Internet DRAFT - draft-kwatsen-netconf-server
draft-kwatsen-netconf-server
NETCONF Working Group K. Watsen
Internet-Draft Juniper Networks
Intended status: Standards Track J. Schoenwaelder
Expires: August 18, 2014 Jacobs University Bremen
February 14, 2014
A YANG Data Model for NETCONF Server Configuration
draft-kwatsen-netconf-server-01
Abstract
This draft defines a NETCONF server configuration data model. This
data model enables configuration of the NETCONF service itself,
including which transports it supports, what ports they listen on,
whether they support device-initiated connections, and associated
parameters.
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 August 18, 2014.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
Watsen & Schoenwaelder Expires August 18, 2014 [Page 1]
Internet-Draft YANG NETCONF Server Configuration February 2014
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 . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Tree Diagrams . . . . . . . . . . . . . . . . . . . . . . 3
2. Objectives . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Support all NETCONF Transports . . . . . . . . . . . . . 3
2.2. Align Transport-Specific Configurations . . . . . . . . . 4
2.3. Support Transport-Independent Configuration . . . . . . . 4
2.4. Support both Inbound and Outbound Connections . . . . . . 4
2.5. For Device-Initiated Outbound Connections . . . . . . . . 4
2.5.1. Support More than One Application . . . . . . . . . . 4
2.5.2. Support Applications Having More than One Server . . 4
2.5.3. Support a Reconnection Strategy . . . . . . . . . . . 5
2.5.4. Support both Persistent and Periodic Connections . . 5
2.5.5. Keep-Alives for Persistent Connections . . . . . . . 5
2.5.6. Customizations for Periodic Connections . . . . . . . 5
3. Data Model Overview . . . . . . . . . . . . . . . . . . . . . 6
3.1. The "listen" Grouping . . . . . . . . . . . . . . . . . . 6
3.2. The "call-home" Grouping . . . . . . . . . . . . . . . . 6
3.3. The SSH Subtree . . . . . . . . . . . . . . . . . . . . . 7
3.4. The TLS Subtree . . . . . . . . . . . . . . . . . . . . . 8
4. NETCONF Server YANG Module . . . . . . . . . . . . . . . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 21
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1. Normative References . . . . . . . . . . . . . . . . . . 22
8.2. Informative References . . . . . . . . . . . . . . . . . 22
Appendix A. Example: SSH . . . . . . . . . . . . . . . . . . . . 22
Appendix B. Example: TLS . . . . . . . . . . . . . . . . . . . . 23
Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 25
C.1. 00 to 01 . . . . . . . . . . . . . . . . . . . . . . . . 25
Appendix D. Open Issues . . . . . . . . . . . . . . . . . . . . 25
1. Introduction
Watsen & Schoenwaelder Expires August 18, 2014 [Page 2]
Internet-Draft YANG NETCONF Server Configuration February 2014
This draft defines a NETCONF [RFC6241] server configuration data
model. This data model enables configuration of the NETCONF service
itself, including which transports it supports, what ports they
listen on, whether they support device-initiated connections, and
associated parameters.
1.1. Terminology
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
1.2. Tree Diagrams
A simplified graphical representation of the data model is used in
this document. The meaning of the symbols in these diagrams is as
follows:
o Brackets "[" and "]" enclose list keys.
o Abbreviations before data node names: "rw" means configuration
(read-write) and "ro" state data (read-only).
o Symbols after data node names: "?" means an optional node, "!"
means a presence container, and "*" denotes a list and leaf-list.
o Parentheses enclose choice and case nodes, and case nodes are also
marked with a colon (":").
2. Objectives
The primary purpose of this YANG module is to enable the
configuration of the NETCONF service on the device. This scope
includes both transport-independent and transport-specific
configuration parameters.
2.1. Support all NETCONF Transports
The YANG module should support all current NETCONF transports, namely
NETCONF over SSH [RFC6242] and NETCONF over TLS
[I-D.ietf-netconf-rfc5539bis], and be extensible to support future
transports as necessary.
Since implementations may not support all transports, the module
should use YANG "feature" statements so that each implementation can
advertise which transports it actually supports.
Watsen & Schoenwaelder Expires August 18, 2014 [Page 3]
Internet-Draft YANG NETCONF Server Configuration February 2014
2.2. Align Transport-Specific Configurations
While each transport is unique in its protocol and may have some
distinct configurations, there remains a significant overlap between
them. Thus the YANG module should use "grouping" statements so that
the common aspects can be configured similarly.
2.3. Support Transport-Independent Configuration
Since some NETCONF server configurations may be independent of any
transport, the module should define a location for these transport-
independent values to be configured.
2.4. Support both Inbound and Outbound Connections
Historically, NETCONF only supported the device opening a port to
listen for inbound client connections. However, the NETCONF working
group is actively defining support for devices to initiate outbound
connections (e.g., "call home"). Thus, the module should enable the
configuration of both inbound and outbound connections.
Since implementations may not support both inbound and outbound
connections, the module should use YANG "feature" statements so that
each implementation can advertise the type of connections it actually
supports.
2.5. For Device-Initiated Outbound Connections
The following objectives only pertain to support for device-initiated
outbound connections.
2.5.1. Support More than One Application
A device may be managed by more than one northbound applications.
For instance, a deployment may have one application for provisioning
and another for fault monitoring. Therefore, when it is desired for
a device to initiate management connections, it should be able to do
so for more than one application.
2.5.2. Support Applications Having More than One Server
An application managing a device may implement a high-availability
strategy employing a multiplicity of active and/or passive servers.
Therefore, when it is desired for a device to initiate connections to
the application, it should be able to connect to any of the
applications servers.
Watsen & Schoenwaelder Expires August 18, 2014 [Page 4]
Internet-Draft YANG NETCONF Server Configuration February 2014
2.5.3. Support a Reconnection Strategy
Assuming an application has more than one server, then it becomes
necessary to understand how a device should reconnect to the
application should it lose its connection to one of the application's
servers. Of primary interest is if the device should start with
first server defined in a user-ordered list of servers or with the
last server it was connected to. Secondary settings might specify
the frequency of attempts and number of attempts per server.
Therefore, a reconnection strategy should be configurable.
Note that the reconnection strategy should apply to both persistent
and periodic connections. How it applies to periodic connections
becomes clear when considering that a periodic "connection" is a
logical connection to a single server. That is, the periods of
unconnectedness are intentional as opposed to due to external
reasons. A periodic "connection" should always reconnect to the same
server until it is no longer able to, at which time the reconnection
strategy guides the device how to get connected to another server.
2.5.4. Support both Persistent and Periodic Connections
Applications may vary greatly on how frequently they need to interact
with a device, how responsive interactions with devices need to be,
and how many simultaneous connections they can support. Some
applications may need a persistent connection to devices to optimize
real-time interactions, while others are satisfied with periodic
interactions and reduced resources required. Therefore, when it is
necessary for devices to initiate connections, the type of connection
desired should be configured.
2.5.5. Keep-Alives for Persistent Connections
If a persistent connection is desired, it is the responsibility of
the connection-initiator to actively test the connection for
aliveness. However, there is a balance between the frequency of the
tests and the networking overhead they generate. The appropriate
balance can only be determined by the application, based on its
interaction requirements. Therefore, for persistent connections,
keep-alive settings should be configurable on a per-application
basis.
2.5.6. Customizations for Periodic Connections
If a periodic connection is desired, it is necessary for the device
to know how often it should connect. This delay essentially
determines how long the application might have to wait to send data
to the device. Note, this setting does not constrain how often the
Watsen & Schoenwaelder Expires August 18, 2014 [Page 5]
Internet-Draft YANG NETCONF Server Configuration February 2014
device must wait to send data to the application, as the device
should immediately connect to the application whenever it has data to
send to it.
A common communication pattern is that one data transmission is many
times closely followed by another. For instance, if the device needs
to send a notification message, there's a high probability that it
will send another shortly thereafter. Likewise, the application may
have a sequence of pending messages to send. Thus, it should be
possible for a device to hold a connection open until some amount of
time of no data being transmitted as transpired.
3. Data Model Overview
3.1. The "listen" Grouping
To enable transports to configure listening on one or more ports in a
common way, this grouping is defined. Being a grouping enables each
transport-specific data-model to augment it as needed (e.g., to
specify a default for the "port" values), as well as enable
implementations to advertise support for listening for inbound
connections using a YANG feature.
+--rw listen
+--rw (one-or-many)?
+--:(one-port)
| +--rw port? inet:port-number
+--:(many-ports)
+--rw interface* [address]
+--rw address inet:ip-address
+--rw port? inet:port-number
3.2. The "call-home" Grouping
To enable transports to configure initiating connections to remote
applications in a common way, this grouping is defined. Being a
grouping enables each transport-specific data-model to augment it as
needed (e.g., to specify a default port value, lists of algorithms to
advertise, etc.), as well as enable implementations to advertise
support for listening for inbound connections using a YANG feature.
+--rw call-home
+--rw applications
+--rw application* [name]
+--rw name string
+--rw description? string
+--rw servers
| +--rw server* [address]
Watsen & Schoenwaelder Expires August 18, 2014 [Page 6]
Internet-Draft YANG NETCONF Server Configuration February 2014
| +--rw address inet:host
| +--rw port? inet:port-number
+--rw connection-type
| +--rw (connection-type)?
| +--:(persistent-connection)
| | +--rw persistent
| | +--rw keep-alives
| | +--rw interval-secs? uint8
| | +--rw count-max? uint8
| +--:(periodic-connection)
| +--rw periodic
| +--rw timeout-mins? uint8
| +--rw linger-secs? uint8
+--rw reconnect-strategy
+--rw start-with? enumeration
+--rw interval-secs? uint8
+--rw count-max? uint8
3.3. The SSH Subtree
The SSH subtree uses both the "listen" and "call-home" groupings
mentioned above. Support for the SSH transport is advertised by the
"ssh" feature, while listening for clients and calling home are
advertised by the "inbound-ssh" and "outbound-ssh" features
respectively. The SSH subtree augments the "call-home" grouping by
adding a "host-keys" container. Also, though not visible in the tree
output below, this subtree refines all the port values with a
suitable default (i.e., 830).
+--rw netconf
+--rw ssh {ssh}?
+--rw listen {inbound-ssh}?
| +--rw (one-or-many)?
| +--:(one-port)
| | +--rw port? inet:port-number
| +--:(many-ports)
| +--rw interface* [address]
| +--rw address inet:ip-address
| +--rw port? inet:port-number
+--rw call-home {outbound-ssh}?
+--rw applications
+--rw application* [name]
+--rw name string
+--rw description? string
+--rw servers
| +--rw server* [address]
| +--rw address inet:host
| +--rw port? inet:port-number
Watsen & Schoenwaelder Expires August 18, 2014 [Page 7]
Internet-Draft YANG NETCONF Server Configuration February 2014
+--rw connection-type
| +--rw (connection-type)?
| +--:(persistent-connection)
| | +--rw persistent
| | +--rw keep-alives
| | +--rw interval-secs? uint8
| | +--rw count-max? uint8
| +--:(periodic-connection)
| +--rw periodic
| +--rw timeout-mins? uint8
| +--rw linger-secs? uint8
+--rw reconnect-strategy
| +--rw start-with? enumeration
| +--rw interval-secs? uint8
| +--rw count-max? uint8
+--rw host-keys
+--rw host-key* [name]
+--rw name string
3.4. The TLS Subtree
The TLS subtree uses both the "listen" and "call-home" groupings
mentioned above, while also defining containers for certificate and
pre-shared key mappings. Support for the TLS transport is advertised
by the "tls" feature, while listening for clients and calling home
are advertised by the "inbound-tls" and "outbound-tls" features
respectively. Also, though not visible in the tree output below,
this submodule refines all the port values with a suitable defaults
(e.g., 6513).
+--rw netconf
+--rw tls {tls}?
+--rw listen {inbound-tls}?
| +--rw (one-or-many)?
| +--:(one-port)
| | +--rw port? inet:port-number
| +--:(many-ports)
| +--rw interface* [address]
| +--rw address inet:ip-address
| +--rw port? inet:port-number
+--rw call-home {outbound-tls}?
| +--rw applications
| +--rw application* [name]
| +--rw name string
| +--rw description? string
| +--rw servers
| | +--rw server* [address]
| | +--rw address inet:host
Watsen & Schoenwaelder Expires August 18, 2014 [Page 8]
Internet-Draft YANG NETCONF Server Configuration February 2014
| | +--rw port? inet:port-number
| +--rw connection-type
| | +--rw (connection-type)?
| | +--:(persistent-connection)
| | | +--rw persistent
| | | +--rw keep-alives
| | | +--rw interval-secs? uint8
| | | +--rw count-max? uint8
| | +--:(periodic-connection)
| | +--rw periodic
| | +--rw timeout-mins? uint8
| | +--rw linger-secs? uint8
| +--rw reconnect-strategy
| +--rw start-with? enumeration
| +--rw interval-secs? uint8
| +--rw count-max? uint8
+--rw cert-maps {tls-map-certificates}?
| +--rw cert-to-name* [id]
| +--rw id uint32
| +--rw fingerprint x509c2n:tls-fingerprint
| +--rw map-type identityref
| +--rw name string
+--rw psk-maps {tls-map-pre-shared-keys}?
+--rw psk-map* [psk-identity]
+--rw psk-identity string
+--rw user-name nacm:user-name-type
+--rw not-valid-before? yang:date-and-time
+--rw not-valid-after? yang:date-and-time
+--rw key yang:hex-string
4. NETCONF Server YANG Module
This YANG module imports YANG extensions from [RFC6536], and imports
YANG types from [RFC6991] and a YANG grouping from
[I-D.ietf-netmod-snmp-cfg].
module ietf-netconf-server {
namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-server";
prefix "ncserver";
import ietf-yang-types {
prefix yang; // RFC 6991
}
import ietf-inet-types {
prefix inet; // RFC 6991
}
import ietf-x509-cert-to-name {
Watsen & Schoenwaelder Expires August 18, 2014 [Page 9]
Internet-Draft YANG NETCONF Server Configuration February 2014
prefix x509c2n; // I-D.ietf-netconf-rfc5539bis
}
import ietf-netconf-acm {
prefix nacm; // RFC 6536
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
WG Chair: Mehmet Ersue
<mailto:mehmet.ersue@nsn.com>
WG Chair: Bert Wijnen
<mailto:bertietf@bwijnen.net>
Editor: Juergen Schoenwaelder
<mailto:j.schoenwaelder@jacobs-university.de>
Kent Watsen
<mailto:kwatsen@juniper.net>";
description
"This module contains a collection of YANG definitions for
configuring NETCONF servers.
Copyright (c) 2014 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD
License set forth in Section 4.c of the IETF Trust's
Legal Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
// RFC Ed.: replace XXXX with actual RFC number and
// remove this note
// RFC Ed.: please update the date to the date of publication
revision "2014-01-24" {
description
Watsen & Schoenwaelder Expires August 18, 2014 [Page 10]
Internet-Draft YANG NETCONF Server Configuration February 2014
"Initial version";
reference
"RFC XXXX: A YANG Data Model for NETCONF Server Configuration";
}
/*
* Features
*/
feature ssh {
description
"A server implements this feature if it supports NETCONF
over Secure Shell (SSH).";
reference
"RFC 6242: Using the NETCONF Protocol over Secure Shell (SSH)";
}
feature inbound-ssh {
description
"The inbound-ssh feature indicates that the server can
open a port to listen for incoming client connections.";
}
feature outbound-ssh {
description
"The outbound-ssh feature indicates that the server can
connect to a client.";
reference
"RFC XXXX: Reverse Secure Shell (Reverse SSH)";
}
feature tls {
description
"A server implements this feature if it supports NETCONF
over Transport Layer Security (TLS).";
reference
"RFC XXXX: NETCONF over Transport Layer Security (TLS)";
}
feature inbound-tls {
description
"The inbound-tls feature indicates that the server can
open a port to listen for incoming client connections.";
}
feature outbound-tls {
description
"The outbound-tls feature indicates that the server can
Watsen & Schoenwaelder Expires August 18, 2014 [Page 11]
Internet-Draft YANG NETCONF Server Configuration February 2014
connect to a client.";
}
feature tls-map-certificates {
description
"The tls-map-certificates feature indicates that the
server implements mapping X.509 certificates to NETCONF
usernames.";
}
feature tls-map-pre-shared-keys {
description
"The tls-map-pre-shared-keys feature indicates that the
server implements mapping TLS pre-shared keys to NETCONF
usernames.";
}
/*
* Groupings
*/
grouping listen-config {
description
"Provides a choice of configuring one of more ports
to listen for incoming client connections.";
choice one-or-many {
default one-port;
case one-port {
leaf port {
type inet:port-number;
description
"The port number the server listens on on all
interfaces.";
}
}
case many-ports {
list interface {
key "address";
leaf address {
type inet:ip-address;
mandatory true;
description
"The local IP address of the interface to listen
on.";
}
leaf port {
Watsen & Schoenwaelder Expires August 18, 2014 [Page 12]
Internet-Draft YANG NETCONF Server Configuration February 2014
type inet:port-number;
description
"The local port number on this interface the
server listens on.";
}
}
}
}
}
grouping call-home-config {
container applications {
description
"A list of applications the device iniates connections
to. The configuration for each application specifies
its details, including its servers, the type of
connection to maintain, and the reconnection strategy
to use.";
list application {
key name;
// min-elements 1; // this forces <call-home>?!
leaf name {
type string {
length 1..64; // XXX why these limits?
}
mandatory true;
description
"An arbitrary name for the application the device
is connecting to.";
}
leaf description {
type string;
description
"An optional description for the application.";
}
container servers {
description
"An ordered listing of the application's servers
that the device should attempt connecting to.";
list server {
key address;
min-elements 1;
ordered-by user;
leaf address {
type inet:host;
mandatory true;
Watsen & Schoenwaelder Expires August 18, 2014 [Page 13]
Internet-Draft YANG NETCONF Server Configuration February 2014
description
"The address or domain-name of the server.";
}
leaf port {
type inet:port-number;
description
"The IP port for this server. The device will use
the IANA-assigned well-known port if not specified.";
}
}
}
container connection-type {
description
"Indicates the application's preference for how the
device's connection is maintained.";
choice connection-type {
default persistent-connection;
case persistent-connection {
container persistent {
description
"Maintain a persistent connection to the
application. If the connection goes down,
immediately start trying to reconnect to it,
using the reconnection strategy.
This connection type minimizes any
application-to-server data-transfer delay,
albeit at the expense of holding resources
longer.";
container keep-alives {
leaf interval-secs {
type uint8;
units seconds;
default 15;
description
"Sets a timeout interval in seconds after which
if no data has been received from the
application, a message will be sent to request
a response from the application. A value of
'0' indicates that no keep-alive messages
should be sent.";
}
leaf count-max {
type uint8;
default 3;
description
"Sets the number of keep-alive messages that may
Watsen & Schoenwaelder Expires August 18, 2014 [Page 14]
Internet-Draft YANG NETCONF Server Configuration February 2014
be sent without receiving any data from the
application before assuming the application is
no longer alive. If this threshold is reached,
the transport-level connection will be
disconnected (thus triggering the reconnection
strategy). The interval timer is reset after
each transmission, thus an unresponsive
application will be disconnected after
approximately count-max * interval-secs
seconds.";
}
}
}
}
case periodic-connection {
container periodic {
description
"Periodically connect to application, using the
reconnection strategy, so it can flush any pending
data it may be holding. This connection type
minimizes resources held open, albeit at the
expense of longer application-to-server
data-transfer delay. Note that for
server-to-application data, the data should be
sent immediately, connecting to application first
if not already.";
leaf timeout-mins {
type uint8;
units minutes;
default 5;
description
"The maximum amount of unconnected time the
device will wait until establishing a
connection to the application again. The
device may establish a connection before this
time if it has data it needs to send to the
application. Note: this value differs from
the reconnection strategy's interval-secs
value.";
}
leaf linger-secs {
type uint8;
units seconds;
default 30;
description
"The amount of time the device should wait after
last receiving data from or sending data to the
Watsen & Schoenwaelder Expires August 18, 2014 [Page 15]
Internet-Draft YANG NETCONF Server Configuration February 2014
application before closing its connection to it.
This is an optimization to prevent unnecessary
connections.";
}
}
}
}
}
// XXX
// Should we have something smarter as the reconnect
// strategy, e.g. an exponential backoff?
container reconnect-strategy {
description
"The reconnection strategy guides how a device reconnects
to an application, after losing a connection to it, even
if due to a reboot. The device starts with the specified
server, tries to connect to it count-max times, waiting
interval-secs between each connection attempt, before
trying the next server in the list (round robin).";
leaf start-with {
type enumeration {
enum first-listed { value 1; }
enum last-connected { value 2; }
}
default first-listed;
description
"Specifies which of the application's servers the
device should start with when trying to connect to
the application. In the case of newly configured
application, the first server listed shall be
considered last-connected.";
}
leaf interval-secs {
type uint8;
units seconds;
default 5;
description
"Specifies the time delay between connection attempts
to the same server. Note: this value differs from the
periodic-connection's timeout-mins value.";
}
leaf count-max {
type uint8;
default 3;
description
"Specifies the number times the device tries to
Watsen & Schoenwaelder Expires August 18, 2014 [Page 16]
Internet-Draft YANG NETCONF Server Configuration February 2014
connect to a specific server before moving on to
the next server in the list (round robin).";
}
}
}
}
}
grouping ssh-config {
description
"Provides a reusable grouping for all the ssh config. This
is done primarily to enable external modules to reference
this definition in a "uses" statement.";
container listen {
if-feature inbound-ssh;
description
"Provides the configuration of the NETCONF server to
open one or more ports to listen for incoming client
connections.";
uses listen-config {
refine one-or-many/one-port/port {
default 830;
}
refine one-or-many/many-ports/interface/port {
default 830;
}
}
}
container call-home {
if-feature outbound-ssh;
description
"Provides the configuration of the NETCONF call-home
clients to connect to, the overall call-home policy,
and the reconnect strategy.";
uses call-home-config {
augment applications/application {
container host-keys {
description
"An ordered listing of the SSH host keys the
device should advertise to the application.";
list host-key {
key name;
min-elements 1;
ordered-by user;
leaf name {
Watsen & Schoenwaelder Expires August 18, 2014 [Page 17]
Internet-Draft YANG NETCONF Server Configuration February 2014
type string {
length 1..64; // XXX why this limit?
}
mandatory true;
description
"The name of a host key the device should
advertise during the SSH key exchange.";
}
}
}
}
}
}
}
grouping tls-config {
description
"Provides a reusable grouping for all the tls config. This
is done primarily to enable external modules to reference
this definition in a "uses" statement.";
container listen {
if-feature inbound-tls;
description
"Provides the configuration of the NETCONF server to
open one or more ports to listen for incoming client
connections.";
uses listen-config {
refine one-or-many/one-port/port {
default 6513;
}
refine one-or-many/many-ports/interface/port {
default 6513;
}
}
}
container call-home {
if-feature outbound-tls;
description
"Provides the configuration of the NETCONF call-home
clients to connect to, the overall call-home policy,
and the reconnect strategy.";
uses call-home-config;
}
/*
* Objects for deriving NETCONF usernames from X.509
Watsen & Schoenwaelder Expires August 18, 2014 [Page 18]
Internet-Draft YANG NETCONF Server Configuration February 2014
* certificates.
*/
container cert-maps {
if-feature tls-map-certificates;
uses x509c2n:cert-to-name;
description
"The cert-maps container is used by a NETCONF server to
map the NETCONF client's presented X.509 certificate to
a NETCONF username.
If no matching and valid cert-to-name list entry can be
found, then the NETCONF server MUST close the connection,
and MUST NOT accept NETCONF messages over it.";
}
/*
* Objects for deriving NETCONF usernames from TLS
* pre-shared keys.
*/
container psk-maps {
if-feature tls-map-pre-shared-keys;
description
"During the TLS Handshake, the client indicates which
key to use by including a PSK identity in the TLS
ClientKeyExchange message. On the server side, this
PSK identity is used to look up an entry in the psk-map
list. If such an entry is found, and the pre-shared keys
match, then the client is authenticated. The server uses
the value from the user-name leaf in the psk-map list as
the NETCONF username. If the server cannot find an entry
in the psk-map list, or if the pre-shared keys do not
match, then the server terminates the connection.";
reference
"RFC 4279: Pre-Shared Key Ciphersuites for Transport Layer
Security (TLS)";
list psk-map {
key psk-identity;
leaf psk-identity {
type string;
description
"The PSK identity encoded as a UTF-8 string. For
details how certain common PSK identity formats can
be encoded in UTF-8, see section 5.1. of RFC 4279.";
reference
Watsen & Schoenwaelder Expires August 18, 2014 [Page 19]
Internet-Draft YANG NETCONF Server Configuration February 2014
"RFC 4279: Pre-Shared Key Ciphersuites for Transport
Layer Security (TLS)";
}
leaf user-name {
type nacm:user-name-type;
mandatory true;
description
"The NETCONF username associated with this PSK
identity.";
}
leaf not-valid-before {
type yang:date-and-time;
description
"This PSK identity is not valid before the given date
and time.";
}
leaf not-valid-after {
type yang:date-and-time;
description
"This PSK identity is not valid after the given date
and time.";
}
leaf key {
type yang:hex-string;
mandatory true;
nacm:default-deny-all;
description
"The key associated with the PSK identity";
reference
"RFC 4279: Pre-Shared Key Ciphersuites for Transport
Layer Security (TLS)";
}
}
}
}
/*
* Configuration data nodes
*/
container netconf {
description
"Top-level container for NETCONF server related
configuration objects.";
container ssh {
if-feature ssh;
Watsen & Schoenwaelder Expires August 18, 2014 [Page 20]
Internet-Draft YANG NETCONF Server Configuration February 2014
uses ssh-config;
}
container tls {
if-feature tls;
uses tls-config;
}
}
}
5. Security Considerations
This document defines a YANG modules to configure NETCONF's SSH and
TLS transports. Please see the Security Considerations section in
those RFCs for transport-specific issues.
6. IANA Considerations
This document registers one URIs in the IETF XML registry [RFC2119].
Following the format in [RFC3688], the following registration is
requested to be made.
URI: urn:ietf:params:xml:ns:yang:ietf-netconf-server
Registrant Contact: The NETCONF WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
This document registers one YANG module in the YANG Module Names
registry [RFC6020].
name: ietf-netconf-server
namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-server
prefix: ncserver
reference: RFC XXXX
7. Acknowledgements
Juergen Schoenwaelder and was partly funded by Flamingo, a Network of
Excellence project (ICT-318488) supported by the European Commission
under its Seventh Framework Programme.
8. References
Watsen & Schoenwaelder Expires August 18, 2014 [Page 21]
Internet-Draft YANG NETCONF Server Configuration February 2014
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels ", BCP 14, RFC 2119, March 1997.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF) ", RFC 6020,
October 2010.
[RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration
Protocol (NETCONF) Access Control Model ", RFC 6536, March
2012.
[RFC6991] Schoenwaelder, J., "Common YANG Data Types", RFC 6991,
July 2013.
[I-D.ietf-netmod-snmp-cfg]
Bjorklund, M. and J. Schoenwaelder, "A YANG Data Model for
SNMP Configuration", draft-ietf-netmod-snmp-cfg-03 (work
in progress), November 2013.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "NETCONF Configuration Protocol", RFC
6241, June 2011.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, June 2011.
[I-D.ietf-netconf-rfc5539bis]
Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the
NETCONF Protocol over Transport Layer Security (TLS) ",
draft-ietf-netconf-rfc5539bis-04 (work in progress),
October 2013.
8.2. Informative References
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004.
Appendix A. Example: SSH
<netconf xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-server">
<ssh>
<listen>
<port>831</port>
</listen>
Watsen & Schoenwaelder Expires August 18, 2014 [Page 22]
Internet-Draft YANG NETCONF Server Configuration February 2014
<call-home>
<applications>
<application>
<name>config-mgr</name>
<description>
This entry requests the device to periodically
connect to the Configuration Manager application
</description>
<servers>
<server>
<address>config-mgr1.example.com</address>
</server>
<server>
<address>config-mgr2.example.com</address>
</server>
</servers>
<connection-type>
<periodic>
<timeout-mins>5</timeout-mins>
<linger-secs>10</linger-secs>
</periodic>
</connection-type>
<reconnect-strategy>
<start-with>last-connected</start-with>
<interval-secs>10</interval-secs>
<count-max>3</count-max>
</reconnect-strategy>
<host-keys>
<host-key>
<name>ssh_host_key_cert</name>
</host-key>
<host-key>
<name>ssh_host_key_cert2</name>
</host-key>
</host-keys>
</application>
</applications>
</call-home>
</ssh>
</netconf>
Appendix B. Example: TLS
<netconf xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-server">
<tls>
<listen>
Watsen & Schoenwaelder Expires August 18, 2014 [Page 23]
Internet-Draft YANG NETCONF Server Configuration February 2014
<interface>
<address>192.0.2.1</address>
<port>6514</port>
</interface>
</listen>
<call-home>
<applications>
<application>
<name>log-monitor</name>
<description>
This entry requests the device to maintain a
persistent connect to the Log Monitor application
</description>
<servers>
<server>
<address>log-monitor1.example.com</address>
</server>
<server>
<address>log-monitor2.example.com</address>
</server>
</servers>
<connection-type>
<persistent>
<keep-alives>
<interval-secs>5</interval-secs>
<count-max>3</count-max>
</keep-alives>
</persistent>
</connection-type>
<reconnect-strategy>
<start-with>first-listed</start-with>
<interval-secs>10</interval-secs>
<count-max>4</count-max>
</reconnect-strategy>
</application>
</applications>
</call-home>
<cert-maps>
<!-- Use a subject alt name field of a specific
certificate as the NC username. -->
<cert-to-name>
<id>1</id>
<fingerprint>11:0A:05:11:00</fingerprint>
<map-type>x509c2n:san-any</map-type>
</cert-to-name>
<!-- Map a specific certificate to the NC username
Watsen & Schoenwaelder Expires August 18, 2014 [Page 24]
Internet-Draft YANG NETCONF Server Configuration February 2014
'Joe Cool'. -->
<cert-to-name>
<id>2</id>
<fingerprint>11:0A:05:11:00</fingerprint>
<map-type>x509c2n:specified</map-type>
<name>Joe Cool</name>
</cert-to-name>
</cert-maps>
<psk-maps>
<psk-map>
<psk-identity>a8gc8]klh59</psk-identity>
<user-name>admin</user-name>
<not-valid-before>2013-01-01T00:00:00Z</not-valid-before>
<not-valid-after>2014-01-01T00:00:00Z</not-valid-after>
</psk-map>
</psk-maps>
</tls>
</netconf>
Appendix C. Change Log
C.1. 00 to 01
o Restructured YANG module slightly, to provide groupings useful to
the ZeroTouch draft.
Appendix D. Open Issues
o NETCONF implementations typically have config parameters such as
session timeouts or hello timeouts. Shall they be included in
this model?
o Do we need knobs to enable/disable call-home without the need to
remove all the call-home client configuration?
o Do we need something equivalent to the host-keys in the TLS
configuration subtree?
Authors' Addresses
Kent Watsen
Juniper Networks
EMail: kwatsen@juniper.net
Watsen & Schoenwaelder Expires August 18, 2014 [Page 25]
Internet-Draft YANG NETCONF Server Configuration February 2014
Juergen Schoenwaelder
Jacobs University Bremen
EMail: j.schoenwaelder@jacobs-university.de
Watsen & Schoenwaelder Expires August 18, 2014 [Page 26]
