Network Working Group C. Jennings Internet-Draft Cisco Systems Intended status: Standards Track July 6, 2008 Expires: January 7, 2009 HTTP API for Updating DNS Records draft-jennings-app-dns-update-00 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), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on January 7, 2009. Copyright Notice Copyright (C) The IETF Trust (2008). Abstract This specification defines a simple HTTP based scheme for clients to update DNS records. The draft is being discussed on the apps-discuss@ietf.org list. Jennings Expires January 7, 2009 [Page 1] Internet-Draft DNS Update July 2008 1. Introduction There are many circumstances in which an application would like to have an easy way to update DNS records. The DynDNS service[5], supported on many residential NATs, is one example: it updates a DNS record to point at the NAT after the NAT receives a dynamically assigned IP address. Another common use case is dynamically created servers in elastic computing environments. When new servers are created, they often need to update DNS records. The approach described in this specification allows a client to make a simple HTTP[1] request to a server. The client is authenticated using a shared secret. The server is authenticated with TLS, which provides both integrity for the transaction and confidentiality for the shared secret. The request contains information that instructs the server to update a particular DNS record. The specification is limited to updating a simple subset of DNS records and does not support more complex operations such as the multiple changes that need to happen as an atomic transactions. 2. Terminology 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 [2]. 3. Update Record Requests This section describes the semantics of requests to update DNS records. 3.1. HTTPS Request The client needs to be configured with the base URL for the server, along with a username and password. The request is created by forming an HTTPS[3] GET request to a URL. The HTTPS GET request is formed by starting with the configured base URL, appending "/dns/ update", and then appending all the required parameters. The request MUST be done using HTTPS to protect the password. The client MUST ensure the certificate is appropriately signed. The HTTP request SHOULD contain a "User-Agent" header that clearly identifies the version of the software making the request, as this facilitates debugging. Jennings Expires January 7, 2009 [Page 2] Internet-Draft DNS Update July 2008 3.2. URL Parameters The request MUST include exactly one user, password, and domain parameter as defined below. Other parameters are optional and can occur at most once. The values of parameters MUST be appropriately escaped as required to become parts of valid HTTP URLs. General Parameters +-----------+-------------------------------------------------------+ | Parameter | Value | | Name | | +-----------+-------------------------------------------------------+ | user | The configured user name for the user making the | | | request. | | password | The configured password for the user making the | | | request base16 encoded as defined in [4]. | | domain | The fully qualified domain name for the record to | | | update. | | ttl | Requested time to live for the DNS records in | | | seconds. If omitted, this will be set to default | | | chosen by the server. | | index | A numeric counter that indicates which record to | | | update when there is more than one record of the | | | given type. This is explained in Section 3.2.1. | +-----------+-------------------------------------------------------+ The request MUST also have exactly one Record Parameter from the following table. Record Parameters +----------------+----------------------------------------------+ | Parameter Name | Value | +----------------+----------------------------------------------+ | a | The value to set for a DNS A record [6]. | | aaaa | The value to set for a DNS AAAA record [7]. | | cname | The value to set for a DNS CNAME record [6]. | | ns | The value to set for a DNS NS record [6]. | | ptr | The value to set for a DNS PTR record [6]. | | srv | The value to set for a DNS SRV record [8]. | | txt | The value to set for a DNS TXT record [9]. | | hip | The value to set for a DNS HIP record [10]. | +----------------+----------------------------------------------+ Jennings Expires January 7, 2009 [Page 3] Internet-Draft DNS Update July 2008 3.2.1. Entries with multiple records Sometimes it is desirable to have multiple records of the same type for the same name. For example, a domain may have multiple MX records. The index parameter provides a number value, call it i, that can be used to indicate that the i'th record MUST be updated. The first record has an index value of 1, not 0. Two special values are defined 0 and -1. The value 0 indicates that there should only be the single record and all others MUST be removed. If a request does not have any index parameters, it is processed as if the index parameter were 0. The index value -1 indicates that, unless the exact value already exists in an existing record, the index MUST be added to the list of existing records. When a record with an index value of -1 is updated and the exact value already exists, a success response is returned, exactly as if the value had not existed and had been appended. 3.2.2. Deleting records If the value of the parameter that would update a record is empty, the record MUST be removed from DNS. 3.3. Return Codes and Errors HTTP response codes are used to indicate success and errors as specified in the following table. Response Codes +-----------------------------------------------------------+-------+ | Error Condition | Value | +-----------------------------------------------------------+-------+ | No Error, requested succeeded | 200 | | Unknown username and Bad username/password combination. | 401 | | Trying to update a record or domain for which this users | 403 | | is not authorized to change. | | | Some problem with the request or parameters. | 406 | | Trying to update a record type which the server does not | 501 | | support. | | +-----------------------------------------------------------+-------+ The body of the response MAY have human readable text that allows a network administrator to learn more about why the request failed. Jennings Expires January 7, 2009 [Page 4] Internet-Draft DNS Update July 2008 4. Example In the examples below, some of the URLs appear broken across multiple lines. This is because of physical width limitations in this document; such URLs need to be read as single URLs with no embedded white space. All of the examples assume that a user called "me@example.net" with password "no" is allowed to update records in the example.com domain. The base URL of the DNS update service is https://dns.example.org in the examples. Each example shows the state of the DNS in a precondition before the request, the requests performed using this specification, and then the resulting state of the DNS in the postcondition. 4.1. Update an A record This example shows a basic update. Precondition: www.example.com A 192.0.2.0 Requests: https://dns.example.org/dns/update?user=me%40example.net?password=6E6F ?domain=www.example.com?a=192.0.2.1 Postcondition: www.example.com A 192.0.2.1 4.2. Update two MX records This example shows how to update entries where there are multiple records. Precondition: Requests: https://dns.example.org/dns/update?user=me%40example.net?password=6E6F ?domain=example.com?index=1?mx=10%20mail1.example.com https://dns.example.org/dns/update?user=me%40example.net?password=6E6F ?domain=example.com?index=2?mx=20%20mail2.example.com Postcondition: example.com MX 10 mail1.example.com example.com MX 20 mail2.example.com Jennings Expires January 7, 2009 [Page 5] Internet-Draft DNS Update July 2008 4.3. Delete an A record This example shows a simple removal of a record. Precondition: www.example.com A 192.0.2.1 Requests: https://dns.example.org/dns/update?user=me%40example.net?password=6E6F ?domain=www.example.com?a= Postcondition: 4.4. Add one more SRV record This example shows how to append a record to a list of existing records. Precondition: _sip._tcp.example.com SRV 10 1 5060 192.0.2.1 _sip._tcp.example.com SRV 10 1 5060 192.0.2.2 Requests: https://dns.example.org/dns/update?user=me%40example.net?password=6E6F ?domain=_sip._tcp.example.com ?index=-1?srv=10%201%205060%20192.0.2.3 Postcondition: _sip._tcp.example.com SRV 10 1 5060 192.0.2.1 _sip._tcp.example.com SRV 10 1 5060 192.0.2.2 _sip._tcp.example.com SRV 10 1 5060 192.0.2.3 4.5. Add existing SRV record This example is similar to the previous one, in that an entry is being appended to a list; but in this case, the entry already exists so no change is made to the list. The request returns the same 200 success response. Jennings Expires January 7, 2009 [Page 6] Internet-Draft DNS Update July 2008 Precondition: _sip._tcp.example.com SRV 10 1 5060 192.0.2.1 _sip._tcp.example.com SRV 10 1 5060 192.0.2.2 _sip._tcp.example.com SRV 10 1 5060 192.0.2.3 Requests: https://dns.example.org/dns/update?user=me%40example.net?password=6E6F ?domain=_sip._tcp.example.com ?index=-1?srv=10%201%205060%20192.0.2.2 Postcondition: _sip._tcp.example.com SRV 10 1 5060 192.0.2.1 _sip._tcp.example.com SRV 10 1 5060 192.0.2.2 _sip._tcp.example.com SRV 10 1 5060 192.0.2.3 5. IANA Considerations This document makes no requests of IANA. 6. Security Considerations TODO 7. Acknowledgements Thanks to TBD. 8. References 8.1. Normative References [1] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [3] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. [4] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", RFC 4648, October 2006. Jennings Expires January 7, 2009 [Page 7] Internet-Draft DNS Update July 2008 8.2. Informative References [5] "http://www.dyndns.com/developers/specs/syntax.html", 2008. [6] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987. [7] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi, "DNS Extensions to Support IP Version 6", RFC 3596, October 2003. [8] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for specifying the location of services (DNS SRV)", RFC 2782, February 2000. [9] Rosenbaum, R., "Using the Domain Name System To Store Arbitrary String Attributes", RFC 1464, May 1993. [10] Nikander, P. and J. Laganier, "Host Identity Protocol (HIP) Domain Name System (DNS) Extensions", RFC 5205, April 2008. Author's Address Cullen Jennings Cisco Systems 170 West Tasman Drive Mailstop SJC-21/2 San Jose, CA 95134 USA Phone: +1 408 902-3341 Email: fluffy@cisco.com Jennings Expires January 7, 2009 [Page 8] Internet-Draft DNS Update July 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). 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. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 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The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Jennings Expires January 7, 2009 [Page 9]