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Versions: 00 01 02

NETCONF Working Group                                          K. Watsen
Internet-Draft                                           Watsen Networks
Intended status: Standards Track                           April 7, 2019
Expires: October 9, 2019


             YANG Groupings for TCP Clients and TCP Servers
               draft-kwatsen-netconf-tcp-client-server-01

Abstract

   This document defines two YANG modules: the first defines a grouping
   for configuring a generic TCP client, and the second defines a
   grouping for configuring a generic TCP server.  It is intended that
   these groupings will be used by applications using the TCP protocol.

Editorial Note (To be removed by RFC Editor)

   This draft contains many placeholder values that need to be replaced
   with finalized values at the time of publication.  This note
   summarizes all of the substitutions that are needed.  No other RFC
   Editor instructions are specified elsewhere in this document.

   Artwork in this document contains placeholder values for the date of
   publication of this draft.  Please apply the following replacement:

   o  "2019-04-07" --> the publication date of this draft

   The following Appendix section is to be removed prior to publication:

   o  Appendix A.  Change Log

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 October 9, 2019.



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Copyright Notice

   Copyright (c) 2019 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
   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 Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  The TCP Client Model  . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .   3
     3.2.  Example Usage . . . . . . . . . . . . . . . . . . . . . .   3
     3.3.  YANG Module . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  The TCP Server Model  . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .   7
     4.2.  Example Usage . . . . . . . . . . . . . . . . . . . . . .   7
     4.3.  YANG Module . . . . . . . . . . . . . . . . . . . . . . .   8
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
     6.1.  The IETF XML Registry . . . . . . . . . . . . . . . . . .  12
     6.2.  The YANG Module Names Registry  . . . . . . . . . . . . .  12
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   This document defines two YANG 1.1 [RFC7950] modules: the first
   defines a grouping for configuring a generic TCP client, and the
   second defines a grouping for configuring a generic TCP server.  It
   is intended that these groupings will be used by applications using
   the TCP protocol.  For instance, these groupings could help define
   the configuration module for an SSH, TLS, or HTTP based application.







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2.  Terminology

   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.

3.  The TCP Client Model

3.1.  Tree Diagram

   This section provides a tree diagram [RFC8340] for the "ietf-tcp-
   client" module.

   module: ietf-tcp-client

     grouping tcp-client-grouping
       +-- tcp-client-parameters
          +-- remote-address    inet:host
          +-- remote-port?      inet:port-number
          +-- local-address?    inet:ip-address
          +-- local-port?       inet:port-number
          +-- keepalives! {tcp-client-keepalives}?
             +-- idle-time         uint16
             +-- max-probes?       uint16
             +-- probe-interval?   uint16

3.2.  Example Usage

   This section presents an example showing the tcp-client-grouping
   populated with some data.

   <tcp-client xmlns="urn:ietf:params:xml:ns:yang:ietf-tcp-client">
     <tcp-client-parameters>
       <remote-address>www.example.com</remote-address>
       <remote-port>443</remote-port>
       <local-address>0.0.0.0</local-address>
       <local-port>0</local-port>
       <keepalives>
         <idle-time>15</idle-time>
         <max-probes>3</max-probes>
         <probe-interval>30</probe-interval>
       </keepalives>
     </tcp-client-parameters>
   </tcp-client>





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3.3.  YANG Module

   This YANG module has normative references to [RFC6991].

   <CODE BEGINS> file "ietf-tcp-client@2019-04-07.yang"
   module ietf-tcp-client {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-tcp-client";
     prefix tcpc;

     import ietf-inet-types {
       prefix inet;
       reference
         "RFC 6991: Common YANG Data Types";
     }

     organization
       "IETF NETCONF (Network Configuration) Working Group";

     contact
       "WG Web:   <http://datatracker.ietf.org/wg/netconf/>
        WG List:  <mailto:netconf@ietf.org>
        Author:   Kent Watsen <mailto:kent+ietf@watsen.net>";

     description
       "This module defines reusable groupings for TCP clients that
        can be used as a basis for specific TCP client instances.

        Copyright (c) 2019 IETF Trust and the persons identified
        as authors of the code. All rights reserved.

        Redistribution and use in source and binary forms, with
        or without modification, is permitted pursuant to, and
        subject to the license terms contained in, the Simplified
        BSD License set forth in Section 4.c of the IETF Trust's
        Legal Provisions Relating to IETF Documents
        (https://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC XXXX
        (https://www.rfc-editor.org/info/rfcXXXX); see the RFC
        itself for full legal notices.;

        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 (RFC 2119)
        (RFC 8174) when, and only when, they appear in all
        capitals, as shown here.";



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     revision 2019-04-07 {
       description
         "Initial version";
       reference
         "RFC XXXX: YANG Groupings for TCP Clients and TCP Servers";
     }

     // Features

     feature tcp-client-keepalives {
       description
         "Per socket TCP keepalive parameters are configurable for
          TCP clients on the server implementing this feature.";
     }

     // Groupings

     grouping tcp-client-grouping {
       description
         "A reusable grouping for configuring a TCP client.";
       container tcp-client-parameters {
         description
           "A container to hold TCP client configuration.";
         leaf remote-address {
           type inet:host;
           mandatory true;
           description
             "The IP address or hostname of the remote peer to
              establish a connection with.  If a domain name is
              configured, then the DNS resolution should happen on
              each connection attempt.  If the the DNS resolution
              results in multiple IP addresses, the IP addresses
              are tried according to local preference order until
              a connection has been established or until all IP
              addresses have failed.";
         }
         leaf remote-port {
           type inet:port-number;
           default "0";
           description
             "The IP port number for the remote peer to establish a
              connection with.  An invalid default value (0) is used
              (instead of 'mandatory true') so that as application
              level data model may 'refine' it with an application
              specific default port number value.";
         }
         leaf local-address {
           type inet:ip-address;



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           description
             "The local IP address/interface (VRF?) to bind to for when
              connecting to the remote peer.  INADDR_ANY ('0.0.0.0') or
              INADDR6_ANY ('0:0:0:0:0:0:0:0' a.k.a. '::') MAY be used to
              explicitly indicate the implicit default, that the server
              can bind to any IPv4 or IPv6 addresses, respectively.";
         }
         leaf local-port {
           type inet:port-number;
           default "0";
           description
             "The local IP port number to bind to for when connecting
              to the remote peer.  The port number '0', which is the
              default value, indicates that any available local port
              number may be used.";
         }
         container keepalives {
           if-feature "tcp-client-keepalives";
           presence "Indicates that keepalives are enabled.";
           description
             "Configures the keep-alive policy, to proactively test the
              aliveness of the TCP server.  Not all clients will use
              all the values, based on capabilities of the underlying
              operating system.  An unresponsive TCP server is dropped
              after approximately (idle-time * 60) + (max-probes *
              probe-interval) seconds.";
           leaf idle-time {
             type uint16 {
               range "1..max";
             }
             units "minutes";
             mandatory true;
             description
               "Sets the amount of time in minutes after which if
                no data has been received from the TCP server, a
                TCP-level probe message will be sent to test the
                aliveness of the TCP server.";
           }
           leaf max-probes {
             type uint16 {
               range "1..max";
             }
             description
               "Sets the maximum number of sequential keep-alive
                probes that can fail to obtain a response from the
                TCP server before assuming the TCP server is no
                longer alive.  If no value is specified, then the
                operating system provided default value is used.";



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           }
           leaf probe-interval {
             type uint16 {
               range "1..max";
             }
             units "seconds";
             description
               "Sets the time interval between failed probes.  If no
                value is specified, then the operating system provided
                default value is used.";
           }
         } // container keepalives
       } // container tcp-client-parameters
     } // grouping tcp-client-grouping
   }
   <CODE ENDS>

4.  The TCP Server Model

4.1.  Tree Diagram

   This section provides a tree diagram [RFC8340] for the "ietf-tcp-
   server" module.

   module: ietf-tcp-server

     grouping tcp-server-grouping
       +-- tcp-server-parameters
          +-- local-address    inet:ip-address
          +-- local-port?      inet:port-number
          +-- keepalives! {tcp-server-keepalives}?
             +-- idle-time         uint16
             +-- max-probes?       uint16
             +-- probe-interval?   uint16

4.2.  Example Usage

   This section presents an example showing the tcp-server-grouping
   populated with some data.












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   <tcp-server xmlns="urn:ietf:params:xml:ns:yang:ietf-tcp-server">
     <tcp-server-parameters>
       <local-address>10.20.30.40</local-address>
       <local-port>7777</local-port>
       <keepalives>
         <idle-time>15</idle-time>
         <max-probes>3</max-probes>
         <probe-interval>30</probe-interval>
       </keepalives>
     </tcp-server-parameters>
   </tcp-server>

4.3.  YANG Module

   This YANG module has normative references to [RFC6991].

   <CODE BEGINS> file "ietf-tcp-server@2019-04-07.yang"
   module ietf-tcp-server {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-tcp-server";
     prefix tcps;

     import ietf-inet-types {
       prefix inet;
       reference
         "RFC 6991: Common YANG Data Types";
     }

     organization
       "IETF NETCONF (Network Configuration) Working Group";

     contact
       "WG Web:   <http://datatracker.ietf.org/wg/netconf/>
        WG List:  <mailto:netconf@ietf.org>
        Author:   Kent Watsen <mailto:kent+ietf@watsen.net>";

     description
       "This module defines reusable groupings for TCP servers that
        can be used as a basis for specific TCP server instances.

        Copyright (c) 2019 IETF Trust and the persons identified
        as authors of the code. All rights reserved.

        Redistribution and use in source and binary forms, with
        or without modification, is permitted pursuant to, and
        subject to the license terms contained in, the Simplified
        BSD License set forth in Section 4.c of the IETF Trust's
        Legal Provisions Relating to IETF Documents



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        (https://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC XXXX
        (https://www.rfc-editor.org/info/rfcXXXX); see the RFC
        itself for full legal notices.;

        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 (RFC 2119)
        (RFC 8174) when, and only when, they appear in all
        capitals, as shown here.";

     revision 2019-04-07 {
       description
         "Initial version";
       reference
         "RFC XXXX: YANG Groupings for TCP Clients and TCP Servers";
     }

     // Features

     feature tcp-server-keepalives {
       description
         "Per socket TCP keepalive parameters are configurable for
          TCP servers on the server implementing this feature.";
     }

     // Groupings

     grouping tcp-server-grouping {
       description
         "A reusable grouping for configuring a TCP server.";
       container tcp-server-parameters {
         description
           "A container to hold TCP server configuration.";
         leaf local-address {
           type inet:ip-address;
           mandatory true;
           description
             "The local IP address to listen on for incoming
              TCL client connections.  INADDR_ANY (0.0.0.0) or
              INADDR6_ANY (0:0:0:0:0:0:0:0 a.k.a. ::) MUST be
              used when the server is to listen on all IPv4 or
              IPv6 addresses, respectively.";
         }
         leaf local-port {
           type inet:port-number;



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           default "0";
           description
             "The local port number to listen on for incoming TCP
              client connections.  An invalid default value (0)
              is used (instead of 'mandatory true') so that an
              application level data model may 'refine' it with
              an application specific default port number value.";
         }
         container keepalives {
           if-feature "tcp-server-keepalives";
           presence "Indicates that keepalives are enabled.";
           description
             "Configures the keep-alive policy, to proactively test the
              aliveness of the TCP client.  Not all servers will use
              all the values, based on capabilities of the underlying
              operating system.  An unresponsive TCP client is dropped
              after approximately (idle-time * 60) + (max-probes *
              probe-interval) seconds.";
           leaf idle-time {
             type uint16 {
               range "1..max";
             }
             units "minutes";
             mandatory true;
             description
               "Sets the amount of time in minutes after which if no
                data has been received from the TCP client, a TCP-level
                probe message will be sent to test the aliveness of
                the TCP client.";
           }
           leaf max-probes {
             type uint16 {
               range "1..max";
             }
             description
               "Sets the maximum number of sequential keep-alive
                probes that can fail to obtain a response from the
                TCP client before assuming the TCP client is no
                longer alive.  If no value is specified, then the
                operating system provided default value is used.";
           }
           leaf probe-interval {
             type uint16 {
               range "1..max";
             }
             units "seconds";
             description
               "Sets the time interval between failed probes.  If no



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                value is specified, then the operating system provided
                default value is used.";
           }
         } // container keepalives
       } // container tcp-server-parameters
     }
   }
   <CODE ENDS>

5.  Security Considerations

   The YANG modules defined in this document are designed to be accessed
   via YANG based management protocols, such as NETCONF [RFC6241] and
   RESTCONF [RFC8040].  Both of these protocols have mandatory-to-
   implement secure transport layers (e.g., SSH, TCP) with mutual
   authentication.

   The NETCONF access control model (NACM) [RFC8341] provides the means
   to restrict access for particular users to a pre-configured subset of
   all available protocol operations and content.

   Since the modules defined in this document only define groupings,
   these considerations are primarily for the designers of other modules
   that use these groupings.

   There are a number of data nodes defined in the YANG modules that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., edit-config)
   to these data nodes without proper protection can have a negative
   effect on network operations.  These are the subtrees and data nodes
   and their sensitivity/vulnerability:

      None of the writable/creatable/deletable data nodes           in
   the YANG modules defined in this document are considered more
              sensitive or vulnerable then standard configuration.

   Some of the readable data nodes in the YANG modules may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.  These are the subtrees and data
   nodes and their sensitivity/vulnerability:

      None of the readable data nodes in the YANG modules
   defined in this document are considered more sensitive or vulnerable
              then standard configuration.





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   This document does not define any RPC actions and hence this section
   does not consider the security of RPCs.

6.  IANA Considerations

6.1.  The IETF XML Registry

   This document registers two URIs in the "ns" subregistry of the IETF
   XML Registry [RFC3688].  Following the format in [RFC3688], the
   following registrations are requested:

      URI: urn:ietf:params:xml:ns:yang:ietf-tcp-client
      Registrant Contact: The NETCONF WG of the IETF.
      XML: N/A, the requested URI is an XML namespace.

      URI: urn:ietf:params:xml:ns:yang:ietf-tcp-server
      Registrant Contact: The NETCONF WG of the IETF.
      XML: N/A, the requested URI is an XML namespace.

6.2.  The YANG Module Names Registry

   This document registers two YANG modules in the YANG Module Names
   registry [RFC6020].  Following the format in [RFC6020], the following
   registrations are requested:

      name:         ietf-tcp-client
      namespace:    urn:ietf:params:xml:ns:yang:ietf-tcp-client
      prefix:       tcpc
      reference:    RFC XXXX

      name:         ietf-tcp-server
      namespace:    urn:ietf:params:xml:ns:yang:ietf-tcp-server
      prefix:       tcps
      reference:    RFC XXXX

7.  References

7.1.  Normative References

   [RFC2119]  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>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.



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   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8174]  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>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

7.2.  Informative References

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

Author's Address

   Kent Watsen
   Watsen Networks

   EMail: kent+ietf@watsen.net









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