Network Working Group T. King Internet-Draft C. Dietzel Intended status: Standards Track DE-CIX Management GmbH Expires: November 29, 2015 G. Doering SpaceNet AG G. Hankins Alcatel-Lucent C. Seitz STRATO AG P. Jiran NIX.CZ Y. Kritski NetIX Ltd. May 28, 2015 BLACKHOLEIXP BGP Community for Blackholing at IXPs draft-ymbk-grow-blackholing-00 Abstract This document describes the use of a well-known Border Gateway Protocol (BGP) community for blackholing at Internet Exchange Points (IXP). This well-known advisory transitive BGP community, namely BLACKHOLEIXP, allows an origin AS to specify through the route server that IXPs should blackhole a specific route. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in [RFC2119] only when they appear in all upper case. They may also appear in lower or mixed case as English words, without normative meaning. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any King, et al. Expires November 29, 2015 [Page 1] Internet-DrBLACKHOLEIXP BGP Community for Blackholing at IXPs May 2015 time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on November 29, 2015. Copyright Notice Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. This document may not be modified, and derivative works of it may not be created, and it may not be published except as an Internet-Draft. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. BLACKHOLEIXP Attribute . . . . . . . . . . . . . . . . . . . 3 3. Operational Recommendations . . . . . . . . . . . . . . . . . 3 3.1. Peering at Route Servers . . . . . . . . . . . . . . . . 3 3.2. Accepting Blackholed IP Prefixes . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 6.1. Normative References . . . . . . . . . . . . . . . . . . 5 6.2. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction Massive DDoS attacks targeting Internet Exchange Point (IXP) members may cause a congestion of their peering port(s). In order to limit the impact of such a scenario on legitimate traffic, IXPs adopted a feature called blackholing. A member may trigger blackholing via BGP through the route server [I-D.ietf-idr-ix-bgp-route-server]. All traffic destined to the such announced prefixes is discarded on the switching fabric of the IXP. This resolves the port congestion caused by the DDoS attack. King, et al. Expires November 29, 2015 [Page 2] Internet-DrBLACKHOLEIXP BGP Community for Blackholing at IXPs May 2015 The concept of blackholing at IXPs is similar to blackholing in iBGP scenarios [RFC3882] and the expansion RTBH filtering [RFC5635]. Different operators of IXPs specified various mechanisms for their members to trigger blackholing. This includes but is not limited to BGP communities from the private community space or specific next hop IP addresses. Having several different mechanisms to trigger blackholing at different IXPs makes it an unnecessary complex, error-prone and cumbersome task for IXPs members. A well-known and commonly agreed BGP community for blackholing at IXPs allows members to easily utilize this feature for all their IXP peerings. Having such a well-known and commonly agreed BGP community for blackholing also supports IXPs as o implementing and monitoring blackholing gets easier if implementation and operational guides do not cover many options to trigger blackholing o the amount of support requests from members about how to trigger blackholing at a particular IXP will be reduced as the mechanism is unified for all IXPs Making it considerably easier for operators and members of IXP to utilize blackholing will reduce the impact of massive DDoS attacks and thus make the Internet more reliable. 2. BLACKHOLEIXP Attribute This document defines the use a new well-known BGP transitive community, BLACKHOLEIXP. The semantics of this attribute is to allow an IXP to interpret the presence of this community as an advisory qualification to drop any traffic being sent towards this prefix. 3. Operational Recommendations 3.1. Peering at Route Servers If a member of an IXP experiences a massive DDoS attack, blackholing can be leveraged to limit the arising collateral damage. Therefore, the member must tag the BGP announcements of their prefix with the BLACKHOLEIXP BGP community. However, if only a sub-prefix is affected by the attack a more specific announcement SHOULD be used. King, et al. Expires November 29, 2015 [Page 3] Internet-DrBLACKHOLEIXP BGP Community for Blackholing at IXPs May 2015 Many IXPs provide the so-called policy control feature as part of their route servers (see e.g. the LINX website [1]). Policy control allows to specify by using BGP communities which ASNs connected to the IXP receives a particular BGP announcement. Combined usage of the BGP communities for blackholing and policy control allows a fine-grained control of a blackhole. Traffic from certain ASes can be blackholed exclusively. In many implementations of blackholing at IXPs, the route server after receiving a BGP announcement carrying the BLACKHOLEIXP BGP community rewrites the next hop IP address to the pre-defined Blackholing IP address before redistruting the announcement. 3.2. Accepting Blackholed IP Prefixes In order to limit the space required to store the routing table on a router, IP prefixes larger than /24 for IPv4 and /48 for IPv6 are usually not accepted (see section 6.1.3 [RFC7454]). However, blackholes in the IP space should be as small as possible in order to limit the impact of blackholing for IP space that is not experiencing a massive DDoS attack. Routers SHOULD accept BGP announcements carrying the BLACKHOLEIXP BGP community up to /32 for IPv4 and /128 for IPv6. 4. IANA Considerations The IANA is requested to register BLACKHOLEIXP as a well-known community with global significance: BLACKHOLEIXP (= 0xFFFF029A) The value 0xFFFF029A is preferable as it can also be written as 65535:666 following the ASN:ASN (16-bit) notation. 65535 is from the reserved ASN space and 666 is often used to signal blackholing in iBGP and eBGP transit provider networks scenarios. 5. Security Considerations BGP contains no specific mechanism to prevent the unauthorized modification of information by the forwarding agent. This allows routing information to be modified, removed, or false information to be added by forwarding agents. Recipients of routing information are not able to detect this modification. Also, RKPI [RFC6810] and BGPSec [I-D.ietf-sidr-bgpsec-overview] do not fully resolve this situation. For instance, BGP communities can still be added or altered by a forwarding agent even if RPKI and BGPSec are in place. King, et al. Expires November 29, 2015 [Page 4] Internet-DrBLACKHOLEIXP BGP Community for Blackholing at IXPs May 2015 The BLACKHOLEIXP BGP community does not alter this situation. A new additional attack vector is introduced into BGP by using the BLACKHOLEIXP BGP community: denial of service attacks for IP prefixes. Unauthorized addition of the BLACKHOLEIXP BGP community to an IP prefix by a forwarding agent may cause a denial of service attack based on denial of reachability. The denial of service will happen if an IXP offering blackholing is traversed. However, denial of service attack vectors to BGP are not new as the injection of false routing information is already possible. In order to further limit the impact of unauthorized BGP announcements carrying the BLACKHOLEIXP BGP community the receiving router or route server SHOULD verify by applying strict filtering (see section 6.2.1.1.2. [RFC7454]) that the peer announcing the prefix is authorized to do so. If not, the BGP announcement should be filtered out. 6. References 6.1. Normative References [I-D.ietf-idr-ix-bgp-route-server] Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker, "Internet Exchange Route Server", draft-ietf-idr-ix-bgp- route-server-06 (work in progress), December 2014. [I-D.ietf-sidr-bgpsec-overview] Lepinski, M. and S. Turner, "An Overview of BGPsec", draft-ietf-sidr-bgpsec-overview-06 (work in progress), January 2015. [RFC1997] Chandrasekeran, R., Traina, P., and T. Li, "BGP Communities Attribute", RFC 1997, August 1996. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3882] Turk, D., "Configuring BGP to Block Denial-of-Service Attacks", RFC 3882, September 2004. [RFC5635] Kumari, W. and D. McPherson, "Remote Triggered Black Hole Filtering with Unicast Reverse Path Forwarding (uRPF)", RFC 5635, August 2009. King, et al. Expires November 29, 2015 [Page 5] Internet-DrBLACKHOLEIXP BGP Community for Blackholing at IXPs May 2015 [RFC6810] Bush, R. and R. Austein, "The Resource Public Key Infrastructure (RPKI) to Router Protocol", RFC 6810, January 2013. [RFC7454] Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations and Security", BCP 194, RFC 7454, February 2015. 6.2. URIs [1] https://www.linx.net/members/support/route-servers.html Authors' Addresses Thomas King DE-CIX Management GmbH Lichtstrasse 43i Cologne 50825 Germany Email: thomas.king@de-cix.net Christoph Dietzel DE-CIX Management GmbH Lichtstrasse 43i Cologne 50825 Germany Email: christoph.dietzel@de-cix.net Gert Doering SpaceNet AG Joseph-Dollinger-Bogen 14 Munich 80807 Germany Email: gert@space.net Greg Hankins Alcatel-Lucent 777 E. Middlefield Road Mountain View, CA 94043 USA Email: greg.hankins@alcatel-lucent.com King, et al. Expires November 29, 2015 [Page 6] Internet-DrBLACKHOLEIXP BGP Community for Blackholing at IXPs May 2015 Christian Seitz STRATO AG Pascalstr. 10 Berlin 10587 Germany Email: seitz@strato.de Petr Jiran NIX.CZ Milesovska 1136/5 Praha 130 00 Czech Republic Email: pj@nix.cz Yordan Kritski NetIX Ltd. 3 Grigorii Gorbatenko Str. Sofia 1784 Bulgaria Email: ykritski@netix.net King, et al. Expires November 29, 2015 [Page 7]