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.

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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

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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:

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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.

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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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.

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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.


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


   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

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

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

   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…