Internet Research Task Force (IRTF)                          RJ Atkinson
Request for Comments: 6746                                    Consultant
Category: Experimental                                         SN Bhatti
ISSN: 2070-1721                                            U. St Andrews
                                                           November 2012


                          IPv4 Options for the
               Identifier-Locator Network Protocol (ILNP)

Abstract

   This document defines two new IPv4 Options that are used only with
   the Identifier-Locator Network Protocol for IPv4 (ILNPv4).  ILNP is
   an experimental, evolutionary enhancement to IP.  This document is a
   product of the IRTF Routing Research Group.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for examination, experimental implementation, and
   evaluation.

   This document defines an Experimental Protocol for the Internet
   community.  This document is a product of the Internet Research Task
   Force (IRTF).  The IRTF publishes the results of Internet-related
   research and development activities.  These results might not be
   suitable for deployment.  This RFC represents the individual
   opinion(s) of one or more members of the Routing Research Group of
   the Internet Research Task Force (IRTF).  Documents approved for
   publication by the IRSG are not a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6746.

Copyright Notice

   Copyright (c) 2012 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
   carefully, as they describe your rights and restrictions with respect
   to this document.

   This document may not be modified, and derivative works of it may not
   be created, except to format it for publication as an RFC or to
   translate it into languages other than English.

Table of Contents

   1. Introduction ....................................................2
      1.1. Document Roadmap ...........................................3
      1.2. Terminology ................................................4
   2. IPv4 Options for ILNPv4 .........................................4
      2.1. ILNPv4 Packet Format .......................................5
      2.2. ILNP Identifier Option for IPv4 ............................7
      2.3. ILNP Nonce Option for IPv4 .................................8
   3. Security Considerations .........................................8
   4. IANA Considerations .............................................9
   5. References ......................................................9
      5.1. Normative References .......................................9
      5.2. Informative References ....................................10
   6. Acknowledgements ...............................................11

1.  Introduction

   This document is part of the ILNP document set, and it has had
   extensive review within the IRTF Routing RG.  ILNP is one of the
   recommendations made by the RG Chairs.  Separately, various refereed
   research papers on ILNP have also been published during this decade.
   So, the ideas contained herein have had much broader review than the
   IRTF Routing RG.  The views in this document were considered
   controversial by the Routing RG, but the RG reached a consensus that
   the document still should be published.  The Routing RG has had
   remarkably little consensus on anything, so virtually all Routing RG
   outputs are considered controversial.

   At present, the Internet research and development community is
   exploring various approaches to evolving the Internet Architecture to
   solve a variety of issues including, but not limited to, scalability

   of inter-domain routing [RFC4984].  A wide range of other issues
   (e.g., site multihoming, node multihoming, site/subnet mobility, node
   mobility) are also active concerns at present.  Several different
   classes of evolution are being considered by the Internet research
   and development community.  One class is often called "Map and
   Encapsulate", where traffic would be mapped and then tunnelled
   through the inter-domain core of the Internet.  Another class being
   considered is sometimes known as "Identifier/Locator Split".  This
   document relates to a proposal that is in the latter class of
   evolutionary approaches.

   The Identifier-Locator Network Protocol (ILNP) is a proposal for
   evolving the Internet Architecture.  It differs from the current
   Internet Architecture primarily by deprecating the concept of an IP
   Address and instead defining two new objects, each having crisp
   syntax and semantics.  The first new object is the Locator, a
   topology-dependent name for a subnetwork.  The other new object is
   the Identifier, which provides a topology-independent name for a
   node.

1.1.  Document Roadmap

   This document describes a new IPv4 Nonce Option used by ILNPv4 nodes
   to carry a security nonce to prevent off-path attacks against ILNP
   ICMP messages and defines a new IPv4 Identifier Option used by ILNPv4
   nodes.

   The ILNP architecture can have more than one engineering
   instantiation.  For example, one can imagine a "clean-slate"
   engineering design based on the ILNP architecture.  In separate
   documents, we describe two specific engineering instances of ILNP.
   The term "ILNPv6" refers precisely to an instance of ILNP that is
   based upon, and backwards compatible with, IPv6.  The term "ILNPv4"
   refers precisely to an instance of ILNP that is based upon, and
   backwards compatible with, IPv4.

   Many engineering aspects common to both ILNPv4 and ILNPv6 are
   described in [RFC6741].  A full engineering specification for either
   ILNPv6 or ILNPv4 is beyond the scope of this document.

   Readers are referred to other related ILNP documents for details not
   described here:

   a) [RFC6740] is the main architectural description of ILNP, including
      the concept of operations.

   b) [RFC6741] describes engineering and implementation considerations
      that are common to both ILNPv4 and ILNPv6.

   c) [RFC6742] defines additional DNS resource records that support
      ILNP.

   d) [RFC6743] defines a new ICMPv6 Locator Update message used by an
      ILNP node to inform its correspondent nodes of any changes to its
      set of valid Locators.

   e) [RFC6744] defines a new IPv6 Nonce Destination Option used by
      ILNPv6 nodes (1) to indicate to ILNP correspondent nodes (by
      inclusion within the initial packets of an ILNP session) that the
      node is operating in the ILNP mode and (2) to prevent off-path
      attacks against ILNP ICMP messages.  This Nonce is used, for
      example, with all ILNP ICMPv6 Locator Update messages that are
      exchanged among ILNP correspondent nodes.

   f) [RFC6745] defines a new ICMPv4 Locator Update message used by an
      ILNP node to inform its correspondent nodes of any changes to its
      set of valid Locators.

   g) [RFC6747] describes extensions to Address Resolution Protocol
      (ARP) for use with ILNPv4.

   h) [RFC6748] describes optional engineering and deployment functions
      for ILNP.  These are not required for the operation or use of ILNP
      and are provided as additional options.

1.2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.  IPv4 Options for ILNPv4

   ILNP for IPv4 (ILNPv4) is merely a different instantiation of the
   ILNP architecture, so it retains the crisp distinction between the
   Locator and the Identifier.  As with ILNP for IPv6 (ILNPv6), when
   ILNPv4 is used for a network-layer session, the upper-layer protocols
   (e.g., TCP/UDP pseudo-header checksum, IPsec Security Association)
   bind only to the Identifiers, never to the Locators.  As with ILNPv6,
   only the Locator values are used for routing and forwarding ILNPv4
   packets.

   However, just as the packet format for IPv4 is different from IPv6,
   so the engineering details for ILNPv4 are different also.  Just as
   ILNPv6 is carefully engineered to be backwards-compatible with IPv6,
   ILNPv4 is carefully engineered to be backwards-compatible with IPv4.

   Each of these options MUST be copied upon fragmentation.  Each of
   these options is used for control, so uses Option Class 0.

   Originally, these two options were specified to use separate IP
   option numbers.  However, only one IP Option (decimal 158) has been
   defined for experimental use with properties of MUST COPY and CONTROL
   [RFC4727].  So these two options have been reworked to share that
   same IP Option number (158).  To distinguish between the two actual
   options, the unsigned 8-bit field ILNPv4_OPT inside this option is
   examined.

   It is important for implementers to understand that IP Option 158 is
   not uniquely allocated to ILNPv4.  Other IPv4-related experiments
   might be using that IP Option value for different IP options having
   different IP Option formats.

2.1.  ILNPv4 Packet Format

   The Source IP Address in the IPv4 header becomes the Source ILNPv4
   Locator value, while the Destination IP Address of the IPv4 header
   becomes the Destination ILNPv4 Locator value.  Of course, backwards
   compatibility requirements mean that ILNPv4 Locators use the same
   number space as IPv4 routing prefixes.

   ILNPv4 uses the same 64-bit Identifier, with the same modified EUI-64
   syntax, as ILNPv6.  Because the IPv4 address fields are much smaller
   than the IPv6 address fields, ILNPv4 cannot carry the Identifier
   values in the fixed portion of the IPv4 header.  The obvious two ways
   to carry the ILNP Identifier with ILNPv4 are either as an IPv4 Option
   or as an IPv6-style Extension Header placed after the IPv4 header and
   before the upper-layer protocol (e.g., OSPF, TCP, UDP, SCTP).

   Currently deployed IPv4 routers from multiple router vendors use
   packet forwarding silicon that is able to parse past IPv4 Options to
   examine the upper-layer protocol header at wire-speed on reasonably
   fast (e.g., 1 Gbps or better) network interfaces.  By contrast, no
   existing IPv4-capable packet forwarding silicon is able to parse past
   a new Extension Header for IPv4.  Hence, for engineering reasons,
   ILNPv4 uses a new IPv4 Option to carry the Identifier values.
   Another new IPv4 Option also carries a nonce value, performing the
   same function for ILNPv4 as the IPv6 Nonce Destination Option
   [RFC6744] performs for ILNPv6.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |Version|  IHL  |Type of Service|          Total Length         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Identification        |Flags|      Fragment Offset    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Time to Live |    Protocol   |         Header Checksum       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                 Source Locator (32 bits)                      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |              Destination Locator (32 bits)                    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |      OT=158   |     OL=5      |      0x00     |ILNPv4_OPT=0x01|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    +                      Source Identifier                        +
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    +                    Destination Identifier                     +
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |     OT=158    |     OL=2      |      0x00     |ILNPv4_OPT=0x02|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      top 32 bits of nonce                     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                     lower 32 bits of nonce                    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 1: ILNPv4 Header with ILNP ID Option and ILNP Nonce Option

           Notation for Figure 1:
                   IHL:  Internet Header Length
                    OT:  Option Type
                    OL:  Option Length

2.2.  ILNP Identifier Option for IPv4

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     OT=158    |     OL=20     |      0x00     |ILNPv4_OPT=0x01|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Source Identifier                        |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Destination Identifier                     |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 2: ILNP Identifier Option for IPv4

          Notation for Figure 2:
                   OT:   Option Type
                   OL:   Option Length

   RFC 791, Page 15 specifies that the Option Length is measured in
   words and includes the Option Type octet, the Option Length octet,
   and the option data octets.

   The Source Identifier and Destination Identifier are unsigned 64-bit
   integers.  [RFC6741] specifies the syntax, semantics, and generation
   of ILNP Identifier values.  Using the same syntax and semantics for
   all instantiations of ILNP Identifiers simplifies specification and
   implementation, while also facilitating translation or transition
   between ILNPv4 and ILNPv6 should that be desirable in future.

   This IP Option MUST NOT be present in an IPv4 packet unless the
   packet is part of an ILNPv4 session.  ILNPv4 sessions MUST include
   this option in the first few packets of each ILNPv4 session and MAY
   include this option in all packets of the ILNPv4 session.  It is
   RECOMMENDED to include this option in all packets of the ILNPv4
   session if packet loss is higher than normal.

2.3.  ILNP Nonce Option for IPv4

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     OT=158    |     OL=2      |      0x00     |ILNPv4_OPT=0x02|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      top 32 bits of nonce                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     lower 32 bits of nonce                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 3: ILNP Nonce Option for IPv4

          Notation for Figure 3:
                   OT:   Option Type
                   OL:   Option Length

   This option contains a 64-bit ILNP Nonce.  As noted in [RFC6740] and
   [RFC6741], all ILNP Nonce values are unidirectional.  This means, for
   example, that when TCP is in use, the underlying ILNPv4 session will
   have two different NONCE values: one from Initiator to Responder and
   another from Responder to Initiator.  The ILNP Nonce is used to
   provide non-cryptographic protection against off-path attacks (e.g.,
   forged ICMP messages from the remote end of a TCP session).

   Each NONCE value MUST be unpredictable (i.e., cryptographically
   random).  Guidance to implementers on generating cryptographically
   random values is provided in [RFC4086].

   This IP Option MUST NOT be present in an IPv4 packet unless the
   packet is part of an ILNPv4 session.  ILNPv4 nodes MUST include this
   option in the first few packets of each ILNP session, MUST include
   this option in all ICMP messages generated by endpoints participating
   in an ILNP session, and MAY include this option in all packets of an
   ILNPv4 session.

3.  Security Considerations

   Security considerations for the overall ILNP Architecture are
   described in [RFC6740].  Additional common security considerations
   are described in [RFC6741].  This section describes security
   considerations specific to ILNPv4 topics discussed in this document.

   If the ILNP Nonce value is predictable, then an off-path attacker
   might be able to forge data or control packets.  This risk also is
   mitigated by the existing common practice of IP Source Address
   filtering [RFC2827] [RFC3704].

   IP Security for ILNP [RFC6741] [RFC4301] provides cryptographic
   protection for ILNP data and control packets.  The ILNP Nonce Option
   is required in the circumstances described in Section 3, even if
   IPsec is also in use.  Deployments of ILNPv4 in high-threat
   environments SHOULD use IPsec for additional risk reduction.

   This option is intended to be used primarily end-to-end between a
   source node and a destination node.  However, unlike IPv6, IPv4 does
   not specify a method to distinguish between options with hop-by-hop
   behaviour versus end-to-end behaviour.

   [FILTERING] provides general discussion of potential operational
   issues with IPv4 options, along with specific advice for handling
   several specific IPv4 options.  Further, many deployed modern IP
   routers (both IPv4 and IPv6) have been explicitly configured to
   ignore all IP options, even including the "Router Alert" option, when
   forwarding packets not addressed to the router itself.  Reports
   indicate this has been done to preclude use of IP options as a
   (Distributed) Denial-of-Service (D)DoS attack vector on backbone
   routers.

4.  IANA Considerations

   This document makes no request of IANA.

   If in the future the IETF decided to standardise ILNPv4, then
   allocation of two unique Header Option values to ILNPv4, one for the
   Identifier option and one for the Nonce option, would be sensible.

5.  References

5.1.  Normative References

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

   [RFC4301]   Kent, S. and K. Seo, "Security Architecture for the
               Internet Protocol", RFC 4301, December 2005.

   [RFC4727]   Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4,
               ICMPv6, UDP, and TCP Headers", RFC 4727, November 2006.

   [RFC6740]   Atkinson, R. and S. Bhatti, "Identifier-Locator Network
               Protocol (ILNP) Architectural Description", RFC 6740,
               November 2012.

   [RFC6741]   Atkinson, R. and S. Bhatti, "Identifier-Locator Network
               Protocol (ILNP) Engineering and Implementation
               Considerations", RFC 6741, November 2012.

   [RFC6742]   Atkinson, R., Bhatti, S. and S. Rose, "DNS Resource
               Records for the Identifier-Locator Network Protocol
               (ILNP)", RFC 6742, November 2012.

   [RFC6745]   Atkinson, R. and S. Bhatti,  "ICMP Locator Update Message
               for the Identifier-Locator Network Protocol Version 4
               (ILNPv4)", RFC 6745, November 2012.

   [RFC6747]   Atkinson, R. and S. Bhatti, "Address Resolution Protocol
               (ARP) Extension for the Identifier-Locator Network
               Protocol Version 4 (ILNPv4)", RFC 6747, November 2012.

5.2.  Informative References

   [FILTERING] Gont, F., Atkinson, R., and C. Pignataro,
               "Recommendations on filtering of IPv4 packets containing
               IPv4 options", Work in Progress, March 2012.

   [RFC2780]   Bradner, S. and V. Paxson, "IANA Allocation Guidelines
               For Values In the Internet Protocol and Related Headers",
               BCP 37, RFC 2780, March 2000.

   [RFC2827]   Ferguson, P. and D. Senie, "Network Ingress Filtering:
               Defeating Denial of Service Attacks which employ IP
               Source Address Spoofing", BCP 38, RFC 2827, May 2000.

   [RFC3704]   Baker, F. and P. Savola, "Ingress Filtering for
               Multihomed Networks", BCP 84, RFC 3704, March 2004.

   [RFC4086]   Eastlake 3rd, D., Schiller, J., and S. Crocker,
               "Randomness Requirements for Security", BCP 106, RFC
               4086, June 2005.

   [RFC4984]   Meyer, D., Ed., Zhang, L., Ed., and K. Fall, Ed., "Report
               from the IAB Workshop on Routing and Addressing", RFC
               4984, September 2007.

   [RFC6743]   Atkinson, R. and S. Bhatti, "ICMP Locator Update Message
               for the Identifier-Locator Network Protocol Version 6
               (ICMPv6)", RFC 6743, November 2012.

   [RFC6744]   Atkinson, R. and S. Bhatti, "IPv6 Nonce Destination
               Option for the Identifier-Locator Network Protocol
               Version 6 (ILNPv6)", RFC 6744, November 2012.

   [RFC6748]   Atkinson, R. and S Bhatti, "Optional Advanced Deployment
               Scenarios for the Identifier-Locator Network Protocol
               (ILNP)", RFC 6748, November 2012.

6.  Acknowledgements

   Steve Blake, Stephane Bortzmeyer, Mohamed Boucadair, Noel Chiappa,
   Wes George, Steve Hailes, Joel Halpern, Mark Handley, Volker Hilt,
   Paul Jakma, Dae-Young Kim, Tony Li, Yakov Rehkter, Bruce Simpson,
   Robin Whittle and John Wroclawski (in alphabetical order) provided
   review and feedback on earlier versions of this document.  Steve
   Blake provided an especially thorough review of an early version of
   the entire ILNP document set, which was extremely helpful.  We also
   wish to thank the anonymous reviewers of the various ILNP papers for
   their feedback.

   Roy Arends provided expert guidance on technical and procedural
   aspects of DNS issues.

Authors' Addresses

   RJ Atkinson
   Consultant
   San Jose, CA 95125
   USA

   EMail: rja.lists@gmail.com

   SN Bhatti
   School of Computer Science
   University of St Andrews
   North Haugh, St Andrews
   Fife, Scotland
   KY16 9SX, UK

   EMail: saleem@cs.st-andrews.ac.uk