Internet DRAFT - draft-grothoff-iesg-special-use-p2p-i2p

draft-grothoff-iesg-special-use-p2p-i2p







Internet Engineering Task Force                              C. Grothoff
Internet-Draft                                                     INRIA
Intended status: Informational                                  M. Wachs
Expires: December 26, 2015              Technische Universitaet Muenchen
                                                            H. Wolf, Ed.
                                                           GNU consensus
                                                            J. Appelbaum
                                                                 L. Ryge
                                                        Tor Project Inc.
                                                           June 30, 2015


                    Special-Use Domain Names for I2P
               draft-grothoff-iesg-special-use-p2p-i2p-00

Abstract

   This document registers a Special-Use Domain Name for use with the
   I2P Peer-to-Peer system, as per RFC6761.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on December 26, 2015.

Copyright Notice

   Copyright (c) 2015 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
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   (http://trustee.ietf.org/license-info) in effect on the date of
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   to this document.  Code Components extracted from this document must



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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Applicability . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Terminology and Conventions Used in This Document . . . . . .   3
   4.  The "I2P" Addressbook pTLD  . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   The Domain Name System (DNS) is primarily used to map human-memorable
   names to IP addresses, which are used for routing but generally not
   meaningful for humans.

   The Invisible Internet Project (I2P) Peer-to-Peer (P2P) system uses a
   specific decentralized mechanism to allocate, register, manage, and
   resolve names.  The I2P Name System operates entirely outside of DNS,
   independently from the DNS root and delegation tree.

   As compatibility with applications using domain names is desired, the
   I2P overlay network defines an exclusive alternative Top-Level Domain
   to avoid conflict between the I2P namespace and the DNS hierarchy.

   In order to avoid interoperability issues with DNS as well as to
   address security and privacy concerns, this document registers the
   "I2P" Special-Use Domain Names for use with the I2P systems.

   I2P uses this pTLD to realize fully-decentralized and censorship-
   resistant naming.

2.  Applicability

   [RFC6761] Section 3 states:

      "[I]f a domain name has special properties that affect the way
      hardware and software implementations handle the name, that apply
      universally regardless of what network the implementation may be
      connected to, then that domain name may be a candidate for having



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      the IETF declare it to be a Special-Use Domain Name and specify
      what special treatment implementations should give to that name.
      On the other hand, if declaring a given name to be special would
      result in no change to any implementations, then that suggests
      that the name may not be special in any material way, and it may
      be more appropriate to use the existing DNS mechanisms [RFC1034]
      to provide the desired delegation, data, or lack-of-data, for the
      name in question.  Where the desired behaviour can be achieved via
      the existing domain name registration processes, that process
      should be used.  Reservation of a Special-Use Domain Name is not a
      mechanism for circumventing normal domain name registration
      processes."

   The Special-Use Domain Name for the I2P System (pTLDs) reserved by
   this document meets this requirement, as it has the following
   specificities:

   o  The "I2P" pTLD is not manageable by some designated
      administration.  Instead, it is managed according to various
      alternate strategies as described in the I2P documentation.

   o  The "I2P" pTLD does not depend on the DNS context for its
      resolution.  It uses I2P-specific logic for name resolution,
      covered by the respective system documentation.

   o  To resolve "I2P" names, the implementation MUST intercept queries
      for the pTLD to ensure I2P names cannot leak into the DNS.

   o  The appropriate resolution procedure can be implemented in
      existing software libraries and APIs to extend regular DNS
      operation and enable I2P name resolution.  However, the default
      hierarchical DNS response to any request to any pTLD MUST be
      NXDOMAIN.

   o  Finally, in order to maximally protect the security and privacy
      expectation of I2P users, this document specifies desirable
      changes in existing DNS software and DNS operations.

3.  Terminology and Conventions Used in This Document

   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].

   The word "peer" is used in the meaning of a individual system on the
   network.





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   The abbreviation "pTLD" is used in this document to mean a pseudo
   Top-Level Domain, i.e., a Special-Use Domain Name per [RFC6761]
   reserved to P2P Systems in this document.  A pTLD is mentioned in
   capitals, and within double quotes to mark the difference with a
   regular DNS gTLD.

   In this document, ".tld" (lowercase, with quotes) means: any domain
   or hostname within the scope of a given pTLD, while .tld (lowercase,
   without quotes) refers to an adjective form.  For example, a
   collection of ".i2p" peers in "I2P", but an .i2p URL.  [TO REMOVE: in
   the IANA Considerations section, we use the simple .tld format to
   request TLD reservation for consistency with previous RFCs].

   The word "NXDOMAIN" refers to an alternate expression for the "Name
   Error" RCODE as described in section 4.1.1 of [RFC1035].  When
   referring to "NXDOMAIN" and negative caching [RFC2308] response, this
   document means an authoritative (AA=1) name error (RCODE=3) response
   exclusively.

4.  The "I2P" Addressbook pTLD

   "I2P" provides accessibility to hidden services within the I2P
   network [zzz2009].  I2P is a scalable, self-organizing, resilient
   packet switched anonymous network layer, upon which any number of
   different anonymity or security-conscious applications can operate,
   using any protocol.

   I2P hidden services and clients are identified by Destinations,
   anonymous analogues of IP addresses.  The "I2P" pTLD, chosen in 2003
   [I2P-CHOICE], houses two methods for looking up Destinations:

      A local table called the addressbook stores a map of .i2p
      addresses to Destinations.  Each user maintains their own mappings
      that can be shared with others, allowing them to "discover" new
      names by importing published addressbooks of peers, and they can
      emulate traditional DNS by choosing to treat these peers as name
      servers.  The comparison however stops here, as only local
      uniqueness is mandated.  As the system is decentralized,
      "example.i2p" may resolve differently for different peers
      depending on the state of their respective addressbooks.

      To address globally unique names, the I2P developers dedicated the
      "B32.I2P" subdomain to hold Base32-encoded [RFC4648] references to
      Destinations.  Like .onion addresses, .b32.i2p addresses are self-
      authenticating.  The details of the encoding are out of scope for
      this document, and documented in [I2P-NAMING].  The purpose of
      .b32.i2p addresses is similar to ".zkey", that is to enable




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      (reverse) mapping for a globally unique hidden service that may
      not have a defined entry in the local addressbook.

   The "I2P" domain is special in the following ways:

   1.  Users can use these names as they would other domain names,
       entering them anywhere that they would otherwise enter a
       conventional DNS domain name.

       Since there is no central authority responsible for assigning
       .i2p names, and that the ultimate mapping is decided by the local
       peer, users need to be aware of that specificity.



   2.  Application software SHOULD recognize .i2p domains as special and
       SHOULD NOT use them as they would other domains.

       Applications SHOULD NOT pass requests for .i2p domains to DNS
       resolvers and libraries.

       As mentioned in points 4 and 5 below, regular DNS resolution is
       expected to respond with NXDOMAIN.  Therefore, if it can
       differentiate between DNS and P2P name resolution, application
       software can expect such a response, and can choose to treat
       other responses from resolvers and libraries as errors.



   3.  Name resolution APIs and libraries SHOULD either respond to
       requests for .i2p names by resolving them via the I2P protocol,
       or respond with NXDOMAIN.



   4.  Caching DNS servers SHOULD recognize .i2p names as special and
       SHOULD NOT attempt to look up NS records for them, or otherwise
       query authoritative DNS servers in an attempt to resolve .i2p
       names.  Instead, caching DNS servers SHOULD generate immediate
       negative responses for all such queries.



   5.  Authoritative DNS servers are not expected to treat .i2p domain
       requests specially.  In practice, they MUST answer with NXDOMAIN,
       as "I2P" is not available via global DNS resolution, and not
       doing so MAY put users' privacy at risk (see item 6).




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   6.  DNS server operators SHOULD be aware that .i2p names are reserved
       for use with I2P, and MUST NOT override their resolution (e.g.,
       to redirect users to another service or error information).



   7.  DNS registries/registrars MUST NOT grant any request to register
       .i2p names.  This helps avoid conflicts [SAC45].  These names are
       defined by the I2P protocol specification, and they fall outside
       the set of names available for allocation by registries/
       registrars.



5.  Security Considerations

   Specific software performs the resolution of the I2P Special-Use
   Domain Names presented in this document; this resolution process
   happens outside of the scope of DNS.  Leakage of requests to such
   domains to the global operational DNS can cause interception of
   traffic that might be misused to monitor, censor, or abuse the user's
   trust, and lead to privacy issues with potentially tragic
   consequences for the user.

   This document reserves these Top-Level Domain names to minimize the
   possibility of confusion, conflict, and especially privacy risks for
   users.

   In the introduction of this document, there's a requirement that DNS
   operators do not override resolution of the I2P Names.  This is a
   regulatory measure and cannot prevent such malicious abuse in
   practice.  Its purpose is to limit any information leak that would
   result from incorrectly configured systems, and to avoid that
   resolvers make unnecessary contact to the DNS Root Zone for such
   domains.  Verisign, Inc., as well as several Internet service
   providers (ISPs) have notoriously abused their position to override
   NXDOMAIN responses to their customers in the past
   [SSAC-NXDOMAIN-Abuse].  For example, if a DNS operator would decide
   to override NXDOMAIN and send advertising to leaked .onion sites, the
   information leak to the DNS would extend to the advertising server,
   with unpredictable consequences.  Thus, implementors should be aware
   that any positive response coming from DNS must be considered with
   extra care, as it suggests a leak to DNS has been made, contrary to
   user's privacy expectations.

   The reality of X.509 Certificate Authorities (CAs) creating
   misleading certificates for I2P pTLDs due to ignorance stresses the
   need to document their special use.  Given the nature of "B32.I2P",



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   X.509 Certificate Authorities MAY create certificates for such
   domains given CSRs signed with the respective private keys
   corresponding to the respective names.

6.  IANA Considerations

   The Internet Assigned Numbers Authority (IANA) reserved the following
   entries in the Special-Use Domain Names registry [RFC6761]:

      .i2p

   [TO REMOVE: the assignement URL is https://www.iana.org/assignments/
   special-use-domain-names/ ]

7.  Acknowledgements

   The authors thank the I2P and Namecoin developers for their
   constructive feedback, as well as Mark Nottingham for his proof-
   reading and valuable feedback.  The authors also thank the members of
   DNSOP WG for their critiques and suggestions.

8.  References

8.1.  Normative References

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, November 1987.

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, November 1987.

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

   [RFC2308]  Andrews, M., "Negative Caching of DNS Queries (DNS
              NCACHE)", RFC 2308, March 1998.

   [RFC6761]  Cheshire, S. and M. Krochmal, "Special-Use Domain Names",
              RFC 6761, February 2013.

8.2.  Informative References

   [I2P-CHOICE]
              Hacker, J. and The I2P Community, "I2P Dev Meeting 059",
              September 2003, <https://geti2p.net/en/meetings/059>.






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   [I2P-NAMING]
              Hacker, J. and The I2P Community, "Naming in I2P and
              Addressbook", April 2014, <https://geti2p.net/en/docs/
              naming>.

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

   [SAC45]    ICANN Security and Stability Advisory Committee, "Invalid
              Top Level Domain Queries at the Root Level of the Domain
              Name System", November 2010,
              <http://www.icann.org/en/groups/ssac/documents/
              sac-045-en.pdf>.

   [SSAC-NXDOMAIN-Abuse]
              ICANN Security and Stability Advisory Committee,
              "Redirection in the COM and NET Domains", July 2004,
              <http://www.icann.org/committees/security/
              ssac-report-09jul04.pdf>.

   [zzz2009]  The I2P Project and L. Schimmer, "Peer Profiling and
              Selection in the I2P Anonymous Network", January 2009,
              <https://geti2p.net/_static/pdf/I2P-PET-CON-2009.1.pdf>.

Authors' Addresses

   Christian Grothoff
   INRIA
   Equipe Decentralisee
   INRIA Rennes Bretagne Atlantique
   263 avenue du General Leclerc
   Campus Universitaire de Beaulieu
   Rennes, Bretagne  F-35042
   FR

   Email: christian@grothoff.org


   Matthias Wachs
   Technische Universitaet Muenchen
   Free Secure Network Systems Group
   Lehrstuhl fuer Netzarchitekturen und Netzdienste
   Boltzmannstrasse 3
   Technische Universitaet Muenchen
   Garching bei Muenchen, Bayern  D-85748
   DE

   Email: wachs@net.in.tum.de



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   Hellekin O. Wolf (editor)
   GNU consensus

   Email: hellekin@gnu.org


   Jacob Appelbaum
   Tor Project Inc.

   Email: jacob@appelbaum.net


   Leif Ryge
   Tor Project Inc.

   Email: leif@synthesize.us



































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