TSVWG                                                           J. Touch
Internet Draft                                    Independent Consultant
Updates: 4727
Intended status: Standards Track                      September 18, 2022
Expires: March 2023


                         User Ports for Experiments
                      draft-ietf-tsvwg-usr-exp-00.txt


Abstract

   This document defines user ports for experiments using transport
   protocols. It describes the use of experiment identifiers to enable
   shared use of these user ports, as well as updating the use of
   system ports for experiments in the same manner.

Status of this Memo

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   (https://trustee.ietf.org/license-info) in effect on the date of
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   respect to this document.

Table of Contents


   1. Introduction.................................................. 2
   2. User Ports for Experiments.................................... 3
   3. Security Considerations....................................... 4
   4. IANA Considerations........................................... 5
   5. References.................................................... 6
      5.1. Normative References..................................... 6
      5.2. Informative References................................... 6
   6. Acknowledgments............................................... 7

1. Introduction

   Various network codepoints have been allocated for experimental use,
   including those for IPv4 [RFC791], IPv6 [RFC8200], ICMPv4 [RFC792],
   ICMPv6 [RFC4443], UDP [RFC768], and TCP [RFC9293]. These include
   transport protocol port numbers 1021 and 1022, using the service
   names "EXP1" and "EXP2" [RFC4727].

   There has always been an expectation that experiments needing
   privileged (system) ports use these assignments and unprivileged
   ports use those from the dynamic range [RFC6335][RFC7605]. However,
   dynamic ports can be difficult to reserve in some systems or blocked
   from traversing some firewalls. As a consequence, there is a need
   for non-privileged, non-dynamic ports - i.e., user ports - for
   experiments.

   This document reserves user ports experimentation and describes the
   use of experiment identifiers to differentiate shared use of these
   ports for concurrent experiments.

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
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.





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3. User Ports for Experiments

   The system, user, and dynamic ranges vary in their properties
   [RFC7605]. System ports often include privileged access, sometimes
   known as 'root'. Dynamic ports are used as client ports when
   establishing associations with services on registered ports. User
   ports have neither privilege nor the risk of use by other
   connections. User ports are also more likely to allow configuration
   to pass through firewalls, where system and dynamic ports can be
   difficult to 'un-block'.

   This document registers USR-EXP1 and USR-EXP2 for user port
   experiments, using port numbers #UPORT1 and #UPORT2. These ports are
   assigned from the user range, allowing non-privileged experiments
   without the need to use ports from the dynamic range.

   This document also creates a registry for port experiment
   identifiers (PExIDs), in the same manner as those created for shared
   TCP option experiments [RFC6994]. Experimenters are encouraged to
   register PExIDs with IANA and to include them in at the beginning of
   their transport data, i.e., at the front of each separate message or
   byte stream, in network standard byte order. The use of PExIDs helps
   differentiate experiments without the need for additional port
   assignments.

   This document also encourages the use of these PExIDs for
   experiments using existing experiment ports, i.e., system ports EXP1
   and EXP2.

   PExIDs differentiate experiments but are not intended to be specific
   to a given experiment port, whether system or user, so a single
   registration is used for all experiment ports. It is the
   responsibility of the experimenter to determine which port(s) each
   experiment uses.

4. Using PExIDs in Transport Protocols

   PExIDs differentiate use of the experiment transport ports, both for
   TCP as previously assigned [RFC4727] and for other transports as
   defined in this document.

   PExIDs are intended appear first in each independent transport data.
   It is intended to appear in network-standard byte order.

   For connection-oriented transport protocols, such as TCP [RFC9293],
   SCTP [RFC9260], and DCCP [RFC4336], the PExID is typically sent once
   for each connection and echoed upon receipt, enabling both ends to


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   confirm the experiment for the connection's socket pair. That socket
   pair is then associated with the experiment identified by that PExID
   for the duration of the connection.

   For connectionless transport protocols, such as UDP [RFC768], the
   PExID is typically included in every message in both directions.

   In most cases, the PExID is sent as user data. SCTP is an exception,
   because of its Payload Protocol Identifier (PPID), as discussed
   further in Section 5.

   Two endpoints can engage in multiple experiments using the same
   experimental port number and transport protocol. In such cases,
   users are expected to support demultiplexing of those different
   experiments using the PExID.

5. SCTP

   SCTP includes a Payload Protocol Identifier (PPID), which identifies
   the information within each user message. PPIDs are assigned on a
   first-come, first-served (FCFS) basis and are abundant (2^32
   codepoints), so there is no need for a separate experimental-use
   PPID. The PExID differentiate shared use of the user experimental
   port number and thus serves a different purpose than the PPID; both
   can be used together or separately for SCTP.

   Because SCTP supports multiple concurrent streams, it is useful for
   experiments to be identified in a particular stream before
   proceeding with other streams, to avoid excessive buffering. For
   SCTP, users SHOULD send the PExID reliably as the first chunk in
   stream 0 (the default stream) and SHOULD avoid transmitting chunks
   on other streams until that chunk is echoed in return. This chunk
   SHOULD use the PPID of #PPID1 assigned for this purpose. That PPID
   chunk MUST contain only the PExID in network standard byte order.

6. Security Considerations

   The creation of new ports for experiment purposes does not create
   any new security considerations. At best, it potentially reduces the
   use of privileged system ports for such experiments, which avoids
   the associated risk of unnecessary privileged access.

   Experimenters are encouraged to include security in any new
   experiment, regardless of port (per Section 7.4 of [RFC7605]).





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7. IANA Considerations

   This document hereby requests the assignment of two user ports for
   experimental purposes below. IANA is asked to replace instances of
   #UPORT1 and #UPORT2 throughout this document based on the actual
   allocation. This paragraph is intended to be removed prior to final
   publication.

   This document also hearby requests the assignment of the SCTP PPID
   "PEXID" for use in association with these port numbers. IANA is
   asked to replace instances of #PPID1 throughout this document based
   on the actual allocation. This paragraph is intended to be removed
   prior to final publication.

   IANA has assigned the following user ports for experiments:

      USR-EXP1 #UPORT1 (desired port 1031) all transports

      USR-EXP2 #UPORT2 (desired port 1032) all transports

   IANA has assigned the following SCTP Payload Protocol Identifier
   (PPID) for experiments associated with these port numbers:

      SCTP PPID #PPID1

   This document directs IANA to create a "Port Experimental Option
   Experiment Identifiers (PExIDs)" registry.  The registry records 32-
   bit PExIDs, consisting of a brief description, document pointer if
   available, assignee name, and e-mail contact for each entry. Once
   registered, PExIDs can be used with either the system (EXP1, EXP2)
   or user (USR-EXP1, USR-EXP2) ports and with any transport protocol.

   Entries are assigned on a First Come, First Served (FCFS) basis
   [RFC8126]. IANA will also record known duplicate uses to assist the
   community in both debugging assigned uses as well as correcting
   unauthorized duplicate uses.

   IANA should impose no requirements on making a registration request
   other than indicating the desired codepoint and providing a point of
   contact. A short description or acronym for the use is desired but
   not required.








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8. References

8.1. Normative References

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

   [RFC4727] Fenner, B., "Experimental Values in IPv4, IPv6, ICMPv4,
             ICMPv6, UDP, and TCP Headers," RFC 4727, Nov. 2026.

   [RFC6994] Touch, J., "Shared Use of Experimental TCP Options," RFC
             6994, Aug. 2013.

   [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
             Writing an IANA Considerations Section in RFCs", BCP 26,
             RFC 8126, June 2017.

   [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
             2119 Key Words", BCP 14, RFC 8174, May 2017.

   [RFC9260] Stewart, R. (Ed.), "Stream Control Transmission Protocol,"
             RFC 9260, Sep. 2007.

8.2. Informative References

   [RFC768]  Postel, J., "User Datagram Protocol," STD 6, RFC 768, Aug.
             1980.

   [RFC791]  Postel, J., "Internet Protocol," STD 5, RFC 791, Sep.
             1981.

   [RFC792]  Postel, J., "Internet Control Message Protocol," STD 5,
             RFC 792, Sep. 1981.

   [RFC4336] Floyd, S., Handley, M., and E. Kohler, "Problem Statement
             for the Datagram Congestion Control Protocol (DCCP)," RFC
             4336, Mar. 2006.

   [RFC4443] Conta, A., Deering, S., and M. Gupta, (Ed.), "Internet
             Control Message Protocol (ICMPv6) for the Internet
             Protocol Version 6 (IPv6) Specification," STD 89, RFC
             4443, Mar. 2006.







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   [RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
             Cheshire, "Internet Assigned Numbers Authority (IANA)
             Procedures for the Management of the Service Name and
             Transport Protocol Port Number Registry," BCP 165, RFC
             6335, Aug. 2011.

   [RFC7605] Touch, J., "Recommendations on Using Assigned Transport
             Port Numbers," BCP 165, RFC 7605, Aug. 2015.

   [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
             (IPv6) Specification," STD 86, RFC 8200, Jul. 2017.

   [RFC9293] Eddy, W. (Ed.), "Transmission Control Protocol (TCP), Aug.
             STD 7, RFC 9293, 2022.

9. Acknowledgments

   This document was prepared using 2-Word-v2.0.template.dot.

Authors' Addresses

   Joe Touch
   Manhattan Beach, CA 90266 USA
   Phone: +1 (310) 560-0334
   Email: touch@strayalpha.com
























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