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Versions: (draft-wildes-netmod-syslog-model) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Draft is active
In: MissingRef
NETMOD WG                                                   Clyde Wildes
Internet-Draft                                             Cisco Systems
Intended status: Informational                    Agrahara Kiran Koushik
Expires: Jan 06, 2016                      Brocade Communication Systems
                                                           Jul 06, 2015


                             SYSLOG YANG model
                  draft-ietf-netmod-syslog-model-04

Abstract

   This document describes a data model for 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 Jan 06, 2016.

Copyright Notice

   Copyright (c) 2015 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.



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Table of Contents

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

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 [RFC3164] in this
   draft.


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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 and Forwarding

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.

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 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.

   Syslog consists of message producers, a group level suppression filter,
   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 to message distributors where
   further suppression filtering can take place.

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

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

    |                                                                |
    +----------------------------------------------------------------+
                 |
                 |
                 |
                 |
         +------------+------------+------------+-----------+
         |            |            |            |           |
         v            v            v            v           v
   Message Distributors
    +----------+ +----------+ +----------+  +----------+  +----------+
    |          | | Log      | | Log      |  |    User  |  |   Remote |
    |  Console | | Buffer   | | File(s)  |  | Terminals|  |   Servers|
    +----------+ +----------+ +----------+  +----------+  +----------+

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

   - console
   - log buffer
   - log file(s)
   - user terminals
   - remote server(s).

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

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3.1.  SYSLOG Module
module: ietf-syslog
   +--rw syslog
      +--rw log-actions
         +--rw console
         |  +--rw log-selector
         |     +--rw (logging-level-scope)?
         |     |  +--:(logging-facility-all)
         |     |  |  +--rw all-facilities?      empty
         |     |  |  +--rw severity?            union
         |     |  +--:(logging-facility-none)
         |     |  |  +--rw no-facilities?       empty
         |     |  +--:(logging-facility)
         |     |     +--rw facilities* [facility]
         |     |        +--rw facility    identityref
         |     |        +--rw severity?   union
         |     +--rw severity-operator?   enumeration {selector-severity-operator-config}?
         |     +--rw pattern-match?       string {selector-match-processing-config}?
         +--rw buffer
         |  +--rw log-buffer* [name]
         |     +--rw name                    string
         |     +--rw log-selector
         |     |  +--rw (logging-level-scope)?
         |     |  |  +--:(logging-facility-all)
         |     |  |  |  +--rw all-facilities?      empty
         |     |  |  |  +--rw severity?            union
         |     |  |  +--:(logging-facility-none)
         |     |  |  |  +--rw no-facilities?       empty
         |     |  |  +--:(logging-facility)
         |     |  |     +--rw facilities* [facility]
         |     |  |        +--rw facility    identityref
         |     |  |        +--rw severity?   union
         |     |  +--rw severity-operator?   enumeration {selector-severity-operator-config}?
         |     |  +--rw pattern-match?       string {selector-match-processing-config}?
         |     +--rw buffer-size-bytes?      uint64 {buffer-limit-bytes}?
         |     +--rw buffer-size-messages?   uint64 {buffer-limit-messages}?
         +--rw file
         |  +--rw log-file* [name]
         |     +--rw name               inet:uri
         |     +--rw log-selector
         |     |  +--rw (logging-level-scope)?
         |     |  |  +--:(logging-facility-all)
         |     |  |  |  +--rw all-facilities?      empty
         |     |  |  |  +--rw severity?            union
         |     |  |  +--:(logging-facility-none)
         |     |  |  |  +--rw no-facilities?       empty
         |     |  |  +--:(logging-facility)
         |     |  |     +--rw facilities* [facility]
         |     |  |        +--rw facility    identityref
         |     |  |        +--rw severity?   union
         |     |  +--rw severity-operator?   enumeration {selector-severity-operator-config}?
         |     |  +--rw pattern-match?       string {selector-match-processing-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 remote-logging-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
         |     +--rw log-selector
         |     |  +--rw (logging-level-scope)?
         |     |  |  +--:(logging-facility-all)
         |     |  |  |  +--rw all-facilities?      empty
         |     |  |  |  +--rw severity?            union
         |     |  |  +--:(logging-facility-none)
         |     |  |  |  +--rw no-facilities?       empty
         |     |  |  +--:(logging-facility)
         |     |  |     +--rw facilities* [facility]
         |     |  |        +--rw facility    identityref
         |     |  |        +--rw severity?   union
         |     |  +--rw severity-operator?   enumeration {selector-severity-operator-config}?
         |     |  +--rw pattern-match?       string {selector-match-processing-config}?
         |     +--rw destination-facility?   identityref
         |     +--rw source-interface?       if:interface-ref
         |     +--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
            +--rw (user-scope)?
               +--:(all-users)
               |  +--rw all-users
               |     +--rw log-selector
               |        +--rw (logging-level-scope)?
               |        |  +--:(logging-facility-all)
               |        |  |  +--rw all-facilities?      empty
               |        |  |  +--rw severity?            union
               |        |  +--:(logging-facility-none)
               |        |  |  +--rw no-facilities?       empty
               |        |  +--:(logging-facility)
               |        |     +--rw facilities* [facility]
               |        |        +--rw facility    identityref
               |        |        +--rw severity?   union
               |        +--rw severity-operator?   enumeration {selector-severity-operator-config}?
               |        +--rw pattern-match?       string {selector-match-processing-config}?
               +--:(per-user) {terminal-facility-user-logging-config}?
                  +--rw user-name* [uname]
                     +--rw uname           string
                     +--rw log-selector
                        +--rw (logging-level-scope)?
                        |  +--:(logging-facility-all)
                        |  |  +--rw all-facilities?      empty
                        |  |  +--rw severity?            union
                        |  +--:(logging-facility-none)
                        |  |  +--rw no-facilities?       empty
                        |  +--:(logging-facility)
                        |     +--rw facilities* [facility]
                        |        +--rw facility    identityref
                        |        +--rw severity?   union
                        +--rw severity-operator?   enumeration {selector-severity-operator-config}?
                        +--rw pattern-match?       string {selector-match-processing-config}?


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4.  SYSLOG YANG Models

4.1.  SYSLOG-TYPES 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>

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

     Editor:   Ladislav Lhotka
               <mailto:lhotka@nic.cz>";
  description
    "This module contains a collection of YANG type definitions for
     SYSLOG.";

  revision 2015-07-06 {
    description
      "Initial Revision";
    reference
      "This model references RFC 5424 - The Syslog Protocol,
       and RFC 5848 - Signed Syslog Messages.";
  }

  typedef severity {
    type enumeration {
      enum "emergency" {
        value 0;
        description
          "Emergency Level Msg";
      }
      enum "alert" {
        value 1;
        description
          "Alert Level Msg";
      }

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      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 identity to represent syslog facilities";
  }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  identity local7 {
    base syslog-facility;
    description
      "The facility for local use 7 messages as defined in
       RFC 5424.";
  }
}

<CODE ENDS>

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4.2. 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>

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

     Editor:   Ladislav Lhotka
               <mailto:lhotka@nic.cz>";
  description
    "This module contains a collection of YANG definitions
     for Syslog configuration.";

  revision 2015-07-06 {
    description
      "Initial Revision";
    reference
      "RFC 5424: The Syslog Protocol
       RFC 5848: Signed Syslog Messages";
  }

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

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  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 {
    description
      "This feature represents the ability to adjust
       log message settings for individual terminal users.";
  }

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

  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
       filter 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.";
          }
        }
      }
      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 unless all is specified which means all severities
         are requested. No value implies no severity is requested.";
    }
  }

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  grouping syslog-selector {
    description
      "This grouping defines a Syslog selector which is used to
       filter log messages for the given action in which the
       selector appears. Choose one of the following:
         logging-facility-all <severity>
         logging-facility-none
         logging-facility [<facility> <severity>...]
       Additional severity comparison operations are available
       using the severity-operator leaf. If the severity-operator
       leaf is not present all messages of the specified severity
       and higher are logged according to the given action.";
    container log-selector {
      description
        "This container describes the log selector parameters
         for Syslog.";
      choice logging-level-scope {
        default logging-facility-all;
        description
          "This choice describes the option to specify all
           facilities, no facilities, or a specific facility.";
        case logging-facility-all {
          description
            "This case specifies all facilities will match when
             comparing the Syslog message facility.";
          leaf all-facilities {
            type empty;
            description
            "This leaf specifies that all facilities participate in
             the filtering of Syslog messages for this action.";
          }
          uses syslog-severity;
        }
        case logging-facility-none {
          description
            "This case specifies no facilities will match when
             comparing the Syslog message facility. This is a method
             that can be used to turn an action off.";
          leaf no-facilities {
            type empty;
            description
            "This leaf specifies that no facilities participate in
             the filtering of Syslog messages for this action.";
          }
        }
        case logging-facility {
          description
            "This case specifies one or more specified facilities
             will match when comparing the Syslog message facility.";
          list facilities {
            key "facility";
            description
              "This list describes a collection of Syslog facilities
               and severities.";
            leaf facility {
              type identityref {
                base syslogtypes:syslog-facility;
              }
              description
                "The leaf uniquely identifies a Syslog facility.";
            }
            uses syslog-severity;
          }
        }
      }

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      leaf severity-operator {
        if-feature selector-severity-operator-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 action";
          }
          enum equals {
            description
              "This enum specifies all messages that are for
               the specified severity are logged according to the
               given action";
          }
          enum not-equals {
            description
              "This enum specifies all messages that are not for
               the specified severity are logged according to the
               given action";
          }
        }
        default equals-or-higher;
        description
          "This leaf describes the option to specify how the
           severity comparison is performed.";
      }
      leaf pattern-match {
        if-feature selector-match-processing-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.";
      }
    }
  }

  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 {
        description
          "This container describes the configuration parameters for
           console logging.";
        uses syslog-selector;
      }

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      container buffer {
        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.";
        list log-buffer {
          key name;
          description
            "This list describes a collection of local logging
             memory buffers.";
          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.";
          }
        }
      }

      container file {
        description
          "This container describes the configuration parameters for
           file logging.";
        list log-file {
          key "name";
          description
            "This list describes a collection of local logging
             files.";
          leaf name {
            type inet:uri;
            description
              "This leaf specifies the name of the log file which
               MUST use the uri scheme file:.";
          }

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          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.";
          }
          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 remote-logging-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.";
          }

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          choice transport {
            mandatory true;
            description
              "This choice describes the transport option.";
            case tcp {
              container tcp {
                description
                  "This container describes the TCP transport
                   options.";
                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.";
                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 {
            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";
          }

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          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.";
            }
          }
        }
      }

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      container terminal {
        description
          "This container describes the configuration parameters for
           the terminal logging configuration.";
        choice user-scope {
          default all-users;
          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 terminals";
          case all-users {
            description
              "This case specifies all users.";
            container all-users {
              description
                "This container describes the configuration
                 parameters for all users.";
              uses syslog-selector;
            }
          }
          case per-user {
            if-feature terminal-facility-user-logging-config;
            description
              "This case specifies a specific user.";
            list user-name {
              key "uname";
              description
                "This list describes a collection of user names.";
              leaf uname {
                type string;
                description
                  "This leaf uniquely describes a user name which is
                   the login name of the user whose terminal session
                   is to receive log messages.";
              }
              uses syslog-selector;
            }
          }
        }
      }
    }
  }
}

<CODE ENDS>

4.3.  A SYSLOG Example

   Requirement:
   Enable console logging of syslogs of severity
   critical(1)

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

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5.  Implementation Status

  [Note to RFC Editor: Please remove this section before publication.]

  This section records the status of known implementations of the Syslog
  YANG model at the time of posting 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 in the base IETF model and three leaves
  were implemented in 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 in this section is intended to assist
  the IETF in its decision processes in progressing drafts to RFCs.

6.  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.


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7.  IANA Considerations

   This document registers a URI in the IETF XML registry [RFC3688]
   [RFC3688].  Following the format in RFC 3688, the following
   registration is requested 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: RFC XXXX

8.  Acknowledgements

The authors wish to thank the following who commented on versions 01 through 03
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

   [RFC3164]  Lonvick, C., "The BSD syslog Protocol", BCP 81, RFC 3164,
              August 2001.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              March 2204.

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

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

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



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

Authors' Addresses

   Clyde Wildes
   Cisco Systems Inc.

   Email: cwildes@cisco.com


   Kiran Agrahara Sreenivasa
   Cisco Systems, Inc.

   Email: kkoushik@cisco.com

















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