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Versions: (draft-bierman-netmod-system-mgmt) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16

Network Working Group                                         A. Bierman
Internet-Draft                                                 YumaWorks
Intended status: Standards Track                            M. Bjorklund
Expires: November 15, 2014                                Tail-f Systems
                                                            May 14, 2014


                A YANG Data Model for System Management
                    draft-ietf-netmod-system-mgmt-16

Abstract

   This document defines a YANG data model for the configuration and
   identification of some common system properties within a device
   containing a NETCONF server.  This includes data node definitions for
   system identification, time-of-day management, user management, DNS
   resolver configuration, and some protocol operations for system
   management.

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 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 November 15, 2014.

Copyright Notice

   Copyright (c) 2014 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
   (http://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



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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
     1.2.  Tree Diagrams  . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Objectives . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  System Identification  . . . . . . . . . . . . . . . . . .  5
     2.2.  System Time Management . . . . . . . . . . . . . . . . . .  5
     2.3.  User Authentication  . . . . . . . . . . . . . . . . . . .  5
     2.4.  DNS Resolver . . . . . . . . . . . . . . . . . . . . . . .  5
     2.5.  System Control . . . . . . . . . . . . . . . . . . . . . .  6
   3.  System Data Model  . . . . . . . . . . . . . . . . . . . . . .  7
     3.1.  System Identification  . . . . . . . . . . . . . . . . . .  7
     3.2.  System Time Management . . . . . . . . . . . . . . . . . .  7
     3.3.  DNS Resolver Model . . . . . . . . . . . . . . . . . . . .  8
     3.4.  RADIUS Client Model  . . . . . . . . . . . . . . . . . . .  8
     3.5.  User Authentication Model  . . . . . . . . . . . . . . . .  9
       3.5.1.  SSH Public Key Authentication  . . . . . . . . . . . .  9
       3.5.2.  Local User Password Authentication . . . . . . . . . . 10
       3.5.3.  RADIUS Password Authentication . . . . . . . . . . . . 10
     3.6.  System Control . . . . . . . . . . . . . . . . . . . . . . 10
   4.  Relationship to the SNMPv2-MIB . . . . . . . . . . . . . . . . 11
   5.  IANA Crypt Hash YANG module  . . . . . . . . . . . . . . . . . 12
   6.  System YANG module . . . . . . . . . . . . . . . . . . . . . . 15
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 33
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 34
   9.  Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 36
     9.1.  00-01  . . . . . . . . . . . . . . . . . . . . . . . . . . 36
     9.2.  01-02  . . . . . . . . . . . . . . . . . . . . . . . . . . 36
     9.3.  02-03  . . . . . . . . . . . . . . . . . . . . . . . . . . 36
     9.4.  03-04  . . . . . . . . . . . . . . . . . . . . . . . . . . 36
     9.5.  04-05  . . . . . . . . . . . . . . . . . . . . . . . . . . 36
     9.6.  05-06  . . . . . . . . . . . . . . . . . . . . . . . . . . 37
     9.7.  06-07  . . . . . . . . . . . . . . . . . . . . . . . . . . 37
     9.8.  07-08  . . . . . . . . . . . . . . . . . . . . . . . . . . 38
     9.9.  08-09  . . . . . . . . . . . . . . . . . . . . . . . . . . 38
     9.10. 09-10  . . . . . . . . . . . . . . . . . . . . . . . . . . 38
     9.11. 11-12  . . . . . . . . . . . . . . . . . . . . . . . . . . 38
     9.12. 13-14  . . . . . . . . . . . . . . . . . . . . . . . . . . 38
     9.13. 14-15  . . . . . . . . . . . . . . . . . . . . . . . . . . 38
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 39
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 39
     10.2. Informative References . . . . . . . . . . . . . . . . . . 40
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 41



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1.  Introduction

   This document defines a YANG [RFC6020] data model for the
   configuration and identification of some common properties within a
   device containing a NETCONF server.

   Devices that are managed by NETCONF and perhaps other mechanisms have
   common properties that need to be configured and monitored in a
   standard way.

   The "ietf-system" YANG module defined in this document provides the
   following features:

   o  system identification configuration and monitoring

   o  system time-of-day configuration and monitoring

   o  user authentication configuration

   o  local users configuration

   o  DNS resolver configuration

   o  system control operations (shutdown, restart, setting time)

1.1.  Terminology

   The keywords "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].

   The following terms are defined in [RFC6241] and are not redefined
   here:

   o  client

   o  configuration data

   o  server

   o  state data

1.2.  Tree Diagrams

   A simplified graphical representation of the data model is used in
   this document.  The meaning of the symbols in these diagrams is as
   follows:



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   o  Brackets "[" and "]" enclose list keys.

   o  Abbreviations before data node names: "rw" means configuration
      (read-write) and "ro" state data (read-only).

   o  Symbols after data node names: "?" means an optional node, "!"
      means a presence container, and "*" denotes a list and leaf-list.

   o  Parentheses enclose choice and case nodes, and case nodes are also
      marked with a colon (":").

   o  Ellipsis ("...") stands for contents of subtrees that are not
      shown.






































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2.  Objectives

2.1.  System Identification

   There are many common properties used to identify devices, operating
   systems, software versions, etc. that need to be supported in the
   system data module.  These objects are defined as operational state
   data and the information returned by the server is intended to be
   specific to the device vendor.

   Some user-configurable administrative strings are also provided, such
   as the system location and description.

2.2.  System Time Management

   The management of the date and time used by the system need to be
   supported.  Use of one or more NTP servers to automatically set the
   system date and time need to be possible.  Utilization of the
   Timezone database [RFC6557] also need to be supported.  It should be
   possible to configure the system to use NTP.

2.3.  User Authentication

   The authentication mechanism needs to support password authentication
   over RADIUS, to support deployment scenarios with centralized
   authentication servers.  Additionally, local users need to be
   supported, for scenarios when no centralized authentication server
   exists, or for situations where the centralized authentication server
   cannot be reached from the device.

   Since the mandatory transport protocol for NETCONF is SSH [RFC6242]
   the authentication model needs to support SSH's "publickey" and
   "password" authentication methods [RFC4252].

   The model for authentication configuration should be flexible enough
   to support authentication methods defined by other standard documents
   or by vendors.  It should be possible to configure the system
   authentication properties.

2.4.  DNS Resolver

   The configuration of the DNS resolver within the system containing
   the NETCONF server is required in order to control how domain names
   are resolved.







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2.5.  System Control

   A few operations are needed to support common tasks such as
   restarting the device or setting the system date and time.















































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3.  System Data Model

3.1.  System Identification

   The data model for system identification has the following structure:

      +--rw system
      |  +--rw contact?          string
      |  +--rw hostname?         inet:domain-name
      |  +--rw location?         string
      +--ro system-state
         +--ro platform
            +--ro os-name?       string
            +--ro os-release?    string
            +--ro os-version?    string
            +--ro machine?       string

3.2.  System Time Management

   The data model for system time management has the following
   structure:

      +--rw system
      |  +--rw clock
      |  |  +--rw (timezone)?
      |  |     +--:(timezone-name)
      |  |     |  +--rw timezone-name?     timezone-name
      |  |     +--:(timezone-utc-offset)
      |  |        +--rw timezone-utc-offset?   int16
      |  +--rw ntp!
      |     +--rw enabled?   boolean
      |     +--rw server* [name]
      |        +--rw name                string
      |        +--rw (transport)
      |        |  +--:(udp)
      |        |     +--rw udp
      |        |        +--rw address    inet:host
      |        |        +--rw port?      inet:port-number
      |        +--rw association-type?   enumeration
      |        +--rw iburst?             boolean
      |        +--rw prefer?             boolean
      +--ro system-state
         +--ro clock
            +--ro current-datetime?      yang:date-and-time
            +--ro boot-datetime?         yang:date-and-time

   New "case" statements can be added over time or augmented to the
   "transport" choice to support other transport protocols.



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3.3.  DNS Resolver Model

   The data model for configuration of the DNS resolver has the
   following structure:

      +--rw system
         +--rw dns-resolver
            +--rw search*    inet:domain-name
            +--rw server* [name]
            |  +--rw name    string
            |  +--rw (transport)
            |     +--:(udp-and-tcp)
            |        +--udp-and-tcp
            |           +--rw address    inet:ip-address
            |           +--rw port?      inet:port-number
            +--rw options
               +--rw timeout?    uint8
               +--rw attempts?   uint8

   New "case" statements can be added over time or augmented to the
   "transport" choice to support other transport protocols.

3.4.  RADIUS Client Model

   The data model for configuration of the RADIUS client has the
   following structure:

      +--rw system
         +--rw radius
            +--rw server* [name]
            |  +--rw name                   string
            |  +--rw (transport)
            |  |  +--:(udp)
            |  |     +--rw udp
            |  |        +--rw address                inet:host
            |  |        +--rw authentication-port?   inet:port-number
            |  |        +--rw shared-secret          string
            |  +--rw authentication-type?   identityref
            +--rw options
               +--rw timeout?    uint8
               +--rw attempts?   uint8

   New "case" statements can be added over time or augmented to the
   "transport" choice to support other transport protocols.







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3.5.  User Authentication Model

   This document defines three authentication methods for use with
   NETCONF:

   o  publickey for local users over SSH

   o  password for local users over any secure transport

   o  password for RADIUS users over any secure transport

   Additional methods can be defined by other standard documents or by
   vendors.

   This document defines two optional YANG features, "local-users" and
   "radius-authentication", which the server advertises to indicate
   support for configuring local users on the device, and support for
   using RADIUS for authentication, respectively.

   The authentication parameters defined in this document are primarily
   used to configure authentication of NETCONF users, but MAY also be
   used by other interfaces, e.g., a Command Line Interface or a Web-
   based User Interface.

   The data model for user authentication has the following structure:

      +--rw system
         +--rw authentication
            +--rw user-authentication-order*   identityref
            +--rw user* [name]
               +--rw name        string
               +--rw password?   ianach:crypt-hash
               +--rw authorized-key* [name]
                  +--rw name         string
                  +--rw algorithm    string
                  +--rw key-data     binary

3.5.1.  SSH Public Key Authentication

   If the NETCONF server advertises the "local-users" feature,
   configuration of local users and their SSH public keys is supported
   in the /system/authentication/user list.

   Public key authentication is requested by the SSH client.  If the
   "local-users" feature is supported, then when a NETCONF client starts
   an SSH session towards the server using the "publickey"
   authentication "method name" [RFC4252], the SSH server looks up the
   user name given in the SSH authentication request in the /system/



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   authentication/user list, and verifies the key as described in
   [RFC4253].

3.5.2.  Local User Password Authentication

   If the NETCONF server advertises the "local-users" feature,
   configuration of local users and their passwords is supported in the
   /system/authentication/user list.

   For NETCONF transport protocols that support password authentication,
   the leaf-list "user-authentication-order" is used to control if local
   user password authentication should be used.

   In SSH, password authentication is requested by the client.  Other
   NETCONF transport protocols MAY also support password authentication.

   When local user password authentication is requested, the NETCONF
   transport looks up the user name provided by the client in the
   /system/authentication/user list, and verifies the password.

3.5.3.  RADIUS Password Authentication

   If the NETCONF server advertises the "radius-authentication" feature,
   the device supports user authentication using RADIUS.

   For NETCONF transport protocols that support password authentication,
   the leaf-list "user-authentication-order" is used to control if
   RADIUS password authentication should be used.

   In SSH, password authentication is requested by the client.  Other
   NETCONF transport protocols MAY also support password authentication.

3.6.  System Control

   The following operations are defined:

      set-current-datetime
      system-restart
      system-shutdown

   Two protocol operations are included to restart or shutdown the
   system.  The 'system-restart' operation can be used to restart the
   entire system (not just the NETCONF server).  The 'system-shutdown'
   operation can be used to power off the entire system.







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4.  Relationship to the SNMPv2-MIB

   If a device implements the SNMPv2-MIB [RFC3418], there are two
   objects that MAY be mapped by the implementation.  See the YANG
   module definition in Section 6 for details.  The following table
   lists the YANG data nodes with corresponding objects in the SNMPv2-
   MIB.

                  +----------------+-------------------+
                  | YANG data node | SNMPv2-MIB object |
                  +----------------+-------------------+
                  | contact        | sysContact        |
                  | location       | sysLocation       |
                  +----------------+-------------------+

      YANG interface configuration data nodes and related SNMPv2-MIB
                                  objects


































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5.  IANA Crypt Hash YANG module

   This YANG module references [RFC1321], [IEEE-1003.1-2008], and
   [FIPS.180-3.2008].

   RFC Ed.: update the date below with the date of RFC publication and
   remove this note.

   <CODE BEGINS> file "iana-crypt-hash@2014-04-04.yang"

   module iana-crypt-hash {
     namespace "urn:ietf:params:xml:ns:yang:iana-crypt-hash";
     prefix ianach;

     organization "IANA";
     contact
       "        Internet Assigned Numbers Authority

        Postal: ICANN
                4676 Admiralty Way, Suite 330
                Marina del Rey, CA 90292

        Tel:    +1 310 823 9358
        E-Mail: iana&iana.org";
     description
       "This YANG module defines a typedef for storing passwords
        using a hash function, and features to indicate which hash
        functions are supported by an implementation.

        The latest revision of this YANG module can be obtained from
        the IANA web site.

        Requests for new values should be made to IANA via
        email (iana&iana.org).

        Copyright (c) 2014 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
        (http://trustee.ietf.org/license-info).

        The initial version of this YANG module is part of RFC XXXX;
        see the RFC itself for full legal notices.";
     // RFC Ed.: replace XXXX with actual RFC number and remove this



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     // note.

     // RFC Ed.: update the date below with the date of RFC publication
     // and remove this note.
     revision 2014-04-04 {
       description
         "Initial revision.";
       reference
         "RFC XXXX: A YANG Data Model for System Management";
     }

     typedef crypt-hash {
       type string {
         pattern
           '$0$.*'
         + '|$1$[a-zA-Z0-9./]{1,8}$[a-zA-Z0-9./]{22}'
         + '|$5$(rounds=\d+$)?[a-zA-Z0-9./]{1,16}$[a-zA-Z0-9./]{43}'
         + '|$6$(rounds=\d+$)?[a-zA-Z0-9./]{1,16}$[a-zA-Z0-9./]{86}';
       }
       description
         "The crypt-hash type is used to store passwords using
          a hash function.  The algorithms for applying the hash
          function and encoding the result are implemented in
          various UNIX systems as the function crypt(3).

          A value of this type matches one of the forms:

            $0$<clear text password>
            $<id>$<salt>$<password hash>
            $<id>$<parameter>$<salt>$<password hash>

          The '$0$' prefix signals that the value is clear text.  When
          such a value is received by the server, a hash value is
          calculated, and the string '$<id>$<salt>$' or
          $<id>$<parameter>$<salt>$ is prepended to the result.  This
          value is stored in the configuration data store.

          If a value starting with '$<id>$', where <id> is not '0', is
          received, the server knows that the value already represents a
          hashed value, and stores it as is in the data store.

          When a server needs to verify a password given by a user, it
          finds the stored password hash string for that user, extracts
          the salt, and calculates the hash with the salt and given
          password as input.  If the calculated hash value is the same
          as the stored value, the password given by the client is
          accepted.




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          This type defines the following hash functions:

            id | hash function | feature
            ---+---------------+-------------------
             1 | MD5           | crypt-hash-md5
             5 | SHA-256       | crypt-hash-sha-256
             6 | SHA-512       | crypt-hash-sha-512

          The server indicates support for the different hash functions
          by advertising the corresponding feature.";
       reference
         "IEEE Std 1003.1-2008 - crypt() function
          RFC 1321: The MD5 Message-Digest Algorithm
          FIPS.180-3.2008: Secure Hash Standard";
     }

     feature crypt-hash-md5 {
       description
         "Indicates that the device supports the MD5
          hash function in 'crypt-hash' values";
       reference "RFC 1321: The MD5 Message-Digest Algorithm";
     }

     feature crypt-hash-sha-256 {
       description
         "Indicates that the device supports the SHA-256
          hash function in 'crypt-hash' values";
       reference "FIPS.180-3.2008: Secure Hash Standard";
     }

     feature crypt-hash-sha-512 {
       description
         "Indicates that the device supports the SHA-512
          hash function in 'crypt-hash' values";
       reference "FIPS.180-3.2008: Secure Hash Standard";
     }

   }

   <CODE ENDS>











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6.  System YANG module

   This YANG module imports YANG extensions from [RFC6536], and imports
   YANG types from [RFC6991].  It also references [RFC1035], [RFC2865],
   [RFC3418], [RFC5607], [RFC5966], [RFC6557].

   RFC Ed.: update the date below with the date of RFC publication and
   remove this note.

   <CODE BEGINS> file "ietf-system@2014-05-14.yang"

   module ietf-system {
     namespace "urn:ietf:params:xml:ns:yang:ietf-system";
     prefix "sys";

     import ietf-yang-types {
       prefix yang;
     }

     import ietf-inet-types {
       prefix inet;
     }

     import ietf-netconf-acm {
       prefix nacm;
     }

     import iana-crypt-hash {
       prefix ianach;
     }

     organization
       "IETF NETMOD (NETCONF Data Modeling Language) Working Group";

     contact
       "WG Web:   <http://tools.ietf.org/wg/netmod/>
        WG List:  <mailto:netmod@ietf.org>

        WG Chair: Thomas Nadeau
                  <mailto:tnadeau@lucidvision.com>

        WG Chair: Juergen Schoenwaelder
                  <mailto:j.schoenwaelder@jacobs-university.de>

        Editor:   Andy Bierman
                  <mailto:andy@yumaworks.com>

        Editor:   Martin Bjorklund



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                  <mailto:mbj@tail-f.com>";

     description
       "This module contains a collection of YANG definitions for the
        configuration and identification of some common system
        properties within a device containing a NETCONF server.  This
        includes data node definitions for system identification,
        time-of-day management, user management, DNS resolver
        configuration, and some protocol operations for system
        management.

        Copyright (c) 2014 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
        (http://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC XXXX; see
        the RFC itself for full legal notices.";

     // RFC Ed.: replace XXXX with actual RFC number and remove this
     // note.

     // RFC Ed.: remove this note
     // Note: extracted from draft-ietf-netmod-system-mgmt-07.txt

     // RFC Ed.: update the date below with the date of RFC publication
     // and remove this note.
     revision "2014-05-14" {
       description
         "Initial revision.";
       reference
         "RFC XXXX: A YANG Data Model for System Management";
     }

     /*
      * Typedefs
      */

     typedef timezone-name {
       type string;
       description
         "A timezone name as used by the Time Zone Database, sometimes
          referred to as the 'Olson Database'.



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          The exact set of valid values is an implementation-specific
          matter.  Client discovery of the exact set of time zone names
          for a particular server is out of scope.";
       reference
         "RFC 6557: Procedures for Maintaining the Time Zone Database";
      }


     /*
      * Features
      */

     feature radius {
       description
         "Indicates that the device can be configured as a RADIUS
          client.";
       reference
         "RFC 2865: Remote Authentication Dial In User Service "
       + "(RADIUS)";
     }

     feature authentication {
       description
         "Indicates that the device supports configuration
          for user authentication.";
     }

     feature local-users {
       if-feature authentication;
       description
         "Indicates that the device supports configuration of
          local user authentication.";
     }

     feature radius-authentication {
       if-feature radius;
       if-feature authentication;
       description
         "Indicates that the device supports configuration of user
          authentication over RADIUS.";
       reference
         "RFC 2865: Remote Authentication Dial In User Service (RADIUS)
          RFC 5607: Remote Authentication Dial-In User Service (RADIUS)
                    Authorization for Network Access Server (NAS)
                    Management";
     }

     feature ntp {



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       description
         "Indicates that the device can be configured
          to use one or more NTP servers to set the
          system date and time.";
     }

     feature ntp-udp-port {
       if-feature ntp;
       description
         "Indicates that the device supports the configuration of
          the UDP port for NTP servers.

          This is a 'feature' since many implementations do not support
          any other port than the default port.";
     }

     feature timezone-name {
       description
         "Indicates that the local timezone on the device
          can be configured to use the TZ database
          to set the timezone and manage daylight savings time.";
       reference
         "RFC 6557: Procedures for Maintaining the Time Zone Database";
     }

     feature dns-udp-tcp-port {
       description
         "Indicates that the device supports the configuration of
          the UDP and TCP port for DNS servers.

          This is a 'feature' since many implementations do not support
          any other port than the default port.";
     }

     /*
      * Identities
      */

     identity authentication-method {
       description
         "Base identity for user authentication methods.";
     }

     identity radius {
       base authentication-method;
       description
         "Indicates user authentication using RADIUS.";
       reference



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         "RFC 2865: Remote Authentication Dial In User Service (RADIUS)
          RFC 5607: Remote Authentication Dial-In User Service (RADIUS)
                    Authorization for Network Access Server (NAS)
                    Management";
     }

     identity local-users {
       base authentication-method;
       description
         "Indicates password-based authentication of locally
          configured users.";
     }

     identity radius-authentication-type {
       description
         "Base identity for RADIUS authentication types.";
     }

     identity radius-pap {
       base radius-authentication-type;
       description
         "The device requests PAP authentication from the RADIUS
          server.";
       reference
         "RFC 2865: Remote Authentication Dial In User Service";
     }

     identity radius-chap {
       base radius-authentication-type;
       description
         "The device requests CHAP authentication from the RADIUS
          server.";
       reference
         "RFC 2865: Remote Authentication Dial In User Service";
     }

     /*
      * Configuration data nodes
      */

     container system {
       description
         "System group configuration.";

       leaf contact {
         type string;
         description
           "The administrator contact information for the system.



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            A server implementation MAY map this leaf to the sysContact
            MIB object.  Such an implementation needs to use some
            mechanism to handle the differences in size and characters
            allowed between this leaf and sysContact.  The definition of
            such a mechanism is outside the scope of this document.";
         reference
           "RFC 3418: Management Information Base (MIB) for the
                      Simple Network Management Protocol (SNMP)
                      SNMPv2-MIB.sysContact";
       }
       leaf hostname {
         type inet:domain-name;
        description
          "The name of the host.  This name can be a single domain
           label, or the fully qualified domain name of the host.";
       }
       leaf location {
         type string;
         description
           "The system location.

            A server implementation MAY map this leaf to the sysLocation
            MIB object.  Such an implementation needs to use some
            mechanism to handle the differences in size and characters
            allowed between this leaf and sysLocation.  The definition
            of such a mechanism is outside the scope of this document.";
         reference
           "RFC 3418: Management Information Base (MIB) for the
                      Simple Network Management Protocol (SNMP)
                      SNMPv2-MIB.sysLocation";
       }

       container clock {
         description
           "Configuration of the system date and time properties.";

         choice timezone {
           description
             "The system timezone information.";

           case timezone-name {
             if-feature timezone-name;
             leaf timezone-name {
               type timezone-name;
               description
                 "The TZ database name to use for the system, such
                  as 'Europe/Stockholm'.";
             }



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           }
           case timezone-utc-offset {
             leaf timezone-utc-offset {
               type int16 {
                 range "-1500 .. 1500";
               }
               units "minutes";
               description
                 "The number of minutes to add to UTC time to
                  identify the timezone for this system.  For example,
                  'UTC - 8:00 hours' would be represented as '-480'.
                  Note that automatic daylight savings time adjustment
                  is not provided, if this object is used.";
             }
           }
         }
       }

       container ntp {
         if-feature ntp;
         presence
           "Enables the NTP client unless the 'enabled' leaf
            (which defaults to 'true') is set to 'false'";
         description
           "Configuration of the NTP client.";

         leaf enabled {
           type boolean;
           default true;
           description
             "Indicates that the system should attempt
              to synchronize the system clock with an
              NTP server from the 'ntp/server' list.";
         }
         list server {
           key name;
           description
             "List of NTP servers to use for
              system clock synchronization.  If '/system/ntp/enabled'
              is 'true', then the system will attempt to
              contact and utilize the specified NTP servers.";

           leaf name {
             type string;
             description
               "An arbitrary name for the NTP server.";
           }
           choice transport {



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             mandatory true;
             description
               "The transport protocol specific parameters for this
                server.";

             case udp {
               container udp {
                 description
                   "Contains UDP specific configuration parameters
                    for NTP.";
                 leaf address {
                   type inet:host;
                   mandatory true;
                   description
                     "The address of the NTP server.";
                 }
                 leaf port {
                   if-feature ntp-udp-port;
                   type inet:port-number;
                   default 123;
                   description
                     "The port number of the NTP server.";
                 }
               }
             }
           }
           leaf association-type {
             type enumeration {
               enum server {
                 description
                   "Use client association mode.  This device
                    will not provide synchronization to the
                    configured NTP server.";
               }
               enum peer {
                 description
                   "Use symmetric active association mode.
                    This device may provide synchronization
                    to the configured NTP server.";
               }
               enum pool {
                 description
                   "Use client association mode with one or
                    more of the NTP servers found by DNS
                    resolution of the domain name given by
                    the 'address' leaf.  This device will not
                    provide synchronization to the servers.";
               }



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             }
             default server;
             description
               "The desired association type for this NTP server.";
           }
           leaf iburst {
             type boolean;
             default false;
             description
               "Indicates whether this server should enable burst
                synchronization or not.";
           }
           leaf prefer {
             type boolean;
             default false;
             description
               "Indicates whether this server should be preferred
                or not.";
           }
         }
       }

       container dns-resolver {
         description
           "Configuration of the DNS resolver.";

         leaf-list search {
           type inet:domain-name;
           ordered-by user;
           description
             "An ordered list of domains to search when resolving
              a host name.";
         }
         list server {
           key name;
           ordered-by user;
           description
             "List of the DNS servers that the resolver should query.

              When the resolver is invoked by a calling application, it
              sends the query to the first name server in this list.  If
              no response has been received within 'timeout' seconds,
              the resolver continues with the next server in the list.
              If no response is received from any server, the resolver
              continues with the first server again.  When the resolver
              has traversed the list 'attempts' times without receiving
              any response, it gives up and returns an error to the
              calling application.



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              Implementations MAY limit the number of entries in this
              list.";

           leaf name {
             type string;
             description
               "An arbitrary name for the DNS server.";
           }
           choice transport {
             mandatory true;
             description
               "The transport protocol specific parameters for this
                server.";

             case udp-and-tcp {
               container udp-and-tcp {
                 description
                   "Contains UDP and TCP specific configuration
                    parameters for DNS.";
                 reference
                   "RFC 1035: Domain Implementation and Specification
                    RFC 5966: DNS over TCP";

                 leaf address {
                   type inet:ip-address;
                   mandatory true;
                   description
                     "The address of the DNS server.";
                 }
                 leaf port {
                   if-feature dns-udp-tcp-port;
                   type inet:port-number;
                   default 53;
                   description
                     "The UDP and TCP port number of the DNS server.";
                 }
               }
             }
           }
         }
         container options {
           description
             "Resolver options.  The set of available options has been
              limited to those that are generally available across
              different resolver implementations, and generally
              useful.";
           leaf timeout {
             type uint8 {



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               range "1..max";
             }
             units "seconds";
             default "5";
             description
               "The amount of time the resolver will wait for a
                response from each remote name server before
                retrying the query via a different name server.";
           }
           leaf attempts {
             type uint8 {
               range "1..max";
             }
             default "2";
             description
               "The number of times the resolver will send a query to
                all its name servers before giving up and returning an
                error to the calling application.";
           }
         }
       }

       container radius {
         if-feature radius;

         description
           "Configuration of the RADIUS client.";

         list server {
           key name;
           ordered-by user;
           description
             "List of RADIUS servers used by the device.

              When the RADIUS client is invoked by a calling
              application, it sends the query to the first server in
              this list.  If no response has been received within
              'timeout' seconds, the client continues with the next
              server in the list.  If no response is received from any
              server, the client continues with the first server again.
              When the client has traversed the list 'attempts' times
              without receiving any response, it gives up and returns an
              error to the calling application.";

           leaf name {
             type string;
             description
               "An arbitrary name for the RADIUS server.";



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           }
           choice transport {
             mandatory true;
             description
               "The transport protocol specific parameters for this
                server.";

             case udp {
               container udp {
                 description
                   "Contains UDP specific configuration parameters
                    for RADIUS.";
                 leaf address {
                   type inet:host;
                   mandatory true;
                   description
                     "The address of the RADIUS server.";
                 }
                 leaf authentication-port {
                   type inet:port-number;
                   default "1812";
                   description
                     "The port number of the RADIUS server.";
                 }
                 leaf shared-secret {
                   type string;
                   mandatory true;
                   nacm:default-deny-all;
                   description
                     "The shared secret which is known to both the
                      RADIUS client and server.";
                   reference
                     "RFC 2865: Remote Authentication Dial In User
                      Service";
                 }
               }
             }
           }
           leaf authentication-type {
             type identityref {
               base radius-authentication-type;
             }
             default radius-pap;
             description
               "The authentication type requested from the RADIUS
                server.";
           }
         }



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         container options {
           description
             "RADIUS client options.";

           leaf timeout {
             type uint8 {
               range "1..max";
             }
             units "seconds";
             default "5";
             description
               "The number of seconds the device will wait for a
                response from each RADIUS server before trying with a
                different server.";
           }
           leaf attempts {
             type uint8 {
               range "1..max";
             }
             default "2";
             description
               "The number of times the device will send a query to
                all its RADIUS servers before giving up.";
           }
         }
       }

       container authentication {
         nacm:default-deny-write;
         if-feature authentication;

          description
            "The authentication configuration subtree.";

          leaf-list user-authentication-order {
            type identityref {
              base authentication-method;
            }
            must '(. != "sys:radius" or ../../radius/server)' {
              error-message
                "When 'radius' is used, a RADIUS server"
              + " must be configured.";
              description
                "When 'radius' is used as an authentication method,
                 a RADIUS server must be configured.";
            }
            ordered-by user;




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            description
              "When the device authenticates a user with a password,
               it tries the authentication methods in this leaf-list in
               order.  If authentication with one method fails, the next
               method is used.  If no method succeeds, the user is
               denied access.

               An empty user-authentication-order leaf-list still allows
               authentication of users using mechanisms that do not
               involve a password.

               If the 'radius-authentication' feature is advertised by
               the NETCONF server, the 'radius' identity can be added to
               this list.

               If the 'local-users' feature is advertised by the
               NETCONF server, the 'local-users' identity can be
               added to this list.";
          }

          list user {
            if-feature local-users;
            key name;
            description
              "The list of local users configured on this device.";

            leaf name {
              type string;
              description
               "The user name string identifying this entry.";
            }
            leaf password {
              type ianach:crypt-hash;
              description
                "The password for this entry.";
            }
            list authorized-key {
              key name;
              description
                "A list of public SSH keys for this user.  These keys
                 are allowed for SSH authentication, as described in
                 RFC 4253.";
              reference
                "RFC 4253: The Secure Shell (SSH) Transport Layer
                           Protocol";

              leaf name {
                type string;



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                description
                  "An arbitrary name for the SSH key.";
              }
              leaf algorithm {
                type string;
                mandatory true;
                description
                  "The public key algorithm name for this SSH key.

                   Valid values are the values in the IANA Secure Shell
                   (SSH) Protocol Parameters registry, Public Key
                   Algorithm Names";
                reference
                  "IANA Secure Shell (SSH) Protocol Parameters registry,
                   Public Key Algorithm Names";
              }
              leaf key-data {
                type binary;
                mandatory true;
                description
                  "The binary public key data for this SSH key, as
                   specified by RFC 4253, Section 6.6, i.e.,:

                     string    certificate or public key format
                               identifier
                     byte[n]   key/certificate data
                   ";
                reference
                  "RFC 4253: The Secure Shell (SSH) Transport Layer
                             Protocol";
              }
            }
          }
        }
     }

     /*
      * Operational state data nodes
      */

     container system-state {
       config false;
       description
         "System group operational state.";

       container platform {
         description
           "Contains vendor-specific information for



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            identifying the system platform and operating system.";
         reference
           "IEEE Std 1003.1-2008 - sys/utsname.h";

         leaf os-name {
           type string;
           description
             "The name of the operating system in use,
              for example 'Linux'";
           reference
             "IEEE Std 1003.1-2008 - utsname.sysname";
         }
         leaf os-release {
           type string;
           description
             "The current release level of the operating
              system in use.  This string MAY indicate
              the OS source code revision.";
           reference
             "IEEE Std 1003.1-2008 - utsname.release";
         }
         leaf os-version {
           type string;
           description
             "The current version level of the operating
              system in use.  This string MAY indicate
              the specific OS build date and target variant
              information.";
           reference
             "IEEE Std 1003.1-2008 - utsname.version";
         }
         leaf machine {
           type string;
           description
             "A vendor-specific identifier string representing
              the hardware in use.";
           reference
             "IEEE Std 1003.1-2008 - utsname.machine";
         }
       }

       container clock {
         description
           "Monitoring of the system
            date and time properties.";

         leaf current-datetime {
           type yang:date-and-time;



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           description
             "The current system date and time.";
         }
         leaf boot-datetime {
           type yang:date-and-time;
           description
             "The system date and time when the system last restarted.";
         }
       }
     }

     rpc set-current-datetime {
       nacm:default-deny-all;
       description
         "Set the /system-state/clock/current-datetime leaf
          to the specified value.

          If the system is using NTP (i.e., /system/ntp/enabled
          is set to 'true'), then this operation will
          fail with error-tag 'operation-failed',
          and error-app-tag value of 'ntp-active'";
       input {
         leaf current-datetime {
           type yang:date-and-time;
           mandatory true;
           description
             "The current system date and time.";
         }
       }
     }

     rpc system-restart {
       nacm:default-deny-all;
       description
         "Request that the entire system be restarted immediately.
          A server SHOULD send an rpc reply to the client before
          restarting the system.";
     }

     rpc system-shutdown {
       nacm:default-deny-all;
       description
         "Request that the entire system be shut down immediately.
          A server SHOULD send an rpc reply to the client before
          shutting down the system.";
     }

   }



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   <CODE ENDS>


















































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7.  IANA Considerations

   IANA is requested to create an IANA-maintained YANG Module called
   "iana-crypt-hash", based on the contents of Section 5, which will
   allow for new hash algorithms to be added to the type "crypt-hash".
   The registration procedure will be Expert Review, as defined by
   [RFC5226].

   This document registers two URIs in the IETF XML registry [RFC3688].
   Following the format in RFC 3688, the following registrations are
   requested to be made.

        URI: urn:ietf:params:xml:ns:yang:iana-crypt-hash
        Registrant Contact: The IESG.
        XML: N/A, the requested URI is an XML namespace.

        URI: urn:ietf:params:xml:ns:yang:ietf-system
        Registrant Contact: The IESG.
        XML: N/A, the requested URI is an XML namespace.

   This document registers two YANG modules in the YANG Module Names
   registry [RFC6020].

     name:         iana-crypt-hash
     namespace:    urn:ietf:params:xml:ns:yang:iana-crypt-hash
     prefix:       ianach
     reference:    RFC XXXX

     name:         ietf-system
     namespace:    urn:ietf:params:xml:ns:yang:ietf-system
     prefix:       sys
     reference:    RFC XXXX



















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8.  Security Considerations

   The YANG modules defined in this memo are designed to be accessed via
   the NETCONF protocol [RFC6241].  The lowest NETCONF layer is the
   secure transport layer and the mandatory-to-implement secure
   transport is SSH [RFC6242].  Authorization for access to specific
   portions of conceptual data and operations within this module is
   provided by the NETCONF access control model (NACM) [RFC6536].

   There are a number of data nodes defined in the "ietf-system" YANG
   module which 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 to
   these data nodes can have a negative effect on network operations.
   It is thus important to control write access (e.g., via edit-config)
   to these data nodes.  These are the subtrees and data nodes and their
   sensitivity/vulnerability:

   o  /system/clock/timezone: This choice contains the objects used to
      control the timezone used by the device.

   o  /system/ntp: This container contains the objects used to control
      the Network Time Protocol servers used by the device.

   o  /system/dns-resolver: This container contains the objects used to
      control the Domain Name System servers used by the device.

   o  /system/radius: This container contains the objects used to
      control the Remote Authentication Dial-In User Service servers
      used by the device.

   o  /system/authentication/user-authentication-order: This leaf
      controls how user login attempts are authenticated by the device.

   o  /system/authentication/user: This list contains the local users
      enabled on the system.

   Some of the readable data nodes in the "ietf-system" YANG module 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:

   o  /system/platform: This container has objects which may help
      identify the specific NETCONF server and/or operating system
      implementation used on the device.





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   o  /system/authentication/user: This list has objects that may help
      identify the specific user names and password information in use
      on the device.

   Some of the remote procedure call (RPC) operations in the
   "ietf-system" YANG module may be considered sensitive or vulnerable
   in some network environments.  It is thus important to control access
   to these operations.  These are the operations and their sensitivity/
   vulnerability:

   o  set-current-datetime: Changes the current date and time on the
      device.

   o  system-restart: Reboots the device.

   o  system-shutdown: Shuts down the device.

   Since this document describes the use of RADIUS for purposes of
   authentication, it is vulnerable to all of the threats that are
   present in other RADIUS applications.  For a discussion of such
   threats, see [RFC2865] and [RFC3162], and section 4 of [RFC3579].

   This document provides configuration parameters for SSH's "publickey"
   and "password" authentication mechanisms.  Section 9.4 of [RFC4251]
   and section 11 of [RFC4252] discuss security considerations for these
   mechanisms.

   The "iana-crypt-hash" YANG module defines a type "crypt-hash" that
   can be used to store MD5 hashes.  [RFC6151] discusses security
   considerations for MD5.  The usage of MD5 is NOT RECOMMENDED.





















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9.  Change Log

       -- RFC Ed.: remove this section before publication.

9.1.  00-01

   o  added configuration-source identities

   o  added configuration-source leaf to ntp and dns (via grouping) to
      choose configuration source

   o  added association-type, iburst, prefer, and true leafs to the ntp-
      server list

   o  extended the ssh keys for a user to a list of keys. support all
      defined key algorithms, not just dsa and rsa

   o  clarified timezone-utc-offset description-stmt

   o  removed '/system/ntp/server/true' leaf from data model

9.2.  01-02

   o  added default-stmts to ntp-server/iburst and ntp-server/prefer
      leafs

   o  changed timezone-location leaf to use iana-timezone typedef
      instead of a string

9.3.  02-03

   o  removed configuration-source identities and leafs

9.4.  03-04

   o  removed ndots dns resolver option

   o  added radius-authentication-type identity, and identities for pap
      and chap, and a leaf to control which authentication type to use
      when communicating with the radius server

   o  made 0 an invalid value for timeouts and attempts

9.5.  04-05

   o  updated tree diagram explanation text





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9.6.  05-06

   o  changed ntp/use-ntp to ntp/enabled

   o  changed ntp/ntp-server to ntp/server

   o  removed /system/platform/nodename leaf

   o  changed /system/name to /system/hostname

   o  simplified must expression in user-authentication-order

   o  added optional rounds to sha hash definition

   o  clarified the crypt-hash description

   o  clarified ntp descriptions

   o  clarified YANG module description to indicate that some system
      properties are supported, not the entire system

   o  clarified that system identification values are vendor specific,
      not the data node objects

   o  clarified sec. 2.2 and 2.3 to indicate that the server should also
      be capable of configuring these properties

   o  changed /system/dns/search from inet:host to inet:domain-name

   o  changed RFC6021 reference to 6021-bis

   o  changed /system/platform/nodename to /system/platform/hostname

   o  changed /system/radius/server/{leafs} to be within a choice and
      'udp' case statement so other transport specific parameters can
      augment this list or they can be added by the WG to a future
      version of this module. {leafs} are authentication-port and
      shared-secret.

   o  updated YANG tree diagrams for objects added in -05 and -06

9.7.  06-07

   o  updated the Abstract and Introduction

   o  updated Tree diagram notation





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   o  identify all external servers (dns, ntp, radius) by name instead
      of address, in order to make the data model extensible for
      additional transport protocol.

   o  updated the Security Considerations section with a reference to
      NACM.

9.8.  07-08

   o  renamed the DNS transport to 'udp-and-tcp' and added references.

   o  moved the operational state nodes into /system-state.

9.9.  08-09

   o  made "ntp" node a presence container

   o  added reference to RFC 6151

   o  updated reference from 6021-bis to RFC 6991

   o  cleaned up usage of config false in the YANG module

9.10.  09-10

   o  clarified relationship with SNMPv2-MIB

9.11.  11-12

   o  added typedef "timezone-name", and removed reference to
      draft-ietf-netmod-iana-timezones

9.12.  13-14

   o  moved the "crypt-hash" typedef to an IANA maintained module.

   o  updated security considerations to mention RADIUS threats.

9.13.  14-15

   o  updated security considerations to mention SSH authentication
      method threats.









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10.  References

10.1.  Normative References

   [FIPS.180-3.2008]
              National Institute of Standards and Technology, "Secure
              Hash Standard", FIPS PUB 180-3, October 2008, <http://
              csrc.nist.gov/publications/fips/fips180-3/
              fips180-3_final.pdf>.

   [IEEE-1003.1-2008]
              Institute of Electrical and Electronics Engineers,
              "POSIX.1-2008", IEEE Standard 1003.1, March 2008.

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, November 1987.

   [RFC1321]  Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
              April 1992.

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

   [RFC2865]  Rigney, C., Willens, S., Rubens, A., and W. Simpson,
              "Remote Authentication Dial In User Service (RADIUS)",
              RFC 2865, June 2000.

   [RFC3162]  Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6",
              RFC 3162, August 2001.

   [RFC3418]  Presuhn, R., "Management Information Base (MIB) for the
              Simple Network Management Protocol (SNMP)", STD 62,
              RFC 3418, December 2002.

   [RFC4251]  Ylonen, T. and C. Lonvick, "The Secure Shell (SSH)
              Protocol Architecture", RFC 4251, January 2006.

   [RFC4252]  Ylonen, T. and C. Lonvick, "The Secure Shell (SSH)
              Authentication Protocol", RFC 4252, January 2006.

   [RFC4253]  Ylonen, T. and C. Lonvick, "The Secure Shell (SSH)
              Transport Layer Protocol", RFC 4253, January 2006.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [RFC5607]  Nelson, D. and G. Weber, "Remote Authentication Dial-In



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              User Service (RADIUS) Authorization for Network Access
              Server (NAS) Management", RFC 5607, July 2009.

   [RFC5966]  Bellis, R., "DNS Transport over TCP - Implementation
              Requirements", RFC 5966, August 2010.

   [RFC6020]  Bjorklund, M., "YANG - A Data Modeling Language for the
              Network Configuration Protocol (NETCONF)", RFC 6020,
              October 2010.

   [RFC6151]  Turner, S. and L. Chen, "Updated Security Considerations
              for the MD5 Message-Digest and the HMAC-MD5 Algorithms",
              RFC 6151, March 2011.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, June 2011.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, June 2011.

   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536,
              March 2012.

   [RFC6991]  Schoenwaelder, J., "Common YANG Data Types", RFC 6991,
              July 2013.

10.2.  Informative References

   [RFC3579]  Aboba, B. and P. Calhoun, "RADIUS (Remote Authentication
              Dial In User Service) Support For Extensible
              Authentication Protocol (EAP)", RFC 3579, September 2003.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              January 2004.

   [RFC6557]  Lear, E. and P. Eggert, "Procedures for Maintaining the
              Time Zone Database", BCP 175, RFC 6557, February 2012.












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Authors' Addresses

   Andy Bierman
   YumaWorks

   Email: andy@yumaworks.com


   Martin Bjorklund
   Tail-f Systems

   Email: mbj@tail-f.com







































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