Internet DRAFT - draft-ietf-grow-route-leak-problem-definition
draft-ietf-grow-route-leak-problem-definition
Global Routing Operations K. Sriram
Internet-Draft D. Montgomery
Intended status: Informational US NIST
Expires: November 6, 2016 D. McPherson
E. Osterweil
Verisign, Inc.
B. Dickson
May 5, 2016
Problem Definition and Classification of BGP Route Leaks
draft-ietf-grow-route-leak-problem-definition-06
Abstract
A systemic vulnerability of the Border Gateway Protocol routing
system, known as 'route leaks', has received significant attention in
recent years. Frequent incidents that result in significant
disruptions to Internet routing are labeled "route leaks", but to
date a common definition of the term has been lacking. This document
provides a working definition of route leaks, keeping in mind the
real occurrences that have received significant attention. Further,
this document attempts to enumerate (though not exhaustively)
different types of route leaks based on observed events on the
Internet. The aim is to provide a taxonomy that covers several forms
of route leaks that have been observed and are of concern to Internet
user community as well as the network operator community.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 6, 2016.
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Copyright Notice
Copyright (c) 2016 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Working Definition of Route Leaks . . . . . . . . . . . . . . 3
3. Classification of Route Leaks Based on Documented Events . . 3
3.1. Type 1: Hairpin Turn with Full Prefix . . . . . . . . . . 4
3.2. Type 2: Lateral ISP-ISP-ISP Leak . . . . . . . . . . . . 5
3.3. Type 3: Leak of Transit-Provider Prefixes to Peer . . . . 5
3.4. Type 4: Leak of Peer Prefixes to Transit Provider . . . . 5
3.5. Type 5: Prefix Re-Origination with Data Path to
Legitimate Origin . . . . . . . . . . . . . . . . . . . . 6
3.6. Type 6: Accidental Leak of Internal Prefixes and More
Specific Prefixes . . . . . . . . . . . . . . . . . . . . 6
4. Additional Comments about the Classification . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. Informative References . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Frequent incidents [Huston2012][Cowie2013][Toonk2015-A][Toonk2015-B][
Cowie2010][Madory][Zmijewski][Paseka][LRL][Khare] that result in
significant disruptions to Internet routing are commonly called
"route leaks". Examination of the details of some of these incidents
reveals that they vary in their form and technical details. In order
to pursue solutions to "the route leak problem" it is important to
first provide a clear, technical definition of the problem and
enumerate its most common forms. Section 2 provides a working
definition of route leaks, keeping in view many recent incidents that
have received significant attention. Section 3 attempts to enumerate
(though not exhaustively) different types of route leaks based on
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observed events on the Internet. Further, Section 3 provides a
taxonomy that covers several forms of route leaks that have been
observed and are of concern to Internet user community as well as the
network operator community. This document builds on and extends
earlier work in the IETF [draft-dickson-sidr-route-leak-def][draft-di
ckson-sidr-route-leak-reqts].
2. Working Definition of Route Leaks
A proposed working definition of route leak is as follows:
A "route leak" is the propagation of routing announcement(s) beyond
their intended scope. That is, an AS's announcement of a learned BGP
route to another AS is in violation of the intended policies of the
receiver, the sender and/or one of the ASes along the preceding AS
path. The intended scope is usually defined by a set of local
redistribution/filtering policies distributed among the ASes
involved. Often, these intended policies are defined in terms of the
pair-wise peering business relationship between ASes (e.g., customer,
transit provider, peer). (For literature related to AS relationships
and routing policies, see [Gao] [Luckie] [Gill]. For measurements of
valley-free violations in Internet routing, see [Anwar] [Giotsas]
[Wijchers].)
The result of a route leak can be redirection of traffic through an
unintended path which may enable eavesdropping or traffic analysis,
and may or may not result in an overload or black-hole. Route leaks
can be accidental or malicious, but most often arise from accidental
misconfigurations.
The above definition is not intended to be all encompassing. Our aim
here is to have a working definition that fits enough observed
incidents so that the IETF community has a basis for developing
solutions for route leak detection and mitigation.
3. Classification of Route Leaks Based on Documented Events
As illustrated in Figure 1, a common form of route leak occurs when a
multi-homed customer AS (such as AS3 in Figure 1) learns a prefix
update from one transit provider (ISP1) and leaks the update to
another transit provider (ISP2) in violation of intended routing
policies, and further the second transit provider does not detect the
leak and propagates the leaked update to its customers, peers, and
transit ISPs.
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/\ /\
\ route-leak(P)/
\ propagated /
\ /
+------------+ peer +------------+
______| ISP1 (AS1) |----------->| ISP2 (AS2)|---------->
/ ------------+ prefix(P) +------------+ route-leak(P)
| prefix | \ update /\ \ propagated
\ (P) / \ / \
------- prefix(P) \ / \
update \ / \
\ /route-leak(P) \/
\/ /
+---------------+
| customer(AS3) |
+---------------+
Figure 1: Illustration of the basic notion of a route leak.
This document proposes the following taxonomy to cover several types
of observed route leaks, while acknowledging that the list is not
meant to be exhaustive. In what follows, the AS that announces a
route that is in violation of the intended policies is referred to as
the "offending AS".
3.1. Type 1: Hairpin Turn with Full Prefix
Description: A multi-homed AS learns a route from one upstream ISP
and simply propagates it to another upstream ISP (the turn
essentially resembling a hairpin). Neither the prefix nor the AS
path in the update is altered. This is similar to a straight forward
path-poisoning attack [Kapela-Pilosov], but with full prefix. It
should be noted that leaks of this type are often accidental (i.e.
not malicious). The update basically makes a hairpin turn at the
offending AS's multi-homed AS. The leak often succeeds (i.e. leaked
update is accepted and propagated) because the second ISP prefers
customer announcement over peer announcement of the same prefix.
Data packets would reach the legitimate destination albeit via the
offending AS, unless they are dropped at the offending AS due to its
inability to handle resulting large volumes of traffic.
o Example incidents: Examples of Type 1 route-leak incidents are (1)
the Dodo-Telstra incident in March 2012 [Huston2012], (2) the
VolumeDrive-Atrato incident in September 2014 [Madory], and (3)
the massive Telekom Malaysia route leak of about 179,000 prefixes,
which in turn Level3 accepted and propagated [Toonk2015-B].
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3.2. Type 2: Lateral ISP-ISP-ISP Leak
Description: The term "lateral" here is synonymous with "non-transit"
or "peer-to-peer". This type of route leak typically occurs when,
for example, three sequential ISP peers (e.g. ISP-A, ISP-B, and ISP-
C) are involved, and ISP-B receives a route from ISP-A and in turn
leaks it to ISP-C. The typical routing policy between laterally
(i.e. non-transit) peering ISPs is that they should only propagate to
each other their respective customer prefixes.
o Example incidents: In [Mauch-nanog][Mauch], route leaks of this
type are reported by monitoring updates in the global BGP system
and finding three or more very large ISP ASNs in a sequence in a
BGP update's AS path. [Mauch] observes that its detection
algorithm detects for these anomalies and potentially route leaks
because very large ISPs do not in general buy transit services
from each other. However, it also notes that there are exceptions
when one very large ISP does indeed buy transit from another very
large ISP, and accordingly exceptions are made in its detection
algorithm for known cases.
3.3. Type 3: Leak of Transit-Provider Prefixes to Peer
Description: This type of route leak occurs when an offending AS
leaks routes learned from its transit provider to a lateral (i.e.
non-transit) peer.
o Example incidents: The incidents reported in [Mauch] include the
Type 3 leaks.
3.4. Type 4: Leak of Peer Prefixes to Transit Provider
Description: This type of route leak occurs when an offending AS
leaks routes learned from a lateral (i.e. non-transit) peer to its
(the AS's) own transit provider. These leaked routes typically
originate from the customer cone of the lateral peer.
o Example incidents: Examples of Type 4 route-leak incidents are (1)
the Axcelx-Hibernia route leak of Amazon Web Services (AWS)
prefixes causing disruption of AWS and a variety of services that
run on AWS [Kephart],(2) the Hathway-Airtel route leak of 336
Google prefixes causing widespread interruption of Google services
in Europe and Asia [Toonk2015-A], (3) the Moratel-PCCW route leak
of Google prefixes causing Google's services to go offline
[Paseka], and (4) Some of the example incidents cited for Type 1
route leaks above are also inclusive of Type 4 route leaks. For
instance, in the Dodo-Telstra incident [Huston2012], the leaked
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routes from Dodo to Telstra included routes that Dodo learned from
its transit providers as well as lateral peers.
3.5. Type 5: Prefix Re-Origination with Data Path to Legitimate Origin
Description: A multi-homed AS learns a route from one upstream ISP
and announces the prefix to another upstream ISP as if it is being
originated by it (i.e. strips the received AS path, and re-originates
the prefix). This can be called re-origination or mis-origination.
However, somehow a reverse path to the legitimate origination AS may
be present and data packets reach the legitimate destination albeit
via the offending AS. (Note: The presence of a reverse path here is
not attributable to the use of path poisoning trick by the offending
AS.) But sometimes the reverse path may not be present, and data
packets destined for the leaked prefix may be simply discarded at the
offending AS.
o Example incidents: Examples of Type 5 route leak include (1) the
China Telecom incident in April 2010 [Hiran][Cowie2010][Labovitz],
(2) the Belarusian GlobalOneBel route leak incidents in February-
March 2013 and May 2013 [Cowie2013], (3) the Icelandic Opin Kerfi-
Simmin route leak incidents in July-August 2013 [Cowie2013], and
(4) the Indosat route leak incident in April 2014 [Zmijewski].
The reverse paths (i.e. data paths from the offending AS to the
legitimate destinations) were present in incidents #1, #2 and #3
cited above, but not in incident #4. In incident #4, the
misrouted data packets were dropped at Indosat's AS.
3.6. Type 6: Accidental Leak of Internal Prefixes and More Specific
Prefixes
Description: An offending AS simply leaks its internal prefixes to
one or more of its transit-provider ASes and/or ISP peers. The
leaked internal prefixes are often more specific prefixes subsumed by
an already announced less specific prefix. The more specific
prefixes were not intended to be routed in eBGP. Further, the AS
receiving those leaks fails to filter them. Typically, these leaked
announcements are due to some transient failures within the AS; they
are short-lived and typically withdrawn quickly following the
announcements. However, these more specific prefixes may momentarily
cause the routes to be preferred over other aggregate (i.e. less
specific) route announcements, thus redirecting traffic from its
normal best path.
o Example incidents: Leaks of internal routes occur frequently (e.g.
multiple times in a week), and the number of prefixes leaked range
from hundreds to thousands per incident. One highly conspicuous
and widely disruptive leak of internal routes happened in August
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2014 when AS701 and AS705 leaked about 22,000 more specifics of
already announced aggregates [Huston2014][Toonk2014].
4. Additional Comments about the Classification
It is worth noting that Types 1 through 4 are similar in that a route
is leaked in violation of policy in each case, but what varies is the
context of the leaked-route source AS and destination AS roles.
Type 5 route leak (i.e. prefix mis-origination with data path to
legitimate origin) can also happen in conjunction with the AS
relationship contexts in Types 2, 3, and 4. While these
possibilities are acknowledged, simply enumerating more types to
consider all such special cases does not add value as far as solution
development for route leaks is concerned. Hence, the special cases
mentioned here are not included in enumerating route leak types.
5. Security Considerations
No security considerations apply since this is a problem definition
document.
6. IANA Considerations
This document does not require an action from IANA.
7. Acknowledgements
The authors wish to thank Jared Mauch, Jeff Haas, Warren Kumari,
Amogh Dhamdhere, Jakob Heitz, Geoff Huston, Randy Bush, Job Snijders,
Ruediger Volk, Andrei Robachevsky, Charles van Niman, Chris Morrow,
and Sandy Murphy for comments, suggestions, and critique. The
authors are also thankful to Padma Krishnaswamy, Oliver Borchert, and
Okhee Kim for their comments and review.
8. Informative References
[Anwar] Anwar, R., Niaz, H., Choffnes, D., Cunha, I., Gill, P.,
and N. Katz-Bassett, "Investigating Interdomain Routing
Policies in the Wild", ACM Internet Measurement
Conference (IMC), October 2015,
<http://www.cs.usc.edu/assets/007/94928.pdf>.
[Cowie2010]
Cowie, J., "China's 18 Minute Mystery", Dyn
Research/Renesys Blog, November 2010,
<http://research.dyn.com/2010/11/
chinas-18-minute-mystery/>.
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[Cowie2013]
Cowie, J., "The New Threat: Targeted Internet Traffic
Misdirection", Dyn Research/Renesys Blog, November 2013,
<http://research.dyn.com/2013/11/
mitm-internet-hijacking/>.
[draft-dickson-sidr-route-leak-def]
Dickson, B., "Route Leaks -- Definitions", IETF Internet
Draft (expired), October 2012,
<https://tools.ietf.org/html/draft-dickson-sidr-route-
leak-def-03>.
[draft-dickson-sidr-route-leak-reqts]
Dickson, B., "Route Leaks -- Requirements for Detection
and Prevention thereof", IETF Internet Draft (expired),
March 2012, <http://tools.ietf.org/html/
draft-dickson-sidr-route-leak-reqts-02>.
[Gao] Gao, L. and J. Rexford, "Stable Internet routing without
global coordination", IEEE/ACM Transactions on
Networking, December 2001,
<http://www.cs.princeton.edu/~jrex/papers/
sigmetrics00.long.pdf>.
[Gill] Gill, P., Schapira, M., and S. Goldberg, "A Survey of
Interdomain Routing Policies", ACM SIGCOMM Computer
Communication Review, January 2014,
<http://www.cs.bu.edu/~goldbe/papers/survey.pdf>.
[Giotsas] Giotsas, V. and S. Zhou, "Valley-free violation in
Internet routing - Analysis based on BGP Community data",
IEEE ICC 2012, June 2012.
[Hiran] Hiran, R., Carlsson, N., and P. Gill, "Characterizing
Large-scale Routing Anomalies: A Case Study of the China
Telecom Incident", PAM 2013, March 2013,
<http://www3.cs.stonybrook.edu/~phillipa/papers/
CTelecom.html>.
[Huston2012]
Huston, G., "Leaking Routes", March 2012,
<http://labs.apnic.net/blabs/?p=139/>.
[Huston2014]
Huston, G., "What's so special about 512?", September
2014, <http://labs.apnic.net/blabs/?p=520/>.
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[Kapela-Pilosov]
Pilosov, A. and T. Kapela, "Stealing the Internet: An
Internet-Scale Man in the Middle Attack", DEFCON-16 Las
Vegas, NV, USA, August 2008,
<https://www.defcon.org/images/defcon-16/dc16-
presentations/defcon-16-pilosov-kapela.pdf>.
[Kephart] Kephart, N., "Route Leak Causes Amazon and AWS Outage",
ThousandEyes Blog, June 2015,
<https://blog.thousandeyes.com/route-leak-causes-amazon-
and-aws-outage>.
[Khare] Khare, V., Ju, Q., and B. Zhang, "Concurrent Prefix
Hijacks: Occurrence and Impacts", IMC 2012, Boston, MA,
November 2012, <http://www.cs.arizona.edu/~bzhang/
paper/12-imc-hijack.pdf>.
[Labovitz]
Labovitz, C., "Additional Discussion of the April China
BGP Hijack Incident", Arbor Networks IT Security Blog,
November 2010,
<http://www.arbornetworks.com/asert/2010/11/additional-
discussion-of-the-april-china-bgp-hijack-incident/>.
[LRL] Khare, V., Ju, Q., and B. Zhang, "Large Route Leaks",
Project web page, 2012,
<http://nrl.cs.arizona.edu/projects/
lsrl-events-from-2003-to-2009/>.
[Luckie] Luckie, M., Huffaker, B., Dhamdhere, A., Giotsas, V., and
kc. claffy, "AS Relationships, Customer Cones, and
Validation", IMC 2013, October 2013,
<http://www.caida.org/~amogh/papers/asrank-IMC13.pdf>.
[Madory] Madory, D., "Why Far-Flung Parts of the Internet Broke
Today", Dyn Research/Renesys Blog, September 2014,
<http://research.dyn.com/2014/09/
why-the-internet-broke-today/>.
[Mauch] Mauch, J., "BGP Routing Leak Detection System", Project
web page, 2014,
<http://puck.nether.net/bgp/leakinfo.cgi/>.
[Mauch-nanog]
Mauch, J., "Detecting Routing Leaks by Counting",
NANOG-41 Albuquerque, NM, USA, October 2007,
<https://www.nanog.org/meetings/nanog41/presentations/
mauch-lightning.pdf>.
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[Paseka] Paseka, T., "Why Google Went Offline Today and a Bit about
How the Internet Works", CloudFare Blog, November 2012,
<http://blog.cloudflare.com/
why-google-went-offline-today-and-a-bit-about/>.
[Toonk2014]
Toonk, A., "What caused today's Internet hiccup", August
2014, <http://www.bgpmon.net/
what-caused-todays-internet-hiccup/>.
[Toonk2015-A]
Toonk, A., "What caused the Google service interruption",
March 2015, <http://www.bgpmon.net/
what-caused-the-google-service-interruption/>.
[Toonk2015-B]
Toonk, A., "Massive route leak causes Internet slowdown",
June 2015, <http://www.bgpmon.net/
massive-route-leak-cause-internet-slowdown/>.
[Wijchers]
Wijchers, B. and B. Overeinder, "Quantitative Analysis of
BGP Route Leaks", RIPE-69, November 2014,
<http://ripe69.ripe.net/
presentations/157-RIPE-69-Routing-WG.pdf>.
[Zmijewski]
Zmijewski, E., "Indonesia Hijacks the World", Dyn
Research/Renesys Blog, April 2014,
<http://research.dyn.com/2014/04/
indonesia-hijacks-world/>.
Authors' Addresses
Kotikalapudi Sriram
US NIST
Email: ksriram@nist.gov
Doug Montgomery
US NIST
Email: dougm@nist.gov
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Danny McPherson
Verisign, Inc.
Email: dmcpherson@verisign.com
Eric Osterweil
Verisign, Inc.
Email: eosterweil@verisign.com
Brian Dickson
Email: brian.peter.dickson@gmail.com
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