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(The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (June 29, 2016) is 2858 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) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). 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: Standards Track DE-CIX Management GmbH 5 Expires: December 31, 2016 J. Snijders 6 NTT 7 G. Doering 8 SpaceNet AG 9 G. Hankins 10 Nokia 11 June 29, 2016 13 BLACKHOLE BGP Community for Blackholing 14 draft-ietf-grow-blackholing-01 16 Abstract 18 This document describes the use of a well-known Border Gateway 19 Protocol (BGP) community for blackholing in IP networks. This well- 20 known advisory transitive BGP community, namely BLACKHOLE, allows an 21 origin AS to specify that a neighboring network should blackhole a 22 specific 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 December 31, 2016. 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 Attribute . . . . . . . . . . . . . . . . . . . . . 3 68 3. Operational Recommendations . . . . . . . . . . . . . . . . . 3 69 3.1. IP Prefix Announcements with BLACKHOLE Community Attached 3 70 3.2. Local Scope of Blackholes . . . . . . . . . . . . . . . . 3 71 3.3. Accepting Blackholed IP Prefixes . . . . . . . . . . . . 4 72 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 73 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 74 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 75 6.1. Normative References . . . . . . . . . . . . . . . . . . 5 76 6.2. Informative References . . . . . . . . . . . . . . . . . 5 77 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 6 78 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 80 1. Introduction 82 Network infrastructures have been increasingly hampered by DDoS 83 attacks. In order to dampen the effects of these DDoS attacks, IP 84 networks have offered BGP blackholing to neighboring networks via 85 various mechanisms such as described in [RFC3882] and [RFC5635]. 87 DDoS attacks targeting a certain IP address may cause congestion of 88 links used to connect to other networks. In order to limit the 89 impact of such a scenario on legitimate traffic, networks adopted a 90 mechanism called BGP blackholing. A network that wants to trigger 91 blackholing needs to understand the triggering mechanism adopted by 92 its neighboring networks. Different networks provide different 93 mechanisms to trigger blackholing, including but not limited to pre- 94 defined blackhole next-hop IP addresses, specific BGP communities or 95 via an out-of-band BGP session with a special BGP speaker. 97 Having several different mechanisms to trigger blackholing in 98 different networks makes it an unnecessarily complex, error-prone and 99 cumbersome task for network operators. Therefore a well-known BGP 100 community [RFC1997] is defined for operational ease. 102 Having such a well-known BGP community for blackholing also supports 103 networks because: 105 o implementing and monitoring blackholing becomes easier when 106 implementation and operational guides do not cover many options 107 that trigger blackholing. 108 o the number of support requests from customers about how to trigger 109 blackholing in a particular neighboring network will be reduced as 110 the codepoint for common blackholing mechanisms is unified. 112 Making it considerably easier for network operators to utilize 113 blackholing makes operations easier. 115 2. BLACKHOLE Attribute 117 This document defines the use of a new well-known BGP transitive 118 community, BLACKHOLE. 120 The semantics of this attribute allow a network to interpret the 121 presence of this community as an advisory qualification to drop any 122 traffic being sent towards this prefix. 124 3. Operational Recommendations 126 3.1. IP Prefix Announcements with BLACKHOLE Community Attached 128 When a network is under DDoS duress, it MAY announce an IP prefix 129 covering the victim's IP address(es) for the purpose of signaling to 130 neighboring networks that any traffic destined for these IP 131 address(es) should be discarded. In such a scenario, the network 132 operator SHOULD attach BLACKHOLE BGP community. 134 3.2. Local Scope of Blackholes 136 A BGP speaker receiving a BGP announcement tagged with the BLACKHOLE 137 BGP community SHOULD add a NO_ADVERTISE, NO_EXPORT or similar 138 community to prevent propagation of this route outside the local AS. 140 Unintentional leaking of more specific IP prefixes to neighboring 141 networks can have adverse effects. Extreme caution should be used 142 when purposefully propagating IP prefixes tagged with the BLACKHOLE 143 BGP community outside the local routing domain. 145 3.3. Accepting Blackholed IP Prefixes 147 It has been observed that announcements of IP prefixes larger than 148 /24 for IPv4 and /48 for IPv6 are usually not accepted on the 149 Internet (see section 6.1.3 [RFC7454]). However, blackhole routes 150 should be as small as possible in order to limit the impact of 151 discarding traffic for adjacent IP space that is not under DDoS 152 duress. Typically, the blackhole route's prefix length is as 153 specific as /32 for IPv4 and /128 for IPv6. 155 BGP speakers SHOULD only accept and honor BGP announcements carrying 156 the BLACKHOLE community if the announced prefix is covered by a 157 shorter prefix for which the neighboring network is authorized to 158 advertise. 160 4. IANA Considerations 162 The IANA is requested to register BLACKHOLE as a well-known BGP 163 community with global significance: 165 BLACKHOLE (= 0xFFFF029A) 167 The low-order two octets in decimal are 666, amongst network 168 operators a value commonly associated with BGP blackholing. 170 5. Security Considerations 172 BGP contains no specific mechanism to prevent the unauthorized 173 modification of information by the forwarding agent. This allows 174 routing information to be modified, removed, or false information to 175 be added by forwarding agents. Recipients of routing information are 176 not able to detect this modification. Also, RPKI [RFC6810] and 177 BGPSec [I-D.ietf-sidr-bgpsec-overview] do not fully resolve this 178 situation. For instance, BGP communities can still be added or 179 altered by a forwarding agent even if RPKI and BGPSec are in place. 181 The BLACKHOLE BGP community does not alter this situation. 183 A new additional attack vector is introduced into BGP by using the 184 BLACKHOLE BGP community: denial of service attacks for IP prefixes. 186 The unauthorized addition of the BLACKHOLE BGP community to an IP 187 prefix by a forwarding agent may cause a denial of service attack 188 based on denial of reachability. The denial of service will happen 189 if a network offering blackholing is traversed. However, denial of 190 service attack vectors to BGP are not new as the injection of false 191 routing information is already possible. 193 In order to further limit the impact of unauthorized BGP 194 announcements carrying the BLACKHOLE BGP community, the receiving BGP 195 speaker SHOULD verify by applying strict filtering (see section 196 6.2.1.1.2. [RFC7454]) that the peer announcing the prefix is 197 authorized to do so. If not, the BGP announcement should be filtered 198 out. 200 The presence of this BLACKHOLE BGP community may introduce a resource 201 exhaustion attack to BGP speakers. If a BGP speaker receives many IP 202 prefixes containing the BLACKHOLE BGP community, its internal 203 resources such as CPU power, memory or FIB capacity might exhaust, 204 especially if usual prefix sanity checks (e.g. such as IP prefix 205 length or number of prefixes) are disabled (see Section 3.3). 207 6. References 209 6.1. Normative References 211 [RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities 212 Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996, 213 . 215 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 216 Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ 217 RFC2119, March 1997, 218 . 220 6.2. Informative References 222 [I-D.ietf-sidr-bgpsec-overview] 223 Lepinski, M. and S. Turner, "An Overview of BGPsec", 224 draft-ietf-sidr-bgpsec-overview-08 (work in progress), 225 June 2016. 227 [RFC3882] Turk, D., "Configuring BGP to Block Denial-of-Service 228 Attacks", RFC 3882, DOI 10.17487/RFC3882, September 2004, 229 . 231 [RFC5635] Kumari, W. and D. McPherson, "Remote Triggered Black Hole 232 Filtering with Unicast Reverse Path Forwarding (uRPF)", 233 RFC 5635, DOI 10.17487/RFC5635, August 2009, 234 . 236 [RFC6810] Bush, R. and R. Austein, "The Resource Public Key 237 Infrastructure (RPKI) to Router Protocol", RFC 6810, DOI 238 10.17487/RFC6810, January 2013, 239 . 241 [RFC7454] Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations 242 and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454, 243 February 2015, . 245 Appendix A. Acknowledgements 247 The authors would like to gratefully acknowledge many people who have 248 contributed discussions and ideas to the making of this proposal. 249 They include Petr Jiran, Yordan Kritski, Christian Seitz, Nick 250 Hilliard, Joel Jaeggli, Christopher Morrow, Thomas Mangin, Will 251 Hargrave and Niels Bakker. 253 Authors' Addresses 255 Thomas King 256 DE-CIX Management GmbH 257 Lichtstrasse 43i 258 Cologne 50825 259 Germany 261 Email: thomas.king@de-cix.net 263 Christoph Dietzel 264 DE-CIX Management GmbH 265 Lichtstrasse 43i 266 Cologne 50825 267 Germany 269 Email: christoph.dietzel@de-cix.net 271 Job Snijders 272 NTT Communications, Inc. 273 Theodorus Majofskistraat 100 274 Amsterdam 1065 SZ 275 NL 277 Email: job@ntt.net 279 Gert Doering 280 SpaceNet AG 281 Joseph-Dollinger-Bogen 14 282 Munich 80807 283 Germany 285 Email: gert@space.net 286 Greg Hankins 287 Nokia 288 777 E. Middlefield Road 289 Mountain View, CA 94043 290 USA 292 Email: greg.hankins@nokia.com