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Versions: 00 01 draft-ietf-grow-blackholing

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
                                                                C. Seitz
                                                               STRATO AG
                                                                P. Jiran
                                                              Y. Kritski
                                                              NetIX Ltd.
                                                            May 28, 2015

           BLACKHOLEIXP BGP Community for Blackholing at IXPs


   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",
   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

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   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
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   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.

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   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.

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   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:


   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.

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   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

   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  [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

              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.

              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.

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   [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

   Email: thomas.king@de-cix.net

   Christoph Dietzel
   DE-CIX Management GmbH
   Lichtstrasse 43i
   Cologne  50825

   Email: christoph.dietzel@de-cix.net

   Gert Doering
   SpaceNet AG
   Joseph-Dollinger-Bogen 14
   Munich  80807

   Email: gert@space.net

   Greg Hankins
   777 E. Middlefield Road
   Mountain View, CA  94043

   Email: greg.hankins@alcatel-lucent.com

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   Christian Seitz
   Pascalstr. 10
   Berlin  10587

   Email: seitz@strato.de

   Petr Jiran
   Milesovska 1136/5
   Praha  130 00
   Czech Republic

   Email: pj@nix.cz

   Yordan Kritski
   NetIX Ltd.
   3 Grigorii Gorbatenko Str.
   Sofia  1784

   Email: ykritski@netix.net

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