rfc6746
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.
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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
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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.
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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.
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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.
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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
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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.
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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].
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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.
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[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.
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[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
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ERRATA
