wdiff rfc9319.original rfc9319.txt

Internet Engineering Task Force (IETF) Y. Gilad
Internet-Draft
Request for Comments: 9319 Hebrew University of Jerusalem
Intended status:
BCP: 185 S. Goldberg
Category: Best Current Practice S. Goldberg
Expires: 15 February 2023 Boston University
ISSN: 2070-1721 K. Sriram
USA NIST
J. Snijders
Fastly
B. Maddison
Workonline Communications
14 August
October 2022

The Use of maxLength in the RPKI
draft-ietf-sidrops-rpkimaxlen-15 Resource Public Key Infrastructure (RPKI)

Abstract

This document recommends ways to reduce the forged-origin hijack
attack surface by prudently limiting the set of IP prefixes that are
included in a Route Origin Authorization (ROA). One recommendation
is to avoid using the maxLength attribute in ROAs except in some
specific cases. The recommendations complement and extend those in
RFC 7115. The This document also discusses the creation of ROAs for
facilitating the use of Distributed Denial of Service (DDoS)
mitigation services. Considerations related to ROAs and origin
validation RPKI-based
Route Origin Validation (RPKI-ROV) in the context of destination-based destination-
based Remotely Triggered Discard Route (RTDR) (elsewhere referred to
as "Remotely Triggered Black Hole") filtering are also highlighted.

Status of This Memo

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provisions of BCP 78 and BCP 79.

Internet-Drafts are working memo documents an Internet Best Current Practice.

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Internet-Drafts are draft documents valid the IETF community. It has
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This Internet-Draft will expire on 15 February 2023.
https://www.rfc-editor.org/info/rfc9319.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Documentation Prefixes . . . . . . . . . . . . . . . . . 4
2. Suggested Reading . . . . . . . . . . . . . . . . . . . . . . 4
3. Forged-Origin Sub-prefix Sub-Prefix Hijack . . . . . . . . . . . . . . . 4
4. Measurements of the RPKI . . . . . . . . . . . . . . . . . . 7
5. Recommendations about Minimal ROAs and maxLength . . . . . . 7
5.1. Facilitating Ad Hoc Routing Changes and DDoS Mitigation . . . . . . . . . . . . . . . . . . . . . . . 8
5.2. Defensive De-aggregation In in Response To to Prefix Hijacks . 10
6. Considerations for RTDR Filtering Scenarios . . . . . . . . . 11
7. User Interface Design Recommendations . . . . . . . . . . . . 11
8. Operational Considerations . . . . . . . . . . . . . . . . . 12
9. Security Considerations . . . . . . . . . . . . . . . . . . . 12
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
12.1.
11.1. Normative References . . . . . . . . . . . . . . . . . . 13
12.2.
11.2. Informative References . . . . . . . . . . . . . . . . . 14
Acknowledgments
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14

1. Introduction

The RPKI Resource Public Key Infrastructure (RPKI) [RFC6480] uses Route
Origin Authorizations (ROAs) to create a cryptographically verifiable
mapping from an IP prefix to a set of
autonomous systems Autonomous Systems (ASes) that
are authorized to originate that prefix. Each ROA contains a set of
IP prefixes, prefixes and the AS number of one of the ASes authorized to
originate all the IP prefixes in the set [RFC6482]. The ROA is
cryptographically signed by the party that holds a certificate for
the set of IP prefixes.

The ROA format also supports a maxLength attribute. According to
[RFC6482], "When present, the maxLength specifies the maximum length
of the IP address prefix that the AS is authorized to advertise."
Thus, rather than requiring the ROA to list each prefix that the AS
is authorized to originate, the maxLength attribute provides a
shorthand that authorizes an AS to originate a set of IP prefixes.

However, measurements of RPKI deployments have found that the use of
the maxLength attribute in ROAs tends to lead to security problems.
In particular, measurements taken in June 2017 showed that of the
prefixes specified in ROAs that use the maxLength attribute, 84% were
vulnerable to a forged-origin sub-prefix hijack [HARMFUL]. [GSG17]. The
forged-origin forged-
origin prefix or sub-prefix hijack involves inserting the legitimate
AS as specified in the ROA as the origin AS in the
AS_PATH, and AS_PATH; the
hijack can be launched against any IP prefix/sub-prefix that has a
ROA. Consider a prefix/sub-prefix that has a ROA but that is
unused, i.e., unused
(i.e., not announced in BGP by a legitimate AS. AS). A forged
origin forged-origin
hijack involving such a prefix/sub-prefix can propagate widely
throughout the Internet. On the other hand, if the prefix/sub-prefix
were announced by the legitimate AS, then the propagation of the
forged-origin hijack is somewhat limited because of its increased
AS_PATH length relative to the legitimate announcement. Of course,
forged-origin hijacks are harmful in both cases cases, but the extent of
harm is greater for unannounced prefixes. See Section 3 for detailed
discussion.

For this reason, this document recommends that, whenever possible,
operators SHOULD use "minimal ROAs" that authorize only those IP
prefixes that are actually originated in BGP, and no other prefixes.
Further, it recommends ways to reduce the forged-origin attack
surface by prudently limiting the address space that is included in
Route Origin Authorizations (ROAs).
ROAs. One recommendation is to avoid using the maxLength attribute
in ROAs except in some specific cases. The recommendations
complement and extend those in [RFC7115]. The document also
discusses the creation of ROAs for facilitating the use of Distributed Denial of Service (DDoS) DDoS
mitigation services. Considerations related to ROAs and origin validation RPKI-ROV in
the context of destination-based Remotely Triggered Discard Route
(RTDR) (elsewhere referred to as "Remotely Triggered Black Hole")
filtering are also highlighted.

Please note that the term "RPKI-based Route Origin Validation" and
the corresponding acronym "RPKI-ROV" that are used in this document
mean the same as the term "Prefix Origin Validation" used in
[RFC6811].

One ideal place to implement the ROA related ROA-related recommendations is in
the user interfaces for configuring ROAs. Recommendations for
implementors of such user interfaces are provided in Section 7
Best current 7.

The practices described in this document require no changes to the
RPKI specification specifications and will not increase the number of signed ROAs
in the RPKI because ROAs already support lists of IP prefixes
[RFC6482].

1.1. Requirements

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.

1.2. Documentation Prefixes

The documentation prefixes recommended in [RFC5737] are insufficient
for use as example prefixes in this document. Therefore, this
document uses [RFC1918] the address space defined in [RFC1918] for constructing
example prefixes.

Note that although the examples in this document are presented using
IPv4 prefixes, all the analysis thereof and the recommendations made
are equally valid for the equivalent IPv6 cases.

2. Suggested Reading

It is assumed that the reader understands BGP [RFC4271], RPKI
[RFC6480], Route Origin Authorizations (ROAs) ROAs [RFC6482], RPKI-based
Prefix Validation RPKI-ROV [RFC6811], and BGPsec [RFC8205].

3. Forged-Origin Sub-prefix Sub-Prefix Hijack

A detailed description and discussion of forged-origin sub-prefix
hijacks are presented here, especially considering the case when the
sub-prefix is not announced in BGP. The forged-origin sub-prefix
hijack is relevant to a scenario in which:

(1) the RPKI [RFC6480] is deployed, and

(2) routers use RPKI origin validation RPKI-ROV to drop invalid routes [RFC6811], but

(3) BGPsec [RFC8205] (or any similar method to validate the
truthfulness of the BGP AS_PATH attribute) is not deployed.

Note that this set of assumptions accurately describes a substantial
and growing number of large Internet networks at the time of writing.

The forged-origin sub-prefix hijack [RFC7115] [GCHSS] is described
here using a running example.

Consider the IP prefix 192.168.0.0/16 192.168.0.0/16, which is allocated to an
organization that also operates AS 64496. In BGP, AS 64496
originates the IP prefix 192.168.0.0/16 as well as its sub-prefix
192.168.225.0/24. Therefore, the RPKI should contain a ROA
authorizing AS 64496 to originate these two IP prefixes.

Suppose, however, the organization issues and publishes a ROA
including a maxLength value of 24:

ROA:(192.168.0.0/16-24, AS 64496)

We refer to the above as a "loose ROA" since it authorizes AS 64496
to originate any sub-prefix of 192.168.0.0/16 up to and including
length /24, rather than only those prefixes that are intended to be
announced in BGP.

Because AS 64496 only originates two prefixes in BGP: 192.168.0.0/16 BGP (192.168.0.0/16
and 192.168.225.0/24, 192.168.225.0/24), all other prefixes authorized by the "loose
ROA" loose ROA
(for instance, 192.168.0.0/24), 192.168.0.0/24) are vulnerable to the following
forged-origin sub-prefix hijack [RFC7115] [GCHSS]:

The hijacker AS 64511 sends a BGP announcement "192.168.0.0/24: AS
64511, AS 64496", falsely claiming that AS 64511 is a neighbor of
AS 64496 and falsely claiming that AS 64496 originates the IP prefix
192.168.0.0/24. In fact, the IP prefix 192.168.0.0/24 is not
originated by AS 64496.

The hijacker's BGP announcement is valid according to the RPKI
since the ROA (192.168.0.0/16-24, AS 64496) authorizes AS 64496 to
originate BGP routes for 192.168.0.0/24.

Because AS 64496 does not actually originate a route for
192.168.0.0/24, the hijacker's route is the only route for
192.168.0.0/24. Longest-prefix-match routing ensures that the
hijacker's route to the sub-prefix 192.168.0.0/24 is always
preferred over the legitimate route to 192.168.0.0/16 originated
by AS 64496.

Thus, the hijacker's route propagates through the Internet, and
traffic destined for IP addresses in 192.168.0.0/24 will be delivered
to the hijacker.

The forged-origin sub-prefix hijack would have failed if a "minimal
ROA" minimal
ROA as described below in Section 5 was used instead of the "loose ROA". loose ROA. In
this example, a "minimal ROA" minimal ROA would be:

ROA:(192.168.0.0/16, 192.168.225.0/24, AS 64496)

This ROA is "minimal" because it includes only those IP prefixes that
AS 64496 originates in BGP, but no other IP prefixes [RFC6907].

The "minimal ROA" minimal ROA renders AS 64511's BGP announcement invalid because:

(1) this ROA "covers" the attacker's announcement (since
192.168.0.0/24 is a sub-prefix of 192.168.0.0/16), and

(2) there is no ROA "matching" the attacker's announcement (there is
no ROA for AS 64511 and IP prefix 192.168.0.0/24) [RFC6811].

If routers ignore invalid BGP announcements, the minimal ROA above
ensures that the sub-prefix hijack will fail.

Thus, if a "minimal ROA" minimal ROA had been used, the attacker would be forced to
launch a forged-origin prefix hijack in order to attract traffic, traffic as
follows:

The hijacker AS 64511 sends a BGP announcement "192.168.0.0/16: AS
64511, AS 64496", falsely claiming that AS 64511 is a neighbor of
AS 64496.

This forged-origin prefix hijack is significantly less damaging than
the forged-origin sub-prefix hijack:

AS 64496 legitimately originates 192.168.0.0/16 in BGP, so the
hijacker AS 64511 is not presenting the only route to
192.168.0.0/16.

Moreover, the path originated by AS 64511 is one hop longer than
the path originated by the legitimate origin AS 64496.

As discussed in [LSG16], this means that the hijacker will attract
less traffic than it would have in the forged-origin sub-prefix
hijack,
hijack where the hijacker presents the only route to the hijacked
sub-prefix.

In summary, a forged-origin sub-prefix hijack has the same impact as
a regular sub-prefix hijack, despite the increased AS_PATH length of
the illegitimate route. A forged-origin sub-prefix hijack is also
more damaging than the forged-origin prefix hijack.

4. Measurements of the RPKI

Network measurements taken in June 2017 showed that 12% of the IP
prefixes authorized in ROAs have a maxLength value longer than their
prefix length. Of these, the vast majority (84%) were non-minimal,
as they included sub-prefixes that are not announced in BGP by the
legitimate
AS, AS and were thus vulnerable to forged-origin sub-prefix
hijacks. See [GSG17] for details.

These measurements suggest that operators commonly misconfigure the
maxLength attribute, attribute and unwittingly open themselves up to forged-
origin sub-prefix hijacks. That is, they are exposing a much larger
attack surface for forged-origin hijacks than necessary.

5. Recommendations about Minimal ROAs and maxLength

Operators SHOULD use "minimal ROAs" minimal ROAs whenever possible. A minimal ROA
contains only those IP prefixes that are actually originated by an AS
in BGP and no other IP prefixes. (See See Section 3 for an example.) example.

In general, operators SHOULD avoid using the maxLength attribute in
their ROAs, since its inclusion will usually make the ROA non-
minimal.

One such exception may be when all more specific prefixes permitted
by the maxLength value are actually announced by the AS in the ROA.
Another exception is where: (a) the maxLength value is substantially
larger compared to the specified prefix length in the ROA, and (b) a
large number of more specific prefixes in that range are announced by
the AS in the ROA. In practice, this case should occur rarely (if at
all). Operator discretion is necessary in this case.

This practice requires no changes to the RPKI specification specifications and need
not increase the number of signed ROAs in the RPKI because ROAs
already support lists of IP prefixes [RFC6482]. See also [GSG17] for
further discussion of why this practice will have minimal impact on
the performance of the RPKI ecosystem.

Operators implementing that implement these recommendations and that have existing ROAs
published in the RPKI system MUST perform a review of such objects,
especially where they make use of the maxLength attribute, to ensure
that the set of included prefixes is "minimal" with respect to the
current BGP origination and routing policies. Published ROAs MUST be
replaced as necessary. Such an exercise MUST be repeated whenever
the operator makes changes to either policy.

5.1. Facilitating Ad Hoc Routing Changes and DDoS Mitigation

Operational requirements may require that a route for an IP prefix be
originated on an ad hoc basis, with little or no prior warning. An
example of such a situation arises when an operator wishes to make
use of DDoS mitigation services that use BGP to redirect traffic via
a "scrubbing center".

In order to ensure that such ad hoc routing changes are effective, a
ROA validating the new route should exist. However However, a difficulty
arises due to the fact that newly created objects in the RPKI are
made visible to relying parties considerably more slowly than routing
updates in BGP.

Ideally, it would not be necessary to pre-create the ROA ROA, which
validates the ad hoc route, and instead create it "on-the-fly" "on the fly" as
required. However, this is practical only if the latency imposed by
the propagation of RPKI data is guaranteed to be within acceptable
limits in the circumstances. For time-critical interventions such as
responding to a DDoS attack, this is unlikely to be the case.

Thus, the ROA in question will usually need to be created well in
advance of the routing intervention, but such a ROA will be non-
minimal, since it includes an IP prefix that is sometimes (but not
always) originated in BGP.

In this case, the ROA SHOULD include only: only include:

(1) the set of IP prefixes that are always originated in BGP, and

(2) the set of IP prefixes that are sometimes, but not always,
originated in BGP.

The ROA SHOULD NOT include any IP prefixes that the operator knows
will not be originated in BGP. In general, the ROA SHOULD NOT make
use of the maxLength attribute unless doing so has no impact on the
set of included prefixes.

The running example is now extended to illustrate one situation where
it is not possible to issue a minimal ROA.

Consider the following scenario prior to the deployment of RPKI.
Suppose AS 64496 announced 192.168.0.0/16 and has a contract with a
Distributed Denial of Service (DDoS)
DDoS mitigation service provider that holds AS 64500. Further,
assume that the DDoS mitigation service contract applies to all IP
addresses covered by 192.168.0.0/22. When a DDoS attack is detected
and reported by AS 64496, AS 64500 immediately originates
192.168.0.0/22, thus attracting all the DDoS traffic to itself. The
traffic is scrubbed at AS 64500 and then sent back to AS 64496 over a
backhaul link. Notice that, during a DDoS attack, the DDoS
mitigation service provider AS 64500 originates a /22 prefix that is
longer than AS 64496's /16 prefix, and so all the traffic (destined to
addresses in 192.168.0.0/22) that normally goes to AS 64496 goes to
AS 64500 instead. In some deployments, the origination of the /22
route is performed by AS 64496 and announced only to AS 64500, which
then announces transit for that prefix. This variation does not
change the properties considered here.

First, suppose the RPKI only had the minimal ROA for AS 64496, as
described in Section 3. But However, if there is no ROA authorizing AS
64500 to announce the /22 prefix, then the DDoS mitigation (and
traffic scrubbing) scheme would not work. That is, if AS 64500
originates the /22 prefix in BGP during DDoS attacks, the
announcement would be invalid [RFC6811].

Therefore, the RPKI should have two ROAs: one for AS 64496 and one
for AS 64500.

ROA:(192.168.0.0/16, 192.168.225.0/24, AS 64496)

ROA:(192.168.0.0/22, AS 64500)

Neither ROA uses the maxLength attribute. But attribute, but the second ROA is not
"minimal" because it contains a /22 prefix that is not originated by
anyone in BGP during normal operations. The /22 prefix is only
originated by AS 64500 as part of its DDoS mitigation service during
a DDoS attack.

Notice, however, that this scheme does not come without risks.
Namely, all IP addresses in 192.168.0.0/22 are vulnerable to a
forged-origin sub-prefix hijack during normal operations, operations when the /22
prefix is not originated. (The hijacker AS 64511 would send the BGP
announcement "192.168.0.0/22: AS 64511, AS 64500", falsely claiming
that AS 64511 is a neighbor of AS 64500 and falsely claiming that AS
64500 originates 192.168.0.0/22.)

In some situations, the DDoS mitigation service at AS 64500 might
want to limit the amount of DDoS traffic that it attracts and scrubs.
Suppose that a DDoS attack only targets IP addresses in
192.168.0.0/24. Then, the DDoS mitigation service at AS 64500 only
wants to attract the traffic designated for the /24 prefix that is
under attack, but not the entire /22 prefix. To allow for this, the
RPKI should have two ROAs: one for AS 64496 and one for AS 64500.

ROA:(192.168.0.0/16, 192.168.225.0/24, AS 64496)

ROA:(192.168.0.0/22-24, AS 64500)

The second ROA uses the maxLength attribute because it is designed to
explicitly enable AS 64500 to originate any /24 sub-prefix of
192.168.0.0/22.

As before, the second ROA is not "minimal" because it contains
prefixes that are not originated by anyone in BGP during normal
operations. As before, Also, all IP addresses in 192.168.0.0/22 are vulnerable
to a forged-origin sub-prefix hijack during normal
operations, operations when
the /22 prefix is not originated.

The use of the maxLength attribute in this second ROA also comes with
additional risk. While it permits the DDoS mitigation service at AS
64500 to originate prefix 192.168.0.0/24 during a DDoS attack in that
space, it also makes the other /24 prefixes covered by the /22 prefix
(i.e., 192.168.1.0/24, 192.168.2.0/24, and 192.168.3.0/24) vulnerable
to forged-
origin forged-origin sub-prefix attacks.

5.2. Defensive De-aggregation In in Response To to Prefix Hijacks

When responding to certain classes of prefix hijack, in hijack (in particular,
the forged-origin sub-prefix hijack described above, above), it may be
desirable for the victim to perform "defensive de-aggregation", i.e. i.e.,
to begin originating more-specific prefixes in order to compete with
the hijack routes for selection as the best path in networks that are
not performing RPKI-based route origin validation (ROV) RPKI-ROV [RFC6811].

In some topologies, topologies where at least one AS on every path between the victim
and hijacker filters ROV RPKI-ROV invalid prefixes, it may be the case
that the existence of a minimal ROA issued by the victim prevents the
defensive more-specific prefixes from being propagated to the
networks topologically close to the attacker, thus hampering the
effectiveness of this response.

Nevertheless, this document recommends that that, where possible, network
operators publish minimal ROAs even in the face of this risk. This
is because:

* Minimal ROAs offer the best possible protection against the
immediate impact of such an attack, rendering the need for such a
response less likely;

* Increasing ROV RPKI-ROV adoption by network operators will, over time,
decrease the size of the neighborhoods in which this risk exists;
and

* Other methods for reducing the size of such neighborhoods are
available to potential victims, such as establishing direct EBGP
External BGP (EBGP) adjacencies with networks from whom the
defensive routes would otherwise be hidden.

6. Considerations for RTDR Filtering Scenarios

Considerations related to ROAs and origin validation RPKI-ROV [RFC6811] for the case of
destination-based Remotely Triggered Discard Route (RTDR) RTDR (elsewhere referred to as "Remotely Triggered
Black Hole") filtering are addressed here. In RTDR filtering, highly
specific prefixes (greater than /24 in IPv4 and greater than /48 in IPv6;
IPv6, or possibly even /32 (IPv4) in IPv4 and /128 (IPv6)) in IPv6) are announced in
BGP. These announcements are tagged with the Well-known well-known BGP Community
community defined by [RFC7999]. It For the reasons set out above, it is
obviously not desirable to use a large maxLength value or include any
such highly specific prefixes in the ROAs to accommodate
destination-based destination-
based RTDR filtering, for the reasons set out above. filtering.

As a result, RPKI-based route origin validation RPKI-ROV [RFC6811] is a poor fit for the validation of
RTDR routes. Specification of new procedures to address this use
case through the use of the RPKI is outside the scope of this
document.

Therefore:

* Operators SHOULD NOT create non-minimal ROAs (either by (by either creating
additional ROAs, ROAs or through using the use of maxLength) maxLength attribute) for the purpose
of advertising RTDR routes; and

* Operators providing a means for operators of neighboring
autonomous systems to advertise RTDR routes via BGP MUST NOT make
the creation of non-minimal ROAs a pre-requisite for its use.

7. User Interface Design Recommendations

Most operator interaction with the RPKI system when creating or
modifying ROAs will occur via a user interface that abstracts the
underlying encoding, signing signing, and publishing operations.

This document recommends that designers and/or providers of such user
interfaces SHOULD provide warnings to draw the user's attention to
the risks of creating non-minimal ROAs in general, general and use of using the
maxLength attribute in particular.

Warnings provided by such a system may vary in nature from generic
warnings based purely on the inclusion of the maxLength attribute, attribute to
customised guidance based on the observable BGP routing policy of the
operator in question. The choices made in this respect are expected
to be dependent on the target user audience of the implementation.

8. Operational Considerations

The recommendations specified in this document, in document (in particular, those
in Section 5, 5) involve trade-offs between operational agility and
security.

Operators adopting the recommended practice of issuing minimal ROAs
will, by definition definition, need to make changes to their existing set of
issued ROAs in order to effect changes to the set of prefixes which that
are originated in BGP.

Even in the case of routing changes that are planned in advance,
existing procedures may need to be updated to incorporate changes to
issued ROAs, ROAs and may require additional time allowed for those changes
to propagate.

Operators are encouraged to carefully review the issues highlighted
(especially those in Section Sections 5.1 and Section 5.2) in light of their specific
operational requirements. Failure to do so could, in the worst case,
result in a self-inflicted denial of service.

The recommendations made in section Section 5 are likely to be more onerous
for operators utilising large IP address space allocations from which
many more-specific advertisements are made in BGP. Operators of such
networks are encouraged to seek opportunities to automate the
required procedures in order to minimise manual operational burden.

9. Security Considerations

This document makes recommendations regarding the use of RPKI-based
origin validation RPKI-ROV as
defined in [RFC6811], and [RFC6811] and, as such such, introduces no additional security
considerations beyond those specified therein.

10. IANA Considerations

This document includes has no request to IANA. IANA actions.

11. Acknowledgments

The authors would like to thank the following people for their review
and contributions to this document: Omar Sagga and Aris Lambrianidis.
Thanks are also due to Matthias Waehlisch, Ties de Kock, Amreesh
Phokeer, Eric Vyncke, Alvaro Retana, John Scudder, Roman Danyliw,
Andrew Alston, and Murray Kucherawy for comments and suggestions, to
Roni Even for the Gen-ART review, to Jean Mahoney for the ART-ART
review, to Acee Lindem for the Routing Directorate review, and to
Sean Turner for the Security Area Directorate review.

12. References

12.1.

11.1. Normative References

[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G G.
J., and E. Lear, "Address Allocation for Private
Internets", BCP 5, RFC 1918, DOI 10.17487/RFC1918,
February 1996, <https://www.rfc-editor.org/info/rfc1918>.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.

[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.

[RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support
Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480,
February 2012, <https://www.rfc-editor.org/info/rfc6480>.

[RFC6482] Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
Origin Authorizations (ROAs)", RFC 6482,
DOI 10.17487/RFC6482, February 2012,
<https://www.rfc-editor.org/info/rfc6482>.

[RFC6811] Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.
Austein, "BGP Prefix Origin Validation", RFC 6811,
DOI 10.17487/RFC6811, January 2013,
<https://www.rfc-editor.org/info/rfc6811>.

[RFC7115] Bush, R., "Origin Validation Operation Based on the
Resource Public Key Infrastructure (RPKI)", BCP 185,
RFC 7115, DOI 10.17487/RFC7115, January 2014,
<https://www.rfc-editor.org/info/rfc7115>.

[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.

12.2.

11.2. Informative References

[GSG17] Gilad, Y., Sagga, O., and S. Goldberg, "Maxlength
Considered Harmful to the RPKI", in ACM CoNEXT 2017,
December 2017, <https://eprint.iacr.org/2016/1015.pdf>.

[LSG16] Lychev, R., Shapira, M., and S. Goldberg, "Rethinking
Security for Internet Routing", in Communications of the
ACM, October 2016, <http://cacm.acm.org/
magazines/2016/10/207763-rethinking-security-for-internet-
routing/>.

[GCHSS] Gilad, Y., Cohen, A., Herzberg, A., Schapira, M., and H.
Shulman, "Are We There Yet? On RPKI's Deployment and
Security", in NDSS 2017, February 2017,
<https://eprint.iacr.org/2016/1010.pdf>.

[HARMFUL]

[GSG17] Gilad, Y., Sagga, O., and S. Goldberg, "MaxLength
Considered Harmful to the RPKI", CoNEXT '17,
DOI 10.1145/3143361.3143363, December 2017,
<https://eprint.iacr.org/2016/1015.pdf>.

[LSG16] Lychev, R., Shapira, M., and S. Goldberg, "Rethinking
security for internet routing", Communications of the ACM,
DOI 10.1145/2896817, October 2016, <http://cacm.acm.org/
magazines/2016/10/207763-rethinking-security-for-internet-
routing/>.

[RFC5737] Arkko, J., Cotton, M., and L. Vegoda, "IPv4 Address Blocks
Reserved for Documentation", RFC 5737,
DOI 10.17487/RFC5737, January 2010,
<https://www.rfc-editor.org/info/rfc5737>.

[RFC6907] Manderson, T., Sriram, K., and R. White, "Use Cases and
Interpretations of Resource Public Key Infrastructure
(RPKI) Objects for Issuers and Relying Parties", RFC 6907,
DOI 10.17487/RFC6907, March 2013,
<https://www.rfc-editor.org/info/rfc6907>.

[RFC7999] King, T., Dietzel, C., Snijders, J., Doering, G., and G.
Hankins, "BLACKHOLE Community", RFC 7999,
DOI 10.17487/RFC7999, October 2016,
<https://www.rfc-editor.org/info/rfc7999>.

[RFC8205] Lepinski, M., Ed. and K. Sriram, Ed., "BGPsec Protocol
Specification", RFC 8205, DOI 10.17487/RFC8205, September
2017, <https://www.rfc-editor.org/info/rfc8205>.

Acknowledgments

The authors would like to thank the following people for their review
and contributions to this document: Omar Sagga and Aris Lambrianidis.
Thanks are also due to Matthias Waehlisch, Ties de Kock, Amreesh
Phokeer, Éric Vyncke, Alvaro Retana, John Scudder, Roman Danyliw,
Andrew Alston, and Murray Kucherawy for comments and suggestions, to
Roni Even for the Gen-ART review, to Jean Mahoney for the ART-ART
review, to Acee Lindem for the Routing Area Directorate review, and
to Sean Turner for the Security Area Directorate review.

Authors' Addresses

Yossi Gilad
Hebrew University of Jerusalem
Rothburg Family Buildings, Buildings
Edmond J. Safra Campus
Jerusalem 9190416
Israel
Email: yossigi@cs.huji.ac.il

Sharon Goldberg
Boston University
111 Cummington St, MCS135
Boston, MA 02215
United States of America
Email: goldbe@cs.bu.edu

Kotikalapudi Sriram
USA National Institute of Standards and Technology
100 Bureau Drive
Gaithersburg, MD 20899
United States of America
Email: kotikalapudi.sriram@nist.gov

Job Snijders
Fastly
Amsterdam
Netherlands
Email: job@fastly.com

Ben Maddison
Workonline Communications
114 West St
Johannesburg
2196
South Africa
Email: benm@workonline.africa