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rfc:rfc6470

Internet Engineering Task Force (IETF) A. Bierman Request for Comments: 6470 Brocade Category: Standards Track February 2012 ISSN: 2070-1721

    Network Configuration Protocol (NETCONF) Base Notifications

Abstract

 The Network Configuration Protocol (NETCONF) provides mechanisms to
 manipulate configuration datastores.  However, client applications
 often need to be aware of common events, such as a change in NETCONF
 server capabilities, that may impact management applications.
 Standard mechanisms are needed to support the monitoring of the base
 system events within the NETCONF server.  This document defines a
 YANG module that allows a NETCONF client to receive notifications for
 some common system events.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6470.

Copyright Notice

 Copyright (c) 2012 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.

Bierman Standards Track [Page 1] RFC 6470 NETCONF Base Notifications February 2012

Table of Contents

 1. Introduction ....................................................2
    1.1. Terminology ................................................2
 2. YANG Module for NETCONF Base Notifications ......................3
    2.1. Overview ...................................................3
    2.2. Definitions ................................................4
 3. IANA Considerations ............................................11
 4. Security Considerations ........................................12
 5. Acknowledgements ...............................................14
 6. Normative References ...........................................14

1. Introduction

 The NETCONF protocol [RFC6241] provides mechanisms to manipulate
 configuration datastores.  However, client applications often need to
 be aware of common events, such as a change in NETCONF server
 capabilities, that may impact management applications.  Standard
 mechanisms are needed to support the monitoring of the base system
 events within the NETCONF server.  This document defines a YANG
 module [RFC6020] that allows a NETCONF client to receive
 notifications for some common system events.

1.1. Terminology

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in [RFC2119].
 The following terms are defined in [RFC6241]:
 o  client
 o  datastore
 o  protocol operation
 o  server
 The following terms are defined in [RFC5277]:
 o  event
 o  stream
 o  subscription
 The following term is defined in [RFC6020]:
 o  data node

Bierman Standards Track [Page 2] RFC 6470 NETCONF Base Notifications February 2012

2. YANG Module for NETCONF Base Notifications

2.1. Overview

 The YANG module defined within this document specifies a small number
 of event notification messages for use within the 'NETCONF' stream,
 and accessible to clients via the subscription mechanism described in
 [RFC5277].  This module imports data types from the 'ietf-netconf'
 module defined in [RFC6241] and 'ietf-inet-types' module defined in
 [RFC6021].
 These notifications pertain to configuration and monitoring portions
 of the managed system, not the entire system.  A server MUST report
 events that are directly related to the NETCONF protocol.  A server
 MAY report events for non-NETCONF management sessions, using the
 'session-id' value of zero.
 This module defines the following notifications for the 'NETCONF'
 stream to notify a client application that the NETCONF server state
 has changed:
 netconf-config-change:
    Generated when the NETCONF server detects that the <running> or
    <startup> configuration datastore has been changed by a management
    session.  The notification summarizes the edits that have been
    detected.
 netconf-capability-change:
    Generated when the NETCONF server detects that the server
    capabilities have changed.  Indicates which capabilities have been
    added, deleted, and/or modified.  The manner in which a server
    capability is changed is outside the scope of this document.
 netconf-session-start:
    Generated when a NETCONF server detects that a NETCONF session has
    started.  A server MAY generate this event for non-NETCONF
    management sessions.  Indicates the identity of the user that
    started the session.
 netconf-session-end:
    Generated when a NETCONF server detects that a NETCONF session has
    terminated.  A server MAY optionally generate this event for
    non-NETCONF management sessions.  Indicates the identity of the
    user that owned the session, and why the session was terminated.

Bierman Standards Track [Page 3] RFC 6470 NETCONF Base Notifications February 2012

 netconf-confirmed-commit:
    Generated when a NETCONF server detects that a confirmed-commit
    event has occurred.  Indicates the event and the current state of
    the confirmed-commit procedure in progress.

2.2. Definitions

 <CODE BEGINS> file="ietf-netconf-notifications@2011-12-09.yang"
 module ietf-netconf-notifications {
    namespace
      "urn:ietf:params:xml:ns:yang:ietf-netconf-notifications";
    prefix ncn;
    import ietf-inet-types { prefix inet; }
    import ietf-netconf { prefix nc; }
    organization
      "IETF NETCONF (Network Configuration Protocol) Working Group";
    contact
      "WG Web:   <http://tools.ietf.org/wg/netconf/>
       WG List:  <mailto:netconf@ietf.org>
       WG Chair: Bert Wijnen
                 <mailto:bertietf@bwijnen.net>
       WG Chair: Mehmet Ersue
                 <mailto:mehmet.ersue@nsn.com>
       Editor:   Andy Bierman
                 <mailto:andy@netconfcentral.org>";
    description
      "This module defines a YANG data model for use with the
       NETCONF protocol that allows the NETCONF client to
       receive common NETCONF base event notifications.
       Copyright (c) 2012 IETF Trust and the persons identified as
       the document authors.  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

Bierman Standards Track [Page 4] RFC 6470 NETCONF Base Notifications February 2012

       set forth in Section 4.c of the IETF Trust's Legal Provisions
       Relating to IETF Documents
       (http://trustee.ietf.org/license-info).
       This version of this YANG module is part of RFC 6470; see
       the RFC itself for full legal notices.";
    revision "2012-02-06" {
      description
        "Initial version.";
      reference
        "RFC 6470: NETCONF Base Notifications";
    }
   grouping common-session-parms {
     description
       "Common session parameters to identify a
        management session.";
     leaf username {
       type string;
       mandatory true;
       description
         "Name of the user for the session.";
     }
     leaf session-id {
       type nc:session-id-or-zero-type;
       mandatory true;
       description
         "Identifier of the session.
          A NETCONF session MUST be identified by a non-zero value.
          A non-NETCONF session MAY be identified by the value zero.";
     }
     leaf source-host {
       type inet:ip-address;
       description
         "Address of the remote host for the session.";
     }
   }

Bierman Standards Track [Page 5] RFC 6470 NETCONF Base Notifications February 2012

    grouping changed-by-parms {
     description
       "Common parameters to identify the source
        of a change event, such as a configuration
        or capability change.";
     container changed-by {
       description
         "Indicates the source of the change.
          If caused by internal action, then the
          empty leaf 'server' will be present.
          If caused by a management session, then
          the name, remote host address, and session ID
          of the session that made the change will be reported.";
       choice server-or-user {
         mandatory true;
         leaf server {
           type empty;
           description
             "If present, the change was caused
              by the server.";
         }
         case by-user {
           uses common-session-parms;
         }
       } // choice server-or-user
     } // container changed-by-parms
   }
   notification netconf-config-change {
     description
       "Generated when the NETCONF server detects that the
        <running> or <startup> configuration datastore
        has been changed by a management session.
        The notification summarizes the edits that
        have been detected.
        The server MAY choose to also generate this
        notification while loading a datastore during the
        boot process for the device.";
     uses changed-by-parms;

Bierman Standards Track [Page 6] RFC 6470 NETCONF Base Notifications February 2012

     leaf datastore {
       type enumeration {
         enum running {
           description "The <running> datastore has changed.";
         }
         enum startup {
           description "The <startup> datastore has changed";
         }
       }
       default "running";
       description
         "Indicates which configuration datastore has changed.";
     }
     list edit {
       description
         "An edit record SHOULD be present for each distinct
          edit operation that the server has detected on
          the target datastore.  This list MAY be omitted
          if the detailed edit operations are not known.
          The server MAY report entries in this list for
          changes not made by a NETCONF session (e.g., CLI).";
       leaf target {
         type instance-identifier;
         description
           "Topmost node associated with the configuration change.
            A server SHOULD set this object to the node within
            the datastore that is being altered.  A server MAY
            set this object to one of the ancestors of the actual
            node that was changed, or omit this object, if the
            exact node is not known.";
       }
       leaf operation {
         type nc:edit-operation-type;
         description
           "Type of edit operation performed.
            A server MUST set this object to the NETCONF edit
            operation performed on the target datastore.";
       }
     } // list edit
   } // notification netconf-config-change

Bierman Standards Track [Page 7] RFC 6470 NETCONF Base Notifications February 2012

   notification netconf-capability-change {
     description
       "Generated when the NETCONF server detects that
        the server capabilities have changed.
        Indicates which capabilities have been added, deleted,
        and/or modified.  The manner in which a server
        capability is changed is outside the scope of this
        document.";
     uses changed-by-parms;
     leaf-list added-capability {
       type inet:uri;
       description
         "List of capabilities that have just been added.";
     }
     leaf-list deleted-capability {
       type inet:uri;
       description
         "List of capabilities that have just been deleted.";
     }
     leaf-list modified-capability {
       type inet:uri;
       description
         "List of capabilities that have just been modified.
          A capability is considered to be modified if the
          base URI for the capability has not changed, but
          one or more of the parameters encoded at the end of
          the capability URI have changed.
          The new modified value of the complete URI is returned.";
     }
   } // notification netconf-capability-change
   notification netconf-session-start {
     description
       "Generated when a NETCONF server detects that a
        NETCONF session has started.  A server MAY generate
        this event for non-NETCONF management sessions.
        Indicates the identity of the user that started
        the session.";
     uses common-session-parms;
   } // notification netconf-session-start

Bierman Standards Track [Page 8] RFC 6470 NETCONF Base Notifications February 2012

   notification netconf-session-end {
     description
       "Generated when a NETCONF server detects that a
        NETCONF session has terminated.
        A server MAY optionally generate this event for
        non-NETCONF management sessions.  Indicates the
        identity of the user that owned the session,
        and why the session was terminated.";
     uses common-session-parms;
     leaf killed-by {
       when "../termination-reason = 'killed'";
       type nc:session-id-type;
       description
         "The ID of the session that directly caused this session
          to be abnormally terminated.  If this session was abnormally
          terminated by a non-NETCONF session unknown to the server,
          then this leaf will not be present.";
     }
     leaf termination-reason {
       type enumeration {
         enum "closed" {
           description
             "The session was terminated by the client in normal
              fashion, e.g., by the NETCONF <close-session>
              protocol operation.";
         }
         enum "killed" {
           description
             "The session was terminated in abnormal
              fashion, e.g., by the NETCONF <kill-session>
              protocol operation.";
         }
         enum "dropped" {
           description
             "The session was terminated because the transport layer
              connection was unexpectedly closed.";
         }
         enum "timeout" {
           description
             "The session was terminated because of inactivity,
              e.g., waiting for the <hello> message or <rpc>
              messages.";
         }

Bierman Standards Track [Page 9] RFC 6470 NETCONF Base Notifications February 2012

         enum "bad-hello" {
           description
             "The client's <hello> message was invalid.";
         }
         enum "other" {
           description
             "The session was terminated for some other reason.";
         }
       }
       mandatory true;
       description
         "Reason the session was terminated.";
     }
   } // notification netconf-session-end
   notification netconf-confirmed-commit {
     description
       "Generated when a NETCONF server detects that a
        confirmed-commit event has occurred.  Indicates the event
        and the current state of the confirmed-commit procedure
        in progress.";
     reference
       "RFC 6241, Section 8.4";
     uses common-session-parms {
       when "../confirm-event != 'timeout'";
     }
     leaf confirm-event {
       type enumeration {
         enum "start" {
           description
             "The confirmed-commit procedure has started.";
         }
         enum "cancel" {
           description
             "The confirmed-commit procedure has been canceled,
              e.g., due to the session being terminated, or an
              explicit <cancel-commit> operation.";
         }
         enum "timeout" {
           description
             "The confirmed-commit procedure has been canceled
              due to the confirm-timeout interval expiring.
              The common session parameters will not be present
              in this sub-mode.";
         }

Bierman Standards Track [Page 10] RFC 6470 NETCONF Base Notifications February 2012

         enum "extend" {
           description
             "The confirmed-commit timeout has been extended,
              e.g., by a new <confirmed-commit> operation.";
         }
         enum "complete" {
           description
             "The confirmed-commit procedure has been completed.";
         }
       }
       mandatory true;
       description
         "Indicates the event that caused the notification.";
     }
     leaf timeout {
       when
         "../confirm-event = 'start' or ../confirm-event = 'extend'";
       type uint32;
       units "seconds";
       description
         "The configured timeout value if the event type
          is 'start' or 'extend'.  This value represents
          the approximate number of seconds from the event
          time when the 'timeout' event might occur.";
     }
   } // notification netconf-confirmed-commit
 }
 <CODE ENDS>

3. IANA Considerations

 This document registers one XML namespace URN in the 'IETF XML
 registry', following the format defined in [RFC3688].
    URI: urn:ietf:params:xml:ns:yang:ietf-netconf-notifications
 Registrant Contact: The IESG.
 XML: N/A; the requested URI is an XML namespace.

Bierman Standards Track [Page 11] RFC 6470 NETCONF Base Notifications February 2012

 This document registers one module name in the 'YANG Module Names'
 registry, defined in [RFC6020].
    name: ietf-netconf-notifications
    prefix: ncn
    namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-notifications
    RFC: 6470

4. Security Considerations

 The YANG module defined in this memo is designed to be accessed via
 the NETCONF protocol [RFC6241].  The lowest NETCONF layer is the
 secure transport layer and the mandatory-to-implement secure
 transport is SSH, defined in [RFC6242].
 Some of the readable data nodes in this YANG module may be considered
 sensitive or vulnerable in some network environments.  It is thus
 important to control read access (e.g., via get, get-config, or
 notification) to these data nodes.  These are the subtrees and data
 nodes and their sensitivity/vulnerability:
 /netconf-config-change:
    Event type itself indicates that the system configuration has
    changed.  This event could alert an attacker that specific
    configuration data nodes have been altered.
 /netconf-config-change/changed-by:
    Indicates whether the server or a specific user management session
    made the configuration change.  Identifies the user name,
    session-id, and source host address associated with the
    configuration change, if any.
 /netconf-config-change/datastore:
    Indicates which datastore has been changed.  This data can be used
    to determine if the non-volatile startup configuration data has
    been changed.
 /netconf-config-change/edit:
    Identifies the specific edit operations and specific datastore
    subtree(s) that have changed.  This data could be used to
    determine if specific server vulnerabilities may now be present.

Bierman Standards Track [Page 12] RFC 6470 NETCONF Base Notifications February 2012

 /netconf-capability-change:
    Event type itself indicates that the system capabilities have
    changed, and may now be vulnerable to unspecified attacks.  An
    attacker will likely need to understand the content represented by
    specific capability URI strings.  For example, knowing that a
    packet capture monitoring capability has been added to the system
    might help an attacker identify the device for possible
    unauthorized eavesdropping.
 /netconf-capability-change/changed-by:
    Indicates whether the server or a specific user management session
    made the capability change.  Identifies the user name, session-id,
    and source host address associated with the capability change, if
    any.
 /netconf-capability-change/added-capability:
    Indicates the specific capability URIs that have been added.  This
    data could be used to determine if specific server vulnerabilities
    may now be present.
 /netconf-capability-change/deleted-capability:
    Indicates the specific capability URIs that have been deleted.
    This data could be used to determine if specific server
    vulnerabilities may now be present.
 /netconf-capability-change/modified-capability:
    Indicates the specific capability URIs that have been modified.
    This data could be used to determine if specific server
    vulnerabilities may now be present.
 /netconf-session-start:
    Event type itself indicates that a NETCONF or other management
    session may start altering the device configuration and/or state.
    It may be possible for an attacker to alter the configuration by
    somehow taking advantage of another session concurrently editing
    an unlocked datastore.
 /netconf-session-start/username:
    Indicates the user name associated with the session.
 /netconf-session-start/source-host:
    Indicates the source host address associated with the session.
 /netconf-session-end:
    Event type itself indicates that a NETCONF or other management
    session may be finished altering the device configuration.  This
    event could alert an attacker that a datastore may have been
    altered.
 /netconf-session-end/username:
    Indicates the user name associated with the session.
 /netconf-session-end/source-host:
    Indicates the source host address associated with the session.

Bierman Standards Track [Page 13] RFC 6470 NETCONF Base Notifications February 2012

 /netconf-confirmed-commit:
    Event type itself indicates that the <running> datastore may have
    changed.  This event could alert an attacker that the device
    behavior has changed.
 /netconf-confirmed-commit/username:
    Indicates the user name associated with the session.
 /netconf-confirmed-commit/source-host:
    Indicates the source host address associated with the session.
 /netconf-confirmed-commit/confirm-event:
    Indicates the specific confirmed-commit state change that
    occurred.  A value of 'complete' probably indicates that the
    <running> datastore has changed.
 /netconf-confirmed-commit/timeout:
    Indicates the number of seconds in the future when the <running>
    datastore may change, due to the server reverting to an older
    configuration.

5. Acknowledgements

 Thanks to Martin Bjorklund, Juergen Schoenwaelder, Kent Watsen, and
 many other members of the NETCONF WG for providing important input to
 this document.

6. Normative References

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
            January 2004.
 [RFC5277]  Chisholm, S. and H. Trevino, "NETCONF Event
            Notifications", RFC 5277, July 2008.
 [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
            the Network Configuration Protocol (NETCONF)", RFC 6020,
            October 2010.
 [RFC6021]  Schoenwaelder, J., Ed., "Common YANG Data Types",
            RFC 6021, October 2010.
 [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
            and A. Bierman, Ed., "Network Configuration Protocol
            (NETCONF)", RFC 6241, June 2011.
 [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
            Shell (SSH)", RFC 6242, June 2011.

Bierman Standards Track [Page 14] RFC 6470 NETCONF Base Notifications February 2012

Author's Address

 Andy Bierman
 Brocade
 EMail: andy@netconfcentral.org

Bierman Standards Track [Page 15]

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