origin AS number" in the 196 "database origin AS number set", then the lookup result is 197 returned as "invalid". 199 Depending on the lookup result, we define a property for each "UPDATE 200 prefix", called as the "validity state" of the prefix. It can assume 201 the following values: 203 +-------+-----------------------------+ 204 | Value | Meaning | 205 +-------+-----------------------------+ 206 | 0 | Lookup result = "valid" | 207 | 1 | Lookup result = "not found" | 208 | 2 | Lookup result = "invalid" | 209 +-------+-----------------------------+ 211 Note that all the routes, regardless of their "validity state" will 212 be stored in the local BGP speaker's Adj-RIB-In. 214 3. Changes to the BGP Decision Process 216 If a BGP router supports prefix validation and is configured to do 217 so, the validation check MUST be performed prior to any of the steps 218 defined in the decision process of [RFC4271]. The validation step is 219 stated as follows: 221 When comparing routes for a BGP destination, if both routes have 222 had their "validity state" computed, the route with the lowest 223 "validity state" value is preferred. 225 In all other respects, the decision process remains unchanged. 227 3.1. Policy Control 229 It MUST be possible to enable or disable the validation step as 230 defined in Section 3 through configuration. The default SHOULD be 231 for the validation step to be enabled. 233 It MUST be possible to exclude routes from the BGP decision process 234 based on their validation state. In particular it is anticipated 235 that it will be desirable to exclude routes from consideration when 236 their validation state is "invalid"; however it may also be desirable 237 to exclude routes whose validation state is "not found" as well. 239 4. Route Aggregation 241 When an UPDATE message carries AGGREGATOR attribute, the "UPDATE 242 origin AS number" is set to the value encoded in the AGGREGATOR 243 instead of being derived from the AS_PATH attribute. 245 5. Interaction with Local Cache 247 Each BGP speaker supporting prefix validation as described in this 248 document is expected to communicate with one or multiple local caches 249 that store a database of RPKI signed objects. The protocol 250 mechanisms used to fetch the data and store them locally at the BGP 251 speaker is beyond the scope of this document. Irrespective of the 252 protocol, the prefix validation algorithm as outlined in this 253 document is expected to function correctly in the event of failures 254 and other timing conditions that may result in an empty and/or 255 partial prefix-to-AS mapping database. Indeed, if the (in-PoP) cache 256 is not available and the mapping database is empty on the BGP 257 speaker, all the lookups will result in "not found" state and the 258 prefixes will be advertised to rest of the network (unless restricted 259 by policy configuration). Similarly, if BGP UPDATEs arrive at the 260 speaker while the fetch operation from the cache is in progress, some 261 prefix lookups will also result in "not found" state. The 262 implementation is expected to handle these timing conditions and re- 263 validate the prefixes once the fetch operation is complete (in an 264 event-driven manner). 266 6. Deployment Considerations 268 It is critical that IBGP speakers within an AS have a consistent 269 routing view of the BGP destinations and do not make conflicting 270 decisions regarding the BGP best path selection that might cause 271 forwarding loops. Thus, the best practice in BGP deployment does not 272 run any policy on IBGP sessions which could potentially create an 273 inconsistent view. Going by the same rules, the prefix validation 274 procedures SHOULD NOT be performed on IBGP learnt routes in an AS. 275 As a general principle, prefix validation SHOULD be executed on EBGP 276 boundaries. In some cases, it may be desirable to run the validation 277 on centralized route servers within an AS to offload the computation. 278 Care should be taken to ensure routing consistency in such cases. 280 7. Contributors 282 David Ward dward@cisco.com 283 Cisco Systems 285 Rex Fernando rex@juniper.net 286 Miya Kohno mkohno@juniper.net 287 Juniper Networks 289 Shin Miyakawa miyakawa@nttv6.jp 290 Taka Mizuguchi 291 Tomoya Yoshida 292 NTT Communications 294 Randy Bush randy@psg.com 295 Internet Initiative Japan 297 Rob Austein sra@isc.org 298 ISC 300 Russ Housley housley@vigilsec.com 301 Vigil Security 303 Junaid Israr jisra052@uottawa.ca 304 Mouhcine Guennoun mguennou@uottawa.ca 305 Hussein Mouftah mouftah@site.uottawa.ca 306 University of Ottawa School of Information Technology and 307 Engineering(SITE) 800 King Edward Avenue, Ottawa, Ontario, Canada, 308 K1N 6N5 310 8. Acknowledgements 312 Junaid Israr's contribution to this specification is part of his PhD 313 research work and thesis at University of Ottawa, Canada. 315 9. IANA Considerations 317 10. Security Considerations 319 Although this specification discusses one portion of a system to 320 validate BGP routes, it should be noted that it relies on a database 321 (RPKI or other) to provide validation information. As such, the 322 security properties of that database must be considered in order to 323 determine the security provided by the overall solution. If 324 "invalid" routes are blocked as this specification suggests, the 325 overall system provides a possible denial-of-service vector, for 326 example if an attacker is able to inject one or more spoofed records 327 into the validation database which lead a good route to be declared 328 invalid. In addition, this system is only able to provide limited 329 protection against a determined attacker -- the attacker need only 330 prepend the "valid" source AS to a forged BGP route announcement in 331 order to defeat the protection provided by this system. This 332 mechanism does not protect against "AS in the middle attacks" or 333 provide any path validation. It only attempts to verify the origin. 334 In general, this system should be thought of more as a protection 335 against misconfiguration than as true "security" in the strong sense. 337 11. Normative References 339 [I-D.ietf-sidr-arch] 340 Lepinski, M., Kent, S., and R. Barnes, "An Infrastructure 341 to Support Secure Internet Routing", 342 draft-ietf-sidr-arch-03 (work in progress), February 2008. 344 [I-D.ietf-sidr-roa-format] 345 Kent, S., "A Profile for Route Origin Authorizations 346 (ROAs)", draft-ietf-sidr-roa-format-03 (work in progress), 347 July 2008. 349 [I-D.ymbk-rpki-rtr-protocol] 350 Bush, R., "The RPKI/Router Protocol", 351 draft-ymbk-rpki-rtr-protocol-00 (work in progress), 352 March 2009. 354 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 355 Requirement Levels", BCP 14, RFC 2119, March 1997. 357 [RFC3779] Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP 358 Addresses and AS Identifiers", RFC 3779, June 2004. 360 [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway 361 Protocol 4 (BGP-4)", RFC 4271, January 2006. 363 Authors' Addresses 365 Pradosh Mohapatra (editor) 366 Cisco Systems 367 170 W. Tasman Drive 368 San Jose, CA 95134 369 USA 371 Email: pmohapat@cisco.com 373 John Scudder (editor) 374 Juniper Networks 375 1194 N. Mathilda Ave 376 Sunnyvale, CA 94089 377 USA 379 Email: jgs@juniper.net