The Use of Maxlength in the RPKI
draft-ietf-sidrops-rpkimaxlen-01
Network Working Group Y. Gilad
Internet-Draft S. Goldberg
Intended status: Best Current Practice Boston University
Expires: April 25, 2019 K. Sriram
USA NIST
J. Snijders
NTT
B. Maddison
Workonline Communications
October 22, 2018
The Use of Maxlength in the RPKI
draft-ietf-sidrops-rpkimaxlen-01
Abstract
This document recommends that operators avoid using the maxLength
attribute when issuing Route Origin Authorizations (ROAs) in the
Resource Public Key Infrastructure (RPKI). These recommendations
complement those in [RFC7115].
Status of This Memo
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This Internet-Draft will expire on April 25, 2019.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 3
2. Suggested Reading . . . . . . . . . . . . . . . . . . . . . . 3
3. Forged Origin Subprefix Hijack . . . . . . . . . . . . . . . 3
4. Measurements of Today's RPKI . . . . . . . . . . . . . . . . 5
5. Use Minimal ROAs without Maxlength . . . . . . . . . . . . . 6
5.1. When a Minimal ROA Cannot Be Used? . . . . . . . . . . . 6
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
The RPKI [RFC6480] uses Route Origin Authorizations (ROAs) to create
a cryptographically verifiable mapping from an IP prefix to a set of
autonomous systems (ASes) that are authorized to originate this
prefix. Each ROA contains a set of IP prefixes, and an AS number of
an AS authorized 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 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 current RPKI deployments have found that use
of the maxLength in ROAs tends to lead to security problems.
Specifically, as of June 2017, 84% of the prefixes specified in ROAs
that use the maxLength attribute, are vulnerable to a forged-origin
subprefix hijack [HARMFUL]. The forged-origin subprefix hijack, as
described below, can be launched against any IP prefix that is
authorized in ROA but is not originated in BGP. The impact of such
an attack is the same as that of a subprefix hijack in the absence of
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