



Internet Engineering Task Force                              M. Loffredo
Internet-Draft                                      L. Luconi Trombacchi
Intended status: Standards Track                           M. Martinelli
Expires: 28 March 2025                               IIT-CNR/Registro.it
                                                             D. Keathley
                                                                J. Gould
                                                          VeriSign, Inc.
                                                       24 September 2024


      Extensible Provisioning Protocol (EPP) Transport over HTTPS
                 draft-loffredo-regext-epp-over-http-05

Abstract

   This document describes how an Extensible Provisioning Protocol (EPP)
   connection is mapped onto a Hypertext Transfer Protocol (HTTP)
   session.  EPP over HTTP (EoH) requires the use of Transport Layer
   Security (TLS) to secure EPP information (i.e.  HTTPS).

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://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 28 March 2025.

Copyright Notice

   Copyright (c) 2024 IETF Trust and the persons identified as the
   document authors.  All rights reserved.










Loffredo, et al.          Expires 28 March 2025                 [Page 1]

Internet-Draft               EPP over HTTPS               September 2024


   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 to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   3
   3.  Session Management  . . . . . . . . . . . . . . . . . . . . .   3
   4.  Message Exchange  . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Transport Considerations  . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   7.  Implementation Status . . . . . . . . . . . . . . . . . . . .   6
     7.1.  Verisign EPP SDK  . . . . . . . . . . . . . . . . . . . .   7
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   10. Normative References  . . . . . . . . . . . . . . . . . . . .   9
   Appendix A.  Change History . . . . . . . . . . . . . . . . . . .  10
     A.1.  Change from 02 to 03  . . . . . . . . . . . . . . . . . .  10
     A.2.  Change from 03 to 04  . . . . . . . . . . . . . . . . . .  10
     A.3.  Change from 04 to 05  . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   This document describes how EPP [RFC5730] is mapped onto HTTP
   [RFC9110].  Note that there are several versions of HTTP currently in
   use, including: HTTP/1.1 [RFC9112], HTTP/2 [RFC9113], and HTTP/3
   [RFC9114].  As the differences among such versions do not affect the
   EPP mapping described in this document, hereinafter the version
   number is omitted except for presenting the special features in the
   underlying layers of the HTTP stack.

   HTTP represents a higher-level abstraction of a network connection,
   removing the need to directly deal with all of the lower-level
   details of transport protocols.  This makes HTTP much more compatible
   with cloud-native infrastructures, and facilitates faster development
   times and reduced maintenance costs in such environments.

   Security services beyond those defined in EPP are provided by TLS via
   HTTPS Section 4.2.2 of [RFC9110].





Loffredo, et al.          Expires 28 March 2025                 [Page 2]

Internet-Draft               EPP over HTTPS               September 2024


2.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [BCP14] when, and only when, they appear in all capitals, as shown
   here.

3.  Session Management

   Mapping EPP session management facilities onto HTTP is accomplished
   using existing HTTP methods, namely GET and POST.  An EPP session
   exists on top of an EPP connection between two peers, one that
   initiates the connection request and one that responds to the
   connection request.  The initiating peer is called the "client", and
   the responding peer is called the "server".  An EPP server
   implementing this specification MUST listen for HTTP session requests
   on a standard HTTP port assigned by IANA.

   Even though HTTP itself is stateless, a stateful EPP session can be
   achieved using the mechanism described in [RFC6265].  This mechanism
   uses "Set-Cookie" and "Cookie" HTTP headers to facilitate a stateful
   HTTP session.  Such a session is initiated by the client via sending
   a GET request to the sever.  The GET request MUST include
   "application/epp+xml" (Appendix B of [RFC5730]) in the "Accept" HTTP
   header.  The server MUST include the EPP Greeting in the response.
   The EPP Greeting must include "application/epp+xml" in the "Content-
   Type" header with the character encoding of the EPP XML (e.g.,
   "application/epp+xml;charset=UTF-8") and MUST include ""no-cache" in
   the "Cache-Control" header and include "0" in the "Expires" header to
   disable caching.  The server MUST use the "Set-Cookie" header to
   include a token that represents the identifier of the HTTP session.
   All subsequent HTTP requests that include the HTTP session identifier
   in the "Cookie" header will be treated as part of the session.  The
   HTTP session represents an EPP connection, referred to as an EPP over
   HTTP (EoH) connection, which is initiated by the initial GET request.

   The EPP session begins with a successful EPP <login> command on the
   EoH connection and can be referred to as an EPP over HTTP (EoH)
   session.

   An EPP session is normally ended by the client issuing an EPP
   <logout> command.  A server receiving an EPP <logout> command MUST
   end the EPP session.  A server MAY also end an EPP session that has
   been either active or inactve for longer than a server-defined
   period.  A server MAY end the HTTP session after ending the EPP
   session.




Loffredo, et al.          Expires 28 March 2025                 [Page 3]

Internet-Draft               EPP over HTTPS               September 2024


4.  Message Exchange

   EPP describes client-server interaction as a command-response
   exchange where the client sends one command to the server and the
   server returns one response to the client.  With the exception of the
   EPP Greeting, EPP messages are initiated by the EPP client in the
   form of EPP commands.  An EPP client MUST send all commands as HTTP
   POST requests (Section 6.4 of [RFC9110]).  Each POST request MUST
   include the HTTP session identifier in the "Cookie" header and
   "application/epp+xml" in the "Accept" header.  An EPP server MUST
   return an EPP response to an EPP command in the HTTP response to the
   respective HTTP request.  The EPP command and the EPP response MUST
   include "application/epp+xml" in the "Content-Type" header with the
   character encoding of the EPP XML (e.g., "application/
   epp+xml;charset=UTF-8").  The EPP response MUST include "no-cache" in
   the "Cache-Control" header and include "0" in the "Expires" header to
   disable caching.

   HTTP does not guarantee that POST requests are idempotent.  However,
   the semantics of EPP do require EPP commands to be idempotent, so
   processing a command more than once will produce the same net effect
   on the repository as successfully processing the command once.

   The EPP command XML is framed by the content of the HTTP POST
   request, and the EPP response XML is framed by the content of the
   HTTP response.  Each HTTP request MUST contain a single EPP message,
   and each HTTP response MUST contain a single EPP response.  Commands
   MUST be processed independently and in the same order as received
   from the client.

   Servers MUST NOT use HTTP return codes to signal clients about the
   failure of the EPP commands.  The HTTP code 200 MUST be used for both
   successful and unsuccessful EPP requests.  Servers MUST use HTTP
   codes to signal clients about the failure of the HTTP requests.

   Servers MUST return an EPP 2002 response (i.e.  Command use error) if
   the client issues an EPP command with either an empty or an invalid
   HTTP session identifier.

   A server SHOULD impose a limit on the amount of time required for a
   client to issue a well-formed EPP command.  A server SHOULD end an
   EPP session if a well-formed command is not received within the time
   limit.

   HTTP/2 and HTTP/3 support a multiplexing feature that was introduced
   to address head-of-line blocking issues in previous HTTP versions.
   In the context of multiple requests being sent on a single HTTP
   connection, multiplexing allows the delivery of responses in a



Loffredo, et al.          Expires 28 March 2025                 [Page 4]

Internet-Draft               EPP over HTTPS               September 2024


   different order from how the requests were made.  Due to this
   behavior, pipelining MUST NOT be used by EoH clients.  EoH clients
   MUST wait for a server response to a command before sending a
   subsequent command.

   A general state machine for an EPP server is described in Section 2
   of [RFC5730].  A general client-server message exchange using HTTP is
   illustrated in Figure 1.

                          Client                  Server
                     |                                     |
                     |             GET Server URL          |
                     | >>------------------------------->> |
                     |                                     |
                     |             Send Greeting           |
                     | <<-------------------------------<< |
                     |                                     |
                     |             POST <login>            |
                     | >>------------------------------->> |
                     |                                     |
                     |             Send Response           |
                     | <<-------------------------------<< |
                     |                                     |
                     |            POST Command X           |
                     | >>------------------------------->> |
                     |                                     |
                     |            Send Response X          |
                     | <<-------------------------------<< |
                     |                                     |
                     |            POST Command Y           |
                     | >>------------------------------->> |
                     |                                     |
                     |            Send Response Y          |
                     | <<-------------------------------<< |
                     |                  .                  |
                                        .
                                        .
                     |            POST <logout>            |
                     | >>------------------------------->> |
                     |                                     |
                     |            Send Response            |
                     | <<-------------------------------<< |

                  Figure 1: HTTP Client-Server Message Exchange

   The EPP server MUST follow the "EPP Server State Machine" procedure
   described in [RFC5730].




Loffredo, et al.          Expires 28 March 2025                 [Page 5]

Internet-Draft               EPP over HTTPS               September 2024


5.  Transport Considerations

   Section 2.1 of [RFC5730] describes considerations to be addressed by
   protocol transport mappings.  This document addresses each of those
   considerations using a combination of features of the HTTP protocol
   itself and features of this document.

   *  Command Order: Section 4 includes a requirement for ordered
      message delivery.

   *  Session Mapping: EPP session management is described in Section 3
      of this document.

   *  Stateful Nature: Achieving the stateful nature of EPP is described
      in Section 3.

   *  Frame Data Units: Section 4 of this document describes how each
      EPP command is framed within the content of HTTP requests and
      responses.

   *  Congestion Avoidance: Section 3.9.3 of [RFC8095] confirms
      congestion avoidance as a feature of HTTP.

   *  Reliability: Section 3.9.3 of [RFC8095] confirms reliable message
      delivery as a feature of HTTP.

   *  Pipelining: Section 4 of this document stipulates that command
      pipelining must not be used in EoH.

6.  IANA Considerations

   This specification does not request any actions by IANA.

7.  Implementation Status

   Note to RFC Editor: Please remove this section and the reference to
   [RFC7942] before publication.














Loffredo, et al.          Expires 28 March 2025                 [Page 6]

Internet-Draft               EPP over HTTPS               September 2024


   This section records the status of known implementations of the
   protocol defined by this specification at the time of posting of this
   Internet-Draft, and is based on a proposal described in [RFC7942].
   The description of implementations in this section is intended to
   assist the IETF in its decision processes in progressing drafts to
   RFCs.  Please note that the listing of any individual implementation
   here does not imply endorsement by the IETF.  Furthermore, no effort
   has been spent to verify the information presented here that was
   supplied by IETF contributors.  This is not intended as, and must not
   be construed to be, a catalog of available implementations or their
   features.  Readers are advised to note that other implementations may
   exist.

   According to [RFC7942], "this will allow reviewers and working groups
   to assign due consideration to documents that have the benefit of
   running code, which may serve as evidence of valuable experimentation
   and feedback that have made the implemented protocols more mature.
   It is up to the individual working groups to use this information as
   they see fit".

7.1.  Verisign EPP SDK

   Organization: Verisign Inc.

   Name: Verisign EPP SDK

   Description: The Verisign EPP SDK includes both a full client
   implementation and a full server stub implementation of draft-
   loffredo-regext-epp-over-http.  Both HTTP/1.1 and HTTP/2 were
   implemented, but HTTP/3 was not due to the lack of support of the
   underlying library.

   Level of maturity: Development

   Coverage: All aspects of the protocol are implemented with HTTP/1.1
   and HTTP/2.

   Licensing: GNU Lesser General Public License

   Contact: jgould@verisign.com

   URL: https://www.verisign.com/en_US/channel-resources/domain-
   registry-products/epp-sdks








Loffredo, et al.          Expires 28 March 2025                 [Page 7]

Internet-Draft               EPP over HTTPS               September 2024


8.  Security Considerations

   Since client credentials are included in the EPP <login> command,
   HTTPS (Section 4.2.2 of [RFC9110]) MUST be used to protect them from
   disclosure while in transit.  HTTPS indicates that TLS is being used
   to secure the HTTP connection between the client and server.
   Transferring over TLS also prevents sniffing the HTTP session
   identifier and, consequently, impersonating a client to perform
   actions on registrars' objects.  Servers are REQUIRED to support TLS
   1.2 [RFC8446][RFC9155] or higher.

   Servers are RECOMMENDED to implement additional measures to verify
   the client.  These measures include IP allow-listing and locking the
   HTTP session identifier to the client's IP address.

   HTTP session identifiers SHOULD be randomly generated to mitigate the
   risk of obtaining a valid one through a brute-force search.  A HTTP
   session identifier SHOULD be at least 128 bits or 16 bytes long.  An
   example of a reliable HTTP session identifier is the Universally
   Unique Identifier (UUID).  Servers MAY limit the lifetime of active
   sessions to avoid them being exchanged for a long time.

   The following measures MAY also be taken to control cookies usage:

   *  Restricting their scope through the "Domain" and "Path" attributes

   *  Limiting their lifetime through the "Max-Age" and "Expire"
      attributes

   Other attributes that are normally used to secure the cookies and
   prevent them to be accessed by unintended parties or scripts, such as
   "HttpOnly" and "Secure", are meaningless in this context.  Finally,
   servers are RECOMMENDED to perform additional checks to limit the
   rate of open EPP sessions and HTTP connections to mitigate the risk
   of congestion of requests.  Here again, IP allow-listing could also
   be implemented to prevent DDoS attacks.

   As a further measure to enforce the security, servers MUST require
   clients to present a digital certificate.  Clients who possess and
   present a valid X.509 digital certificate, issued by a recognized
   Certification Authority (CA), could be identified and authenticated
   by a server who trusts the corresponding CA.  This certificate-based
   mechanism is supported by HTTPS and can be used with EPP over HTTP.

   If the EPP server is configured as a load balancer routing the
   requests to a pool of backend servers, some of the aforementioned
   checks SHOULD be implemented on the load balancer side.




Loffredo, et al.          Expires 28 March 2025                 [Page 8]

Internet-Draft               EPP over HTTPS               September 2024


9.  Acknowledgements

   The authors wish to acknowledge the input from the .IT technical
   team.

10.  Normative References

   [BCP14]    Best Current Practice 14,
              <https://www.rfc-editor.org/info/bcp14>.
              At the time of writing, this BCP comprises the following:

              Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

              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>.

   [RFC5730]  Hollenbeck, S., "Extensible Provisioning Protocol (EPP)",
              STD 69, RFC 5730, DOI 10.17487/RFC5730, August 2009,
              <https://www.rfc-editor.org/info/rfc5730>.

   [RFC6265]  Barth, A., "HTTP State Management Mechanism", RFC 6265,
              DOI 10.17487/RFC6265, April 2011,
              <https://www.rfc-editor.org/info/rfc6265>.

   [RFC7942]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
              Code: The Implementation Status Section", BCP 205,
              RFC 7942, DOI 10.17487/RFC7942, July 2016,
              <https://www.rfc-editor.org/info/rfc7942>.

   [RFC8095]  Fairhurst, G., Ed., Trammell, B., Ed., and M. Kuehlewind,
              Ed., "Services Provided by IETF Transport Protocols and
              Congestion Control Mechanisms", RFC 8095,
              DOI 10.17487/RFC8095, March 2017,
              <https://www.rfc-editor.org/info/rfc8095>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [RFC9110]  Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
              Ed., "HTTP Semantics", STD 97, RFC 9110,
              DOI 10.17487/RFC9110, June 2022,
              <https://www.rfc-editor.org/info/rfc9110>.




Loffredo, et al.          Expires 28 March 2025                 [Page 9]

Internet-Draft               EPP over HTTPS               September 2024


   [RFC9112]  Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
              Ed., "HTTP/1.1", STD 99, RFC 9112, DOI 10.17487/RFC9112,
              June 2022, <https://www.rfc-editor.org/info/rfc9112>.

   [RFC9113]  Thomson, M., Ed. and C. Benfield, Ed., "HTTP/2", RFC 9113,
              DOI 10.17487/RFC9113, June 2022,
              <https://www.rfc-editor.org/info/rfc9113>.

   [RFC9114]  Bishop, M., Ed., "HTTP/3", RFC 9114, DOI 10.17487/RFC9114,
              June 2022, <https://www.rfc-editor.org/info/rfc9114>.

   [RFC9155]  Velvindron, L., Moriarty, K., and A. Ghedini, "Deprecating
              MD5 and SHA-1 Signature Hashes in TLS 1.2 and DTLS 1.2",
              RFC 9155, DOI 10.17487/RFC9155, December 2021,
              <https://www.rfc-editor.org/info/rfc9155>.

Appendix A.  Change History

A.1.  Change from 02 to 03

   1.  Added Dan Keathley and James Gould as co-authors.

A.2.  Change from 03 to 04

   1.  Clarified the difference between an EoH connection and an EPP
       session.
   2.  Added inclusion of the "Content-Type" header in every request and
       response except for the initial GET establishing the EoH
       connection.
   3.  Revised the Security Considerations section.

A.3.  Change from 04 to 05

   1.  Added the Implementation Status section with the Verisign EPP SDK
       implementation.
   2.  Removed the "Internationalization Considerations" section and
       added the EoH character encoding matching the EPP XML character
       encoding for the EPP Greeting, the EPP commands, and the EPP
       responses.
   3.  Added inclusion of the "Cache-Control" and "Expires" headers for
       the the EPP Greeting, the EPP commands, and the EPP responses.

Authors' Addresses








Loffredo, et al.          Expires 28 March 2025                [Page 10]

Internet-Draft               EPP over HTTPS               September 2024


   Mario Loffredo
   IIT-CNR/Registro.it
   Via Moruzzi,1
   56124 Pisa
   Italy
   Email: mario.loffredo@iit.cnr.it
   URI:   https://www.iit.cnr.it


   Lorenzo Luconi Trombacchi
   IIT-CNR/Registro.it
   Via Moruzzi,1
   56124 Pisa
   Italy
   Email: lorenzo.luconi@iit.cnr.it
   URI:   https://www.iit.cnr.it


   Maurizio Martinelli
   IIT-CNR/Registro.it
   Via Moruzzi,1
   56124 Pisa
   Italy
   Email: maurizio.martinelli@iit.cnr.it
   URI:   https://www.iit.cnr.it


   Daniel Keathley
   VeriSign, Inc.
   12061 Bluemont Way
   Reston, VA 20190
   United States of America
   Email: dkeathley@verisign.com
   URI:   http://www.verisigninc.com


   James Gould
   VeriSign, Inc.
   12061 Bluemont Way
   Reston, VA 20190
   United States of America
   Email: jgould@verisign.com
   URI:   http://www.verisigninc.com








Loffredo, et al.          Expires 28 March 2025                [Page 11]
