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

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 © 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.

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

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.
   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 © 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
         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.";
       }
     }
      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;
       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
     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
     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.";
           }
           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.";
           }
           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. 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.
   /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.
   /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.

Author's Address

Andy Bierman Brocade
   EMail: andy@netconfcentral.org