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(The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (August 12, 2016) is 2786 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: A later version (-23) exists of draft-ietf-sidr-bgpsec-protocol-17 -- Obsolete informational reference (is this intentional?): RFC 5575 (Obsoleted by RFC 8955) Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group T. King 3 Internet-Draft C. Dietzel 4 Intended status: Informational DE-CIX Management GmbH 5 Expires: February 13, 2017 J. Snijders 6 NTT 7 G. Doering 8 SpaceNet AG 9 G. Hankins 10 Nokia 11 August 12, 2016 13 BLACKHOLE BGP Community for Blackholing 14 draft-ietf-grow-blackholing-03 16 Abstract 18 This document describes the use of a well-known Border Gateway 19 Protocol (BGP) community for destination-based blackholing in IP 20 networks. This well-known advisory transitive BGP community named 21 BLACKHOLE allows an origin AS to specify that a neighboring network 22 should discard any traffic destined towards the tagged IP prefix. 24 Requirements Language 26 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 27 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to 28 be interpreted as described in [RFC2119] only when they appear in all 29 upper case. They may also appear in lower or mixed case as English 30 words, without normative meaning. 32 Status of This Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at http://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on February 13, 2017. 49 Copyright Notice 51 Copyright (c) 2016 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 This document is subject to BCP 78 and the IETF Trust's Legal 55 Provisions Relating to IETF Documents 56 (http://trustee.ietf.org/license-info) in effect on the date of 57 publication of this document. Please review these documents 58 carefully, as they describe your rights and restrictions with respect 59 to this document. Code Components extracted from this document must 60 include Simplified BSD License text as described in Section 4.e of 61 the Trust Legal Provisions and are provided without warranty as 62 described in the Simplified BSD License. 64 Table of Contents 66 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 67 2. BLACKHOLE Community . . . . . . . . . . . . . . . . . . . . . 3 68 3. Operational Recommendations . . . . . . . . . . . . . . . . . 3 69 3.1. IP Prefix Announcements with BLACKHOLE Community Attached 3 70 3.2. Local Scope of Blackholes . . . . . . . . . . . . . . . . 4 71 3.3. Accepting Blackholed IP Prefixes . . . . . . . . . . . . 4 72 4. Vendor Implementation Recommendations . . . . . . . . . . . . 5 73 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 74 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 75 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 76 7.1. Normative References . . . . . . . . . . . . . . . . . . 6 77 7.2. Informative References . . . . . . . . . . . . . . . . . 6 78 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 7 79 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 81 1. Introduction 83 Network infrastructures have been increasingly hampered by DDoS 84 attacks. In order to dampen the effects of these DDoS attacks, IP 85 networks have offered blackholing with BGP [RFC4271] using various 86 mechanisms such as those described in [RFC3882] and [RFC5635]. 88 DDoS attacks targeting a certain IP address may cause congestion of 89 links used to connect to adjacent networks. In order to limit the 90 impact of such a scenario on legitimate traffic, networks adopted a 91 mechanism called BGP blackholing. A network that wants to trigger 92 blackholing needs to understand the triggering mechanism adopted by 93 its neighboring networks. Different networks provide different 94 mechanisms to trigger blackholing, including but not limited to pre- 95 defined blackhole next-hop IP addresses, specific BGP communities or 96 via an out-of-band BGP session with a special BGP speaker. 98 Having several different mechanisms to trigger blackholing in 99 different networks makes it an unnecessarily complex, error-prone and 100 cumbersome task for network operators. Therefore, a well-known BGP 101 community [RFC1997] is defined for operational ease. 103 Having such a well-known BGP community for blackholing also further 104 simplifies network operations because: 106 o Implementing and monitoring blackholing becomes easier when 107 implementation, and operational guides do not cover many 108 variations to trigger blackholing. 109 o The number of support requests from customers about how to trigger 110 blackholing in a particular neighboring network will be reduced as 111 the codepoint for common blackholing mechanisms is unified and 112 well-known. 114 2. BLACKHOLE Community 116 This document defines the use of a new well-known BGP transitive 117 community, BLACKHOLE. 119 The semantics of this community allow a network to interpret the 120 presence of this community as an advisory qualification to drop any 121 traffic being sent towards this prefix. 123 3. Operational Recommendations 125 3.1. IP Prefix Announcements with BLACKHOLE Community Attached 127 Accepting and honoring the BLACKHOLE community, or ignoring it, is a 128 choice that is made by each operator. This community MAY be used in 129 all bilateral and multilateral BGP deployment scenarios. In a 130 bilateral peering relationship, use of the BLACKHOLE community MUST 131 be agreed upon by the two networks before advertising it. In a 132 multilateral peering relationship, the decision to honor or ignore 133 the BLACKHOLE community is to be made according to the operator's 134 routing policy. The community SHOULD be ignored, if it is received 135 by a network that it not using it. 137 When a network is under DDoS duress, it MAY announce an IP prefix 138 covering the victim's IP address(es) for the purpose of signaling to 139 neighboring networks that any traffic destined for these IP 140 address(es) should be discarded. In such a scenario, the network 141 operator SHOULD attach the BLACKHOLE BGP community. 143 The BLACKHOLE community MAY also be used as one of the trigger 144 communities in a [RFC5635] destination-based RTBH configuration. 146 3.2. Local Scope of Blackholes 148 A BGP speaker receiving an announcement tagged with the BLACKHOLE 149 community SHOULD add the NO_ADVERTISE or NO_EXPORT community as 150 defined in [RFC1997], or a similar community to prevent propagation 151 of the prefix outside the local AS. The community to prevent 152 propagation SHOULD be chosen according to the operator's routing 153 policy. 155 Unintentional leaking of more specific IP prefixes to neighboring 156 networks can have adverse effects. Extreme caution should be used 157 when purposefully propagating IP prefixes tagged with the BLACKHOLE 158 BGP community outside the local routing domain, unless policy 159 explicitly aims at doing just that. 161 3.3. Accepting Blackholed IP Prefixes 163 It has been observed in provider networks running BGP that 164 announcements of IP prefixes longer than /24 for IPv4 and /48 for 165 IPv6 are usually not accepted on the Internet (see section 6.1.3 166 [RFC7454]). However, blackhole prefix length should be as long as 167 possible in order to limit the impact of discarding traffic for 168 adjacent IP space that is not under DDoS duress. The blackhole 169 prefix length is typically as specific as possible, a /32 for IPv4 or 170 a /128 for IPv6. 172 BGP speakers in a bilateral peering relationship using the BLACKHOLE 173 community MUST only accept and honor BGP announcements carrying the 174 BLACKHOLE community under the two following conditions: 176 o the announced prefix is covered by an equal or shorter prefix that 177 the neighboring network is authorized to advertise. 178 o the receiving party agreed to honor the BLACKHOLE community on the 179 particular BGP session 181 In topologies with a route server or other multilateral peering 182 relationships, BGP speakers SHOULD accept and honor BGP announcements 183 under the same conditions. 185 An operator MUST ensure that origin validation techniques (such as 186 [RFC6811]) do not inadvertently block legitimate announcements 187 carrying the BLACKHOLE community. 189 The BLACKHOLE community is not intended to be used with [RFC5575] 190 NLRI to distribute traffic flow specifications. 192 The error handling for this community follows the process in 193 [RFC7606] that causes a malformed community to be treated as a 194 withdrawn. 196 Operators are encouraged to store all BGP updates in their network 197 carrying the BLACKHOLE community for long term analysis or internal 198 audit purposes. 200 4. Vendor Implementation Recommendations 202 Without an explicit configuration directive set by the operator, 203 network elements SHOULD NOT discard traffic destined towards IP 204 prefixes which are tagged with the BLACKHOLE BGP community. The 205 operator is expected to explicitly configure the network element to 206 honor the BLACKHOLE BGP community in a way that is compliant with the 207 operator's routing policy. 209 Vendors MAY provide a shorthand keyword in their configuration 210 language to reference the well-known BLACKHOLE BGP community 211 attribute value. The suggested string to be used is "blackhole". 213 5. IANA Considerations 215 The IANA is requested to register BLACKHOLE as a well-known BGP 216 community with global significance: 218 BLACKHOLE (= 0xFFFF029A) 220 The low-order two octets in decimal are 666, a value commonly 221 associated with BGP blackholing among network operators. 223 6. Security Considerations 225 BGP contains no specific mechanism to prevent the unauthorized 226 modification of information by the forwarding agent. This allows 227 routing information to be modified, removed, or false information to 228 be added by forwarding agents. Recipients of routing information are 229 not able to detect this modification. BGPSec 230 [I-D.ietf-sidr-bgpsec-protocol] does not resolve this situation. 231 Even when BGPSec is in place, a forwarding agent can alter, add or 232 remove BGP communities. 234 The unauthorized addition of the BLACKHOLE BGP community to an IP 235 prefix by an adversary may cause a denial of service attack based on 236 denial of reachability. 238 In order to further limit the impact of unauthorized BGP 239 announcements carrying the BLACKHOLE BGP community, the receiving BGP 240 speaker SHOULD verify by applying strict filtering (see section 241 6.2.1.1.2 [RFC7454]) that the peer announcing the prefix is 242 authorized to do so. If not, the BGP announcement should be 243 filtered. 245 BGP announcements carrying the BLACKHOLE community should only be 246 accepted and honored, if the neighboring network is authorized to 247 advertise the prefix. The method of validating announcements is to 248 be chosen according to the operator's routing policy. 250 It is RECOMMENDED that operators use best common practices to protect 251 their BGP sessions, such as the ones in [RFC7454]. 253 7. References 255 7.1. Normative References 257 [RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities 258 Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996, 259 . 261 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 262 Requirement Levels", BCP 14, RFC 2119, 263 DOI 10.17487/RFC2119, March 1997, 264 . 266 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 267 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 268 DOI 10.17487/RFC4271, January 2006, 269 . 271 [RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K. 272 Patel, "Revised Error Handling for BGP UPDATE Messages", 273 RFC 7606, DOI 10.17487/RFC7606, August 2015, 274 . 276 7.2. Informative References 278 [I-D.ietf-sidr-bgpsec-protocol] 279 Lepinski, M. and K. Sriram, "BGPsec Protocol 280 Specification", draft-ietf-sidr-bgpsec-protocol-17 (work 281 in progress), June 2016. 283 [RFC3882] Turk, D., "Configuring BGP to Block Denial-of-Service 284 Attacks", RFC 3882, DOI 10.17487/RFC3882, September 2004, 285 . 287 [RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J., 288 and D. McPherson, "Dissemination of Flow Specification 289 Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009, 290 . 292 [RFC5635] Kumari, W. and D. McPherson, "Remote Triggered Black Hole 293 Filtering with Unicast Reverse Path Forwarding (uRPF)", 294 RFC 5635, DOI 10.17487/RFC5635, August 2009, 295 . 297 [RFC6811] Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R. 298 Austein, "BGP Prefix Origin Validation", RFC 6811, 299 DOI 10.17487/RFC6811, January 2013, 300 . 302 [RFC7454] Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations 303 and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454, 304 February 2015, . 306 Appendix A. Acknowledgements 308 The authors would like to gratefully acknowledge many people who have 309 contributed discussions and ideas to the making of this proposal. 310 They include Petr Jiran, Yordan Kritski, Christian Seitz, Nick 311 Hilliard, Joel Jaeggli, Christopher Morrow, Thomas Mangin, Will 312 Hargrave, Niels Bakker, David Farmer, Jared Mauch, John Heasley and 313 Terry Manderson. 315 Authors' Addresses 317 Thomas King 318 DE-CIX Management GmbH 319 Lichtstrasse 43i 320 Cologne 50825 321 Germany 323 Email: thomas.king@de-cix.net 325 Christoph Dietzel 326 DE-CIX Management GmbH 327 Lichtstrasse 43i 328 Cologne 50825 329 Germany 331 Email: christoph.dietzel@de-cix.net 332 Job Snijders 333 NTT Communications 334 Theodorus Majofskistraat 100 335 Amsterdam 1065 SZ 336 NL 338 Email: job@ntt.net 340 Gert Doering 341 SpaceNet AG 342 Joseph-Dollinger-Bogen 14 343 Munich 80807 344 Germany 346 Email: gert@space.net 348 Greg Hankins 349 Nokia 350 777 E. Middlefield Road 351 Mountain View, CA 94043 352 USA 354 Email: greg.hankins@nokia.com