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(The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (July 1, 2016) is 2856 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- 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: Informational DE-CIX Management GmbH 5 Expires: January 2, 2017 J. Snijders 6 NTT 7 G. Doering 8 SpaceNet AG 9 G. Hankins 10 Nokia 11 July 1, 2016 13 BLACKHOLE BGP Community for Blackholing 14 draft-ietf-grow-blackholing-02 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, namely 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 January 2, 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 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. Vendor Implementation Recommendations . . . . . . . . . . . . 4 73 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 74 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 75 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 76 7.1. Normative References . . . . . . . . . . . . . . . . . . 5 77 7.2. Informative References . . . . . . . . . . . . . . . . . 5 78 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 6 79 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 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 BGP blackholing to neighboring networks via 86 various mechanisms such as described in [RFC3882] and [RFC5635]. 88 DDoS attacks targeting a certain IP address may cause congestion of 89 links used to connect to other 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 supports 104 networks because: 106 o implementing and monitoring blackholing becomes easier when 107 implementation and operational guides do not cover many options 108 that 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. 113 Making it considerably easier for network operators to utilize 114 blackholing makes operations easier. 116 2. BLACKHOLE Attribute 118 This document defines the use of a new well-known BGP transitive 119 community, BLACKHOLE. 121 The semantics of this attribute allow a network to interpret the 122 presence of this community as an advisory qualification to drop any 123 traffic being sent towards this prefix. 125 3. Operational Recommendations 127 3.1. IP Prefix Announcements with BLACKHOLE Community Attached 129 When a network is under DDoS duress, it MAY announce an IP prefix 130 covering the victim's IP address(es) for the purpose of signaling to 131 neighboring networks that any traffic destined for these IP 132 address(es) should be discarded. In such a scenario, the network 133 operator SHOULD attach BLACKHOLE BGP community. 135 3.2. Local Scope of Blackholes 137 A BGP speaker receiving a BGP announcement tagged with the BLACKHOLE 138 BGP community SHOULD add a NO_ADVERTISE, NO_EXPORT or similar 139 community to prevent propagation of this route outside the local AS. 141 Unintentional leaking of more specific IP prefixes to neighboring 142 networks can have adverse effects. Extreme caution should be used 143 when purposefully propagating IP prefixes tagged with the BLACKHOLE 144 BGP community outside the local routing domain. 146 3.3. Accepting Blackholed IP Prefixes 148 It has been observed that announcements of IP prefixes larger than 149 /24 for IPv4 and /48 for IPv6 are usually not accepted on the 150 Internet (see section 6.1.3 [RFC7454]). However, blackhole routes 151 should be as small as possible in order to limit the impact of 152 discarding traffic for adjacent IP space that is not under DDoS 153 duress. Typically, the blackhole route's prefix length is as 154 specific as /32 for IPv4 and /128 for IPv6. 156 BGP speakers SHOULD only accept and honor BGP announcements carrying 157 the BLACKHOLE community if the announced prefix is covered by a 158 shorter prefix for which the neighboring network is authorized to 159 advertise. 161 4. Vendor Implementation Recommendations 163 Without an explicit configuration directive set by the operator, 164 network elements SHOULD NOT discard traffic destined towards IP 165 prefixes which are tagged with the BLACKHOLE BGP community. The 166 operator is expected to explicitly configure the network element to 167 honor the BLACKHOLE BGP community in a way that is compliant with the 168 operator's routing policy. 170 Vendors MAY provide a short-hand keyword in their configuration 171 language to reference the well-known BLACKHOLE BGP community 172 attribute value. The suggested string to be used is "blackhole". 174 5. IANA Considerations 176 The IANA is requested to register BLACKHOLE as a well-known BGP 177 community with global significance: 179 BLACKHOLE (= 0xFFFF029A) 181 The low-order two octets in decimal are 666, amongst network 182 operators a value commonly associated with BGP blackholing. 184 6. Security Considerations 186 BGP contains no specific mechanism to prevent the unauthorized 187 modification of information by the forwarding agent. This allows 188 routing information to be modified, removed, or false information to 189 be added by forwarding agents. Recipients of routing information are 190 not able to detect this modification. Also, RPKI [RFC6810] and 191 BGPSec [I-D.ietf-sidr-bgpsec-overview] do not fully resolve this 192 situation. For instance, BGP communities can still be added or 193 altered by a forwarding agent even if RPKI and BGPSec are in place. 195 The unauthorized addition of the BLACKHOLE BGP community to an IP 196 prefix by an adversery may cause a denial of service attack based on 197 denial of reachability. 199 In order to further limit the impact of unauthorized BGP 200 announcements carrying the BLACKHOLE BGP community, the receiving BGP 201 speaker SHOULD verify by applying strict filtering (see section 202 6.2.1.1.2. [RFC7454]) that the peer announcing the prefix is 203 authorized to do so. If not, the BGP announcement should be filtered 204 out. 206 7. References 208 7.1. Normative References 210 [RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities 211 Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996, 212 . 214 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 215 Requirement Levels", BCP 14, RFC 2119, 216 DOI 10.17487/RFC2119, March 1997, 217 . 219 7.2. Informative References 221 [I-D.ietf-sidr-bgpsec-overview] 222 Lepinski, M. and S. Turner, "An Overview of BGPsec", 223 draft-ietf-sidr-bgpsec-overview-08 (work in progress), 224 June 2016. 226 [RFC3882] Turk, D., "Configuring BGP to Block Denial-of-Service 227 Attacks", RFC 3882, DOI 10.17487/RFC3882, September 2004, 228 . 230 [RFC5635] Kumari, W. and D. McPherson, "Remote Triggered Black Hole 231 Filtering with Unicast Reverse Path Forwarding (uRPF)", 232 RFC 5635, DOI 10.17487/RFC5635, August 2009, 233 . 235 [RFC6810] Bush, R. and R. Austein, "The Resource Public Key 236 Infrastructure (RPKI) to Router Protocol", RFC 6810, 237 DOI 10.17487/RFC6810, January 2013, 238 . 240 [RFC7454] Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations 241 and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454, 242 February 2015, . 244 Appendix A. Acknowledgements 246 The authors would like to gratefully acknowledge many people who have 247 contributed discussions and ideas to the making of this proposal. 248 They include Petr Jiran, Yordan Kritski, Christian Seitz, Nick 249 Hilliard, Joel Jaeggli, Christopher Morrow, Thomas Mangin, Will 250 Hargrave, Niels Bakker and David Farmer. 252 Authors' Addresses 254 Thomas King 255 DE-CIX Management GmbH 256 Lichtstrasse 43i 257 Cologne 50825 258 Germany 260 Email: thomas.king@de-cix.net 262 Christoph Dietzel 263 DE-CIX Management GmbH 264 Lichtstrasse 43i 265 Cologne 50825 266 Germany 268 Email: christoph.dietzel@de-cix.net 270 Job Snijders 271 NTT Communications, Inc. 272 Theodorus Majofskistraat 100 273 Amsterdam 1065 SZ 274 NL 276 Email: job@ntt.net 278 Gert Doering 279 SpaceNet AG 280 Joseph-Dollinger-Bogen 14 281 Munich 80807 282 Germany 284 Email: gert@space.net 285 Greg Hankins 286 Nokia 287 777 E. Middlefield Road 288 Mountain View, CA 94043 289 USA 291 Email: greg.hankins@nokia.com