Internet DRAFT - draft-ietf-grow-blackholing
draft-ietf-grow-blackholing
Network Working Group T. King
Internet-Draft C. Dietzel
Intended status: Standards Track DE-CIX Management GmbH
Expires: May 12, 2016 J. Snijders
NTT
G. Doering
SpaceNet AG
G. Hankins
Alcatel-Lucent
November 9, 2015
BLACKHOLE BGP Community for Blackholing
draft-ietf-grow-blackholing-00
Abstract
This document describes the use of a well-known Border Gateway
Protocol (BGP) community for blackholing at IP networks and Internet
Exchange Points (IXP). This well-known advisory transitive BGP
community, namely BLACKHOLE, allows an origin AS to specify that a
neighboring IP network or IXP should blackhole a specific IP prefix.
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
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Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 12, 2016.
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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
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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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. BLACKHOLE Attribute . . . . . . . . . . . . . . . . . . . . . 3
3. Operational Recommendations . . . . . . . . . . . . . . . . . 3
3.1. IP Prefix Announcements with BLACKHOLE Community Attached 3
3.2. Local Scope of Blackholes . . . . . . . . . . . . . . . . 3
3.3. Accepting Blackholed IP Prefixes . . . . . . . . . . . . 4
3.4. IXPs: Peering at Route Servers . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . 6
6.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
The network infrastructure has been getting hammered by DDoS attacks
for years. In order to block DDoS attacks, IP networks have offered
BGP blackholing to neighboring networks (iBGP scenarios [RFC3882] and
RTBH filtering [RFC5635]), much like some IXPs have recently started
to do.
DDoS attacks targeting a certain IP network may cause congestion of
links used to connect to other networks. In order to limit the
impact of such a scenario on legitimate traffic, IP networks and IXPs
adopted a mechanism called BGP blackholing. A network that wants to
trigger blackholing needs to understand the triggering mechanism
adopted by its neighboring IP networks and IXPs. Different IP
networks and IXPs provide different BGP mechanisms to trigger
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blackholing, including pre-defined blackhole next- hop IP addresses
and pre-defined BGP communities.
Having several different mechanisms to trigger blackholing at
different IP networks and IXPs makes it an unnecessarily complex,
error-prone and cumbersome task for network operators. Therefore a
well-known BGP community [RFC1997] is defined for operational ease.
Having such a well-known BGP community for blackholing also supports
IP networks and IXPs because
o implementing and monitoring blackholing gets easier if
implementation and operational guides do not cover many options
that trigger blackholing
o the number of support requests from customers about how to trigger
blackholing at a particular IP network or IXP will be reduced as
the mechanism is unified
Making it considerably easier for network operators to utilize
blackholing makes operations easier.
2. BLACKHOLE Attribute
This document defines the use of a new well-known BGP transitive
community, BLACKHOLE.
The semantics of this attribute allow a network 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. IP Prefix Announcements with BLACKHOLE Community Attached
When an IP network is under DDoS duress, it MAY announce an IP prefix
covering the victim's IP address(es) for the purpose of signaling to
neighboring IP networks or IXPs that any traffic destined for these
IP address(es) should be discarded. In such a scenario, the network
operator SHOULD attach BLACKHOLE BGP community.
3.2. Local Scope of Blackholes
A BGP speaker receiving a BGP announcement tagged with the BLACKHOLE
BGP community SHOULD add a NO_ADVERTISE, NO_EXPORT or similar
community to prevent propagation of this route outside the local AS.
Unintentional leaking of more specific IP prefixes to neighboring
networks can have adverse effects. Extreme caution should be used
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when purposefully propagating IP prefixes tagged with the BLACKHOLE
BGP community outside the local routing domain.
3.3. Accepting Blackholed IP Prefixes
It has been observed that announcements of IP prefixes larger than
/24 for IPv4 and /48 for IPv6 are usually not accepted on the
Internet (see section 6.1.3 [RFC7454]). However, blackhole routes
should be as small as possible in order to limit the impact of
discarding traffic for adjacent IP space that is not under DDoS
duress. Typically, the blackhole route's prefix length is as
specific as /32 for IPv4 and /128 for IPv6.
BGP speakers SHOULD only accept and honor BGP announcements carrying
the BLACKHOLE community if the announced prefix is covered by a
shorter prefix for which the neighboring network is authorized to
advertise.
3.4. IXPs: Peering at Route Servers
Many IXPs provide the so-called policy control feature as part of
their route servers [I-D.ietf-idr-ix-bgp-route-server] (see e.g. the
LINX website [1]). Policy control allows members to specify, by
using BGP communities, which ASNs connected to the route server
receive a particular BGP announcement.
Combined usage of the BGP communities for blackholing and policy
control allows a fine-grained control of a blackhole.
In some implementations of blackholing at IXPs, the route server
after receiving a BGP announcement tagged with the BLACKHOLE BGP
community rewrites the next-hop IP address to the pre-defined
blackholing IP address before redistributing the announcement.
4. IANA Considerations
The IANA is requested to register BLACKHOLE as a well-known BGP
community with global significance:
BLACKHOLE (= 0xFFFF029A)
The low-order two octets in decimal are 666, amongst IP network
operators a value commonly associated with BGP blackholing.
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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, RPKI [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.
The BLACKHOLE BGP community does not alter this situation.
A new additional attack vector is introduced into BGP by using the
BLACKHOLE BGP community: denial of service attacks for IP prefixes.
The unauthorized addition of the BLACKHOLE 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 IP network or 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 BLACKHOLE BGP community, the receiving BGP
speaker 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.
The presence of this BLACKHOLE BGP community may introduce a resource
exhaustion attack to BGP speakers. If a BGP speaker receives many IP
prefixes containing the BLACKHOLE BGP community, its internal
resources such as CPU power and/or memory might get consumed,
especially if usual prefix sanity checks (e.g. such as IP prefix
length or number of prefixes) are disabled (see Section 3.3).
6. References
6.1. Normative References
[RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities
Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996,
<http://www.rfc-editor.org/info/rfc1997>.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
6.2. Informative References
[I-D.ietf-idr-ix-bgp-route-server]
Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker,
"Internet Exchange BGP Route Server", draft-ietf-idr-ix-
bgp-route-server-09 (work in progress), October 2015.
[I-D.ietf-sidr-bgpsec-overview]
Lepinski, M., "An Overview of BGPsec", draft-ietf-sidr-
bgpsec-overview-07 (work in progress), June 2015.
[RFC3882] Turk, D., "Configuring BGP to Block Denial-of-Service
Attacks", RFC 3882, DOI 10.17487/RFC3882, September 2004,
<http://www.rfc-editor.org/info/rfc3882>.
[RFC5635] Kumari, W. and D. McPherson, "Remote Triggered Black Hole
Filtering with Unicast Reverse Path Forwarding (uRPF)",
RFC 5635, DOI 10.17487/RFC5635, August 2009,
<http://www.rfc-editor.org/info/rfc5635>.
[RFC6810] Bush, R. and R. Austein, "The Resource Public Key
Infrastructure (RPKI) to Router Protocol", RFC 6810, DOI
10.17487/RFC6810, January 2013,
<http://www.rfc-editor.org/info/rfc6810>.
[RFC7454] Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations
and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454,
February 2015, <http://www.rfc-editor.org/info/rfc7454>.
6.3. URIs
[1] https://www.linx.net/members/support/route-servers.html
Appendix A. Acknowledgements
The authors gratefully acknowledges the contributions of:
o Petr Jiran, NIX.CZ, Milesovska 1136/5, Praha 130 00, Czech
Republic, Email: pj@nix.cz
o Yordan Kritski, NetIX Ltd., 3 Grigorii Gorbatenko Str., Sofia
1784, Bulgaria, Email: ykritski@netix.net
o Christian Seitz, STRATO AG, Pascalstr. 10, Berlin 10587, Germany,
Email: seitz@strato.de
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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
Job Snijders
NTT Communications, Inc.
Theodorus Majofskistraat 100
Amsterdam 1065 SZ
NL
Email: job@ntt.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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