NETCONF Working Group K. Watsen
Internet-Draft Juniper Networks
Intended status: Standards Track G. Wu
Expires: January 9, 2017 Cisco Networks
J. Schoenwaelder
Jacobs University Bremen
July 8, 2016
NETCONF Client and Server Models
draft-ietf-netconf-netconf-client-server-00
Abstract
This document defines two YANG modules, one module to configure a
NETCONF client and the other module to configure a NETCONF server.
Both modules support both the SSH and TLS transport protocols, and
support both standard NETCONF and NETCONF Call Home connections.
Editorial Note (To be removed by RFC Editor)
This draft contains many placeholder values that need to be replaced
with finalized values at the time of publication. This note
summarizes all of the substitutions that are needed. No other RFC
Editor instructions are specified elsewhere in this document.
This document contains references to other drafts in progress, both
in the Normative References section, as well as in body text
throughout. Please update the following references to reflect their
final RFC assignments:
o draft-ietf-netconf-system-keychain
o draft-ietf-netconf-ssh-client-server
o draft-ietf-netconf-tls-client-server
Artwork in this document contains shorthand references to drafts in
progress. Please apply the following replacements:
o "XXXX" --> the assigned RFC value for this draft
o "YYYY" --> the assigned RFC value for draft-ietf-netconf-ssh-
client-server
o "ZZZZ" --> the assigned RFC value for draft-ietf-netconf-tls-
client-server
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o "AAAA" --> the assigned RFC value for draft-ietf-netconf-call-home
Artwork in this document contains placeholder values for the date of
publication of this draft. Please apply the following replacement:
o "2016-07-08" --> the publication date of this draft
The following two Appendix sections are to be removed prior to
publication:
o Appendix A. Change Log
o Appendix B. Open Issues
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 January 9, 2017.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Tree Diagrams . . . . . . . . . . . . . . . . . . . . . . 4
2. The NETCONF Client Model . . . . . . . . . . . . . . . . . . 4
2.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 5
2.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 6
2.3. YANG Model . . . . . . . . . . . . . . . . . . . . . . . 8
3. The NETCONF Server Model . . . . . . . . . . . . . . . . . . 14
3.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 15
3.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 17
3.3. YANG Model . . . . . . . . . . . . . . . . . . . . . . . 21
4. Design Considerations . . . . . . . . . . . . . . . . . . . . 31
4.1. Support all NETCONF transports . . . . . . . . . . . . . 31
4.2. Enable each transport to select which keys to use . . . . 32
4.3. Support authenticating NETCONF clients certificates . . . 32
4.4. Support mapping authenticated NETCONF client certificates
to usernames . . . . . . . . . . . . . . . . . . . . . . 32
4.5. Support both listening for connections and call home . . 32
4.6. For Call Home connections . . . . . . . . . . . . . . . . 32
4.6.1. Support more than one NETCONF client . . . . . . . . 32
4.6.2. Support NETCONF clients having more than one endpoint 33
4.6.3. Support a reconnection strategy . . . . . . . . . . . 33
4.6.4. Support both persistent and periodic connections . . 33
4.6.5. Reconnection strategy for periodic connections . . . 33
4.6.6. Keep-alives for persistent connections . . . . . . . 33
4.6.7. Customizations for periodic connections . . . . . . . 34
5. Security Considerations . . . . . . . . . . . . . . . . . . . 34
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34
6.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 34
6.2. The YANG Module Names Registry . . . . . . . . . . . . . 34
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 35
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 35
8.1. Normative References . . . . . . . . . . . . . . . . . . 35
8.2. Informative References . . . . . . . . . . . . . . . . . 36
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 38
A.1. server-model-09 to 00 . . . . . . . . . . . . . . . . . . 38
Appendix B. Open Issues . . . . . . . . . . . . . . . . . . . . 38
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 38
1. Introduction
This document defines two YANG [RFC6020] modules, one module to
configure a NETCONF client and the other module to configure a
NETCONF server. Both modules support both the SSH and TLS transport
protocols, and support both standard NETCONF and NETCONF Call Home
connections.
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NETCONF is defined by [RFC6241]. SSH is defined by [RFC4252],
[RFC4253], and [RFC4254]. TLS is defined by [RFC5246]. NETCONF Call
Home is defined by [draft-ietf-netconf-call-home]).
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 models is used in
this document. The meaning of the symbols in these diagrams is as
follows:
o Brackets "[" and "]" enclose list keys.
o Braces "{" and "}" enclose feature names, and indicate that the
named feature must be present for the subtree to be present.
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 (":").
o Ellipsis ("...") stands for contents of subtrees that are not
shown.
2. The NETCONF Client Model
The NETCONF client model presented in this section supports both
clients initiating connections to servers, as well as clients
listening for connections from servers calling home.
This model supports both the SSH and TLS transport protocols, using
the SSH client and TLS client groupings defined in
[draft-ietf-netconf-ssh-client-server] and
[draft-ietf-netconf-tls-client-server] respectively.
All private keys and trusted certificates are held in the keychain
model defined in [draft-ietf-netconf-system-keychain].
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YANG feature statements are used to enable implementations to
advertise which parts of the model the NETCONF client supports.
2.1. Tree Diagram
Note: all lines are folded at column 71 with no '\' character.
module: ietf-netconf-client
+--rw netconf-client
+--rw initiate {initiate}?
| +--rw netconf-server* [name]
| +--rw name string
| +--rw (transport)
| +--:(ssh) {ssh-initiate}?
| +--rw ssh
| +--rw address inet:host
| +--rw port? inet:port-number
| +--rw server-auth
| | +--rw trusted-ssh-host-keys? -> /kc:keychain/
trusted-ssh-host-keys/name
| | +--rw trusted-ca-certs? -> /kc:keychain/
trusted-certificates/name {ssh-x509-certs}?
| | +--rw trusted-server-certs? -> /kc:keychain/
trusted-certificates/name
| +--rw client-auth
| +--rw matches* [name]
| +--rw name string
| +--rw match* [name]
| | +--rw name string
| | +--rw trusted-ssh-host-keys? -> /kc:key
chain/trusted-ssh-host-keys/name
| | +--rw trusted-ca-certs? -> /kc:key
chain/trusted-certificates/name
| | +--rw trusted-server-certs? -> /kc:key
chain/trusted-certificates/name
| +--rw user-auth-credentials? -> /kc:keycha
in/user-auth-credentials/user-auth-credential/username
+--rw listen {listen}?
+--rw max-sessions? uint16
+--rw idle-timeout? uint16
+--rw endpoint* [name]
+--rw name string
+--rw (transport)
+--:(ssh) {ssh-listen}?
+--rw ssh
+--rw address? inet:ip-address
+--rw port? inet:port-number
+--rw server-auth
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| +--rw trusted-ssh-host-keys? -> /kc:keychain/
trusted-ssh-host-keys/name
| +--rw trusted-ca-certs? -> /kc:keychain/
trusted-certificates/name {ssh-x509-certs}?
| +--rw trusted-server-certs? -> /kc:keychain/
trusted-certificates/name
+--rw client-auth
+--rw matches* [name]
+--rw name string
+--rw match* [name]
| +--rw name string
| +--rw trusted-ssh-host-keys? -> /kc:key
chain/trusted-ssh-host-keys/name
| +--rw trusted-ca-certs? -> /kc:key
chain/trusted-certificates/name
| +--rw trusted-server-certs? -> /kc:key
chain/trusted-certificates/name
+--rw user-auth-credentials? -> /kc:keycha
in/user-auth-credentials/user-auth-credential/username
2.2. Example Usage
The following example illustrates configuring a NETCONF client to
initiate connections, using both the SSH and TLS transport protocols,
as well as listening for call-home connections, again using both the
SSH and TLS transport protocols.
This example is consistent with the examples presented in Section 2.2
of [draft-ietf-netconf-system-keychain].
corp-fw1
corp-fw1.example.com
deployment-specific-ca-certs
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deployment-specific-ca-certs
Bob
Intranet-facing listener
11.22.33.44
deployment-specific-ca-certs
explicitly-trusted-server-certs
explicitly-trusted-ssh-host-keys
deployment-specific-ca-certs
admin
explicitly-trusted-server-certs
admin
explicitly-trusted-ssh-host-keys
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admin
2.3. YANG Model
This YANG module imports YANG types from [RFC6991] and [RFC7407].
file "ietf-netconf-client@2016-07-08.yang"
module ietf-netconf-client {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-client";
prefix "ncc";
import ietf-inet-types {
prefix inet;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-x509-cert-to-name {
prefix x509c2n;
reference
"RFC 7407: A YANG Data Model for SNMP Configuration";
}
import ietf-ssh-client {
prefix ss;
revision-date 2016-07-08; // stable grouping definitions
reference
"RFC YYYY: SSH Client and Server Models";
}
import ietf-tls-client {
prefix ts;
revision-date 2016-07-08; // stable grouping definitions
reference
"RFC ZZZZ: TLS Client and Server Models";
}
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organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web:
WG List:
WG Chair: Mehmet Ersue
WG Chair: Mahesh Jethanandani
Author: Kent Watsen
Author: Gary Wu
";
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.";
revision "2016-07-08" {
description
"Initial version";
reference
"RFC XXXX: NETCONF Client and Server Models";
}
// Features
feature initiate {
description
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"The 'initiate' feature indicates that the NETCONF client
supports initiating NETCONF connections to NETCONF servers
using at least one transport (e.g., SSH, TLS, etc.).";
}
feature ssh-initiate {
description
"The 'ssh-initiate' feature indicates that the NETCONF client
supports initiating SSH connections to NETCONF servers.";
reference
"RFC 6242: Using the NETCONF Protocol over Secure Shell (SSH)";
}
feature tls-initiate {
description
"The 'tls-initiate' feature indicates that the NETCONF client
supports initiating TLS connections to NETCONF servers.";
reference
"RFC 7589: Using the NETCONF Protocol over Transport
Layer Security (TLS) with Mutual X.509
Authentication";
}
feature listen {
description
"The 'listen' feature indicates that the NETCONF client
supports opening a port to accept NETCONF server call home
connections using at least one transport (e.g., SSH, TLS, etc.).";
}
feature ssh-listen {
description
"The 'ssh-listen' feature indicates that the NETCONF client
supports opening a port to listen for incoming NETCONF
server call-home SSH connections.";
reference
"RFC AAAA: NETCONF Call Home and RESTCONF Call Home";
}
feature tls-listen {
description
"The 'tls-listen' feature indicates that the NETCONF client
supports opening a port to listen for incoming NETCONF
server call-home TLS connections.";
reference
"RFC AAAA: NETCONF Call Home and RESTCONF Call Home";
}
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container netconf-client {
description
"Top-level container for NETCONF client configuration.";
container initiate {
if-feature initiate;
description
"Configures client intiating underlying TCP connections.";
list netconf-server {
key name;
description
"List of NETCONF servers the NETCONF client is to initiate
connections to.";
leaf name {
type string;
description
"An arbitrary name for the NETCONF server.";
}
choice transport {
mandatory true;
description
"Selects between available transports.";
case ssh {
if-feature ssh-initiate;
container ssh {
description
"Specifies SSH-specific transport configuration.";
leaf address {
type inet:host;
mandatory true;
description
"The IP address or hostname of the endpoint. If a
hostname is configured and the DNS resolution results
in more than one IP address, the NETCONF client
will process the IP addresses as if they had been
explicitly configured in place of the hostname.";
}
leaf port {
type inet:port-number;
default 830;
description
"The IP port for this endpoint. The NETCONF client will
use the IANA-assigned well-known port if no value is
specified.";
}
uses ss:initiating-ssh-client-grouping;
}
}
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/*
case tls {
if-feature tls-initiate;
container tls {
description
"Specifies TLS-specific transport configuration.";
uses endpoints-container {
refine endpoints/endpoint/port {
default 6513;
}
}
uses ts:listening-tls-client-grouping {
augment "client-auth" {
description
"Augments in the cert-to-name structure.";
uses cert-maps-grouping;
}
}
}
}
*/
}
}
} // end initiate
container listen {
if-feature listen;
description
"Configures client accepting call-home TCP connections.";
leaf max-sessions {
type uint16;
default 0;
description
"Specifies the maximum number of concurrent sessions
that can be active at one time. The value 0 indicates
that no artificial session limit should be used.";
}
leaf idle-timeout {
type uint16;
units "seconds";
default 3600; // one hour
description
"Specifies the maximum number of seconds that a NETCONF
session may remain idle. A NETCONF session will be dropped
if it is idle for an interval longer than this number of
seconds. If set to zero, then the server will never drop
a session because it is idle. Sessions that have a
notification subscription active are never dropped.";
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}
list endpoint {
key name;
description
"List of endpoints to listen for NETCONF connections on.";
leaf name {
type string;
description
"An arbitrary name for the NETCONF listen endpoint.";
}
choice transport {
mandatory true;
description
"Selects between available transports.";
case ssh {
if-feature ssh-listen;
container ssh {
description
"SSH-specific listening configuration for inbound
connections.";
uses ss:listening-ssh-client-grouping {
refine port {
default 4334;
}
}
}
}
/*
case tls {
if-feature tls-listen;
container tls {
description
"TLS-specific listening configuration for inbound
connections.";
uses ts:listening-tls-client-grouping {
refine port {
default 4335;
}
augment "client-auth" {
description
"Augments in the cert-to-name structure.";
uses cert-maps-grouping;
}
}
}
}
*/
}
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}
} // end listen
}
grouping cert-maps-grouping {
description
"A grouping that defines a container around the
cert-to-name structure defined in RFC 7407.";
container cert-maps {
uses x509c2n:cert-to-name;
description
"The cert-maps container is used by a TLS-based 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.";
reference
"RFC WWWW: NETCONF over TLS, Section 7";
}
}
}
3. The NETCONF Server Model
The NETCONF server model presented in this section supports servers
both listening for connections as well as initiating call-home
connections.
This model also supports both the SSH and TLS transport protocols,
using the SSH server and TLS server groupings defined in
[draft-ietf-netconf-ssh-client-server] and
[draft-ietf-netconf-tls-client-server] respectively.
All private keys and trusted certificates are held in the keychain
model defined in [draft-ietf-netconf-system-keychain].
YANG feature statements are used to enable implementations to
advertise which parts of the model the NETCONF server supports.
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3.1. Tree Diagram
Note: all lines are folded at column 71 with no '\' character.
module: ietf-netconf-server
+--rw netconf-server
+--rw session-options
| +--rw hello-timeout? uint16
+--rw listen {listen}?
| +--rw max-sessions? uint16
| +--rw idle-timeout? uint16
| +--rw endpoint* [name]
| +--rw name string
| +--rw (transport)
| +--:(ssh) {ssh-listen}?
| | +--rw ssh
| | +--rw address? inet:ip-address
| | +--rw port? inet:port-number
| | +--rw host-keys
| | | +--rw host-key* [name]
| | | +--rw name string
| | | +--rw (type)?
| | | +--:(public-key)
| | | | +--rw public-key? -> /kc:keychain/p
rivate-keys/private-key/name
| | | +--:(certificate)
| | | +--rw certificate? -> /kc:keychain/p
rivate-keys/private-key/certificate-chains/certificate-chain/name {ssh-
x509-certs}?
| | +--rw client-cert-auth {ssh-x509-certs}?
| | +--rw trusted-ca-certs? -> /kc:keychain/t
rusted-certificates/name
| | +--rw trusted-client-certs? -> /kc:keychain/t
rusted-certificates/name
| +--:(tls) {tls-listen}?
| +--rw tls
| +--rw address? inet:ip-address
| +--rw port? inet:port-number
| +--rw certificates
| | +--rw certificate* [name]
| | +--rw name -> /kc:keychain/private-keys/p
rivate-key/certificate-chains/certificate-chain/name
| +--rw client-auth
| +--rw trusted-ca-certs? -> /kc:keychain/t
rusted-certificates/name
| +--rw trusted-client-certs? -> /kc:keychain/t
rusted-certificates/name
| +--rw cert-maps
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| +--rw cert-to-name* [id]
| +--rw id uint32
| +--rw fingerprint x509c2n:tls-fingerpr
int
| +--rw map-type identityref
| +--rw name string
+--rw call-home {call-home}?
+--rw netconf-client* [name]
+--rw name string
+--rw (transport)
| +--:(ssh) {ssh-call-home}?
| | +--rw ssh
| | +--rw endpoints
| | | +--rw endpoint* [name]
| | | +--rw name string
| | | +--rw address inet:host
| | | +--rw port? inet:port-number
| | +--rw host-keys
| | | +--rw host-key* [name]
| | | +--rw name string
| | | +--rw (type)?
| | | +--:(public-key)
| | | | +--rw public-key? -> /kc:keychain/p
rivate-keys/private-key/name
| | | +--:(certificate)
| | | +--rw certificate? -> /kc:keychain/p
rivate-keys/private-key/certificate-chains/certificate-chain/name {ssh-
x509-certs}?
| | +--rw client-cert-auth {ssh-x509-certs}?
| | +--rw trusted-ca-certs? -> /kc:keychain/t
rusted-certificates/name
| | +--rw trusted-client-certs? -> /kc:keychain/t
rusted-certificates/name
| +--:(tls) {tls-call-home}?
| +--rw tls
| +--rw endpoints
| | +--rw endpoint* [name]
| | +--rw name string
| | +--rw address inet:host
| | +--rw port? inet:port-number
| +--rw certificates
| | +--rw certificate* [name]
| | +--rw name -> /kc:keychain/private-keys/p
rivate-key/certificate-chains/certificate-chain/name
| +--rw client-auth
| +--rw trusted-ca-certs? -> /kc:keychain/t
rusted-certificates/name
| +--rw trusted-client-certs? -> /kc:keychain/t
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rusted-certificates/name
| +--rw cert-maps
| +--rw cert-to-name* [id]
| +--rw id uint32
| +--rw fingerprint x509c2n:tls-fingerpr
int
| +--rw map-type identityref
| +--rw name string
+--rw connection-type
| +--rw (connection-type)?
| +--:(persistent-connection)
| | +--rw persistent!
| | +--rw idle-timeout? uint32
| | +--rw keep-alives
| | +--rw max-wait? uint16
| | +--rw max-attempts? uint8
| +--:(periodic-connection)
| +--rw periodic!
| +--rw idle-timeout? uint16
| +--rw reconnect_timeout? uint16
+--rw reconnect-strategy
+--rw start-with? enumeration
+--rw max-attempts? uint8
3.2. Example Usage
The following example illustrates configuring a NETCONF server to
listen for NETCONF client connections using both the SSH and TLS
transport protocols, as well as configuring call-home to two NETCONF
clients, one using SSH and the other using TLS.
This example is consistent with the examples presented in Section 2.2
of [draft-ietf-netconf-system-keychain].
netconf/ssh
11.22.33.44
my-rsa-key
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TPM key
deployment-specific-ca-certs
explicitly-trusted-client-certs
netconf/tls
11.22.33.44
ex-key-sect571r1-cert
deployment-specific-ca-certs
explicitly-trusted-client-certs
1
11:0A:05:11:00
x509c2n:san-any
2
B3:4F:A1:8C:54
x509c2n:specified
scooby-doo
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config-mgr
east-data-center
11.22.33.44
west-data-center
55.66.77.88
TPM key
deployment-specific-ca-certs
explicitly-trusted-client-certs
300
60
last-connected
3
event-correlator
east-data-center
22.33.44.55
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west-data-center
33.44.55.66
ex-key-sect571r1-cert
deployment-specific-ca-certs
explicitly-trusted-client-certs
1
11:0A:05:11:00
x509c2n:san-any
2
B3:4F:A1:8C:54
x509c2n:specified
scooby-doo
300
30
3
first-listed
3
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3.3. YANG Model
This YANG module imports YANG types from [RFC6991] and [RFC7407].
file "ietf-netconf-server@2016-07-08.yang"
module ietf-netconf-server {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-server";
prefix "ncs";
import ietf-inet-types {
prefix inet;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-x509-cert-to-name {
prefix x509c2n;
reference
"RFC 7407: A YANG Data Model for SNMP Configuration";
}
import ietf-ssh-server {
prefix ss;
revision-date 2016-07-08; // stable grouping definitions
reference
"RFC YYYY: SSH Client and Server Models";
}
import ietf-tls-server {
prefix ts;
revision-date 2016-07-08; // stable grouping definitions
reference
"RFC ZZZZ: TLS Client and Server Models";
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web:
WG List:
WG Chair: Mehmet Ersue
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WG Chair: Mahesh Jethanandani
Editor: Kent Watsen
";
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.";
revision "2016-07-08" {
description
"Initial version";
reference
"RFC XXXX: NETCONF Client and Server Models";
}
// Features
feature listen {
description
"The 'listen' feature indicates that the NETCONF server
supports opening a port to accept NETCONF client connections
using at least one transport (e.g., SSH, TLS, etc.).";
}
feature ssh-listen {
description
"The 'ssh-listen' feature indicates that the NETCONF server
supports opening a port to accept NETCONF over SSH
client connections.";
reference
"RFC 6242: Using the NETCONF Protocol over Secure Shell (SSH)";
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}
feature tls-listen {
description
"The 'tls-listen' feature indicates that the NETCONF server
supports opening a port to accept NETCONF over TLS
client connections.";
reference
"RFC 7589: Using the NETCONF Protocol over Transport
Layer Security (TLS) with Mutual X.509
Authentication";
}
feature call-home {
description
"The 'call-home' feature indicates that the NETCONF server
supports initiating NETCONF call home connections to NETCONF
clients using at least one transport (e.g., SSH, TLS, etc.).";
reference
"RFC YYYY: NETCONF Call Home and RESTCONF Call Home";
}
feature ssh-call-home {
description
"The 'ssh-call-home' feature indicates that the NETCONF
server supports initiating a NETCONF over SSH call
home connection to NETCONF clients.";
reference
"RFC YYYY: NETCONF Call Home and RESTCONF Call Home";
}
feature tls-call-home {
description
"The 'tls-call-home' feature indicates that the NETCONF
server supports initiating a NETCONF over TLS call
home connection to NETCONF clients.";
reference
"RFC YYYY: NETCONF Call Home and RESTCONF Call Home";
}
// top-level container (groupings below)
container netconf-server {
description
"Top-level container for NETCONF server configuration.";
container session-options { // SHOULD WE REMOVE THIS ALTOGETHER?
description
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"NETCONF session options, independent of transport
or connection strategy.";
leaf hello-timeout {
type uint16;
units "seconds";
default 600;
description
"Specifies the maximum number of seconds that a SSH/TLS
connection may wait for a hello message to be received.
A connection will be dropped if no hello message is
received before this number of seconds elapses. If set
to zero, then the server will wait forever for a hello
message.";
}
}
container listen {
if-feature listen;
description
"Configures listen behavior";
leaf max-sessions {
type uint16;
default 0;
description
"Specifies the maximum number of concurrent sessions
that can be active at one time. The value 0 indicates
that no artificial session limit should be used.";
}
leaf idle-timeout {
type uint16;
units "seconds";
default 3600; // one hour
description
"Specifies the maximum number of seconds that a NETCONF
session may remain idle. A NETCONF session will be dropped
if it is idle for an interval longer than this number of
seconds. If set to zero, then the server will never drop
a session because it is idle. Sessions that have a
notification subscription active are never dropped.";
}
list endpoint {
key name;
description
"List of endpoints to listen for NETCONF connections on.";
leaf name {
type string;
description
"An arbitrary name for the NETCONF listen endpoint.";
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}
choice transport {
mandatory true;
description
"Selects between available transports.";
case ssh {
if-feature ssh-listen;
container ssh {
description
"SSH-specific listening configuration for inbound
connections.";
uses ss:listening-ssh-server-grouping {
refine port {
default 830;
}
}
}
}
case tls {
if-feature tls-listen;
container tls {
description
"TLS-specific listening configuration for inbound
connections.";
uses ts:listening-tls-server-grouping {
refine port {
default 6513;
}
augment "client-auth" {
description
"Augments in the cert-to-name structure.";
uses cert-maps-grouping;
}
}
}
}
}
}
}
container call-home {
if-feature call-home;
description
"Configures call-home behavior";
list netconf-client {
key name;
description
"List of NETCONF clients the NETCONF server is to initiate
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call-home connections to.";
leaf name {
type string;
description
"An arbitrary name for the remote NETCONF client.";
}
choice transport {
mandatory true;
description
"Selects between available transports.";
case ssh {
if-feature ssh-call-home;
container ssh {
description
"Specifies SSH-specific call-home transport
configuration.";
uses endpoints-container {
refine endpoints/endpoint/port {
default 4334;
}
}
uses ss:non-listening-ssh-server-grouping;
}
}
case tls {
if-feature tls-call-home;
container tls {
description
"Specifies TLS-specific call-home transport
configuration.";
uses endpoints-container {
refine endpoints/endpoint/port {
default 4335;
}
}
uses ts:non-listening-tls-server-grouping {
augment "client-auth" {
description
"Augments in the cert-to-name structure.";
uses cert-maps-grouping;
}
}
}
}
}
container connection-type {
description
"Indicates the kind of connection to use.";
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choice connection-type {
description
"Selects between available connection types.";
case persistent-connection {
container persistent {
presence true;
description
"Maintain a persistent connection to the NETCONF
client. If the connection goes down, immediately
start trying to reconnect to it, using the
reconnection strategy.
This connection type minimizes any NETCONF client
to NETCONF server data-transfer delay, albeit at
the expense of holding resources longer.";
leaf idle-timeout {
type uint32;
units "seconds";
default 86400; // one day;
description
"Specifies the maximum number of seconds that a
a NETCONF session may remain idle. A NETCONF
session will be dropped if it is idle for an
interval longer than this number of seconds.
If set to zero, then the server will never drop
a session because it is idle. Sessions that
have a notification subscription active are
never dropped.";
}
container keep-alives {
description
"Configures the keep-alive policy, to proactively
test the aliveness of the SSH/TLS client. An
unresponsive SSH/TLS client will be dropped after
approximately max-attempts * max-wait seconds.";
reference
"RFC YYYY: NETCONF Call Home and RESTCONF Call
Home, Section 3.1, item S6";
leaf max-wait {
type uint16 {
range "1..max";
}
units seconds;
default 30;
description
"Sets the amount of time in seconds after which
if no data has been received from the SSH/TLS
client, a SSH/TLS-level message will be sent
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to test the aliveness of the SSH/TLS client.";
}
leaf max-attempts {
type uint8;
default 3;
description
"Sets the maximum number of sequential keep-alive
messages that can fail to obtain a response from
the SSH/TLS client before assuming the SSH/TLS
client is no longer alive.";
}
}
}
}
case periodic-connection {
container periodic {
presence true;
description
"Periodically connect to the NETCONF client, so that
the NETCONF client may deliver messages pending for
the NETCONF server. The NETCONF client must close
the connection when it is ready to release it. Once
the connection has been closed, the NETCONF server
will restart its timer until the next connection.";
leaf idle-timeout {
type uint16;
units "seconds";
default 300; // five minutes
description
"Specifies the maximum number of seconds that a
a NETCONF session may remain idle. A NETCONF
session will be dropped if it is idle for an
interval longer than this number of seconds.
If set to zero, then the server will never drop
a session because it is idle. Sessions that
have a notification subscription active are
never dropped.";
}
leaf reconnect_timeout {
type uint16 {
range "1..max";
}
units minutes;
default 60;
description
"Sets the maximum amount of unconnected time the
NETCONF server will wait before re-establishing
a connection to the NETCONF client. The NETCONF
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server may initiate a connection before this
time if desired (e.g., to deliver an event
notification message).";
}
}
}
}
}
container reconnect-strategy {
description
"The reconnection strategy directs how a NETCONF server
reconnects to a NETCONF client, after discovering its
connection to the client has dropped, even if due to a
reboot. The NETCONF server starts with the specified
endpoint and tries to connect to it max-attempts times
before trying the next endpoint in the list (round
robin).";
leaf start-with {
type enumeration {
enum first-listed {
description
"Indicates that reconnections should start with
the first endpoint listed.";
}
enum last-connected {
description
"Indicates that reconnections should start with
the endpoint last connected to. If no previous
connection has ever been established, then the
first endpoint configured is used. NETCONF
servers SHOULD be able to remember the last
endpoint connected to across reboots.";
}
}
default first-listed;
description
"Specifies which of the NETCONF client's endpoints the
NETCONF server should start with when trying to connect
to the NETCONF client.";
}
leaf max-attempts {
type uint8 {
range "1..max";
}
default 3;
description
"Specifies the number times the NETCONF server tries to
connect to a specific endpoint before moving on to the
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next endpoint in the list (round robin).";
}
}
}
}
}
grouping cert-maps-grouping {
description
"A grouping that defines a container around the
cert-to-name structure defined in RFC 7407.";
container cert-maps {
uses x509c2n:cert-to-name;
description
"The cert-maps container is used by a TLS-based 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.";
reference
"RFC WWWW: NETCONF over TLS, Section 7";
}
}
grouping endpoints-container {
description
"This grouping is used by both the ssh and tls containers
for call-home configurations.";
container endpoints {
description
"Container for the list of endpoints.";
list endpoint {
key name;
min-elements 1;
ordered-by user;
description
"User-ordered list of endpoints for this NETCONF client.
Defining more than one enables high-availability.";
leaf name {
type string;
description
"An arbitrary name for this endpoint.";
}
leaf address {
type inet:host;
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mandatory true;
description
"The IP address or hostname of the endpoint. If a
hostname is configured and the DNS resolution results
in more than one IP address, the NETCONF server
will process the IP addresses as if they had been
explicitly configured in place of the hostname.";
}
leaf port {
type inet:port-number;
description
"The IP port for this endpoint. The NETCONF server will
use the IANA-assigned well-known port if no value is
specified.";
}
}
}
}
}
4. Design Considerations
Editorial: this section is a hold over from before, previously called
"Objectives". It was only written two support the "server" (not the
"client"). The question is if it's better to add the missing
"client" parts, or remove this section altogether.
The primary purpose of the YANG modules defined herein is to enable
the configuration of the NETCONF client and servers. This scope
includes the following objectives:
4.1. Support all NETCONF transports
The YANG module should support all current NETCONF transports, namely
NETCONF over SSH [RFC6242], NETCONF over TLS [RFC7589], and to be
extensible to support future transports as necessary.
Because implementations may not support all transports, the modules
should use YANG "feature" statements so that implementations can
accurately advertise which transports are supported.
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4.2. Enable each transport to select which keys to use
Servers may have a multiplicity of host-keys or server-certificates
from which subsets may be selected for specific uses. For instance,
a NETCONF server may want to use one set of SSH host-keys when
listening on port 830, and a different set of SSH host-keys when
calling home. The data models provided herein should enable
configuration of which keys to use on a per-use basis.
4.3. Support authenticating NETCONF clients certificates
When a certificate is used to authenticate a NETCONF client, there is
a need to configure the server to know how to authenticate the
certificates. The server should be able to authenticate the client's
certificate either by using path-validation to a configured trust
anchor or by matching the client-certificate to one previously
configured.
4.4. Support mapping authenticated NETCONF client certificates to
usernames
When a client certificate is used for TLS client authentication, the
NETCONF server must be able to derive a username from the
authenticated certificate. Thus the modules defined herein should
enable this mapping to be configured.
4.5. Support both listening for connections and call home
The NETCONF protocols were originally defined as having the server
opening a port to listen for client connections. More recently the
NETCONF working group defined support for call-home
([draft-ietf-netconf-call-home]), enabling the server to initiate the
connection to the client. Thus the modules defined herein should
enable configuration for both listening for connections and calling
home. Because implementations may not support both listening for
connections and calling home, YANG "feature" statements should be
used so that implementation can accurately advertise the connection
types it supports.
4.6. For Call Home connections
The following objectives only pertain to call home connections.
4.6.1. Support more than one NETCONF client
A NETCONF server may be managed by more than one NETCONF client. For
instance, a deployment may have one client for provisioning and
another for fault monitoring. Therefore, when it is desired for a
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server to initiate call home connections, it should be able to do so
to more than one client.
4.6.2. Support NETCONF clients having more than one endpoint
A NETCONF client managing a NETCONF server may implement a high-
availability strategy employing a multiplicity of active and/or
passive endpoint. Therefore, when it is desired for a server to
initiate call home connections, it should be able to connect to any
of the client's endpoints.
4.6.3. Support a reconnection strategy
Assuming a NETCONF client has more than one endpoint, then it becomes
necessary to configure how a NETCONF server should reconnect to the
client should it lose its connection to one the client's endpoints.
For instance, the NETCONF server may start with first endpoint
defined in a user-ordered list of endpoints or with the last
endpoints it was connected to.
4.6.4. Support both persistent and periodic connections
NETCONF clients may vary greatly on how frequently they need to
interact with a NETCONF server, how responsive interactions need to
be, and how many simultaneous connections they can support. Some
clients may need a persistent connection to servers to optimize real-
time interactions, while others prefer periodic interactions in order
to minimize resource requirements. Therefore, when it is necessary
for server to initiate connections, it should be configurable if the
connection is persistent or periodic.
4.6.5. Reconnection strategy for periodic connections
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 how to connect to another server.
4.6.6. Keep-alives for persistent connections
If a persistent connection is desired, it is the responsibility of
the connection initiator to actively test the "aliveness" of the
connection. The connection initiator must immediately work to
reestablish a persistent connection as soon as the connection is
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lost. How often the connection should be tested is driven by NETCONF
client requirements, and therefore keep-alive settings should be
configurable on a per-client basis.
4.6.7. Customizations for periodic connections
If a periodic connection is desired, it is necessary for the NETCONF
server to know how often it should connect. This frequency
determines the maximum amount of time a NETCONF client may have to
wait to send data to a server. A server may connect to a client
before this interval expires if desired (e.g., to send data to a
client).
5. Security Considerations
A denial of service (DoS) attack MAY occur if the NETCONF server
limits the maximum number of NETCONF sessions it will accept (i.e.
the 'max-sessions' field in the ietf-netconf-server module is not
zero) and either the "hello-timeout" or "idle-timeout" fields in
ietf-netconf-server module have been set to indicate the NETCONF
server should wait forever (i.e. set to zero).
6. IANA Considerations
6.1. The IETF XML Registry
This document registers two URIs in the IETF XML registry [RFC2119].
Following the format in [RFC3688], the following registrations are
requested:
URI: urn:ietf:params:xml:ns:yang:ietf-netconf-client
Registrant Contact: The NETCONF WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
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.
6.2. The YANG Module Names Registry
This document registers two YANG modules in the YANG Module Names
registry [RFC6020]. Following the format in [RFC6020], the the
following registrations are requested:
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name: ietf-netconf-client
namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-client
prefix: ncc
reference: RFC XXXX
name: ietf-netconf-server
namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-server
prefix: ncs
reference: RFC XXXX
7. Acknowledgements
The authors would like to thank for following for lively discussions
on list and in the halls (ordered by last name): Andy Bierman, Martin
Bjorklund, Benoit Claise, Mehmet Ersue, David Lamparter, Alan Luchuk,
Ladislav Lhotka, Radek Krejci, Tom Petch, Phil Shafer, Sean Turner,
and Bert Wijnen.
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
8.1. Normative References
[draft-ietf-netconf-ssh-client-server]
Watsen, K., "SSH Client and Server Models", draft-ieft-
netconf-ssh-client-server-00 (work in progress), 2016,
.
[draft-ietf-netconf-system-keychain]
Watsen, K., "System Keychain Model", draft-ieft-netconf-
system-keychain-00 (work in progress), 2016,
.
[draft-ietf-netconf-tls-client-server]
Watsen, K., "TLS Client and Server Models", draft-ieft-
netconf-tls-client-server-00 (work in progress), 2016,
.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
.
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[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
.
[RFC7407] Bjorklund, M. and J. Schoenwaelder, "A YANG Data Model for
SNMP Configuration", RFC 7407, DOI 10.17487/RFC7407,
December 2014, .
[RFC7589] Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the
NETCONF Protocol over Transport Layer Security (TLS) with
Mutual X.509 Authentication", RFC 7589,
DOI 10.17487/RFC7589, June 2015,
.
8.2. Informative References
[draft-ietf-netconf-call-home]
Watsen, K., "NETCONF Call Home and RESTCONF Call Home",
draft-ieft-netconf-call-home-17 (work in progress), 2015,
.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
.
[RFC4252] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
Authentication Protocol", RFC 4252, DOI 10.17487/RFC4252,
January 2006, .
[RFC4253] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
Transport Layer Protocol", RFC 4253, DOI 10.17487/RFC4253,
January 2006, .
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[RFC4254] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
Connection Protocol", RFC 4254, DOI 10.17487/RFC4254,
January 2006, .
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
.
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Appendix A. Change Log
A.1. server-model-09 to 00
o This draft was split out from draft-ietf-netconf-server-model-09.
o Added in previously missing ietf-netconf-client module.
o Added in new features 'listen' and 'call-home' so future
transports can be augmented in.
Appendix B. Open Issues
Please see: https://github.com/netconf-wg/netconf-client-server/
issues.
Authors' Addresses
Kent Watsen
Juniper Networks
EMail: kwatsen@juniper.net
Gary Wu
Cisco Networks
EMail: garywu@cisco.com
Juergen Schoenwaelder
Jacobs University Bremen
EMail: j.schoenwaelder@jacobs-university.de
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