pdns-qof/i-d/pdns-qof.txt

Internet Engineering Task Force                              A. Dulaunoy
Internet-Draft                                                     CIRCL
Intended status: Informational                                 A. Kaplan
Expires: June 28, 2014                                           CERT.at
                                                                P. Vixie
                                                                H. Stern
                                                 Farsight Security, Inc.
                                                       December 25, 2013


                   Passive DNS - Common Output Format
                 draft-ietf-dulaunoy-kaplan-pDNS-cof-00

Abstract

   This document describes a common output format of Passive DNS Servers
   which clients can query.  The output format description includes also
   in addition a common semantic for each Passive DNS system.  By having
   multiple Passive DNS Systems adhere to the same output format for
   queries, users of multiple Passive DNS servers will be able to
   combine result sets easily.

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 June 28, 2014.

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   Copyright (c) 2013 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
   publication of this document.  Please review these documents



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   carefully, as they describe your rights and restrictions with respect
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   described in the Simplified BSD License.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . . . 3
   2.  Limitation  . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Common Output Format  . . . . . . . . . . . . . . . . . . . . . 4
     3.1.  Overview and Example  . . . . . . . . . . . . . . . . . . . 4
     3.2.  Mandatory Fields  . . . . . . . . . . . . . . . . . . . . . 4
       3.2.1.  rrname  . . . . . . . . . . . . . . . . . . . . . . . . 4
       3.2.2.  rrtype  . . . . . . . . . . . . . . . . . . . . . . . . 4
       3.2.3.  rdata . . . . . . . . . . . . . . . . . . . . . . . . . 5
       3.2.4.  time_first  . . . . . . . . . . . . . . . . . . . . . . 5
       3.2.5.  time_last . . . . . . . . . . . . . . . . . . . . . . . 5
     3.3.  Optional Fields . . . . . . . . . . . . . . . . . . . . . . 5
       3.3.1.  count . . . . . . . . . . . . . . . . . . . . . . . . . 5
       3.3.2.  Bailiwick . . . . . . . . . . . . . . . . . . . . . . . 5
     3.4.  Additional Fields . . . . . . . . . . . . . . . . . . . . . 5
       3.4.1.  sensor_id . . . . . . . . . . . . . . . . . . . . . . . 6
       3.4.2.  zone_time_first . . . . . . . . . . . . . . . . . . . . 6
       3.4.3.  zone_time_last  . . . . . . . . . . . . . . . . . . . . 6
     3.5.  Additional Fields Registry  . . . . . . . . . . . . . . . . 6
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 7
     7.2.  References  . . . . . . . . . . . . . . . . . . . . . . . . 7
     7.3.  Informative References  . . . . . . . . . . . . . . . . . . 8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 8















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1.  Introduction

   Passive DNS is a technique described by Florian Weimer in 2005 in
   Passive DNS replication, F Weimer - 17th Annual FIRST Conference on
   Computer Security [WEINERPDNS].  Since then multiple Passive DNS
   implementations evolved over time.  Users of these Passive DNS
   servers may query a server (often via WHOIS [RFC3912] or HTTP REST
   [REST]), parse the results and process them in other applications.

   There are multiple implementations of Passive DNS software.  Users of
   passive DNS query each implementation and aggregate the results for
   their search.  This document describes the output format of four
   Passive DNS Systems ([DNSDB],[PDNSCERTAT], [PDNSCIRCL] and [PDNSCOF])
   which are in use today and which already share a nearly identical
   output format.  As the format and the meaning of output fields from
   each Passive DNS need to be consistent, we propose in this document a
   solution to commonly name each field along with their corresponding
   interpretation.  The format follows a simple key-value structure in
   JSON [RFC4627] format.  The benefit of having a consistent Passive
   DNS output format is that multiple client implementations can query
   different servers without having to have a separate parser for each
   individual server. passivedns-client [PDNSCLIENT]currently implements
   multiple parsers due to a lack of standardization.  The document does
   not describe the protocol (e.g.  WHOIS [RFC3912], HTTP REST [REST])
   nor the query format used to query the Passive DNS.  Neither does
   this document describe "pre-recursor" Passive DNS Systems.  Both of
   these are separate topics and deserve their own RFC document.

1.1.  Requirements Language

   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 [RFC2119].


2.  Limitation

   As a Passive DNS can include protection mechanisms for their
   operation, results might be different due to those protection
   measures.  These mechanisms filter out DNS answers if they fail some
   criteria.  The bailiwick algorithm [BAILIWICK] protects the Passive
   DNS Database from cache poisoning attacks [CACHEPOISONING].  Another
   limitiation that clients querying the database need to be aware of is
   that each query simply gets an snapshot-answer of the time of
   querying.  Clients MUST NOT rely on consistent answers.  Nor must
   they assume that answers must be identical across multiple Passive
   DNS Servers.




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3.  Common Output Format

   The formatting of the answer follows the JSON [RFC4627] format.  The
   order of the fields is not significant for the same resource type.
   That means, the same name tuple plus timing information identifies a
   unique answer per server.

3.1.  Overview and Example

   The intent of this output format is to be easily parsable by scripts.
   Every implementation MUST support the JSON output format.

   A sample output using the JSON format:

   ... (list of )...
   { "count": 97167,
   "time_first": "1277353744",
   "rrtype": "A", "rrname": "google-public-dns-a.google.com.",
   "rdata": "8.8.8.8",
   "time_last": "1386405372" }
   ... (separated by newline)...

3.2.  Mandatory Fields

   Implementation MUST support all the mandatory fields.

   The tuple (rrname,rrtype,rdata) will always be unique within one
   answer per server.

3.2.1.  rrname

   This field returns the name of the queried resource.

3.2.2.  rrtype

   This field returns the resource record type as seen by the passive
   DNS.  The key is rrtype and the value is in the interpreted record
   type.  If the value cannot be interpreted the decimal value is
   returned following the principle of transparency as described in RFC
   3597 [RFC3597].  The resource record type can be any values as
   described by IANA in the DNS parameters document in the section 'DNS
   Label types' (http://www.iana.org/assignments/dns-parameters).
   Currently known and supported textual descriptions of rrtypes are: A,
   AAAA, CNAME, PTR, SOA, TXT, DNAME, NS, SRV, RP, NAPTR, HINFO, A6.  A
   client MUST be able to understand these textual rtype values.  In
   addition, a client MUST be able to handle a decimal value (as
   mentioned above) as answer.




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3.2.3.  rdata

   This field returns the data of the queried resource.  In general,
   this is to be interpreted as string.  Depending on the rtype, this
   can be an IPv4 or IPv6 address, a domain name (as in the case of
   CNAMEs), an SPF record, etc.  A client MUST be able to interpret any
   value which is legal as the right hand side in a DNS zone file RFC
   1035 [RFC1035] and RFC 1034 [RFC1034].  If the rdata came from an
   unknown DNS resource records, the server must follow the transparency
   principle as described in RFC 3597 [RFC3597].

3.2.4.  time_first

   This field returns the first time that the record / unique tuple
   (rrname, rrtype, rdata) has been seen by the passive DNS.  The date
   is expressed in seconds (decimal ASCII) since 1st of January 1970
   (Unix timestamp).  The time zone MUST be UTC.

3.2.5.  time_last

   This field returns the last time that the unique tuple (rrname,
   rrtype, rdata) record has been seen by the passive DNS.  The date is
   expressed in seconds (decimal ASCII) since 1st of January 1970 (Unix
   timestamp).  The time zone MUST be UTC.

3.3.  Optional Fields

   Implementations SHOULD support one or more field.

3.3.1.  count

   Specifies how many authoritative DNS answers were received at the
   Passive DNS Server's collectors with the set of answers (i.e. same
   data).  The number of requests is expressed as a decimal value.

   Specifies the number of times this particular event denoted by the
   other type fields has been seen in the given time interval (between
   time_last and time_first).  Decimal number.

3.3.2.  Bailiwick

   The bailiwick is the best estimate of the apex of the zone where this
   data is authoritative.  String.

3.4.  Additional Fields

   Implementations MAY support the following fields:




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3.4.1.  sensor_id

   This field returns the sensor information where the record was seen.
   The sensor_id is an opaque byte string as defined by RFC 5001 in
   section 2.3 [RFC5001].

3.4.2.  zone_time_first

   This field returns the first time that the unique tuple (rrname,
   rrtype, rdata) record has been seen via zone file import.  The date
   is expressed in seconds (decimal ASCII) since 1st of January 1970
   (Unix timestamp).  The time zone MUST be UTC.

3.4.3.  zone_time_last

   This field returns the last time that the unique tuple (rrname,
   rrtype, rdata) record has been seen via zone file import.  The date
   is expressed in seconds (decimal ASCII) since 1st of January 1970
   (Unix timestamp).  The time zone MUST be UTC.

3.5.  Additional Fields Registry

   In accordance with [RFC6648], designers of new passive DNS
   applications that would need additional fields can request and
   register new field name at
   https://github.com/adulau/pdns-qof/wiki/Additional-Fields.


4.  Acknowledgements

   Thanks to the Passive DNS developers who contributed to the document.


5.  IANA Considerations

   This memo includes no request to IANA.


6.  Security Considerations

   In some cases, Passive DNS output might contain confidential
   information and its access might be restricted.  When a user is
   querying multiple Passive DNS and aggregating the data, the
   sensitivity of the data must be considered.


7.  References




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7.1.  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.

   [RFC3597]  Gustafsson, A., "Handling of Unknown DNS Resource Record
              (RR) Types", RFC 3597, September 2003.

   [RFC3912]  Daigle, L., "WHOIS Protocol Specification", RFC 3912,
              September 2004.

   [RFC4627]  Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", RFC 4627, July 2006.

   [RFC5001]  Austein, R., "DNS Name Server Identifier (NSID) Option",
              RFC 5001, August 2007.

   [RFC6648]  Saint-Andre, P., Crocker, D., and M. Nottingham,
              "Deprecating the "X-" Prefix and Similar Constructs in
              Application Protocols", BCP 178, RFC 6648, June 2012.

7.2.  References

   [BAILIWICK]
              "Passive DNS Hardening", 2010, <https://
              archive.farsightsecurity.com/Passive_DNS/
              passive_dns_hardening_handout.pdf>.

   [CACHEPOISONING]
              "Black ops 2008: It's the end of the cache as we know
              it.", 2008, <http://kurser.lobner.dk/dDist/DMK_BO2K8.pdf>.

   [DNSDB]    "DNSDB API", 2013, <https://api.dnsdb.info/>.

   [PDNSCERTAT]
              "pDNS presentation at 4th Centr R&D workshop Frankfurt Jun
              5th 2012", 2012, <http://www.centr.org/system/files/
              agenda/attachment/rd4-papst-passive_dns.pdf>.

   [PDNSCIRCL]
              "CIRCL Passive DNS", 2012, <http://pdns.circl.lu/>.




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   [PDNSCLIENT]
              "Queries 5 major Passive DNS databases: BFK, CERTEE,
              DNSParse, ISC, and VirusTotal.", 2013,
              <https://github.com/chrislee35/passivedns-client>.

   [PDNSCOF]  "Passive DNS server interface using the common output
              format", 2013,
              <https://github.com/adulau/pdns-qof-server/>.

   [REST]     "Representational State Transfer (REST)", 2000, <http://
              www.ics.uci.edu/~fielding/pubs/dissertation/
              rest_arch_style.htm>.

   [WEINERPDNS]
              "Passive DNS Replication", 2005, <http://www.enyo.de/fw/
              software/dnslogger/first2005-paper.pdf>.

7.3.  Informative References

   [I-D.narten-iana-considerations-rfc2434bis]
              Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs",
              draft-narten-iana-considerations-rfc2434bis-09 (work in
              progress), March 2008.

   [RFC3552]  Rescorla, E. and B. Korver, "Guidelines for Writing RFC
              Text on Security Considerations", BCP 72, RFC 3552,
              July 2003.


Authors' Addresses

   Alexandre Dulaunoy
   CIRCL
   41, avenue de la gare
   Luxembourg,   L-1611
   LU

   Phone: (+352) 247 88444
   Email: alexandre.dulaunoy@circl.lu
   URI:   http://www.circl.lu/










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   L. Aaron Kaplan
   CERT.at
   Karlsplatz 1/2/9
   Vienna,   A-1010
   AT

   Phone: +43 1 5056416 78
   Email: kaplan@cert.at
   URI:   http://www.cert.at/


   Paul Vixie
   Farsight Security, Inc.


   Phone:
   Email: paul@redbarn.org
   URI:   /


   Henry Stern
   Farsight Security, Inc.
   1741 Brunswick Street, Suite 500
   Halifax, Nova Scotia  B3J 3X8
   Canada

   Phone: +1 408 922 4555
   Email: hestern@cisco.com
   URI:   http://www.cisco.com/security






















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