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
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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
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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be created, and it may not be published except as an Internet-Draft.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:
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.
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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
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.
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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
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
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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
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