rfc

Vor 20 Jahren: IPv6 lernt das Laufen

By heise online

Mit dem von Jon Postel und Robert Hinden herausgegebenen RFC 1897 begann man nach langen Jahren der Vorarbeit mit den ersten Umsetzungen des neuen IPv6-Protokolls im Netz der Netze, das vieles anders macht als IPv4 und manches weit besser.

Read more here:: www.heise.de/netze/rss/netze-atom.xml

Thinking Ahead on Privacy in the Domain Name System

By Burt Kaliski

Earlier this year, I wrote about a recent enhancement to privacy in the Domain Name System (DNS) called qname-minimization. Following the principle of minimum disclosure, this enhancement reduces the information content of a DNS query to the minimum necessary to get either an authoritative response from a name server, or a referral to another name server.

In typical DNS deployments, queries sent to an authoritative name server originate at a recursive name server that acts on behalf of a community of users, for instance, employees at a company or subscribers at an Internet Service Provider (ISP). A recursive name server maintains a cache of previous responses, and only sends queries to an authoritative name server when it doesn’t have a recent response in its cache. As a result, DNS query traffic from a recursive name server to an authoritative name server corresponds to samples of a community’s browsing patterns. Therefore, qname-minimization may be an adequate starting point to address privacy concerns for these exchanges, both in terms of information available to outside parties and to the authoritative name server.

DNS query traffic from a client to a recursive name server, in contrast, corresponds to individual users’ browsing patterns. To the extent that that these exchanges present a privacy concern, a complementary privacy enhancement, DNS-over-TLS (Transport Layer Security), may be an appropriate mitigation. Just as Web traffic is typically protected by establishing a TLS connection between client and server, DNS traffic can be encrypted by running the DNS protocol over TLS. The encryption takes away any direct information about the query from outside parties, while still maintaining full information at the recursive name server so that it can respond to the client’s request.

(There are also some more sophisticated methods, such as described by Haya Shulman in her recent paper, whereby other parties can get indirect “side” information from the timing or size of encrypted queries. However, the primary risk of direct access to query information is effectively mitigated by the encryption.)

Privacy has received a significant increase in attention within the Internet Engineering Task Force (IETF) over the past two years as a result of concerns about security and pervasive monitoring. The DNS PRIVate Exchange (DPRIVE) working group was formed during this time and, among other documents, has produced an Informational RFC (Request for Comments) on DNS privacy considerations, and is also developing specifications for the enhancements just described.

The session “Protecting Privacy at the Infrastructure Level: The Evolution of Domain Name System Security” at the Privacy.Security.Risk 2015 conference gives an overview of these enhancements and how privacy professionals can integrate them into their portfolio of privacy risk mitigations. Broadly speaking, privacy risks in a DNS-based system can be organized into four categories, depending on where unauthorized disclosure of DNS traffic may occur:

  1. Between client and recursive
  2. At recursive name server
  3. Between recursive and authoritative
  4. At authoritative name server

In addition, unauthorized modification of DNS traffic can present a privacy risk if a client is misdirected to a resource controlled by an adversary.

Mitigations to the disclosure risks include qname-minimization and DNS-over-TLS, as already mentioned, as well as data handling policies, technologies and audits at the various components involved. The modification risk can also be addressed by DNS-over-TLS (because TLS authenticates as well as encrypts traffic), proper data handling, and domain name security extensions (DNSSEC) and DNS-based Authentication of Named Entities (DANE).

Similar to the way privacy risks elsewhere in an information system are assessed and mitigated, privacy professionals should consider these steps when considering DNS-based systems:

  • Ask if these risks apply
  • Ask if existing mitigations are sufficient
  • Consider how these mitigations can help
  • Ask your DNS provider about its privacy practices

DNS privacy will be getting more attention over the coming years, as attacks as well as defenses move from the application to the network layer. It’s good to see efforts like DPRIVE looking ahead and Verisign will continue to support them with practical contributions.

What privacy concerns do you see in your DNS-based systems, and how do you see privacy enhancements such as qname-minimization and DNS-over-TLS playing out?

Written by Burt Kaliski, Chief Technology Officer at Verisign

Follow CircleID on Twitter

More under: DNS, DNS Security, Privacy, Security

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Book review – IPv6 Fundamentals: A Straightforward Approach to Understanding IPv6

There are many IPv6 books around nowadays with many different approaches to the subject. IPv6 Fundamentals: A Straightforward Approach to Understanding IPv6 by Rick Graziani is an excellent book that will help you fully understand the fundamentals of IPv6. It has a great balance of theory and practical information and is a good starting point for learning about IPv6. Other IPv6 books can be found on our books and e-books pages. We have included a number of Amazon reader reviews below:

[amazon template=image&asin=1587143135]
[amazon template=add to cart&asin=1587143135]

Graziani provides straightforward understanding.
By M.B. Reynolds on June 5, 2013

The title of the book is an accurate depiction of the contents of this work. The material is presented in a straightforward, methodical manner. The material is presented with understanding and teaching in mind utilizing repetition, sample code, examples, and review. The book is primarily a walk through the various Internet Engineering Task Force (IETF) Requests for Comments (RFC) that comprises the aspects, features, and options of IPv6. Most of these RFC walkthroughs are accompanied with Cisco IOS example code for setting up a router to implement the RFC.

After some of these examples, output from a packet sniffer demonstrates the changes to the packet headers. The book finishes with mechanisms for implementing mixed IPv4 and IPv6 environments and approaches to transitioning from IPv4 to IPv6. Additional references and notes point the reader to more details or topics not covered by the book. Overall I certainly recommend this book as a starting point into IPv6 if the reader has some IPv4 and routing experience. I believe for the novice an additional more general book on networking should be digested first.
The book covers the Internet history and the motivation of IPv6. The IPv6 headers and Extension headers are presented in (again) a straightforward explanation with plenty of diagrams and tables. This explanation includes the specific differences between IPv4 and IPv6 headers. A nice overview of IPSec headers includes authentication, transport, and tunneling modes. Chapter four outlines the multitude of unicast, multicast, and anycast address types. The Neighborhood Discovery Protocol is a new feature of Internet Control Message Protocol version 6 (ICMPv6). Graziani shows ICMPv6 with its enhancements is an important change in how IP hosts identify themselves and others hosts and routers on the network.

The middle of the book discusses IPv6 configuration and routing. Initially, a router is configured from scratch with the various address types. The same example configuration and network is nicely used through the middle of the book. This method is useful for continuity and context. Building on this initial configuration static routes and routing tables are built. The old and new RIPng, EIGRP, and OSPF are compared and contrasted in Chapter 8. The middle ends with Dynamic Host Configuration Protocol version 6 (DHCPv6). The new features such as stateless & stateful DHCP and relay agents are covered. Some interesting differences in Domain Name Service (DNS), TCP, and UDP are explained.

The book ends with mixed IPv4 and IPv6 environments. Graziani shows dual stack allows for parallel IPv4 and IPv6 networks. He covers tunneling methods such as 6to4 and ISATAP that allow for IPv6 packets to be encapsulated in IPv4 packets and routed through an IPv4 network. He shows this allows for a smooth transition from IPv4. Finally Network Address Translation IPv6 to IPv4 (NAT64) is walked through. He shows this allows and IPv4 address to be mapped to a IPv6 address and vice versa to allow coexisting IPv4 and IPv6 networks to communicate.

 

One of the most substantial changes from IPv4 to IPv6 is the addresses and their types. After introducing hexadecimal and the address format short hands, Graziani explains well the structure of the new 128-bit address: prefix, subnet, and interface id.

After trying others – THIS is THE BOOK!
By John Scott on March 22, 2013

The review written by Cosmic Traveler says it well. I purchased 2 other books before this one and they both ended up on the bottom shelf of my bookshelf. I ordered this one and I couldn’t put it down. If the mere thought of a 128-bit address represented in hexadecimal format makes your hair stand up, you need to order this book and then go have a glass of wine – or a cold beer.

IPv6
By Matthew Petersen on February 14, 2014

To support future business continuity, growth, and innovation, organizations must transition to IPv6, the next generation protocol for defining how computers communicate over networks. IPv6 Fundamentals provides a thorough yet easy-to-understand introduction to the new knowledge and skills network professionals and students need to deploy and manage IPv6 networks.

Excellent book, highly recommended!
By MSG causes migraines on October 15, 2013

Even though I have been a CCIE since the 1990s and have dealt with IPv6 successfully on the re-certification exams, this book added a lot of needed clarity on the context and usage of IPv6 so the concepts are more readily absorbed and made intuitive. For those network engineers not yet exposed to IPv6 due to their individual customer/employer situations, it is a near-term reality everyone is going to have to deal with as the IPv4 private addressing RFC 1918 (and the updated IPv4 content in RFC 6761) cannot eliminate the reality that IPv4 is nearing address depletion.
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UNDERSTANDING IPV6!!!
By COSMIC TRAVELER on November 17, 2012

Are you a network engineer; network designer; network technician; part of the technical staff; and, networking student, including those of the Cisco Networking Academy; who are seeking a solid understanding of the fundamentals of IPv6? If you are, then this book is for you! Author Rick Graziani, has done an outstanding job of writing a book that focuses on the basics of IPv6.

Author Graziani, begins by discussing how the Internet of today requires a new network layer protocol, Ipv6, to meet the demands of its users. Then, the author examines the Ipv6 protocol and its fields. Next, he introduces IPv6 addressing and address types. The author continues by examining the different types of IPv6 addresses in detail. Then, he examines ICMPv6. The author then illustrates the configuration of IPv6, addressing the use of a common topology. Next, he examines the IPv6 routing table and changes in the configurations pertaining to IPv6. The author continues by discussing three routing protocols: RIPng, EIGRP for IPv6 and OSPFv3. Then, he examines DHCP for IPv6 or DHCPv6. The author then covers two of three strategies for IPv4 and IPv6 integration and coexistence: dual-stack and tunneling. Finally, he discusses the third technique for transition from IPv4 and IPv6: Network Address Translation or NAT.

This most excellent book provides a thorough yet easy-to-understand introduction to IPv6. More importantly, this great book is also intended to provide a foundation in IPv6 that will allow you to build on it.

Great book to begin IPv6 study
By Cord Scott on March 22, 2013

Really like this book. Information is accurate and concise and concentrates on the protocol and not just how to configure Cisco gear for IPv6, which is what too many people look for. Not a whole lot on migration but Cisco Press has another book that deals with that.

Everyone should start IPv6 with this book
By Andras Dosztal on May 13, 2013

Detailed but still easy to understand, having a good balance of theory and practical knowledge. Up to date, covers all topics needed for someone who’s getting familiar with IPv6. Having prior IPv4 and routing knowledge is recommended.

[amazon template=add to cart&asin=1587143135]

RFC 3232 – Assigned Numbers: RFC 1700 is Replaced by an On-line Database

Network Working Group                                J. Reynolds, Editor
Request for Comments: 3232                                    RFC Editor
Obsoletes: 1700                                             January 2002
Category: Informational


Assigned Numbers: RFC 1700 is Replaced by an On-line Database


Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

   This memo obsoletes RFC 1700 (STD 2) "Assigned Numbers", which
   contained an October 1994 snapshot of assigned Internet protocol
   parameters.

Description

   From November 1977 through October 1994, the Internet Assigned
   Numbers Authority (IANA) periodically published tables of the
   Internet protocol parameter assignments in RFCs entitled, "Assigned
   Numbers".  The most current of these Assigned Numbers RFCs had
   Standard status and carried the designation: STD 2.  At this time,
   the latest STD 2 is RFC 1700.

   Since 1994, this sequence of RFCs have been replaced by an online
   database accessible through a web page (currently, www.iana.org).
   The purpose of the present RFC is to note this fact and to officially
   obsolete RFC 1700, whose status changes to Historic.  RFC 1700 is
   obsolete, and its values are incomplete and in some cases may be
   wrong.

   We expect this series to be revived in the future by the new IANA
   organization.

Security Considerations

   This memo does not affect the technical security of the Internet.





Reynolds                     Informational                      [Page 1]

RFC 3232         RFC 1700 Replaced by On-line Database      January 2002


Author's Address

   Joyce K. Reynolds
   RFC Editor
   4676 Admiralty Way
   Marina del Rey, CA  90292
   USA

   EMail: rfc-editor@rfc-editor.org

The beginning of the end

IPv6 flip clock

Today is 6/6/2012, World IPv6 Launch Day. The day the Internet community permanently enables the IPv6 Internet protocol on their infrastructure. Some refer to this protocol as ‘The New Internet Protocol’. But is it new? No. Not at all.

To deal with the anticipated IPv4 address exhaustion, the Internet Engineering Task Force (IETF) developed IPv6 and described it in Internet standard document RFC 2460. This was published in December 1998. Due to the incompatibilty with the current IPv4 protocol, it was never widely adopted. Now that address exhaustion is imminent, the world is in a hurry to set things straight.

I am the proud owner of what is arguably the coolest IPv6 Internet domain name in the world: ipv6.net. I have owned it for a long time. Not too long ago I realized that 6 days after 6/6/2012, it has been exactly 15 years since the domain name was registered. Apparently, back in 1997, I envisioned that IPv6 was going to be big. I just didn’t know it would take such a long time. But are we there yet? No. Not even close.

Back then the community thought we would run out of IP addresses in just a couple of years. With some tricks we managed to stretch things out until now. We even back-ported some cool stuff from the new protocol into the old. It wasn’t until mid 2011 that we saw some serious global industry initiatives to promote adoption of IPv6: World IPv6 Day on June 8th. On that day some of the smaller as well as larger members of the global Internet community temporarily enabled IPv6 on their infrastructure. For some, just to see what would happen. For others a good test of their transition plan or chosen technology. Some ‘forgot’ to switch it off again. For most it was a big success; a final rehearsal for the big step: a global transition from IPv4 towards IPv6.

Today is the start of that transition. Content providers around the globe will provide access to their services over IPv6. Access providers will provide IPv6 access to their end-users. Hard- and software manufacturers will bring out IPv6 support for their products. This broad involvement will certainly help to solve the chicken and egg, content versus access, problem.

So what will happen after today? If all goes well, and I certainly expect so, we will have marked the beginning of the end of IPv4. It will take many years before IPv6 has become the dominant protocol and IPv4 is marked ‘legacy’. But I expect that after today more and more companies will make a start with their transition. For many it will be hard to make a good business case for it as there is not always a clear added business value. Just don’t wait too long as the landscape is rapidly changing.

Some advice for those about to take the plunge: take ample time to gather knowledge, create awareness among those involved, decide on a sound transition scenario, test and start planning.

And for me? Well, as an IT professional I will be helping out customers doing just that. Personally, I will continue to blog and tweet about IPv6 for a long time to come…

Cheers,

Erwin

RFC 2464 – Transmission of IPv6 Packets over Ethernet Networks

Network Working Group M. Crawford
Request for Comments: 2464 Fermilab
Obsoletes: 1972 December 1998
Category: Standards Track

Transmission of IPv6 Packets over Ethernet Networks

Status of this Memo

This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (1998). All Rights Reserved.

1. Introduction

This document specifies the frame format for transmission of IPv6
packets and the method of forming IPv6 link-local addresses and
statelessly autoconfigured addresses on Ethernet networks. It also
specifies the content of the Source/Target Link-layer Address option
used in Router Solicitation, Router Advertisement, Neighbor
Solicitation, Neighbor Advertisement and Redirect messages when those
messages are transmitted on an Ethernet.

This document replaces RFC 1972, "A Method for the Transmission of
IPv6 Packets over Ethernet Networks", which will become historic.

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 [RFC 2119].

2. Maximum Transmission Unit

The default MTU size for IPv6 [IPV6] packets on an Ethernet is 1500
octets. This size may be reduced by a Router Advertisement [DISC]
containing an MTU option which specifies a smaller MTU, or by manual
configuration of each node. If a Router Advertisement received on an
Ethernet interface has an MTU option specifying an MTU larger than
1500, or larger than a manually configured value, that MTU option may
be logged to system management but must be otherwise ignored.

For purposes of this document, information received from DHCP is
considered "manually configured" and the term Ethernet includes
CSMA/CD and full-duplex subnetworks based on ISO/IEC 8802-3, with
various data rates.

3. Frame Format

IPv6 packets are transmitted in standard Ethernet frames. The
Ethernet header contains the Destination and Source Ethernet
addresses and the Ethernet type code, which must contain the value
86DD hexadecimal. The data field contains the IPv6 header followed
immediately by the payload, and possibly padding octets to meet the
minimum frame size for the Ethernet link.

0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination |
+- -+
| Ethernet |
+- -+
| Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source |
+- -+
| Ethernet |
+- -+
| Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0 0 0 0 1 1 0 1 1 0 1 1 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 |
+- -+
| header |
+- -+
| and |
+- -+
/ payload ... /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

(Each tic mark represents one bit.)

4. Stateless Autoconfiguration

The Interface Identifier [AARCH] for an Ethernet interface is based
on the EUI-64 identifier [EUI64] derived from the interface's built-
in 48-bit IEEE 802 address. The EUI-64 is formed as follows.
(Canonical bit order is assumed throughout.)

The OUI of the Ethernet address (the first three octets) becomes the
company_id of the EUI-64 (the first three octets). The fourth and
fifth octets of the EUI are set to the fixed value FFFE hexadecimal.
The last three octets of the Ethernet address become the last three
octets of the EUI-64.

The Interface Identifier is then formed from the EUI-64 by
complementing the "Universal/Local" (U/L) bit, which is the next-to-
lowest order bit of the first octet of the EUI-64. Complementing
this bit will generally change a 0 value to a 1, since an interface's
built-in address is expected to be from a universally administered
address space and hence have a globally unique value. A universally
administered IEEE 802 address or an EUI-64 is signified by a 0 in the
U/L bit position, while a globally unique IPv6 Interface Identifier
is signified by a 1 in the corresponding position. For further
discussion on this point, see [AARCH].

For example, the Interface Identifier for an Ethernet interface whose
built-in address is, in hexadecimal,

34-56-78-9A-BC-DE

would be

36-56-78-FF-FE-9A-BC-DE.

A different MAC address set manually or by software should not be
used to derive the Interface Identifier. If such a MAC address must
be used, its global uniqueness property should be reflected in the
value of the U/L bit.

An IPv6 address prefix used for stateless autoconfiguration [ACONF]
of an Ethernet interface must have a length of 64 bits.

5. Link-Local Addresses

The IPv6 link-local address [AARCH] for an Ethernet interface is
formed by appending the Interface Identifier, as defined above, to
the prefix FE80::/64.

10 bits 54 bits 64 bits
+----------+-----------------------+----------------------------+
|1111111010| (zeros) | Interface Identifier |
+----------+-----------------------+----------------------------+

6. Address Mapping -- Unicast

The procedure for mapping IPv6 unicast addresses into Ethernet link-
layer addresses is described in [DISC]. The Source/Target Link-layer
Address option has the following form when the link layer is
Ethernet.

0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+- Ethernet -+
| |
+- Address -+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Option fields:

Type 1 for Source Link-layer address.
2 for Target Link-layer address.

Length 1 (in units of 8 octets).

Ethernet Address
The 48 bit Ethernet IEEE 802 address, in canonical bit
order. This is the address the interface currently
responds to, and may be different from the built-in
address used to derive the Interface Identifier.

7. Address Mapping -- Multicast

An IPv6 packet with a multicast destination address DST, consisting
of the sixteen octets DST[1] through DST[16], is transmitted to the
Ethernet multicast address whose first two octets are the value 3333
hexadecimal and whose last four octets are the last four octets of
DST.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 1 1 0 0 1 1|0 0 1 1 0 0 1 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DST[13] | DST[14] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DST[15] | DST[16] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

8. Differences From RFC 1972

The following are the functional differences between this
specification and RFC 1972.

The Address Token, which was a node's 48-bit MAC address, is
replaced with the Interface Identifier, which is 64 bits in
length and based on the EUI-64 format [EUI64]. An IEEE-defined
mapping exists from 48-bit MAC addresses to EUI-64 form.

A prefix used for stateless autoconfiguration must now be 64 bits
long rather than 80. The link-local prefix is also shortened to
64 bits.

9. Security Considerations

The method of derivation of Interface Identifiers from MAC addresses
is intended to preserve global uniqueness when possible. However,
there is no protection from duplication through accident or forgery.

10. References

[AARCH] Hinden, R. and S. Deering "IP Version 6 Addressing
Architecture", RFC 2373, July 1998.

[ACONF] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998.

[DISC] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery
for IP Version 6 (IPv6)", RFC 2461, December 1998.

[EUI64] "Guidelines For 64-bit Global Identifier (EUI-64)",
http://standards.ieee.org/db/oui/tutorials/EUI64.html

[IPV6] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.

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

11. Author's Address

Matt Crawford
Fermilab MS 368
PO Box 500
Batavia, IL 60510
USA

Phone: +1 630 840-3461
EMail: crawdad@fnal.gov

12. Full Copyright Statement

Copyright (C) The Internet Society (1998). All Rights Reserved.

This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.

The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


RFC 1885 – Internet Control Message Protocol (ICMPv6) for IPv6 (OBSOLETE)

 
Network Working Group             A. Conta, Digital Equipment Corporation
Request for Comments: 1885 S. Deering, Xerox PARC
Category: Standards Track December 1995

Internet Control Message Protocol (ICMPv6)
for the Internet Protocol Version 6 (IPv6)
Specification

Status of this Memo

This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.

Abstract

This document specifies a set of Internet Control Message Protocol
(ICMP) messages for use with version 6 of the Internet Protocol
(IPv6). The Internet Group Management Protocol (IGMP) messages
specified in STD 5, RFC 1112 have been merged into ICMP, for IPv6,
and are included in this document.

Table of Contents

1. Introduction........................................3

2. ICMPv6 (ICMP for IPv6)..............................3

2.1 Message General Format.......................3

2.2 Message Source Address Determination.........4

2.3 Message Checksum Calculation.................5

2.4 Message Processing Rules.....................5

3. ICMPv6 Error Messages...............................8

3.1 Destination Unreachable Message..............8

3.2 Packet Too Big Message......................10

3.3 Time Exceeded Message.......................11

3.4 Parameter Problem Message...................12

4. ICMPv6 Informational Messages......................14

4.1 Echo Request Message........................14

4.2 Echo Reply Message..........................15

4.3 Group Membership Messages...................17

5. References.........................................19

6. Acknowledgements...................................19

7. Security Considerations............................19

Authors' Addresses....................................20

1. Introduction

The Internet Protocol, version 6 (IPv6) is a new version of IP. IPv6
uses the Internet Control Message Protocol (ICMP) as defined for IPv4
[RFC-792], with a number of changes. The Internet Group Membership
Protocol (IGMP) specified for IPv4 [RFC-1112] has also been revised
and has been absorbed into ICMP for IPv6. The resulting protocol is
called ICMPv6, and has an IPv6 Next Header value of 58.

This document describes the format of a set of control messages used
in ICMPv6. It does not describe the procedures for using these
messages to achieve functions like Path MTU discovery or multicast
group membership maintenance; such procedures are described in other
documents (e.g., [RFC-1112, RFC-1191]). Other documents may also
introduce additional ICMPv6 message types, such as Neighbor Discovery
messages [IPv6-DISC], subject to the general rules for ICMPv6
messages given in section 2 of this document.

Terminology defined in the IPv6 specification [IPv6] and the IPv6
Routing and Addressing specification [IPv6-ADDR] applies to this
document as well.

2. ICMPv6 (ICMP for IPv6)

ICMPv6 is used by IPv6 nodes to report errors encountered in
processing packets, and to perform other internet-layer functions,
such as diagnostics (ICMPv6 "ping") and multicast membership
reporting. ICMPv6 is an integral part of IPv6 and MUST be fully
implemented by every IPv6 node.

2.1 Message General Format

ICMPv6 messages are grouped into two classes: error messages and
informational messages. Error messages are identified as such by
having a zero in the high-order bit of their message Type field
values. Thus, error messages have message Types from 0 to 127;
informational messages have message Types from 128 to 255.

This document defines the message formats for the following ICMPv6
messages:

ICMPv6 error messages:

1 Destination Unreachable (see section 3.1)
2 Packet Too Big (see section 3.2)
3 Time Exceeded (see section 3.3)
4 Parameter Problem (see section 3.4)

ICMPv6 informational messages:

128 Echo Request (see section 4.1)
129 Echo Reply (see section 4.2)
130 Group Membership Query (see section 4.3)
131 Group Membership Report (see section 4.3)
132 Group Membership Reduction (see section 4.3)

Every ICMPv6 message is preceded by an IPv6 header and zero or more
IPv6 extension headers. The ICMPv6 header is identified by a Next
Header value of 58 in the immediately preceding header. (NOTE: this
is different than the value used to identify ICMP for IPv4.)

The ICMPv6 messages have the following general format:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Message Body +
| |

The type field indicates the type of the message. Its value
determines the format of the remaining data.

The code field depends on the message type. It is used to create an
additional level of message granularity.

The checksum field is used to detect data corruption in the ICMPv6
message and parts of the IPv6 header.

2.2 Message Source Address Determination

A node that sends an ICMPv6 message has to determine both the Source
and Destination IPv6 Addresses in the IPv6 header before calculating
the checksum. If the node has more than one unicast address, it must
choose the Source Address of the message as follows:

(a) If the message is a response to a message sent to one of the
node's unicast addresses, the Source Address of the reply must
be that same address.

(b) If the message is a response to a message sent to a multicast or
anycast group in which the node is a member, the Source Address
of the reply must be a unicast address belonging to the
interface on which the multicast or anycast packet was received.

(c) If the message is a response to a message sent to an address
that does not belong to the node, the Source Address should be
that unicast address belonging to the node that will be most
helpful in diagnosing the error. For example, if the message is
a response to a packet forwarding action that cannot complete
successfully, the Source Address should be a unicast address
belonging to the interface on which the packet forwarding
failed.

(d) Otherwise, the node's routing table must be examined to
determine which interface will be used to transmit the message
to its destination, and a unicast address belonging to that
interface must be used as the Source Address of the message.

2.3 Message Checksum Calculation

The checksum is the 16-bit one's complement of the one's complement
sum of the entire ICMPv6 message starting with the ICMPv6 message
type field, prepended with a "pseudo-header" of IPv6 header fields,
as specified in [IPv6, section 8.1]. The Next Header value used in
the pseudo-header is 58. (NOTE: the inclusion of a pseudo-header in
the ICMPv6 checksum is a change from IPv4; see [IPv6] for the
rationale for this change.)

For computing the checksum, the checksum field is set to zero.

2.4 Message Processing Rules

Implementations MUST observe the following rules when processing
ICMPv6 messages (from [RFC-1122]):

(a) If an ICMPv6 error message of unknown type is received, it MUST
be passed to the upper layer.

(b) If an ICMPv6 informational message of unknown type is received,
it MUST be silently discarded.

(c) Every ICMPv6 error message (type < 128) includes as much of the
IPv6 offending (invoking) packet (the packet that caused the
error) as will fit without making the error message packet
exceed 576 octets.

(d) In those cases where the internet-layer protocol is required to
pass an ICMPv6 error message to the upper-layer protocol, the
upper-layer protocol type is extracted from the original packet
(contained in the body of the ICMPv6 error message) and used to
select the appropriate upper-layer protocol entity to handle the
error.

If the original packet had an unusually large amount of
extension headers, it is possible that the upper-layer protocol
type may not be present in the ICMPv6 message, due to truncation
of the original packet to meet the 576-octet limit. In that
case, the error message is silently dropped after any IPv6-layer
processing.

(e) An ICMPv6 error message MUST NOT be sent as a result of
receiving:

(e.1) an ICMPv6 error message, or

(e.2) a packet destined to an IPv6 multicast address (there are
two exceptions to this rule: (1) the Packet Too Big
Message - Section 3.2 - to allow Path MTU discovery to
work for IPv6 multicast, and (2) the Parameter Problem
Message, Code 2 - Section 3.4 - reporting an unrecognized
IPv6 option that has the Option Type highest-order two
bits set to 10), or

(e.3) a packet sent as a link-layer multicast, (the exception
from e.2 applies to this case too), or

(e.4) a packet sent as a link-layer broadcast, (the exception
from e.2 applies to this case too), or

(e.5) a packet whose source address does not uniquely identify
a single node -- e.g., the IPv6 Unspecified Address, an
IPv6 multicast address, or an address known by the ICMP
message sender to be an IPv6 anycast address.

(f) Finally, to each sender of an erroneous data packet, an IPv6
node MUST limit the rate of ICMPv6 error messages sent, in order
to limit the bandwidth and forwarding costs incurred by the
error messages when a generator of erroneous packets does not
respond to those error messages by ceasing its transmissions.

There are a variety of ways of implementing the rate-limiting
function, for example:

(f.1) Timer-based - for example, limiting the rate of
transmission of error messages to a given source, or to
any source, to at most once every T milliseconds.

(f.2) Bandwidth-based - for example, limiting the rate at
which error messages are sent from a particular interface
to some fraction F of the attached link's bandwidth.

The limit parameters (e.g., T or F in the above examples) MUST
be configurable for the node, with a conservative default value
(e.g., T = 1 second, NOT 0 seconds, or F = 2 percent, NOT 100
percent).

The following sections describe the message formats for the above
ICMPv6 messages.

3. ICMPv6 Error Messages

3.1 Destination Unreachable Message

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unused |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| As much of invoking packet |
+ as will fit without the ICMPv6 packet +
| exceeding 576 octets |

IPv6 Fields:

Destination Address

Copied from the Source Address field of the invoking
packet.

ICMPv6 Fields:

Type 1

Code 0 - no route to destination
1 - communication with destination
administratively prohibited
2 - not a neighbor
3 - address unreachable
4 - port unreachable

Unused This field is unused for all code values.
It must be initialized to zero by the sender
and ignored by the receiver.
Description

A Destination Unreachable message SHOULD be generated by a router, or
by the IPv6 layer in the originating node, in response to a packet
that cannot be delivered to its destination address for reasons other
than congestion. (An ICMPv6 message MUST NOT be generated if a
packet is dropped due to congestion.)

If the reason for the failure to deliver is lack of a matching entry
in the forwarding node's routing table, the Code field is set to 0
(NOTE: this error can occur only in nodes that do not hold a "default
route" in their routing tables).

If the reason for the failure to deliver is administrative
prohibition, e.g., a "firewall filter", the Code field is set to 1.

If the reason for the failure to deliver is that the next destination
address in the Routing header is not a neighbor of the processing
node but the "strict" bit is set for that address, then the Code
field is set to 2.

If there is any other reason for the failure to deliver, e.g.,
inability to resolve the IPv6 destination address into a
corresponding link address, or a link-specific problem of some sort,
then the Code field is set to 3.

A destination node SHOULD send a Destination Unreachable message with
Code 4 in response to a packet for which the transport protocol
(e.g., UDP) has no listener, if that transport protocol has no
alternative means to inform the sender.

Upper layer notification

A node receiving the ICMPv6 Destination Unreachable message MUST
notify the upper-layer protocol.

3.2 Packet Too Big Message

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MTU |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| As much of invoking packet |
+ as will fit without the ICMPv6 packet +
| exceeding 576 octets |

IPv6 Fields:

Destination Address

Copied from the Source Address field of the invoking
packet.

ICMPv6 Fields:

Type 2

Code 0

MTU The Maximum Transmission Unit of the next-hop link.

Description

A Packet Too Big MUST be sent by a router in response to a packet
that it cannot forward because the packet is larger than the MTU of
the outgoing link. The information in this message is used as part
of the Path MTU Discovery process [RFC-1191].

Sending a Packet Too Big Message makes an exception to one of the
rules of when to send an ICMPv6 error message, in that unlike other
messages, it is sent in response to a packet received with an IPv6
multicast destination address, or a link-layer multicast or link-
layer broadcast address.

Upper layer notification

An incoming Packet Too Big message MUST be passed to the upper-layer
protocol.

3.3 Time Exceeded Message

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unused |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| As much of invoking packet |
+ as will fit without the ICMPv6 packet +
| exceeding 576 octets |

IPv6 Fields:

Destination Address
Copied from the Source Address field of the invoking
packet.

ICMPv6 Fields:

Type 3

Code 0 - hop limit exceeded in transit

1 - fragment reassembly time exceeded

Unused This field is unused for all code values.
It must be initialized to zero by the sender
and ignored by the receiver.

Description

If a router receives a packet with a Hop Limit of zero, or a router
decrements a packet's Hop Limit to zero, it MUST discard the packet
and send an ICMPv6 Time Exceeded message with Code 0 to the source of
the packet. This indicates either a routing loop or too small an
initial Hop Limit value.

The router sending an ICMPv6 Time Exceeded message with Code 0 SHOULD
consider the receiving interface of the packet as the interface on
which the packet forwarding failed in following rule (d) for
selecting the Source Address of the message.

Upper layer notification

An incoming Time Exceeded message MUST be passed to the upper-layer
protocol.

3.4 Parameter Problem Message

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Pointer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| As much of invoking packet |
+ as will fit without the ICMPv6 packet +
| exceeding 576 octets |

IPv6 Fields:

Destination Address

Copied from the Source Address field of the invoking
packet.

ICMPv6 Fields:

Type 4

Code 0 - erroneous header field encountered

1 - unrecognized Next Header type encountered

2 - unrecognized IPv6 option encountered

Pointer Identifies the octet offset within the
invoking packet where the error was detected.

The pointer will point beyond the end of the ICMPv6
packet if the field in error is beyond what can fit
in the 576-byte limit of an ICMPv6 error message.

Description

If an IPv6 node processing a packet finds a problem with a field in
the IPv6 header or extension headers such that it cannot complete
processing the packet, it MUST discard the packet and SHOULD send an
ICMPv6 Parameter Problem message to the packet's source, indicating
the type and location of the problem.

The pointer identifies the octet of the original packet's header
where the error was detected. For example, an ICMPv6 message with
Type field = 4, Code field = 1, and Pointer field = 40 would indicate

that the IPv6 extension header following the IPv6 header of the
original packet holds an unrecognized Next Header field value.

Upper layer notification

A node receiving this ICMPv6 message MUST notify the upper-layer
protocol.

4. ICMPv6 Informational Messages

4.1 Echo Request Message

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data ...
+-+-+-+-+-

IPv6 Fields:

Destination Address

Any legal IPv6 address.

ICMPv6 Fields:

Type 128

Code 0

Identifier An identifier to aid in matching Echo Replies
to this Echo Request. May be zero.

Sequence Number

A sequence number to aid in matching Echo Replies
to this Echo Request. May be zero.

Data Zero or more octets of arbitrary data.

Description

Every node MUST implement an ICMPv6 Echo responder function that
receives Echo Requests and sends corresponding Echo Replies. A node
SHOULD also implement an application-layer interface for sending Echo
Requests and receiving Echo Replies, for diagnostic purposes.

Upper layer notification

A node receiving this ICMPv6 message MAY notify the upper-layer
protocol.

4.2 Echo Reply Message

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data ...
+-+-+-+-+-

IPv6 Fields:

Destination Address

Copied from the Source Address field of the invoking
Echo Request packet.

ICMPv6 Fields:

Type 129

Code 0

Identifier The identifier from the invoking Echo Request message.

Sequence The sequence number from the invoking Echo Request
Number message.

Data The data from the invoking Echo Request message.

Description

Every node MUST implement an ICMPv6 Echo responder function that
receives Echo Requests and sends corresponding Echo Replies. A node
SHOULD also implement an application-layer interface for sending Echo
Requests and receiving Echo Replies, for diagnostic purposes.

The source address of an Echo Reply sent in response to a unicast
Echo Request message MUST be the same as the destination address of
that Echo Request message.

An Echo Reply SHOULD be sent in response to an Echo Request message
sent to an IPv6 multicast address. The source address of the reply
MUST be a unicast address belonging to the interface on which the
multicast Echo Request message was received.

The data received in the ICMPv6 Echo Request message MUST be returned
entirely and unmodified in the ICMPv6 Echo Reply message, unless the
Echo Reply would exceed the MTU of the path back to the Echo
requester, in which case the data is truncated to fit that path MTU.

Upper layer notification

Echo Reply messages MUST be passed to the ICMPv6 user interface,
unless the corresponding Echo Request originated in the IP layer.

4.3 Group Membership Messages

The ICMPv6 Group Membership Messages have the following format:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Response Delay | Unused |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| Multicast |
+ +
| Address |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv6 Fields:

Destination Address

In a Group Membership Query message, the multicast
address of the group being queried, or the Link-Local
All-Nodes multicast address.

In a Group Membership Report or a Group Membership
Reduction message, the multicast address of the
group being reported or terminated.

Hop Limit 1

ICMPv6 Fields:

Type 130 - Group Membership Query
131 - Group Membership Report
132 - Group Membership Reduction

Code 0

Maximum Response Delay

In Query messages, the maximum time that responding
Report messages may be delayed, in milliseconds.

In Report and Reduction messages, this field is
is initialized to zero by the sender and ignored by
receivers.

Unused Initialized to zero by the sender; ignored by receivers.

Multicast Address

The address of the multicast group about which the
message is being sent. In Query messages, the Multicast
Address field may be zero, implying a query for all
groups.

Description

The ICMPv6 Group Membership messages are used to convey information
about multicast group membership from nodes to their neighboring
routers. The details of their usage is given in [RFC-1112].

5. References

[IPv6] Deering, S., and R. Hinden, "Internet Protocol, Version
6, Specification", RFC 1883, Xerox PARC, Ipsilon
Networks, December 1995.

[IPv6-ADDR] Hinden, R., and S. Deering, Editors, "IP Version 6
Addressing Architecture", RFC 1884, Ipsilon Networks,
Xerox PARC, December 1995.

[IPv6-DISC] Narten, T., Nordmark, E., and W. Simpson, "Neighbor
Discovery for IP Version 6 (IPv6)", Work in Progress.

[RFC-792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, USC/Information Sciences Institute, September
1981.

[RFC-1112] Deering, S., "Host Extensions for IP Multicasting", STD
5, RFC 1112, Stanford University, August 1989.

[RFC-1122] Braden, R., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, USC/Information
Sciences Institute, October 1989.

[RFC-1191] Mogul, J., and S. Deering, "Path MTU Discovery", RFC
1191, DECWRL, Stanford University, November 1990.

6. Acknowledgements

The document is derived from previous ICMP drafts of the SIPP and
IPng working group.

The IPng working group and particularly Robert Elz, Jim Bound, Bill
Simpson, Thomas Narten, Charlie Lynn, Bill Fink, and Scott Bradner
(in chronological order) provided extensive review information and
feedback.

7. Security Considerations

Security issues are not discussed in this memo.

Authors' Addresses:

Alex Conta Stephen Deering
Digital Equipment Corporation Xerox Palo Alto Research Center
110 Spitbrook Rd 3333 Coyote Hill Road
Nashua, NH 03062 Palo Alto, CA 94304

Phone: +1-603-881-0744 Phone: +1-415-812-4839
EMail: conta@zk3.dec.com EMail: deering@parc.xerox.com