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DNSOP Working Group                                              E. Hunt
Internet-Draft                                                D. Mahoney
Updates: 6195 (if approved)                                          ISC
Intended status: Standards Track                            July 6, 2019
Expires: January 7, 2020

       A DNS Resource Record for Confidential Comments (NOTE RR)


   While the DNS zone master file format has always allowed comments,
   there is no existing mechanism to preserve comments once the zone has
   been loaded into memory or converted to a binary representation.
   This note proposes a new RR type "NOTE", to be allocated from the
   Covert-RR type range proposed in [I-D.krecicki-dns-covert], so that
   confidential comments can be stored alongside zone data, and included
   in zone transfers when Covert semantics are supported by the

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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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 7, 2020.

Copyright Notice

   Copyright (c) 2019 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
   (https://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

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   to this document.  Code Components extracted from this document must
   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
     1.1.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  The NOTE RR Type  . . . . . . . . . . . . . . . . . . . . . .   3
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   4.  Security and Privacy Considerations . . . . . . . . . . . . .   3
   5.  Normative References  . . . . . . . . . . . . . . . . . . . .   3
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   DNS zone master files may include comments: any text on a line
   following an unquoted semicolon is ignored when parsing the file
   [RFC1034].  These comments are often used by administrators to keep
   notes about the zone data; for example, the purpose of a particular
   host, or the person responsible for maintaining it.

   When the zone is loaded, however, comments may be lost.  Servers
   which dump backup copies of dynamically updated or automatically
   signed zones may obliterate comments that were in the original zone
   files.  Secondary servers do not receive comment text when
   transferring zones from primary servers.

   Comments could be stored in the zone itself as TXT RRs; these would
   be preserved after zone updates and across zone transfers.  However,
   TXT records are available to any DNS query.  Because zone file
   comments commonly include information about internal networks and/or
   personnel that could be of use to potential attackers, it is better
   for distribution of comment data to be restricted.

   A Covert Resource Record, as described in [I-D.krecicki-dns-covert],
   could be used for the storage of private text information within zone
   data itself.  This data could be transferred from primary to
   secondary servers when Covert semantics are supported, and but would
   be concealed from normal DNS queries (except from specific trusted
   DNS clients) and from secondary servers that do not signal their
   support of Covert data transfer.

   This document proposes the allocation of a new RR type NOTE from the
   Covert-RR type range for this purpose.  Comments that the operator
   wishes to be stored and transferred with zone data can be encoded as

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   NOTE records.  Traditional zone file comments, indicated by
   semicolons, would still be ignored.

1.1.  Definitions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  The NOTE RR Type

   The NOTE RR is defined for all classes, with mnemonic NOTE and type
   code (TBD).  The RDATA and presentation formats are identical to
   those of the TXT RR defined in [RFC1035], e.g:

       $ORIGIN example.com.
       joesbox   7200  IN  A
       7200            IN  AAAA    2001:DB8:3F:B019::17
                 0     IN  NOTE    "Desktop system for Joe Smith, x7889"

   The RR type code MUST be allocated from the Covert-RR type range, and
   NOTE record data MUST be treated as Covert [I-D.krecicki-dns-covert].

3.  IANA Considerations

   IANA is requested to allocate a DNS RR type number from the Covert-RR
   type range for the NOTE RR type.

4.  Security and Privacy Considerations

   NOTE data should only be accessible via Covert DNS queries, because
   zone file comments commonly include information that could be of use
   to potential attackers.  Failure to implement the restrictions
   outlined in [I-D.krecicki-dns-covert] could allow leakage of
   sensitive information.

5.  Normative References

              Krecicki, W., Hunt, E., and D. Mahoney, "Domain Name
              System (DNS) Resource Record types for transferring covert
              information from primary to secondaries", draft-krecicki-
              dns-covert-00 (work in progress), July 2019.

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   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
              November 1987, <https://www.rfc-editor.org/info/rfc1035>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

Authors' Addresses

   Evan Hunt
   950 Charter St
   Redwood City, CA  94063

   Email: each@isc.org

   Dan Mahoney
   950 Charter St
   Redwood City, CA  94063

   Email: dmahoney@isc.org

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