Secure Inter-Domain Routing                                D. Mandelberg
Internet-Draft                                          BBN Technologies
Intended status: Best Current Practice                   October 7, 2015
Expires: Standards Track                          April 9, 13, 2016
Expires: October 15, 2016

   Simplified Local internet nUmber Resource Management with the RPKI


   The Resource Public Key Infrastructure (RPKI) is a global
   authorization infrastructure that allows the holder of Internet
   Number Resources (INRs) to make verifiable statements about those
   resources.  Network operators, e.g., Internet Service Providers
   (ISPs), can use the RPKI to validate BGP route origination
   assertions.  In the future, ISPs also will be able to use the RPKI to
   validate the path of a BGP route.  Some ISPs locally use BGP with
   private address space or private AS numbers (see RFC6890).  These
   local BGP routes cannot be verified by the global RPKI, and SHOULD be
   considered invalid based on the global RPKI (see RFC6491).  The
   mechanisms described below provide ISPs with a way to make local
   assertions about private (reserved) INRs while using the RPKI's
   assertions about all other INRs.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Validation Output Filtering . . . . . . . . . . . . . . . . .   4
   3.  Locally Adding Assertions . . . . . . . . . . . . . . . . . .   4
   4.  Configuring SLURM . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Combining Mechanisms  . . . . . . . . . . . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     9.1.  Informative References  . . . . . . . . . . . . . . . . .   8
     9.2.  Normative References  . . . . . . . . . . . . . . . . . .  10   9
   Appendix A.  Example SLURM File . . . . . . . . . . . . . . . . .  10
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   The Resource Public Key Infrastructure (RPKI) is a global
   authorization infrastructure that allows the holder of Internet
   Number Resources (INRs) to make verifiable statements about those
   resources.  For example, the holder of a block of IP(v4 or v6)
   addresses can issue a Route Origination Authorization (ROA) [RFC6482]
   to authorize an Autonomous System (AS) to originate routes for that

   Internet Service Providers (ISPs) can then use the RPKI to validate
   BGP routes.  (Validation of the origin of a route is described in
   [RFC6483], and validation of the path of a route is described in
   [I-D.ietf-sidr-bgpsec-overview].)  However, some ISPs locally use BGP
   with private address space ([RFC1918], [RFC4193], [RFC6598]) or
   private AS numbers ([RFC1930], [RFC6996]).  These local BGP routes
   cannot be verified by the global RPKI, and SHOULD be considered
   invalid when using the RPKI.  For example, [RFC6491] recommends the
   creation of ROAs that would invalidate routes for reserved and
   unallocated address space.

   This document specifies two new mechanisms to enable ISPs to make
   local assertions about some INRs while using the RPKI's assertions
   about all other INRs.  These mechanisms primarily support the second
   use case in [I-D.ietf-sidr-lta-use-cases], and may additionally
   support the third use cases in [I-D.ietf-sidr-lta-use-cases]. case.  The second use case describes use of
   [RFC1918] addresses or use of public address space not allocated to
   the ISP that is using it.  The third use case describes a situation
   in which an ISP publishes a variant of the RPKI hierarchy (for its
   customers).  In this variant some prefixes and/or AS numbers are
   different from what the RPKI repository system presents to the
   general ISP population.  The result is that routes for consumers of
   this variant hierarchy will be re-directed (via routing).  Note that
   it also is possible to use SLURM to (locally) manipulate assertions
   about non-private INRs, e.g., allocated address space that is not
   globally routed.  Network operators who elect to use SLURM in this
   fashion should use extreme caution.  (The fact that SLURM can be used
   in this fashion is not an endorsement of such use by the author.)

   Both mechanisms are specified in terms of abstract sets of
   assertions.  For Origin Validation [RFC6483], an assertion is a tuple
   of {IP prefix, prefix length, maximum length, AS number} as used by
   rpki-rtr version 0 [RFC6810] and version 1
   [I-D.ietf-sidr-rpki-rtr-rfc6810-bis].  For BGPsec
   [I-D.ietf-sidr-bgpsec-overview], an assertion is a tuple of {AS
   number, subject key identifier, router public key} as used by rpki-
   rtr version 1.  (For the remainder of this document, these assertions
   are called Origin Validation assertions and BGPsec assertions,
   respectively.)  Output Filtering, described in Section 2, filters out
   (removes from consideration for routing decisions) any assertions by in
   the RPKI about locally reserved INRs.  Locally Adding Assertions,
   described in Section 3, adds local assertions about locally reserved
   INRs.  The combination of both mechanisms is described in Section 5.

   To ensure local consistency, the effect of SLURM MUST be atomic.
   That is, the output of the relying party must be either the same as
   if SLURM were not used, or it must reflect the entire SLURM
   configuration.  For an example of why this is required, consider the
   case of two local routes for the same prefix but different origin AS
   numbers.  Both routes are configured with Locally Adding Assertions.
   If neither addition occurs, then both routes could be in the unknown
   state [RFC6483].  If both additions occur then both routes would be
   in the valid state.  However, if one addition occurs and the other
   does not, then one could be invalid while the other is valid.

   In general, the primary output of an RPKI relying party is the data
   it sends to routers over the rpki-rtr protocol.  The rpki-rtr
   protocol enables routers to query a relying party for all assertions
   it knows about (Reset Query) or for an update of only the changes in
   assertions (Serial Query).  The mechanisms specified in this document
   are to be applied to the result set for a Reset Query, and to both
   the old and new sets that are compared for a Serial Query.  Relying
   party software MAY modify other forms of output in comparable ways,
   but that is outside the scope of this document.

   This document is intended to supersede [I-D.ietf-sidr-ltamgmt] while
   focusing only on local management of private INRs.  Another draft
   [I-D.kent-sidr-suspenders] focuses on the other aspects of local

1.1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

2.  Validation Output Filtering

   To prevent the global RPKI from affecting routes with locally
   reserved INRs, a relying party may be is locally configured with a (possibly
   empty) list of IP prefixes and/or AS numbers that are used locally, locally.
   (In general, these IP prefixes and AS numbers will be taken from
   reserved INR spaces. spaces.)  Any Origin Validation assertions where the IP
   prefix is equal to or subsumed by a locally reserved IP prefix, are
   removed from the relying party's output.  Any Origin Validation
   assertions where the IP prefix contains a locally reserved IP prefix
   are removed; the relying party software SHOULD issue a warning when
   this action is taken.  (Note that an Origin
   Validation assertion is not removed due to its AS number matching a
   locally reserved AS number.)  Any BGPsec assertion where the AS
   number is equal to a locally reserved AS number is removed from the
   relying party's output.

3.  Locally Adding Assertions

   Each relying party is locally configured with a (possibly empty) list
   of assertions.  This list is added to the relying party's output.

4.  Configuring SLURM

   Relying party software SHOULD support the following configuration
   format for Validation Output Filtering and Locally Adding Assertions.
   The format is defined using the Augmented Backus-Naur Form (ABNF)
   notation and core rules from [RFC5234] and the rules <IPv4address>
   and <IPv6address> from Appendix A of [RFC3986].  See Appendix A for
   an example SLURM file.

   A SLURM configuration file, <SLURMFile>, consists of a head and a
   body.  The head identifies the file as a SLURM configuration file,
   specifies the version of SLURM for which the file was written, and
   optionally contains other information described below.  The body
   contains the configuration for Validation Output Filtering and
   Locally Adding Assertions.

      SLURMFile = head body

      head = firstLine *(commentLine / headLine)

      body = *(commentLine / bodyLine)

      firstLine = %x53.4c.55.52.4d SP "1.0" EOL ; "SLURM 1.0"

      commentLine = *WSP [comment] EOL

      headLine = *WSP headCommand [ 1*WSP [comment] ] EOL

      bodyLine = *WSP bodyCommand [ 1*WSP [comment] ] EOL

      comment = "#" *(VCHAR / WSP)

      EOL = CRLF / LF

   The head may specify a target.  If present, the target string
   identifies the environment in which the SLURM file is intended to be
   used.  The meaning of the target string, if any, is determined by the
   user.  If a target is present, a relying party SHOULD verify that
   that the target is an acceptable value, and reject the SLURM file if
   the target is not acceptable.  For example, the relying party could
   be configured to accept SLURM files only if they do not specify a
   target, have a target value of "", or have a
   target value of "as=65536".  If more than one target line is present,
   all targets must be acceptable to the RP.

      headCommand = target

      target =
         %x74. 1*WSP ; "target"

   The body contains zero or more configuration lines for Validation
   Output Filtering and Locally Adding Assertions.  Each <del> command
   specifies an INR to use for Validation Output Filtering.  Each <add>
   command specifies an assertion to use for Locally Adding Assertions.

      bodyCommand = add / del

      add =
         %x61.64.64 1*WSP ; "add"

      del =
         %x64.65.6c 1*WSP ; "del"

      addItem = addItemPrefixAS / addItemASKey

      ; Add a mapping from a prefix and max length to an AS number.
      addItemPrefixAS =
         %x6f. 1*WSP ; "origination"
         IPprefixMaxLen 1*WSP

      ; Add a mapping from an AS number to a router public key.
      addItemASKey =
         %x62. 1*WSP ; "bgpsec"
         ASnum 1*WSP
         RouterSKI 1*WSP

      delItem = delItemPrefix / delItemAS

      ; Filter prefix-AS mappings, using the given prefix
      delItemPrefix =
         %x6f. 1*WSP ; "origination"

      ; Filter AS-key mappings for the given AS
      delItemAS =
         %x62. 1*WSP ; "bgpsec"

      IPprefix = IPv4prefix / IPv6prefix

      IPprefixMaxLen = IPv4prefixMaxLen / IPv6prefixMaxLen

      IPv4prefix = IPv4address "/" 1*2DIGIT
      IPv6prefix = IPv6address "/" 1*3DIGIT

      ; In the following two rules, if the maximum length component is
      ; missing, it is treated as equal to the prefix length.
      IPv4prefixMaxLen = IPv4prefix ["-" 1*2DIGIT]
      IPv6prefixMaxLen = IPv6prefix ["-" 1*3DIGIT]

      ASnum = 1*DIGIT

      ; This is the Base64 [RFC4648] encoding of a router certificate's
      ; Subject Key Identifer, as described in
      ; [I-D.ietf-sidr-bgpsec-pki-profiles] and [RFC6487]. This is the
      ; value of the ASN.1 OCTET STRING without the ASN.1 tag or length
      ; fields.

      RouterSKI = Base64

      ; This is the Base64 [RFC4648] encoding of a router public key's
      ; subjectPublicKeyInfo value, as described in
      ; [I-D.ietf-sidr-bgpsec-algs]. This is the full ASN.1 DER encoding
      ; of the subjectPublicKeyInfo, including the ASN.1 tag and length
      ; values of the subjectPublicKeyInfo SEQUENCE.
      RouterPubKey = Base64

      Base64 = 1*(ALPHA / DIGIT / "+" / "/") 0*2"="

   An implementation MAY support the concurrent use of multiple SLURM
   files.  In this case, the resulting inputs to Validation Output
   Filtering and Locally Adding Assertions are the respective unions of
   the inputs from each file.  The envisioned typical use case for
   multiple files is when the files have distinct scopes.  For example,
   an organization may belong to two separate networks that use
   different private-use IP prefixes and AS numbers.  To detect conflict
   between multiple SLURM files, a relying party SHOULD issue a warning
   in the following cases:

   1.  There may be conflicting changes to Origin Validation assertions
       if there exists an IP address X and distinct SLURM files Y,Z such
       that X is contained by any prefix in any <addItemPrefixAS> or
       <delItemPrefix> in file Y and X is contained by any prefix in any
       <addItemPrefixAS> or <delItemPrefix> in file Z.

   2.  There may be conflicting changes to BGPsec assertions if there
       exists an AS number X and distinct SLURM files Y,Z such that X is
       used in any <addItemASKey> or <delItemAS> in file Y and X is used
       in any <addItemASKey> or <delItemAS> in file Z.

5.  Combining Mechanisms

   In the envisioned typical use case, a relying party uses both output
   filtering and locally added assertions.  In this case, the resulting
   assertions MUST be the same as if output filtering were performed
   before locally adding assertions.  I.e., locally added assertions
   MUST NOT be removed by output filtering.

   If a relying party chooses to use both SLURM and Suspenders
   [I-D.kent-sidr-suspenders], the SLURM mechanisms MUST be performed on
   the output of Suspenders.

6.  IANA Considerations



7.  Security Considerations

   The mechanisms described in this document provide a network operator
   with additional ways to control its own network while making use of
   RPKI data.  These mechanisms are applied only locally; they do not
   influence how other network operators interpret RPKI data.
   Nonetheless, care should be taken in how these mechanisms are

8.  Acknowledgements

   The author would like to thank Stephen Kent for his guidance and
   detailed reviews of this document.  Thanks go to Wesley Wang for the
   idea behind the target command, to Declan Ma for the idea behind use
   of multiple SLURM files, and to Richard Hansen for his careful

9.  References

9.1.  Informative References

              Lepinski, M., "An Overview of BGPsec", draft-ietf-sidr-
              bgpsec-overview-07 (work in progress), June 2015.

              Bush, R., "RPKI Local Trust Anchor Use Cases", draft-ietf-
              sidr-lta-use-cases-04 (work in progress), June December 2015.

              Reynolds, M., Kent, S., and M. Lepinski, "Local Trust
              Anchor Management for the Resource Public Key
              Infrastructure", draft-ietf-sidr-ltamgmt-08 (work in
              progress), April 2013.

              Bush, R. and R. Austein, "The Resource Public Key
              Infrastructure (RPKI) to Router Protocol", draft-ietf-
              sidr-rpki-rtr-rfc6810-bis-07 (work in progress), October

              Kent, S. and D. Mandelberg, "Suspenders: A Fail-safe
              Mechanism for the RPKI", draft-kent-sidr-suspenders-03
              (work in progress), April 2015. March

   [RFC1918]  Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,
              and E. Lear, "Address Allocation for Private Internets",
              BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996,

   [RFC1930]  Hawkinson, J. and T. Bates, "Guidelines for creation,
              selection, and registration of an Autonomous System (AS)",
              BCP 6, RFC 1930, DOI 10.17487/RFC1930, March 1996,

   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005,

   [RFC6482]  Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
              Origin Authorizations (ROAs)", RFC 6482,
              DOI 10.17487/RFC6482, February 2012,

   [RFC6483]  Huston, G. and G. Michaelson, "Validation of Route
              Origination Using the Resource Certificate Public Key
              Infrastructure (PKI) and Route Origin Authorizations
              (ROAs)", RFC 6483, DOI 10.17487/RFC6483, February 2012,

   [RFC6491]  Manderson, T., Vegoda, L., and S. Kent, "Resource Public
              Key Infrastructure (RPKI) Objects Issued by IANA",
              RFC 6491, DOI 10.17487/RFC6491, February 2012,

   [RFC6598]  Weil, J., Kuarsingh, V., Donley, C., Liljenstolpe, C., and
              M. Azinger, "IANA-Reserved IPv4 Prefix for Shared Address
              Space", BCP 153, RFC 6598, DOI 10.17487/RFC6598, April
              2012, <>.

   [RFC6810]  Bush, R. and R. Austein, "The Resource Public Key
              Infrastructure (RPKI) to Router Protocol", RFC 6810,
              DOI 10.17487/RFC6810, January 2013,

   [RFC6890]  Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman,
              "Special-Purpose IP Address Registries", BCP 153,
              RFC 6890, DOI 10.17487/RFC6890, April 2013,

   [RFC6996]  Mitchell, J., "Autonomous System (AS) Reservation for
              Private Use", BCP 6, RFC 6996, DOI 10.17487/RFC6996, July
              2013, <>.

9.2.  Normative References

              Turner, S., "BGP Algorithms, Key Formats, & Signature
              Formats", draft-ietf-sidr-bgpsec-algs-11 draft-ietf-sidr-bgpsec-algs-14 (work in
              progress), August November 2015.

              Reynolds, M. and S. Kent, "A Profile for BGPsec Router
              Certificates, Certificate Revocation Lists, and
              Certification Requests", draft-ietf-sidr-bgpsec-pki-
              profiles-16 (work in progress), August 2015. March 2016.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,

   [RFC6487]  Huston, G., Michaelson, G., and R. Loomans, "A Profile for
              X.509 PKIX Resource Certificates", RFC 6487,
              DOI 10.17487/RFC6487, February 2012,

Appendix A.  Example SLURM File
   SLURM 1.0

   # This file is only intended to be used on a relying party running
   # on
   target # this is a comment

   # Reserve IP prefixes for local use.
   del origination
   del origination fd0b:dd1d:2dcc::/48

   # Reserve AS numbers for local use.
   del bgpsec 64512
   del bgpsec 64513

   # Allow either 64512 or 64513 to originate routes to
   add origination 64512
   add origination 64513

   # 64512 originates fd0b:dd1d:2dcc::/52 and sub-prefixes up to length
   # 56.
   add origination fd0b:dd1d:2dcc::/52-56 64512

   # However, 64513 originates fd0b:dd1d:2dcc:42::/64.
   add origination fd0b:dd1d:2dcc:42::/64 64513

   # 64513 also originates fd0b:dd1d:2dcc:100::/52
   add origination fd0b:dd1d:2dcc:100::/52 64513

   # Authorize router keys to sign BGPsec paths on behalf of the
   # specified ASes. Note that the Base64 strings used in this
   # example are not valid SKIs or router public keys, due to line
   # length restrictions in RFCs.
   add bgpsec 64512 Zm9v VGhpcyBpcyBub3QgYSByb3V0ZXIgcHVibGljIGtleQ==
   add bgpsec 64512 YmFy b3IgYSBmbG9jayBvZiBkdWNrcw==
   add bgpsec 64513 YWJj bWF5YmUgYSBkaWZmZXJlbnQgYXZpYW4gY2Fycmllcj8=

Author's Address

   David Mandelberg
   BBN Technologies
   10 Moulton St.
   Cambridge, MA  02138