NETMOD WG                                                   Clyde Wildes                                                 C. Wildes, Ed.
Internet-Draft                                              Kiran Koushik                                           K. Koushik, Ed.
Intended status: Informational Standards Track                      Cisco Systems Inc.
Expires: Jun 16, September 21, 2016                               March 20, 2016                                       Dec 23, 2015

                           SYSLOG YANG model
                      draft-ietf-netmod-syslog-model-06 Model
                   draft-ietf-netmod-syslog-model-07

Abstract

   This document describes a data model for the Syslog protocol which is
   used to convey event notification messages.

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 Jun 16, September 21, 2016.

Copyright Notice

   Copyright (c) 2015 2016 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
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Definitions and Acronyms  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Design of the SYSLOG Model  . . . . . . . . . . . . . . . . .   3
     3.1.  SYSLOG Module . . . . . . . . . . . . . . . . . . . . . .   4   6
   4.  SYSLOG YANG Models  . . . . . . . . . . . . . . . . . . . . .   6   9
     4.1.  SYSLOG TYPES  SYSLOG-TYPES Module . . . . . . . . . . . . . . . . . . .   6   9
     4.2.  SYSLOG module  Syslog Module . . . . . . . . . . . . . . . . . . . . . .  10  15
     4.3.  A SYSLOG Syslog Example  . . . . . . . . . . . . . . . . . . . .  18  29
   5.  Implementation Status  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  19  31
   6.  Security  IANA Considerations . . . . . . . . . . . . . . . . . . .  19 . .  31
   7.  IANA  Security Considerations . . . . . . . . . . . . . . . . . . .  32
   8.  References  . .  20
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . .  20
   9.  Change log [RFC Editor: Please remove] .  32
     8.1.  Normative References  . . . . . . . . . .  20
   10. References . . . . . . . .  32
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  20  33
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  21  33

1.  Introduction

   Operating systems, processes and applications generate messages
   indicating their own status or the occurrence of events.  These
   messages are useful for managing and/or debugging the network and its
   services.  The BSD Syslog protocol is a widely adopted protocol that
   is used for transmission and processing of the messages.

   Since each process, application and operating system was written
   somewhat independently, there is little uniformity to the content of
   Syslog messages.  For this reason, no assumption is made upon the
   formatting or contents of the messages.  The protocol is simply
   designed to transport these event messages.  No acknowledgement of
   the receipt is made.

   Essentially, a Syslog process receives messages (from the kernel,
   processes, applications or other Syslog processes) and processes
   those.  The processing involves logging to a local file, displaying
   on console, user terminal, and/or relaying to syslog processes on
   other machines.  The processing is determined by the "facility" that
   originated the message and the "severity" assigned to the message by
   the facility.

   We are using definitions of Syslog protocol from [RFC5424] in this
   draft.

1.1.  Definitions and Acronyms

   IP: Internet Protocol

   IPv4: Internet Protocol version 4

   IPv6: Internet Protocol version 6

   UDP: User Datagram Protocol

   VRF: Virtual Routing  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and Forwarding "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

2.  Problem Statement

   This document defines a YANG [RFC6020] configuration data model that
   may be used to monitor and control one or more syslog processes
   running on a system.  YANG models can be used with network management
   agents such as NETCONF [RFC6241] to install, manipulate, and delete
   the configuration of network devices.

   This module makes use of the YANG "feature" construct which allows
   implementations to support only those Syslog features that lie within
   their capabilities.

   This module can be used to configure the SYSLOG application
   conceptual layer [RFC5424].

3.  Design of the SYSLOG Model

   The syslog model was designed by comparing various syslog features
   implemented by various vendors' in different implementations.

   This draft addresses the common leafs between all vendors implementations and
   creates a common model, which can be augmented with proprietary
   features, if necessary.  The base model is designed to be very simple
   for maximum flexibility.

   Many vendors extend the list of facilities available for logging in
   their implementation.  Here is an example that shows how additional
   facilities could be added to the list of available facilities (in
   this case two facilities are added):

   module vendor-syslog-types {
     namespace "urn:vendor:params:xml:ns:yang:vendor-syslog-types";
     prefix vendor-syslogtypes;

     import ietf-syslog-types {
       prefix syslogtypes;
     }

     organization "Vendor, Inc.";
     contact
       "Vendor, Inc.
        Customer Service

        E-mail: syslog-yang@vendor.com";

     description
       "This module contains a collection of vendor-sprecific YANG type
        definitions for SYSLOG.";

     revision 2016-03-20 {
       description
         "Version 1.0";
       reference
         "Vendor SYSLOG Types: SYSLOG YANG Model";
     }

     identity vendor_specific_type_1 {
       base syslogtypes:syslog-facility;
     }

     identity vendor_specific_type_2 {
       base syslogtypes:syslog-facility;
     }
   }

   Syslog consists of message producers, a group level suppression filter, originators, and message distributors.
   The following digram shows syslog messages flowing from a message producer, through the group level suppression
   filter, and if passed by the group filter
   originator, to message distributors where
   further suppression filtering can
   take place.

   Message Producers Originators
     +-------------+  +-------------+  +-------------+  +-------------+
     |  Various    |  |     OS      |  |             |  |   Remote    |
     | Components  |  |   Kernel    |  | Line Cards  |  |   Servers   |
     +-------------+  +-------------+  +-------------+  +-------------+

     +-------------+  +-------------+  +-------------+  +-------------+
     |    SNMP     |  |  Interface  |  |   Standby   |  |   Syslog    |
     |   Events    |  |   Events    |  |  Supervisor |  |   Itself    |
     +-------------+  +-------------+  +-------------+  +-------------+

     |                                                                |
     +----------------------------------------------------------------+
                  |
                  |
                  |
                  |
          +-----------+------------+--------------+
          |           |            |              |
          v           v            v              |
   Message Distributors                           |
     +----------+ +----------+ +----------+       |
     |          | | Log      | | Log      |       |
     |  Console | | Buffer(s)| | File(s)  |       |
     +----------+ +----------+ +----------+       |
                                                  |
                                    +-------------+-------------+
                                    |             |             |
                                    v             v             v

                            +-------------+

                         +----------------+ +-----------+ +-----------+
                         |Remote       | Relay(s)/| |           | |User       |
                            |Collectors(s)|
                         |Collectors(s)   | |Terminal(s)| |Sessions(s)|
                            +-------------+
                         +----------------+ +-----------+ +-----------+

   The leaves in the base syslog model log-actions container correspond
   to the group level
   suppression filter and each message distributor:

   -

      console
   -
      log buffer(s)
   -
      log file(s)
   -
      remote collector(s)
   - relay(s)/collector(s)
      terminal(s)
   -
      user session(s).

   Optional features are used to specified fields functionality that are not is present
   in
   all specific vendor configurations.

3.1.  SYSLOG Module

   A simplified graphical representation of the complete data tree is
   presented here.

   Each node is printed as:

   <status> <flags> <name> <opts> <type> <if-features>

   <status> is one of:

             +  for current
             x  for deprecated
             o  for obsolete

   <flags> is one of:

             rw  for configuration data
             ro  for non-configuration data
             -x  for rpcs
             -n  for notifications

   <name> is the name of the node

             (<name>) means that the node is a choice node
             :(<name>) means that the node is a case node

   If the node is augmented into the tree from another module, its name
   is printed as <prefix>:<name>.

   <opts> is one of:

             ?  for an optional leaf or choice
             !  for a presence container
             *  for a leaf-list or list
             [<keys>] for a list's keys

   <type> is the name of the type for leafs and leaf-lists

   If the type is a leafref, the type is printed as "-> TARGET", where
   TARGET is either the leafref path, with prefixed removed if possible.

   <if-features> is the list of features this node depends on, printed
   within curly brackets and a question mark "{...}?"

module: ietf-syslog
   +--rw syslog
      +--rw log-actions
         +--rw console! {console-action}?
         |  +--rw log-selector
         |     +--rw (selector-facility)
         |     |  +--:(no-log-facility)
         |     |  |  +--rw no-facilities?   empty
         |     |  +--:(log-facility)
         |     |     +--rw log-facility* [facility]
         |     |        +--rw facility             union
         |     |        +--rw severity             union
         |     |        +--rw severity-operator?   enumeration {selector-severity-operator-config}? {selector-sevop-config}?
         |     +--rw pattern-match?   string {selector-match-processing-config}? {selector-match-config}?
         +--rw buffer {buffer-action}?
         |  +--rw log-buffer* [name]
         |     +--rw name                    string
         |     +--rw log-selector
         |     |  +--rw (selector-facility)
         |     |  |  +--:(no-log-facility)
         |     |  |  |  +--rw no-facilities?   empty
         |     |  |  +--:(log-facility)
         |     |  |     +--rw log-facility* [facility]
         |     |  |        +--rw facility             union
         |     |  |        +--rw severity             union
         |     |  |        +--rw severity-operator?   enumeration {selector-severity-operator-config}? {selector-sevop-config}?
         |     |  +--rw pattern-match?   string {selector-match-processing-config}? {selector-match-config}?
         |     +--rw buffer-size-bytes?      uint64 {buffer-limit-bytes}?
         |     +--rw buffer-size-messages?   uint64 {buffer-limit-messages}?
         |     +--rw structured-data?        boolean {structured-data-config}?
         +--rw file
         |  +--rw log-file* [name]
         |     +--rw name               inet:uri
         |     +--rw log-selector
         |     |  +--rw (selector-facility)
         |     |  |  +--:(no-log-facility)
         |     |  |  |  +--rw no-facilities?   empty
         |     |  |  +--:(log-facility)
         |     |  |     +--rw log-facility* [facility]
         |     |  |        +--rw facility             union
         |     |  |        +--rw severity             union
         |     |  |        +--rw severity-operator?   enumeration {selector-severity-operator-config}? {selector-sevop-config}?
         |     |  +--rw pattern-match?   string {selector-match-processing-config}? {selector-match-config}?
         |     +--rw structured-data?   boolean {structured-data-config}?
         |     +--rw file-archive
         |        +--rw number-of-files?   uint32 {file-limit-size}?
         |        +--rw max-file-size?     uint64 {file-limit-size}?
         |        +--rw rollover?          uint32 {file-limit-duration}?
         |        +--rw retention?         uint16 {file-limit-duration}?
         +--rw remote
         |  +--rw destination* [name]
         |     +--rw name                    string
         |     +--rw (transport)
         |     |  +--:(tcp)
         |     |  |  +--rw tcp
         |     |  |     +--rw address?   inet:host
         |     |  |     +--rw port?      inet:port-number
         |     |  +--:(udp)
         |     |  |  +--rw udp
         |     |  |     +--rw address?   inet:host
         |     |  |     +--rw port?      inet:port-number
         |     |  +--:(tls)
         |     |     +--rw tls
         |     |        +--rw address?   inet:host
         |     |        +--rw port?      inet:port-number
         |     +--rw log-selector
         |     |  +--rw (selector-facility)
         |     |  |  +--:(no-log-facility)
         |     |  |  |  +--rw no-facilities?   empty
         |     |  |  +--:(log-facility)
         |     |  |     +--rw log-facility* [facility]
         |     |  |        +--rw facility             union
         |     |  |        +--rw severity             union
         |     |  |        +--rw severity-operator?   enumeration {selector-severity-operator-config}? {selector-sevop-config}?
         |     |  +--rw pattern-match?   string {selector-match-processing-config}? {selector-match-config}?
         |     +--rw destination-facility?   identityref
         |     +--rw source-interface?       if:interface-ref
         |     +--rw structured-data?        boolean {structured-data-config}?
         |     +--rw syslog-sign! {signed-messages-config}?
         |        +--rw cert-initial-repeat    uint16
         |        +--rw cert-resend-delay      uint16
         |        +--rw cert-resend-count      uint16
         |        +--rw sig-max-delay          uint16
         |        +--rw sig-number-resends     uint16
         |        +--rw sig-resend-delay       uint16
         |        +--rw sig-resend-count       uint16
         +--rw terminal {terminal-action}?
         |  +--rw (terminal-scope)
         |     +--:(all-terminals)
         |     |  +--rw all-terminals all-terminals!
         |  |  +--rw log-selector
         |  |     +--rw (selector-facility)
         |  |     |  +--:(no-log-facility)
         |  |     |  |  +--rw no-facilities?   empty
         |  |     |  +--:(log-facility)
         |  |     |     +--rw log-facility* [facility]
         |  |     |        +--rw facility             union
         |  |     |        +--rw severity             union
         |  |     |        +--rw severity-operator?   enumeration {selector-severity-operator-config}? {selector-sevop-config}?
         |  |     +--rw pattern-match?   string {selector-match-processing-config}?
         |     +--:(per-terminal) {terminal-facility-user-logging-config}? {selector-match-config}?
         |  +--rw device-name* [dname] terminal* [name] {terminal-facility-user-logging-config}?
         |     +--rw dname name            string
         |     +--rw log-selector
         |        +--rw (selector-facility)
         |        |  +--:(no-log-facility)
         |        |  |  +--rw no-facilities?   empty
         |        |  +--:(log-facility)
         |        |     +--rw log-facility* [facility]
         |        |        +--rw facility             union
         |        |        +--rw severity             union
         |        |        +--rw severity-operator?   enumeration {selector-severity-operator-config}? {selector-sevop-config}?
         |        +--rw pattern-match?   string {selector-match-processing-config}? {selector-match-config}?
         +--rw session {session-action}?
            +--rw (user-scope)
               +--:(all-users)
               |  +--rw all-users all-users!
            |  +--rw log-selector
            |     +--rw (selector-facility)
            |     |  +--:(no-log-facility)
            |     |  |  +--rw no-facilities?   empty
            |     |  +--:(log-facility)
            |     |     +--rw log-facility* [facility]
            |     |        +--rw facility             union
            |     |        +--rw severity             union
            |     |        +--rw severity-operator?   enumeration {selector-severity-operator-config}? {selector-sevop-config}?
            |     +--rw pattern-match?   string {selector-match-processing-config}?
               +--:(per-user) {session-facility-user-logging-config}? {selector-match-config}?
            +--rw user-name* [uname] user* [name] {session-facility-user-logging-config}?
               +--rw uname name            string
               +--rw log-selector
                  +--rw (selector-facility)
                  |  +--:(no-log-facility)
                  |  |  +--rw no-facilities?   empty
                  |  +--:(log-facility)
                  |     +--rw log-facility* [facility]
                  |        +--rw facility             union
                  |        +--rw severity             union
                  |        +--rw severity-operator?   enumeration {selector-severity-operator-config}? {selector-sevop-config}?
                  +--rw pattern-match?   string {selector-match-processing-config}? {selector-match-config}?

4.  SYSLOG YANG Models

4.1.  SYSLOG-TYPES module Module

<CODE BEGINS> file "ietf-syslog-types.yang"
module ietf-syslog-types {
  namespace "urn:ietf:params:xml:ns:yang:ietf-syslog-types";
  prefix syslogtypes;

  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: Tom Nadeau
               <mailto:tnadeau@lucidvision.com> Lou Berger
               <mailto:lberger@labn.net>

     WG Chair: Jurgen Schonwalder
               <mailto:j.schoenwaelder@jacobs-university.de>

     WG Chair: Kent Watsen
               <mailto:kwatsen@juniper.net>

     Editor:   Ladislav Lhotka
               <mailto:lhotka@nic.cz>";   Kiran Agrahara Sreenivasa
               <mailto:kkoushik@cisco.com>

     Editor:   Clyde Wildes
               <mailto:cwildes@cisco.com>";
  description
    "This module contains a collection of YANG type definitions for
     SYSLOG.";

  revision 2015-11-09 {
    description
      "Initial Revision";
    reference
      "This model references RFC 5424 -
     SYSLOG.

     Copyright (c) 2015 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 Syslog Protocol, key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
     NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'MAY', and
     'OPTIONAL' in the module text are to be interpreted as described
     in RFC 5848 - Signed 2119 (http://tools.ietf.org/html/rfc2119).

     This version of this YANG module is part of RFC XXXX
     (http://tools.ietf.org/html/rfcXXXX); see the RFC itself for
     full legal notices.";

  reference
    "RFC 5424: The Syslog Messages."; Protocol";

  revision 2016-03-20{
    description
      "Initial Revision";
    reference
      "RFC XXXX: SYSLOG YANG Model";

  }

  typedef severity {
    type enumeration {
      enum "emergency" {
        value 0;
        description
          "Emergency Level Msg";
      }
      enum "alert" {
        value 1;
        description
          "Alert Level Msg";
      }
      enum "critical" {
        value 2;
        description
          "Critical Level Msg";
      }
      enum "error" {
        value 3;
        description
          "Error Level Msg";
      }
      enum "warning" {
        value 4;
        description
          "Warning Level Msg";
      }
      enum "notice" {
        value 5;
        description
          "Notification Level Msg";
      }
      enum "info" {
        value 6;
        description
          "Informational Level Msg";
      }
      enum "debug" {
        value 7;
        description
          "Debugging Level Msg";
      }
    }
    description
      "The definitions for Syslog message severity as per RFC 5424.";
  }
  identity syslog-facility {
    description
      "The base
      "This identity to represent is used as a base for all syslog facilities"; facilities as
       per RFC 5424.";
  }

  identity kern {
    base syslog-facility;
    description
      "The facility for kernel messages (0) as defined in RFC 5424.";
  }

  identity user {
    base syslog-facility;
    description
      "The facility for user-level messages (1) as defined in RFC 5424.";
  }

  identity mail {
    base syslog-facility;
    description
      "The facility for the mail system (2) as defined in RFC 5424.";
  }

  identity daemon {
    base syslog-facility;
    description
      "The facility for the system daemons (3) as defined in RFC 5424.";
   }

  identity auth {
    base syslog-facility;
    description
      "The facility for security/authorization messages (4) as defined
       in RFC 5424.";
  }

  identity syslog {
    base syslog-facility;
    description
      "The facility for messages generated internally by syslogd
       facility as (5)as defined in RFC 5424.";
  }

  identity lpr {
    base syslog-facility;
    description
      "The facility for the line printer subsystem (6) as defined in
       RFC 5424.";
  }

  identity news {
    base syslog-facility;
    description
      "The facility for the network news subsystem (7) as defined in
       RFC 5424.";
  }

  identity uucp {
    base syslog-facility;
    description
      "The facility for the UUCP subsystem (8) as defined in RFC 5424.";
  }

  identity cron {
    base syslog-facility;
    description
      "The facility for the clock daemon (9) as defined in RFC 5424.";
  }

  identity authpriv {
    base syslog-facility;
    description
      "The facility for privileged security/authorization messages (10)
       as defined in RFC 5424.";
  }

  identity ftp {
    base syslog-facility;
    description
      "The facility for the FTP daemon (11) as defined in RFC 5424.";
  }

  identity ntp {
    base syslog-facility;
    description
      "The facility for the NTP subsystem (12) as defined in RFC 5424.";
  }

  identity audit {
    base syslog-facility;
    description
      "The facility for log audit messages (13) as defined in RFC 5424.";
  }

  identity console {
    base syslog-facility;
    description
      "The facility for log alert messages (14) as defined in RFC 5424.";
  }

  identity cron2 {
    base syslog-facility;
    description
      "The facility for the second clock daemon (15) as defined in
       RFC 5424.";
  }

  identity local0 {
    base syslog-facility;
    description
      "The facility for local use 0 messages (16) as defined in
       RFC 5424.";
  }

  identity local1 {
    base syslog-facility;
    description
      "The facility for local use 1 messages (17) as defined in
       RFC 5424.";
  }

  identity local2 {
    base syslog-facility;
    description
      "The facility for local use 2 messages (18) as defined in
       RFC 5424.";
  }

  identity local3 {
    base syslog-facility;
    description
      "The facility for local use 3 messages (19) as defined in
       RFC 5424.";
  }

  identity local4 {
    base syslog-facility;
    description
      "The facility for local use 4 messages (20) as defined in
       RFC 5424.";
  }

  identity local5 {
    base syslog-facility;
    description
      "The facility for local use 5 messages (21) as defined in
       RFC 5424.";
  }

  identity local6 {
    base syslog-facility;
    description
      "The facility for local use 6 messages (22) as defined in
       RFC 5424.";
  }

  identity local7 {
    base syslog-facility;
    description
      "The facility for local use 7 messages (23) as defined in
       RFC 5424.";
  }
}
<CODE ENDS>

4.2. SYSLOG module  Syslog Module

<CODE BEGINS> file "ietf-syslog.yang"
module ietf-syslog {
  namespace "urn:ietf:params:xml:ns:yang:ietf-syslog";
  prefix syslog;

  import ietf-inet-types {
    prefix inet;
  }

  import ietf-interfaces {
    prefix if;
  }

  import ietf-syslog-types {
    prefix syslogtypes;
  }

  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: Tom Nadeau
               <mailto:tnadeau@lucidvision.com> Lou Berger
               <mailto:lberger@labn.net>

     WG Chair: Jurgen Schonwalder
               <mailto:j.schoenwaelder@jacobs-university.de>

     WG Chair: Kent Watsen
               <mailto:kwatsen@juniper.net>

     Editor:   Ladislav Lhotka
               <mailto:lhotka@nic.cz>";   Kiran Agrahara Sreenivasa
               <mailto:kkoushik@cisco.com>

     Editor:   Clyde Wildes
               <mailto:cwildes@cisco.com>";
  description
    "This module contains a collection of YANG definitions
     for Syslog configuration.";

  revision 2015-11-09 {
    description
      "Initial Revision"; configuration.

     Copyright (c) 2015 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 key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
     NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'MAY', and
     'OPTIONAL' in the module text are to be interpreted as described
     in RFC 2119 (http://tools.ietf.org/html/rfc2119).

     This version of this YANG module is part of RFC XXXX
     (http://tools.ietf.org/html/rfcXXXX); see the RFC itself for
     full legal notices.";

  reference
    "RFC 5424: The Syslog Protocol
     RFC 5848: Signed Syslog Messages";

  revision 2016-03-20{
    description
      "Initial Revision";
    reference
      "RFC XXXX: SYSLOG YANG Model";
  }

  feature console-action {
    description
      "This feature indicates that logging to the console is
       supported.";
  }

  feature buffer-action {
    description
      "This feature indicates that logging to an in-memory
       buffer is supported.";
  }

  feature buffer-limit-bytes {
    description
      "This feature indicates that local memory logging buffers
       are limited in size using a limit expressed in bytes.";
  }

  feature buffer-limit-messages {
    description
      "This feature indicates that local memory logging buffers
       are limited in size using a limit expressed in number
       of messages.";
  }

  feature structured-data-config {
    description
      "This feature represents the ability to log messages
       in structured-data format as per RFC 5424.";
  }
  feature file-limit-size {
    description
      "This feature indicates that file logging resources
       are managed using size and number limits.";
  }

  feature file-limit-duration {
    description
      "This feature indicates that file logging resources
       are managed using time based limits.";
  }

  feature terminal-facility-user-logging-config terminal-action {
    description
      "This feature represents indicates that logging to a terminal
       is supported.";
  }

  feature terminal-facility-user-logging-config {
    description
      "This feature represents the ability to adjust
       log message settings for individual terminal
       devices.";
  }
  feature session-action {
    description
      "This feature indicates that logging to user
       CLI session is supported.";
  }

  feature session-facility-user-logging-config {
    description
      "This feature represents the ability to adjust
       log message settings for individual user CLI
       sessions.";
  }

  feature selector-severity-operator-config selector-sevop-config {
    description
      "This feature represents the ability to select messages
       using the additional operators equal to, or not equal to
       when comparing the Syslog message severity.";
  }

  feature selector-match-processing-config selector-match-config {
    description
      "This feature represents the ability to select messages based
       on a Posix 1003.2 regular expression pattern match.";
  }

  feature structured-data-config {
    description
      "This feature represents the ability to log messages
       in structured-data format as per RFC 5424.";
  }

  feature signed-messages-config {
    description
      "This feature represents the ability to configure signed
       syslog messages according to RFC 5848.";
  }

  grouping syslog-severity {
    description
      "This grouping defines the Syslog severity which is used to
       select log messages.";
    leaf severity {
      type union {
        type syslogtypes:severity;
        type enumeration {
          enum all {
            value -1;
            description
              "This enum describes the case where all severities
               are requested."; selected.";
          }
          enum none {
            value -2;
            description
              "This enum describes the case where no severities
               are requested."; selected.";
          }
        }
      }
      mandatory true;
      description
        "This leaf specifies the Syslog message severity. When
         severity is specified, the default severity comparison
         is all messages of the specified severity and greater are
         logged.
         selected. 'all' is a special case which means all severities
         are requested. selected. 'none' is a special case which means that
         no severity selection should occur."; occur or disable this filter.";
    }
    leaf severity-operator {
      when '../severity != "all" and
           ../severity != "none"' {
        description
          "The severity-operator is not applicable for severity 'all' or
          severity 'none'";
      }
      if-feature selector-severity-operator-config; selector-sevop-config;
      type enumeration {
        enum equals-or-higher {
          description
            "This enum specifies all messages of the specified
             severity and higher are logged according to the
             given log-action";
        }
        enum equals {
          description
            "This enum specifies all messages that are for
             the specified severity are logged according to the
             given log-action";
        }
        enum not-equals {
          description
            "This enum specifies all messages that are not for
             the specified severity are logged according to the
             given log-action";
        }

      }
      default equals-or-higher;
      description
        "This leaf describes the option to specify how the
         severity comparison is performed.";
    }
  }

  grouping syslog-selector {
    description
      "This grouping defines a Syslog selector which is used to
       select log messages for the log-action (buffer, file,
       etc). Choose one of the following:
         no-log-facility
         log-facility [<facility> <severity>...]";
    container log-selector {
      description
        "This container describes the log selector parameters
         for Syslog.";
      choice selector-facility {
        mandatory true;
        description
          "This choice describes the option to specify no
           facilities, or a specific facility which can be
           all for all facilities.";
        case no-log-facility {
          description
            "This case specifies no facilities will match when
             comparing the Syslog message facility. This is a
             method that can be used to effectively disable a
             particular log-action (buffer, file, etc).";
          leaf no-facilities {
            type empty;
            description
            "This leaf specifies that no facilities are selected
             for this log-action.";
          }
        }
        case log-facility {
          description
            "This case specifies one or more specified facilities
             will match when comparing the Syslog message facility.";
          list log-facility {
            key facility;
            description
              "This list describes a collection of Syslog
               facilities and severities.";
            leaf facility {
              type union {
                type identityref {
                  base syslogtypes:syslog-facility;
                }
                type enumeration {
                  enum all {
                    description
                      "This enum describes the case where all
                       facilities are requested.";
                  }
                }
              }
              description
                "The leaf uniquely identifies a Syslog facility.";
            }
            uses syslog-severity;
          }
        }
      }
      leaf pattern-match {
        if-feature selector-match-processing-config; selector-match-config;
        type string;
        description
          "This leaf desribes a Posix 1003.2 regular expression
           string that can be used to select a Syslog message for
           logging. The match is performed on the RFC 5424
           SYSLOG-MSG field.";
      }
    }
  }

  grouping syslog-structured-data {
    description
      "This grouping defines the Syslog structured data option
       which is used to select the format used to write log
       messages.";
    leaf structured-data {
      if-feature structured-data-config;
      type boolean;
      default false;
      description
        "This leaf describes how log messages are written to
         the log file. If true, messages will be written
         with one or more STRUCTURED-DATA elements as per
         RFC5424; if false, messages will be written with
         STRUCTURED-DATA = NILVALUE.";
    }
  }
  container syslog {
    description
      "This container describes the configuration parameters for
       Syslog.";
    container log-actions {
      description
        "This container describes the log-action parameters
         for Syslog.";
      container console {
        if-feature console-action;
        presence "Enables logging console configuration";
        description
          "This container describes the configuration parameters for
           console logging.";
        uses syslog-selector;
      }
      container buffer {
        if-feature buffer-action;
        description
          "This container describes the configuration parameters for
           local memory buffer logging. The buffer is circular in
           nature, so newer messages overwrite older messages after
           the buffer is filled."; filled. The method used to read syslog messages
           from the buffer is supplied by the local implementation.";
        list log-buffer {
          key name;
          description
            "This list describes a collection of local logging
             memory buffers."; buffers. If buffer size limits are not supplied, it
             is assumed that the local implementation defined
             limits will be used.";
          leaf name {
            type string;
            description
              "This leaf specifies the name of the log buffer.";
          }
          uses syslog-selector;
          leaf buffer-size-bytes {
            if-feature buffer-limit-bytes;
            type uint64;
            units "bytes";
            description
              "This leaf configures the amount of memory (in bytes) that
               will be dedicated to the local memory logging buffer.
               The default value varies by implementation.";
          }
          leaf buffer-size-messages {
            if-feature buffer-limit-messages;
            type uint64;
            units "log messages";
            description
              "This leaf configures the amount number of log messages that
               can be stored in the local memory logging buffer. The
               default value varies by implementation.";
          }
          uses syslog-structured-data;
        }
      }
      container file {
        description
          "This container describes the configuration parameters for
           file logging."; logging. If file-archive limits are not supplied, it
           is assumed that the local implementation defined limits will
           be used.";
        list log-file {
          key "name";
          description
            "This list describes a collection of local logging
             files.";
          leaf name {
            type inet:uri; inet:uri {
              pattern 'file:.*';
            }
            description
              "This leaf specifies the name of the log file which
               MUST use the uri scheme file:.";
          }
          uses syslog-selector;
          leaf structured-data {
            if-feature structured-data-config;
            type boolean;
            default false;
            description
              "This leaf describes how log messages are written to
               the log file. If true, messages will be written
               with one or more STRUCTURED-DATA elements as per
               RFC5424; if false, messages will be written with
               STRUCTURED-DATA = NILVALUE.";
          }
          uses syslog-structured-data;
          container file-archive {
            description
              "This container describes the configuration
               parameters for log file archiving.";
            leaf number-of-files {
              if-feature file-limit-size;
              type uint32;
              description
                "This leaf specifies the maximum number of log
                 files retained. Specify 1 for implementations
                 that only support one log file.";
            }
            leaf max-file-size {
              if-feature file-limit-size;
              type uint64;
              units "megabytes";
              description
                "This leaf specifies the maximum log file size.";
            }
            leaf rollover {
              if-feature file-limit-duration;
              type uint32;
              units "minutes";
              description
                "This leaf specifies the length of time that log
                 events should be written to a specific log file.
                 Log events that arrive after the rollover period
                 cause the current log file to be closed and a new
                 log file to be opened.";
            }
            leaf retention {
              if-feature file-limit-duration;
              type uint16;
              units "hours";
              description
                "This leaf specifies the length of time that
                 completed/closed log event files should be stored
                 in the file system before they are deleted.";
            }
          }
        }
      }
      container remote {
        description
          "This container describes the configuration parameters for
           remote logging.";
        list destination {
          key "name";
          description
            "This list describes a collection of remote logging
             destinations.";
          leaf name {
            type string;
            description
              "An arbitrary name for the endpoint to connect to.";
          }
          choice transport {
            mandatory true;
            description
              "This choice describes the transport option.";
            case tcp {
              container tcp {
                description
                  "This container describes the TCP transport
                   options.";

                reference
                  "RFC 6587: Transmission of Syslog Messages over TCP";
                leaf address {
                  type inet:host;
                  description
                    "The leaf uniquely specifies the address of
                     the remote host. One of the following must
                     be specified: an ipv4 address, an ipv6
                     address, or a host name.";
                }
                leaf port {
                  type inet:port-number;
                  default 514;
                  description
                    "This leaf specifies the port number used to
                     deliver messages to the remote server.";
                }
              }
            }
            case udp {
              container udp {
                description
                  "This container describes the UDP transport
                   options.";
                reference
                  "RFC 5426: Transmission of Syslog Messages over UDP";
                leaf address {
                  type inet:host;
                  description
                    "The leaf uniquely specifies the address of
                     the remote host. One of the following must be
                     specified: an ipv4 address, an ipv6 address,
                     or a host name.";
                }
                leaf port {
                  type inet:port-number;
                  default 514;
                  description
                    "This leaf specifies the port number used to
                     deliver messages to the remote server.";
                }
              }
            }
          }
          uses syslog-selector;
          leaf destination-facility
            case tls {
            type identityref
              container tls {
              base syslogtypes:syslog-facility;
                description
                  "This container describes the TLS transport options.";
                reference
                  "RFC 5425: Transport Layer Security (TLS) Transport
                   Mapping for Syslog ";
                leaf address {
                  type inet:host;
                  description
                    "The leaf uniquely specifies the address of
                     the remote host. One of the following must be
                     specified: an ipv4 address, an ipv6 address,
                     or a host name.";
                }
                leaf port {
                  type inet:port-number;
                  default 6514;
                  description
                    "This leaf specifies the port number used to
                     deliver messages to the remote server.";
                }
              }
            }
          }
          uses syslog-selector;
          leaf destination-facility {
            type identityref {
              base syslogtypes:syslog-facility;
            }
            default syslogtypes:local7;
            description
              "This leaf specifies the facility used in messages
               delivered to the remote server.";
          }
          leaf source-interface {
            type if:interface-ref;
            description
              "This leaf sets the source interface for the remote
               Syslog server. Either the interface name or the
               interface IP address can be specified. If not set,
               messages sent to a remote syslog server will
               contain the IP address of the interface the syslog
               message uses to exit the network element";
          }
          uses syslog-structured-data;
          container syslog-sign {
            if-feature signed-messages-config;
            presence
              "If present, syslog-sign is activated.";
            description
              "This container describes the configuration
               parameters for signed syslog messages as described
               by RFC 5848.";
            reference
              "RFC 5848: Signed Syslog Messages";
            leaf cert-initial-repeat {
              type uint16;
              mandatory true;
              description
              "This leaf specifies the number of times each
               Certificate Block should be sent before the first
               message is sent.";
            }
            leaf cert-resend-delay {
              type uint16;
              mandatory true;
              description
                "This leaf specifies the maximum time delay in
                 seconds until resending the Certificate Block.";
            }
            leaf cert-resend-count {
              type uint16;
              mandatory true;
              description
                "This leaf specifies the maximum number of other
                 syslog messages to send until resending the
                 Certificate Block.";
            }
            leaf sig-max-delay {
              type uint16;
              mandatory true;
              description
                "This leaf specifies when to generate a new
                 Signature Block. If this many seconds have
                 elapsed since the message with the first message
                 number of the Signature Block was sent, a new
                 Signature Block should be generated.";
            }
            leaf sig-number-resends {
              type uint16;
              mandatory true;
              description
                "This leaf specifies the number of times a
                 Signature Block is resent. (It is recommended to
                 select a value of greater than 0 in particular
                 when the UDP transport [RFC5426] is used.).";
            }
            leaf sig-resend-delay {
              type uint16;
              mandatory true;
              description
                "This leaf specifies when to send the next
                 Signature Block transmission based on time. If
                 this many seconds have elapsed since the previous
                 sending of this Signature Block, resend it.";
            }
            leaf sig-resend-count {
              type uint16;
              mandatory true;
              description
                "This leaf specifies when to send the next
                 Signature Block transmission based on a count.
                 If this many other syslog messages have been sent
                 since the previous sending of this Signature
                 Block, resend it.";
            }
          }
        }
      }
      container terminal {
        if-feature terminal-action;
        description
          "This container describes the configuration parameters for
           the terminal logging configuration.";
        choice terminal-scope {
          mandatory true;
          description
            "This choice describes the option to specify all
             terminals or a specific terminal. The all terminals
             case implies that messages will be sent to all
             sessions on that terminal";
          case
        container all-terminals {
            description
              "This case specifies
          presence "Enables logging to all terminals.";
            container all-terminals {
          description
            "This container describes the configuration
             parameters for all terminals.";
          uses syslog-selector;
        }
          }
          case per-terminal
        list terminal {
          if-feature terminal-facility-user-logging-config;
            description
              "This case specifies one or more terminals.";
            list device-name {
          key "dname"; "name";
          description
            "This list describes a collection of device names."; ";
          leaf dname name {
            type string;
            description
              "This leaf uniquely describes a device name terminal which
                   is the device to
               will receive log messages.";
          }
          uses syslog-selector;
        }
      }
        }
      }
      container session {
        if-feature session-action;
        description
          "This container describes the configuration parameters for
           user CLI session logging configuration.";
        choice user-scope {
          mandatory true;
          description
            "This choice describes the option to specify all users
             or a specific user. The all users case implies that
             messages will be sent to all sessions";
          case all-users {
            description
              "This case specifies all users.";
        container all-users {
          presence "Enables logging to all user sessions.";
          description
            "This container describes the configuration
             parameters for all users.";
          uses syslog-selector;
        }
          }
          case per-user
        list user {
          if-feature session-facility-user-logging-config;
            description
              "This case specifies a specific user.";
            list user-name {
          key "uname"; "name";
          description
            "This list describes a collection of user names.";
          leaf uname name {
            type string;
            description
              "This leaf uniquely describes a user name which
               is the login name of the user whose session
               is to receive log messages.";
          }
          uses syslog-selector;
        }
      }
    }
  }
}
  }
}
<CODE ENDS>

4.3.  A SYSLOG Syslog Example

   Requirement:
   Enable console logging of syslogs of severity critical

   Here is the example syslog configuration xml:
   <rpc message-id="101" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <edit-config>
       <target>
         <candidate/>
       </target>
       <config xmlns:xc="urn:ietf:params:xml:ns:netconf:base:1.0">
         <syslog xmlns="urn:ietf:params:xml:ns:yang:ietf-syslog"
                 xmlns:syslog="urn:ietf:params:xml:ns:yang:ietf-syslog">
           <log-actions>
             <console>
               <log-selector>
                 <log-facility>
                   <facility>all</facility>
                   <severity>critical</severity>
                 </log-facility>
               </log-selector>
             </console>
           </log-actions>
         </syslog>
       </config>
     </edit-config>
   </rpc>

   <?xml version="1.0" encoding="UTF-8"?>
   <rpc-reply message-id="101" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <ok/>
   </rpc-reply>

   Enable remote logging of syslogs to udp destination 1.1.1.1
   for facility auth, severity error

   <rpc message-id="101" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <edit-config>
       <target>
         <candidate/>
       </target>
       <config xmlns:xc="urn:ietf:params:xml:ns:netconf:base:1.0">
         <syslog xmlns="urn:ietf:params:xml:ns:yang:ietf-syslog"
                 xmlns:syslog="urn:ietf:params:xml:ns:yang:ietf-syslog">
           <log-actions>
             <remote>
               <destination>
                 <name>remote1</name>
                 <udp>
                   <address>1.1.1.1</address>
                 </udp>
                 <log-selector>
                   <log-facility>
                     <facility xmlns:syslogtypes=
                       "urn:ietf:params:xml:ns:yang:ietf-syslog-types">
                       syslogtypes:auth</facility>
                     <severity>error</severity>
                   </log-facility>
                 </log-selector>
               </destination>
             </remote>
           </log-actions>
         </syslog>
       </config>
     </edit-config>
   </rpc>
   <?xml version="1.0" encoding="UTF-8"?>
   <rpc-reply message-id="101" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
   <ok/>
   </rpc-reply>

5.  Implementation Status

  [Note  Acknowledgements

   The authors wish to RFC Editor: Please remove this section before publication.]

  This section records the status of known implementations of the Syslog
  YANG model at thank the time of posting following who commented on versions 01
   through 06 of this Internet-Draft.

  Cisco Systems, Inc. has implemented the proposed IETF Syslog model
  for the Nexus 7000 NXOS OS as a prototype, together with an
  augmentation model for operating system specific Syslog configuration
  features.

  Five leaves were implemented proposal:

      Martin Bjorklund <mbjorklu@cisco.com>
      Jim Gibson <gibson@cisco.com>
      Jeffrey Haas <jhaas@pfrc.org>
      John Heasley <heas@shrubbery.net>
      Giles Heron <giheron@cisco.com>
      Lisa Huang <yihuan@cisco.com>
      Jeffrey K Lange <jeffrey.K.lange@ge.com>
      Jan Lindblad <jlindbla@cisco.com>
      Chris Lonvick <lonvick@gmail.com>
      Tom Petch <ietfc@btconnect.com>
      Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
      Jason Sterne <jason.sterne@alcatel-lucent.com>
      Peter Van Horne <petervh@cisco.com>
      Bert Wijnen <bertietf@bwijnen.net>
      Aleksandr Zhdankin <azhdanki@cisco.com>

6.  IANA Considerations

   This document registers two URIs in the base IETF model and three leaves
  were implemented in XML registry [RFC3688].

   Following the Cisco specific augmentation model as follows:

      Leaf XPATH                   Sample NXOS CLI Command(s)

  syslog:log-actions/console     logging console 1
  syslog:log-actions/file        logging logfile mylog.log 2 4096
  syslog:log-actions/terminal    logging monitor 2
  syslog:log-actions/remote     *logging server server.cisco.com 2
                                         facility user
                                *logging source-interface loopback 0
  cisco-syslog:logging-timestamp-config  logging timestamp milli-seconds
  cisco-syslog:origin-id-cfg  logging origin-id string abcdef
  cisco-syslog:module-logging logging module 1

  *The "logging server" and "logging source-interface" commands were
  combined into one base model leaf.

  The description of implementations format in this section RFC 3688, the following registration is intended
   requested to assist be made:

   URI: urn:ietf:params:xml:ns:yang:ietf-syslog-types

   Registrant Contact: The IESG.

   XML: N/A, the IETF requested URI is an XML namespace.

   This document registers a YANG module in its decision processes the YANG Module Names
   registry [RFC6020].

   name: ietf-syslog-types namespace: urn:ietf:params:xml:ns:yang:ietf-
   syslog-types

   prefix: ietf-syslog-types reference: RFC XXXX
   Following the format in progressing drafts RFC 3688, the following registration is
   requested to RFCs.

6. be made:

   URI: urn:ietf:params:xml:ns:yang:ietf-syslog

   Registrant Contact: The IESG.

   XML: N/A, the requested URI is an XML namespace.

   This document registers a YANG module in the YANG Module Names
   registry [RFC6020].

   name: ietf-syslog namespace: urn:ietf:params:xml:ns:yang:ietf-syslog

   prefix: ietf-syslog reference: RFC XXXX

7.  Security Considerations

   The YANG module defined in this memo is designed to be accessed via
   the NETCONF protocol [RFC6241] [RFC6241].  The lowest NETCONF layer is the
   secure transport layer and the mandatory-to-implement secure
   transport is SSH [RFC6242] [RFC6242].  The NETCONF access control model
   [RFC6536] [RFC6536] provides the means to restrict access for particular
   NETCONF users to a pre-configured subset of all available NETCONF
   protocol operations and content.

   There are a number of data nodes defined in the 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 (e.g., <edit-config>)
   to these data nodes without proper protection can have a negative
   effect on network operations.

   TBD: List specific Subtrees and data nodes and their sensitivity/
   vulnerability.

7.  IANA Considerations

   This document registers a URI in the IETF XML registry [RFC3688]
   [RFC3688].  Following the format

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFC 3688, the following
   registration is requested RFCs to be made:

   URI: urn:ietf:params:xml:ns:yang:syslog

   Registrant Contact: The IESG.

   XML: N/A, the requested URI is an XML namespace.

   This document registers a YANG module in the YANG Module Names
   registry [RFC6020].

   name: syslog namespace: urn:ietf:params:xml:ns:yang:syslog
   prefix: syslog reference: Indicate
              Requirement Levels", BCP 14, RFC XXXX

8.  Acknowledgements

The authors wish to thank the following who commented on versions 01 through 05
of this proposal:

Martin Bjorklund <mbjorklu@cisco.com>
Jim Gibson <gibson@cisco.com>
Jeffrey Haas <jhaas@pfrc.org>
John Heasley <heas@shrubbery.net>
Giles Heron <giheron@cisco.com>
Lisa Huang <yihuan@cisco.com>
Jeffrey K Lange <jeffrey.K.lange@ge.com>
Jan Lindblad <jlindbla@cisco.com>
Chris Lonvick <lonvick@gmail.com>
Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
Jason Sterne <jason.sterne@alcatel-lucent.com>
Peter Van Horne <petervh@cisco.com>
Bert Wijnen <bertietf@bwijnen.net>
Aleksandr Zhdankin <azhdanki@cisco.com>

9.  Change log [RFC Editor: Please remove]

10. References 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC5424]  Gerhards, R., "The Syslog Protocol", BCP 78, RFC 5424,
              DOI 10.17487/RFC5424, March 2009.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, 2009,
              <http://www.rfc-editor.org/info/rfc5424>.

   [RFC5425]  Miao, F., Ed., Ma, Y., Ed., and J. Salowey, Ed.,
              "Transport Layer Security (TLS) Transport Mapping for
              Syslog", RFC 5425, DOI 10.17487/RFC5425, March 2009,
              <http://www.rfc-editor.org/info/rfc5425>.

   [RFC5426]  Okmianski, A., "Transmission of Syslog Messages over UDP",
              RFC 3688, 5426, DOI 10.17487/RFC5426, March 2004.

   [RFC6020]  Bjorklund, M., "YANG - A Data Modeling Language for the
              Network Configuration Protocol (NETCONF)", 2009,
              <http://www.rfc-editor.org/info/rfc5426>.

   [RFC5848]  Kelsey, J., Callas, J., and A. Clemm, "Signed Syslog
              Messages", RFC 6020,
              October 2010. 5848, DOI 10.17487/RFC5848, May 2010,
              <http://www.rfc-editor.org/info/rfc5848>.

   [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. 2011,
              <http://www.rfc-editor.org/info/rfc6241>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011.

   [RFC6536]  Bierman, A. 2011,
              <http://www.rfc-editor.org/info/rfc6242>.

   [RFC6587]  Gerhards, R. and M. C. Lonvick, "Transmission of Syslog
              Messages over TCP", RFC 6587, DOI 10.17487/RFC6587, April
              2012, <http://www.rfc-editor.org/info/rfc6587>.

8.2.  Informative References

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

   [RFC6020]  Bjorklund, "Network M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF) Access Control Model", (NETCONF)", RFC 6536, March
              2012. 6020,
              DOI 10.17487/RFC6020, October 2010,
              <http://www.rfc-editor.org/info/rfc6020>.

Authors' Addresses

   Clyde Wildes (editor)
   Cisco Systems Inc.
   170 West Tasman Drive
   San Jose, CA  95134
   US

   Phone: +1 408 527-2672
   Email: cwildes@cisco.com
   Kiran Agrahara Sreenivasa Koushik (editor)
   Cisco Systems, Systems Inc.
   12515Research Blvd., Building 4
   Austin, TX  78759
   US

   Phone: +1 512 378-1482
   Email: kkoushik@cisco.com