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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: Best Current Practice June 23, 2016 5 Expires: December 25, 2016 7 BGPsec Operational Considerations 8 draft-ietf-sidr-bgpsec-ops-10 10 Abstract 12 Deployment of the BGPsec architecture and protocols has many 13 operational considerations. This document attempts to collect and 14 present the most critical and universal. It is expected to evolve as 15 BGPsec is formalized and initially deployed. 17 Requirements Language 19 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 20 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to 21 be interpreted as described in RFC 2119 [RFC2119] only when they 22 appear in all upper case. They may also appear in lower or mixed 23 case as English words, without normative meaning. 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 December 25, 2016. 42 Copyright Notice 44 Copyright (c) 2016 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 . . . . . . . . . . . . . . . . . . . . . . . . 2 60 2. Suggested Reading . . . . . . . . . . . . . . . . . . . . . . 3 61 3. RPKI Distribution and Maintenance . . . . . . . . . . . . . . 3 62 4. AS/Router Certificates . . . . . . . . . . . . . . . . . . . 3 63 5. Within a Network . . . . . . . . . . . . . . . . . . . . . . 3 64 6. Considerations for Edge Sites . . . . . . . . . . . . . . . . 4 65 7. Routing Policy . . . . . . . . . . . . . . . . . . . . . . . 4 66 8. Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 67 9. Security Considerations . . . . . . . . . . . . . . . . . . . 7 68 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 69 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 70 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 71 12.1. Normative References . . . . . . . . . . . . . . . . . . 7 72 12.2. Informative References . . . . . . . . . . . . . . . . . 8 73 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8 75 1. Introduction 77 BGPsec, [I-D.ietf-sidr-bgpsec-overview], is a new protocol with many 78 operational considerations. It is expected to be deployed 79 incrementally over a number of years. As core BGPsec-capable routers 80 may require large memory and/or modern CPUs, it is thought that 81 origin validation based on the RPKI, [RFC6811], will occur over the 82 next two to three years and that BGPsec will start to deploy well 83 after that. 85 BGPsec relies on widespread propagation of the Resource Public Key 86 Infrastructure (RPKI) [RFC6480]. How the RPKI is distributed and 87 maintained globally and within an operator's infrastructure may be 88 different for BGPsec than for origin validation. 90 BGPsec needs to be spoken only by an AS's eBGP speaking, AKA border, 91 routers, and is designed so that it can be used to protect 92 announcements which are originated by resource constrained edge 93 routers. This has special operational considerations. 95 Different prefixes may have different timing and replay protection 96 considerations. 98 2. Suggested Reading 100 It is assumed that the reader understands BGP, see [RFC4271], BGPsec, 101 [I-D.ietf-sidr-bgpsec-overview], the RPKI, see [RFC6480], the RPKI 102 Repository Structure, see [RFC6481], and ROAs, see [RFC6482]. 104 3. RPKI Distribution and Maintenance 106 All non-ROA considerations in the section on RPKI Distribution and 107 Maintenance of [RFC7115] apply. 109 4. AS/Router Certificates 111 As described in [I-D.ietf-sidr-rtr-keying] BGPsec-speaking routers 112 are either capable of generating their own public/private key-pairs 113 and having their certificates signed and published in the RPKI by the 114 RPKI CA system, and/or are given public/private key-pairs by the 115 operator. 117 A site/operator MAY use a single certificate/key in all their 118 routers, one certificate/key per router, or any granularity in 119 between. 121 A large operator, concerned that a compromise of one router's key 122 would make other routers vulnerable, may accept a more complex 123 certificate/key distribution burden to reduce this exposure. 125 On the other extreme, an edge site with one or two routers may choose 126 to use a single certificate/key. 128 In anticipation of possible key compromise, a prudent operator will 129 pre-provision each router's 'next' key in the RPKI so there is no 130 propagation delay for provisioning the new key. 132 5. Within a Network 134 BGPsec is spoken by edge routers in a network, those which border 135 other networks/ASs. 137 In a fully BGPsec enabled AS, Route Reflectors MUST have BGPsec 138 enabled if and only if there are eBGP speakers in their client cone, 139 i.e. an RR client or the transitive closure of their customers' 140 customers' customers' etc. 142 A BGPsec capable router MAY use the data it receives to influence 143 local policy within its network, see Section 7. In deployment this 144 policy should fit into the AS's existing policy, preferences, etc. 146 This allows a network to incrementally deploy BGPsec enabled border 147 routers. 149 eBGP speakers which face more critical peers or up/downstreams would 150 be candidates for early deployment. Both securing one's own 151 announcements and validating received announcements should be 152 considered in partial deployment. 154 The operator should be aware that BGPsec, as any other policy change, 155 can cause traffic shifts in their network. And, as with normal 156 policy shift practice, a prudent operator has tools and methods to 157 predict, measure, modify, etc. 159 On the other hand, an operator wanting to monitor router loading, 160 shifts in traffic, etc. might deploy incrementally while watching 161 those and similar effects. 163 As they are not formally verifiable, an eBGP listener SHOULD NOT 164 strongly trust unsigned security markings such as communities 165 received across a trust boundary. 167 6. Considerations for Edge Sites 169 An edge site which does not provide transit and trusts its 170 upstream(s) SHOULD only originate a signed prefix announcement and 171 need not validate received announcements. 173 Operators might need to use hardware with limited resources. In such 174 cases, BGPsec protocol capability negotiation allows for a resource 175 constrained edge router to hold only its own signing key(s) and sign 176 its announcements, but not receive signed announcements. Therefore, 177 the router would not have to deal with the majority of the RPKI, 178 potentially saving the need for additional hardware. 180 As the vast majority (84%) of ASs are stubs, and they announce the 181 majority of prefixes, this allows for simpler and less expensive 182 incremental deployment. It may also mean that edge sites concerned 183 with routing security will be attracted to upstreams which support 184 BGPsec. 186 7. Routing Policy 188 Unlike origin validation based on the RPKI, BGPsec marks a received 189 announcement as Valid or Not Valid, there is no explicit NotFound 190 state. In some sense, an unsigned BGP4 path is the equivalent of 191 NotFound. How this is used in routing is up to the operator's local 192 policy, similar to origin validation as in [RFC6811]. 194 As BGPsec will be rolled out over years and does not allow for 195 intermediate non-signing edge routers, coverage will be spotty for a 196 long time. Hence a normal operator's policy SHOULD NOT be overly 197 strict, perhaps preferring Valid paths and giving very low 198 preference, but still using, Not Valid paths. 200 Operators should be aware that accepting Not Valid announcements, no 201 matter the local preference, will often be the equivalent of treating 202 them as fully Valid. Local preference affects only routes to the 203 same set of destinations. Consider having a Valid announcement from 204 neighbor V for prefix 10.0.0.0/16 and an Not Valid announcement for 205 10.0.666.0/24 from neighbor I. If local policy on the router is not 206 configured to discard the Not Valid announcement from I, then longest 207 match forwarding will send packets to neighbor I no matter the value 208 of local preference. 210 Validation of signed paths is usually deployed at the eBGP edge. 212 Local policy on the eBGP edge MAY convey the validation state of a 213 BGP signed path through normal local policy mechanisms, e.g. setting 214 a BGP community for internal use, or modifying a metric value such as 215 local-preference or MED. Some may choose to use the large Local-Pref 216 hammer. Others may choose to let AS-Path rule and set their internal 217 metric, which comes after AS-Path in the BGP decision process. 219 Because of possible RPKI version skew, an AS Path which does not 220 validate at router R0 might validate at R1. Therefore, signed paths 221 that are Not Valid and yet propagated (because they are chosen as 222 best path) SHOULD have their signatures kept intact and MUST be 223 signed if sent to external BGPsec speakers. 225 This implies that updates which a speaker judges to be Not Valid MAY 226 be propagated to iBGP peers. Therefore, unless local policy ensures 227 otherwise, a signed path learned via iBGP MAY be Not Valid. If 228 needed, the validation state should be signaled by normal local 229 policy mechanisms such as communities or metrics. 231 On the other hand, local policy on the eBGP edge might preclude iBGP 232 or eBGP announcement of signed AS Paths which are Not Valid. 234 A BGPsec speaker receiving a path SHOULD perform origin validation 235 per [RFC6811] and [RFC7115]. 237 A route server is usually 'transparent'. To operate transparently in 238 an environment in which the route server connects BGPsec-enabled 239 peers, the route server MUST run BGPsec as well. A BGPsec-aware 240 route server needs to validate the incoming BGPsec_Path, and to 241 forward updates which can be validated by clients which know the 242 route server's AS. This implies that the route server creates 243 signatures per client including its own AS in the BGPsec_Path and the 244 target ASes, see 2.2.2 of [I-D.ietf-idr-ix-bgp-route-server]. The 245 route server uses pCount of zero to not increase the effective AS hop 246 count. 248 If it is known that a BGPsec neighbor is not a transparent route 249 server, and the router provides a knob to disallow a received pCount 250 (prepend count, zero for transparent route servers) of zero, that 251 knob SHOULD be applied. Routers should disallow pCount 0 by default. 253 To prevent exposure of the internals of BGP Confederations [RFC5065], 254 a BGPsec speaker which is a Member-AS of a Confederation MUST NOT 255 sign updates sent to another Member-AS of the same Confederation. 257 8. Notes 259 For protection from attacks replaying BGP data on the order of a day 260 or longer old, re-keying routers with new keys (previously) 261 provisioned in the RPKI is sufficient. For one approach, see 262 [I-D.ietf-sidr-bgpsec-rollover] 264 Like the DNS, the global RPKI presents only a loosely consistent 265 view, depending on timing, updating, fetching, etc. Thus, one cache 266 or router may have different data about a particular prefix or router 267 than another cache or router. There is no 'fix' for this, it is the 268 nature of distributed data with distributed caches. 270 Operators who manage certificates SHOULD have RPKI GhostBuster 271 Records (see [RFC6493]), signed indirectly by End Entity 272 certificates, for those certificates on which others' routing depends 273 for certificate and/or ROA validation. 275 Operators should be aware of impending algorithm transitions, which 276 will be rare and slow-paced, see [RFC6916]. They should work with 277 their vendors to ensure support for new algorithms. 279 As a router must evaluate certificates and ROAs which are time 280 dependent, routers' clocks MUST be correct to a tolerance of 281 approximately an hour. 283 If a router has reason to believe its clock is seriously incorrect, 284 e.g. it has a time earlier than 2011, it SHOULD NOT attempt to 285 validate incoming updates. It SHOULD defer validation until it 286 believes it is within reasonable time tolerance. 288 Operators should deploy servers that provide time service, such as 289 [RFC5905], to client routers. 291 9. Security Considerations 293 The major security considerations for the BGPsec protocol are 294 described in [I-D.ietf-sidr-bgpsec-protocol]. 296 10. IANA Considerations 298 This document has no IANA Considerations. 300 11. Acknowledgments 302 The author wishes to thank the BGPsec design group, Thomas King, and 303 Arnold Nipper. 305 12. References 307 12.1. Normative References 309 [I-D.ietf-sidr-bgpsec-overview] 310 Lepinski, M. and S. Turner, "An Overview of BGPSEC", 311 draft-ietf-sidr-bgpsec-overview-02 (work in progress), May 312 2012. 314 [I-D.ietf-sidr-bgpsec-protocol] 315 Lepinski, M., "BGPSEC Protocol Specification", draft-ietf- 316 sidr-bgpsec-protocol-07 (work in progress), February 2013. 318 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 319 Requirement Levels", BCP 14, RFC 2119, March 1997. 321 [RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support 322 Secure Internet Routing", RFC 6480, February 2012. 324 [RFC6481] Huston, G., Loomans, R., and G. Michaelson, "A Profile for 325 Resource Certificate Repository Structure", RFC 6481, 326 February 2012. 328 [RFC6482] Lepinski, M., Kent, S., and D. Kong, "A Profile for Route 329 Origin Authorizations (ROAs)", RFC 6482, February 2012. 331 [RFC6493] Bush, R., "The Resource Public Key Infrastructure (RPKI) 332 Ghostbusters Record", RFC 6493, February 2012. 334 [RFC7115] Bush, R., "Origin Validation Operation Based on the 335 Resource Public Key Infrastructure (RPKI)", BCP 185, 336 RFC 7115, DOI 10.17487/RFC7115, January 2014, 337 . 339 12.2. Informative References 341 [I-D.ietf-idr-ix-bgp-route-server] 342 Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker, 343 "Internet Exchange Route Server", draft-ietf-idr-ix-bgp- 344 route-server-02 (work in progress), February 2013. 346 [I-D.ietf-sidr-bgpsec-rollover] 347 Gagliano, R., Patel, K., and B. Weis, "BGPSEC router key 348 rollover as an alternative to beaconing", draft-ietf-sidr- 349 bgpsec-rollover-01 (work in progress), October 2012. 351 [I-D.ietf-sidr-rtr-keying] 352 Turner, S., Patel, K., and R. Bush, "Router Keying for 353 BGPsec", draft-ietf-sidr-rtr-keying-01 (work in progress), 354 February 2013. 356 [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway 357 Protocol 4 (BGP-4)", RFC 4271, January 2006. 359 [RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous 360 System Confederations for BGP", RFC 5065, August 2007. 362 [RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network 363 Time Protocol Version 4: Protocol and Algorithms 364 Specification", RFC 5905, June 2010. 366 [RFC6811] Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R. 367 Austein, "BGP Prefix Origin Validation", RFC 6811, January 368 2013. 370 [RFC6916] Gagliano, R., Kent, S., and S. Turner, "Algorithm Agility 371 Procedure for the Resource Public Key Infrastructure 372 (RPKI)", BCP 182, RFC 6916, DOI 10.17487/RFC6916, April 373 2013, . 375 Author's Address 377 Randy Bush 378 Internet Initiative Japan 379 5147 Crystal Springs 380 Bainbridge Island, Washington 98110 381 US 383 Email: randy@psg.com