RFC 6470
Network Configuration Protocol (NETCONF) Base Notifications
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 NotificationsAbstract
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.
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 ...........................................141. 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 (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
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: 64704. 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