Internet Engineering Task Force Dulaunoy Internet-Draft CIRCL Intended status: Informational Kaplan Expires: July 5, 2013 CERT.at January 2013 Passive DNS - Common Output Format draft-ietf-dulaunoy-kaplan-pdns-cof-01 Abstract This document describes the output format used between Passive DNS query interface. The output format description includes also a common meaning per Passive DNS system. Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on July 5, 2013. Dulaunoy & Kaplan Expires July 5, 2013 [Page 1] Internet-Draft Abbreviated Title January 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. Limitation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Output Format . . . . . . . . . . . . . . . . . . . . . . 4 3.1.1. Whois Human Readable . . . . . . . . . . . . . . . . . 4 3.1.2. JSON . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1.3. Bind format . . . . . . . . . . . . . . . . . . . . . 5 4. Mandatory Fields . . . . . . . . . . . . . . . . . . . . . . . 5 4.1. rrname . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.2. rrtype . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.3. rdata . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.4. time_first . . . . . . . . . . . . . . . . . . . . . . . . 6 4.5. time_last . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Optional Fields . . . . . . . . . . . . . . . . . . . . . . . 6 5.1. sensor_id . . . . . . . . . . . . . . . . . . . . . . . . 6 5.2. count . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.3. ttl . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.4. bailiwick . . . . . . . . . . . . . . . . . . . . . . . . 6 5.5. class . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6. Extended Fields . . . . . . . . . . . . . . . . . . . . . . . 7 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 9. Security Considerations . . . . . . . . . . . . . . . . . . . 7 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 10.1. Normative References . . . . . . . . . . . . . . . . . . . 7 10.2. Informative References . . . . . . . . . . . . . . . . . . 8 Appendix A. Additional Stuff . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . . . 10 Dulaunoy & Kaplan Expires July 5, 2013 [Page 2] Internet-Draft Abbreviated Title January 2013 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. Since then multiple Passive DNS implementations evolved over time. Users of these Passive DNS servers query a server (often via Whois [Ref: WHOIS]), parse the results and process them in other applications. There are multiple implementation 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 three Passive DNS Systems 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 format is following a simple key-value structure. 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. [http://code.google.com/p/passive-dns-query-tool/] currently implements multiple parsers due to a lack of standardization. The document does not describe the protocol (e.g. whois, HTTP REST or XMPP) used to query the Passive DNS. 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 (c.f. http://www.isc.org/files/passive_dns_hardening_handout.pdf) protects the Passive DNS Database from cache poisoning attacks [ref: Dan Kaminsky]. 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. Dulaunoy & Kaplan Expires July 5, 2013 [Page 3] Internet-Draft Abbreviated Title January 2013 3. Format A field is composed a key followed by a value separated by the single ':' character and a space before the value. The format is based on the initial work done by Florian Weimer and the RIPE whois format (ref:http://www.enyo.de/fw/software/dnslogger/whois.html). The order of the fields is not significant for the same resource type. That measn, the same name tuple plus timing information identifies a unique answer per server. A sample output using the common format: rrname: www.foo.be rrtype: AAAA rdata: 2001:6f8:202:2df::2 time_first: 2010-07-26 13:04:01 time_last: 2012-02-06 09:59:00 count: 87 3.1. Output Format Depending on the clients request, there might be one of three different answers from the server: Whois (human readable) output format (key-value), JSON [RFC4627] output and optionally Bind zone file output format. XXX FIXME: how does the client select which answer format he wants? XXX 3.1.1. Whois Human Readable This output format originates with the original design of BFK's passive DNS server implementation. The intent is to be be human readable. Every implementation MUST support the Whois human readable format. A sample output using the Whois format: rrname: www.foo.be rrtype: AAAA rdata: 2001:6f8:202:2df::2 time_first: 2010-07-26 13:04:01 time_last: 2012-02-06 09:59:00 count: 87 3.1.2. JSON The intent of this output format is to be easily parseable by scripts. Every implementation SHOULD support the JSON output format. Dulaunoy & Kaplan Expires July 5, 2013 [Page 4] Internet-Draft Abbreviated Title January 2013 A sample output using the JSON format: ... (list of )... { "count": 97167, "time_first": "2010-06-25 17:07:02", "rrtype": "A", "rrname": "google-public-dns-a.google.com.", "rdata": "8.8.8.8", "time_last": "2013-02-05 17:34:03" } ... (separated by newline)... 3.1.3. Bind format A sample output using the Bind format: google-public-dns-a.google.com. IN A 8.8.8.8 4. Mandatory Fields Implementation MUST support all the mandatory fields. The tuple (rrtype,rrname,rdata) will always be unique within one answer per server. 4.1. rrname This field returns the name of the queried resource. 4.2. 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. 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 descritptions 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. 4.3. 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 Dulaunoy & Kaplan Expires July 5, 2013 [Page 5] Internet-Draft Abbreviated Title January 2013 value which is legal as the right hand side in a DNS zone file RFC 1035 [RFC1035] and RFC 1034 [RFC1034]. 4.4. 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 ISO 8601 and UTC. 4.5. 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 ISO 8601 and UTC. 5. Optional Fields Implementation SHOULD support one or more field. 5.1. sensor_id This field returns the sensor information where the record was seen. The sensor_id is expressed in a decimal value. 5.2. count Specifies how many authoritative answers were received with the set of answers (i.e. same data) over all sensors. The number of requests is expressed as a decimal value. 5.3. ttl the TTL as specified in RFC 1035 [RFC1035] as a decimal value. 5.4. bailiwick XXX FIXME: input from ISC needed 5.5. class the class as specified in RFC 1035 [RFC1035]. Valid values are IN, HS (for HESIOD), CH (for CHAOS). May be omitted, the default assumption that a client should make is IN. Dulaunoy & Kaplan Expires July 5, 2013 [Page 6] Internet-Draft Abbreviated Title January 2013 6. Extended Fields An x- prefixed key means that is an extension and a non-standard field defined by the implementation of the passive DNS. 7. Acknowledgements Thanks to the Passive DNS developers who contributed to the document. 8. IANA Considerations This memo includes no request to IANA. 9. Security Considerations In some cases, Passive DNS output might contain confidential information and its access might be restricted. When an user is querying multiple Passive DNS and aggregating the data, the sensitivity of the data must be considered. Authentication and signing of the output MAY be implemented on the server via an extended field, namely x-signature-sha265 which contains a SHA256 signature of the output text, signed with the ssh- key of the server sending the answer. All drafts are required to have a security considerations section. See RFC 3552 [RFC3552] for a guide. 10. References 10.1. 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. [RFC4627] Crockford, D., "The application/json Media Type for JavaScript Object Notation (JSON)", RFC 4627, July 2006. Dulaunoy & Kaplan Expires July 5, 2013 [Page 7] Internet-Draft Abbreviated Title January 2013 [min_ref] authSurName, authInitials., "Minimal Reference", 2006. 10.2. Informative References [DOMINATION] Mad Dominators, Inc., "Ultimate Plan for Taking Over the World", 1984, . [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. [RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629, June 1999. [RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC Text on Security Considerations", BCP 72, RFC 3552, July 2003. Appendix A. Additional Stuff This becomes an Appendix. 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/ Dulaunoy & Kaplan Expires July 5, 2013 [Page 8] Internet-Draft Abbreviated Title January 2013 Leon 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/ Dulaunoy & Kaplan Expires July 5, 2013 [Page 9] Internet-Draft Abbreviated Title January 2013 Full Copyright Statement Copyright (C) The IETF Trust (2013). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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