NETCONF Working Group K. Watsen
Internet-Draft Juniper Networks
Intended status: Standards Track October 22, 2018
Expires: April 25, 2019
RESTCONF Client and Server Models
draft-ietf-netconf-restconf-client-server-08
Abstract
This document defines two YANG modules, one module to configure a
RESTCONF client and the other module to configure a RESTCONF server.
Both modules support the TLS transport protocol with both standard
RESTCONF and RESTCONF 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 I-D.ietf-netconf-keystore
o I-D.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 "ZZZZ" --> the assigned RFC value for I-D.ietf-netconf-tls-client-
server
Artwork in this document contains placeholder values for the date of
publication of this draft. Please apply the following replacement:
o "2018-10-22" --> the publication date of this draft
The following Appendix section is to be removed prior to publication:
o Appendix A. Change Log
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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-
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 25, 2019.
Copyright Notice
Copyright (c) 2018 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
(https://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 . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. The RESTCONF Client Model . . . . . . . . . . . . . . . . . . 3
2.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 7
2.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 9
3. The RESTCONF Server Model . . . . . . . . . . . . . . . . . . 18
3.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 18
3.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 21
3.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 24
4. Security Considerations . . . . . . . . . . . . . . . . . . . 34
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35
5.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 35
5.2. The YANG Module Names Registry . . . . . . . . . . . . . 35
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6. References . . . . . . . . . . . . . . . . . . . . . . . . . 36
6.1. Normative References . . . . . . . . . . . . . . . . . . 36
6.2. Informative References . . . . . . . . . . . . . . . . . 37
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 38
A.1. 00 to 01 . . . . . . . . . . . . . . . . . . . . . . . . 38
A.2. 01 to 02 . . . . . . . . . . . . . . . . . . . . . . . . 38
A.3. 02 to 03 . . . . . . . . . . . . . . . . . . . . . . . . 38
A.4. 03 to 04 . . . . . . . . . . . . . . . . . . . . . . . . 38
A.5. 04 to 05 . . . . . . . . . . . . . . . . . . . . . . . . 38
A.6. 05 to 06 . . . . . . . . . . . . . . . . . . . . . . . . 39
A.7. 06 to 07 . . . . . . . . . . . . . . . . . . . . . . . . 39
A.8. 07 to 08 . . . . . . . . . . . . . . . . . . . . . . . . 39
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 39
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 39
1. Introduction
This document defines two YANG [RFC7950] modules, one module to
configure a RESTCONF client and the other module to configure a
RESTCONF server [RFC8040]. Both modules support the TLS [RFC8446]
transport protocol with both standard RESTCONF and RESTCONF Call Home
connections [RFC8071].
1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. The RESTCONF Client Model
The RESTCONF 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, like that presented in
[I-D.ietf-netconf-netconf-client-server], is designed to support any
number of possible transports. RESTCONF only supports the TLS
transport currently, thus this model only supports the TLS transport.
All private keys and trusted certificates are held in the keystore
model defined in [I-D.ietf-netconf-keystore].
YANG feature statements are used to enable implementations to
advertise which parts of the model the RESTCONF client supports.
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2.1. Tree Diagram
The following tree diagram [RFC8340] provides an overview of the data
model for the "ietf-restconf-client" module. Just the container is
displayed below, but there is also a reusable grouping called
"restconf-client-grouping" that the container is using.
[Note: '\' line wrapping for formatting only]
module: ietf-restconf-client
+--rw restconf-client
+--rw initiate! {initiate}?
| +--rw restconf-server* [name]
| +--rw name string
| +--rw endpoints
| +--rw endpoint* [name]
| +--rw name string
| +--rw (transport)
| | +--:(tls) {tls-initiate}?
| | +--rw tls
| | +--rw address inet:host
| | +--rw port? inet:port-number
| | +--rw client-identity
| | | +--rw (auth-type)
| | | +--:(certificate)
| | | +--rw certificate
| | | +--rw (local-or-keystore)
| | | +--:(local)
| | | | {local-keys-suppor\
ted}?
| | | | +--rw algorithm?
| | | | | asymmetric-key-e\
ncryption-algorithm-ref
| | | | +--rw public-key?
| | | | | binary
| | | | +--rw private-key?
| | | | | union
| | | | +---x generate-hidden-key
| | | | | +---w input
| | | | | +---w algorithm
| | | | | asymmetric\
-key-encryption-algorithm-ref
| | | | +---x install-hidden-key
| | | | | +---w input
| | | | | +---w algorithm
| | | | | | asymmetric\
-key-encryption-algorithm-ref
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| | | | | +---w public-key?
| | | | | | binary
| | | | | +---w private-key?
| | | | | binary
| | | | +--rw cert?
| | | | | end-entity-cert-\
cms
| | | | +---n certificate-expira\
tion
| | | | +-- expiration-date
| | | | yang:date-and\
-time
| | | +--:(keystore)
| | | {keystore-supporte\
d}?
| | | +--rw reference?
| | | ks:asymmetric-ke\
y-certificate-ref
| | +--rw server-auth
| | | +--rw pinned-ca-certs?
| | | | ta:pinned-certificates-ref
| | | | {ta:x509-certificates}?
| | | +--rw pinned-server-certs?
| | | ta:pinned-certificates-ref
| | | {ta:x509-certificates}?
| | +--rw hello-params
| | {tls-client-hello-params-config}?
| | +--rw tls-versions
| | | +--rw tls-version* identityref
| | +--rw cipher-suites
| | +--rw cipher-suite* identityref
| +--rw connection-type
| | +--rw (connection-type)
| | +--:(persistent-connection)
| | | +--rw persistent!
| | | +--rw keep-alives
| | | +--rw max-wait? uint16
| | | +--rw max-attempts? uint8
| | +--:(periodic-connection)
| | +--rw periodic!
| | +--rw period? uint16
| | +--rw anchor-time? yang:date-and-time
| | +--rw idle-timeout? uint16
| +--rw reconnect-strategy
| +--rw start-with? enumeration
| +--rw max-attempts? uint8
+--rw listen! {listen}?
+--rw idle-timeout? uint16
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+--rw endpoint* [name]
+--rw name string
+--rw (transport)
+--:(tls) {tls-listen}?
+--rw tls
+--rw address? inet:ip-address
+--rw port? inet:port-number
+--rw client-identity
| +--rw (auth-type)
| +--:(certificate)
| +--rw certificate
| +--rw (local-or-keystore)
| +--:(local) {local-keys-supported\
}?
| | +--rw algorithm?
| | | asymmetric-key-encrypt\
ion-algorithm-ref
| | +--rw public-key?
| | | binary
| | +--rw private-key?
| | | union
| | +---x generate-hidden-key
| | | +---w input
| | | +---w algorithm
| | | asymmetric-key-e\
ncryption-algorithm-ref
| | +---x install-hidden-key
| | | +---w input
| | | +---w algorithm
| | | | asymmetric-key-e\
ncryption-algorithm-ref
| | | +---w public-key? bin\
ary
| | | +---w private-key? bin\
ary
| | +--rw cert?
| | | end-entity-cert-cms
| | +---n certificate-expiration
| | +-- expiration-date
| | yang:date-and-time
| +--:(keystore) {keystore-supporte\
d}?
| +--rw reference?
| ks:asymmetric-key-cert\
ificate-ref
+--rw server-auth
| +--rw pinned-ca-certs?
| | ta:pinned-certificates-ref
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| | {ta:x509-certificates}?
| +--rw pinned-server-certs?
| ta:pinned-certificates-ref
| {ta:x509-certificates}?
+--rw hello-params
{tls-client-hello-params-config}?
+--rw tls-versions
| +--rw tls-version* identityref
+--rw cipher-suites
+--rw cipher-suite* identityref
2.2. Example Usage
The following example illustrates configuring a RESTCONF client to
initiate connections, as well as listening for call-home connections.
This example is consistent with the examples presented in Section 3.2
of [I-D.ietf-netconf-keystore].
[Note: '\' line wrapping for formatting only]
file "ietf-restconf-client@2018-10-22.yang"
module ietf-restconf-client {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-restconf-client";
prefix "rcc";
import ietf-yang-types {
prefix yang;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-inet-types {
prefix inet;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-tls-client {
prefix ts;
revision-date 2018-10-22; // stable grouping definitions
reference
"RFC ZZZZ: YANG Groupings for TLS Clients and TLS Servers";
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web:
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WG List:
Author: Kent Watsen
Author: Gary Wu
";
description
"This module contains a collection of YANG definitions for
configuring RESTCONF clients.
Copyright (c) 2017 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 "2018-10-22" {
description
"Initial version";
reference
"RFC XXXX: RESTCONF Client and Server Models";
}
// Features
feature initiate {
description
"The 'initiate' feature indicates that the RESTCONF client
supports initiating RESTCONF connections to RESTCONF servers
using at least one transport (e.g., TLS, etc.).";
}
feature tls-initiate {
if-feature initiate;
description
"The 'tls-initiate' feature indicates that the RESTCONF client
supports initiating TLS connections to RESTCONF servers. This
feature exists as TLS might not be a mandatory to implement
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transport in the future.";
reference
"RFC 8040: RESTCONF Protocol";
}
feature listen {
description
"The 'listen' feature indicates that the RESTCONF client
supports opening a port to accept RESTCONF server call
home connections using at least one transport (e.g.,
TLS, etc.).";
}
feature tls-listen {
if-feature listen;
description
"The 'tls-listen' feature indicates that the RESTCONF client
supports opening a port to listen for incoming RESTCONF
server call-home TLS connections. This feature exists as
TLS might not be a mandatory to implement transport in the
future.";
reference
"RFC 8071: NETCONF Call Home and RESTCONF Call Home";
}
container restconf-client {
uses restconf-client-grouping;
description
"Top-level container for RESTCONF client configuration.";
}
grouping restconf-client-grouping {
description
"Top-level grouping for RESTCONF client configuration.";
container initiate {
if-feature initiate;
presence "Enables client to initiate TCP connections";
description
"Configures client initiating underlying TCP connections.";
list restconf-server {
key name;
min-elements 1;
description
"List of RESTCONF servers the RESTCONF client is to
initiate connections to in parallel.";
leaf name {
type string;
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description
"An arbitrary name for the RESTCONF server.";
}
container endpoints {
description
"Container for the list of endpoints.";
list endpoint {
key name;
min-elements 1;
ordered-by user;
description
"A non-empty user-ordered list of endpoints for this
RESTCONF client to try to connect to in sequence.
Defining more than one enables high-availability.";
leaf name {
type string;
description
"An arbitrary name for this endpoint.";
}
choice transport {
mandatory true;
description
"Selects between available transports. This is a
'choice' statement so as to support additional
transport options to be augmented in.";
case tls {
if-feature tls-initiate;
container tls {
description
"Specifies TLS-specific transport
configuration.";
leaf address {
type inet:host;
mandatory true;
description
"The IP address or hostname of the endpoint.
If a domain name is configured, then the
DNS resolution should happen on each usage
attempt. If the the DNS resolution results
in multiple IP addresses, the IP addresses
will be tried according to local preference
order until a connection has been established
or until all IP addresses have failed.";
}
leaf port {
type inet:port-number;
default 443;
description
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"The IP port for this endpoint. The RESTCONF
client will use the IANA-assigned well-known
port for 'https' (443) if no value is
specified.";
}
uses ts:tls-client-grouping {
refine "client-identity/auth-type" {
mandatory true;
description
"RESTCONF clients MUST pass some
authentication credentials.";
}
}
}
} // end tls
} // end transport
container connection-type {
description
"Indicates the kind of connection to use.";
choice connection-type {
mandatory true;
description
"Selects between available connection types.";
case persistent-connection {
container persistent {
presence
"Indicates that a persistent connection is
to be maintained.";
description
"Maintain a persistent connection to the
RESTCONF server. If the connection goes down,
immediately start trying to reconnect to it,
using the reconnection strategy. This
connection type minimizes any RESTCONF server
to RESTCONF client data-transfer delay, albeit
at the expense of holding resources longer.";
container keep-alives {
description
"Configures the keep-alive policy, to
proactively test the aliveness of the TLS
server. An unresponsive TLS server will
be dropped after approximately max-attempts
* max-wait seconds.";
leaf max-wait {
type uint16 {
range "1..max";
}
units seconds;
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default 30;
description
"Sets the amount of time in seconds after
which if no data has been received from
the TLS server, a TLS-level message will
be sent to test the aliveness of the TLS
server.";
}
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 TLS server
before assuming the TLS server is no
longer alive.";
}
}
}
}
case periodic-connection {
container periodic {
presence
"Indicates that a periodic connection is to be
maintained.";
description
"Periodically connect to the NETCONF server.
The RESTCONF server should close the underlying
TLS connection upon completing planned
activities.
This connection type increases resource
utilization, albeit with increased delay in
RESTCONF server to RESTCONF client
interactions.";
leaf period {
type uint16;
units "minutes";
default 60;
description
"Duration of time between periodic
connections.";
}
leaf anchor-time {
type yang:date-and-time {
// constrained to minute-level granularity
pattern '\d{4}-\d{2}-\d{2}T\d{2}:\d{2}'
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+ '(Z|[\+\-]\d{2}:\d{2})';
}
description
"Designates a timestamp before or after which
a series of periodic connections are
determined. The periodic connections occur
at a whole multiple interval from the anchor
time. For example, for an anchor time is 15
minutes past midnight and a period interval
of 24 hours, then a periodic connection will
occur 15 minutes past midnight everyday.";
}
leaf idle-timeout {
type uint16;
units "seconds";
default 120; // two minutes
description
"Specifies the maximum number of seconds
that the underlying TLS session may remain
idle. A TLS session will be dropped if it
is idle for an interval longer than this
number of seconds If set to zero, then the
RESTCONF client will never drop a session
because it is idle.";
}
}
} // end periodic-connection
} // end connection-type
} // end connection-type
container reconnect-strategy {
description
"The reconnection strategy directs how a RESTCONF
client reconnects to a RESTCONF server, after
discovering its connection to the server has
dropped, even if due to a reboot. The RESTCONF
client 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
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"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. RESTCONF clients
SHOULD be able to remember the last
endpoint connected to across reboots.";
}
enum random-selection {
description
"Indicates that reconnections should start with
a random endpoint.";
}
}
default first-listed;
description
"Specifies which of the RESTCONF server's
endpoints the RESTCONF client should start
with when trying to connect to the RESTCONF
server.";
}
leaf max-attempts {
type uint8 {
range "1..max";
}
default 3;
description
"Specifies the number times the RESTCONF client
tries to connect to a specific endpoint before
moving on to the next endpoint in the list
(round robin).";
}
} // end reconnect-strategy
} // end endpoint
} // end endpoints
} // end restconf-server
} // end initiate
container listen {
if-feature listen;
presence "Enables client to accept call-home connections";
description
"Configures client accepting call-home TCP connections.";
leaf idle-timeout {
type uint16;
units "seconds";
default 3600; // one hour
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description
"Specifies the maximum number of seconds that an
underlying TLS session may remain idle. A TLS 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;
min-elements 1;
description
"List of endpoints to listen for RESTCONF connections.";
leaf name {
type string;
description
"An arbitrary name for the RESTCONF listen endpoint.";
}
choice transport {
mandatory true;
description
"Selects between available transports. This is a
'choice' statement so as to support additional
transport options to be augmented in.";
case tls {
if-feature tls-listen;
container tls {
description
"TLS-specific listening configuration for inbound
connections.";
leaf address {
type inet:ip-address;
description
"The IP address to listen on for incoming call-
home connections. The RESTCONF client will
listen on all configured interfaces if no
value is specified. INADDR_ANY (0.0.0.0) or
INADDR6_ANY (0:0:0:0:0:0:0:0 a.k.a. ::) MUST
be used when the server is to listen on all
IPv4 or IPv6 addresses, respectively.";
}
leaf port {
type inet:port-number;
default 4336;
description
"The port number to listen on for call-home
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connections. The RESTCONF client will listen
on the IANA-assigned well-known port for
'restconf-ch-tls' (4336) if no value is
specified.";
}
uses ts:tls-client-grouping {
refine "client-identity/auth-type" {
mandatory true;
description
"RESTCONF clients MUST pass some authentication
credentials.";
}
}
}
}
} // end transport
} // end endpoint
} // end listen
} // end restconf-client
}
3. The RESTCONF Server Model
The RESTCONF server model presented in this section supports servers
both listening for connections as well as initiating call-home
connections.
All private keys and trusted certificates are held in the keystore
model defined in [I-D.ietf-netconf-keystore].
YANG feature statements are used to enable implementations to
advertise which parts of the model the RESTCONF server supports.
3.1. Tree Diagram
The following tree diagram [RFC8340] provides an overview of the data
model for the "ietf-restconf-server" module. Just the container is
displayed below, but there is also a reusable grouping called
"restconf-server-grouping" that the container is using.
[Note: '\' line wrapping for formatting only]
module: ietf-restconf-server
+--rw restconf-server
+--rw listen! {listen}?
| +--rw endpoint* [name]
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| +--rw name string
| +--rw (transport)
| +--:(tls) {tls-listen}?
| +--rw tls
| +--rw address? inet:ip-address
| +--rw port? inet:port-number
| +--rw server-identity
| | +--rw (local-or-keystore)
| | +--:(local) {local-keys-supported}?
| | | +--rw algorithm?
| | | | asymmetric-key-encryption-algor\
ithm-ref
| | | +--rw public-key? binary
| | | +--rw private-key? union
| | | +---x generate-hidden-key
| | | | +---w input
| | | | +---w algorithm
| | | | asymmetric-key-encryption\
-algorithm-ref
| | | +---x install-hidden-key
| | | | +---w input
| | | | +---w algorithm
| | | | | asymmetric-key-encryption\
-algorithm-ref
| | | | +---w public-key? binary
| | | | +---w private-key? binary
| | | +--rw cert?
| | | | end-entity-cert-cms
| | | +---n certificate-expiration
| | | +-- expiration-date
| | | yang:date-and-time
| | +--:(keystore) {keystore-supported}?
| | +--rw reference?
| | ks:asymmetric-key-certificate-r\
ef
| +--rw client-auth
| | +--rw pinned-ca-certs?
| | | ta:pinned-certificates-ref
| | | {ta:x509-certificates}?
| | +--rw pinned-client-certs?
| | | ta:pinned-certificates-ref
| | | {ta:x509-certificates}?
| | +--rw cert-maps
| | +--rw cert-to-name* [id]
| | +--rw id uint32
| | +--rw fingerprint
| | | x509c2n:tls-fingerprint
| | +--rw map-type identityref
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| | +--rw name string
| +--rw hello-params
| {tls-server-hello-params-config}?
| +--rw tls-versions
| | +--rw tls-version* identityref
| +--rw cipher-suites
| +--rw cipher-suite* identityref
+--rw call-home! {call-home}?
+--rw restconf-client* [name]
+--rw name string
+--rw endpoints
| +--rw endpoint* [name]
| +--rw name string
| +--rw (transport)
| +--:(tls) {tls-call-home}?
| +--rw tls
| +--rw address inet:host
| +--rw port? inet:port-number
| +--rw server-identity
| | +--rw (local-or-keystore)
| | +--:(local) {local-keys-supported}?
| | | +--rw algorithm?
| | | | asymmetric-key-encryption\
-algorithm-ref
| | | +--rw public-key?
| | | | binary
| | | +--rw private-key?
| | | | union
| | | +---x generate-hidden-key
| | | | +---w input
| | | | +---w algorithm
| | | | asymmetric-key-encr\
yption-algorithm-ref
| | | +---x install-hidden-key
| | | | +---w input
| | | | +---w algorithm
| | | | | asymmetric-key-encr\
yption-algorithm-ref
| | | | +---w public-key? binary
| | | | +---w private-key? binary
| | | +--rw cert?
| | | | end-entity-cert-cms
| | | +---n certificate-expiration
| | | +-- expiration-date
| | | yang:date-and-time
| | +--:(keystore) {keystore-supported}?
| | +--rw reference?
| | ks:asymmetric-key-certifi\
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cate-ref
| +--rw client-auth
| | +--rw pinned-ca-certs?
| | | ta:pinned-certificates-ref
| | | {ta:x509-certificates}?
| | +--rw pinned-client-certs?
| | | ta:pinned-certificates-ref
| | | {ta:x509-certificates}?
| | +--rw cert-maps
| | +--rw cert-to-name* [id]
| | +--rw id uint32
| | +--rw fingerprint
| | | x509c2n:tls-fingerprint
| | +--rw map-type identityref
| | +--rw name string
| +--rw hello-params
| {tls-server-hello-params-config}?
| +--rw tls-versions
| | +--rw tls-version* identityref
| +--rw cipher-suites
| +--rw cipher-suite* identityref
+--rw connection-type
| +--rw (connection-type)
| +--:(persistent-connection)
| | +--rw persistent!
| | +--rw keep-alives
| | +--rw max-wait? uint16
| | +--rw max-attempts? uint8
| +--:(periodic-connection)
| +--rw periodic!
| +--rw period? uint16
| +--rw anchor-time? yang:date-and-time
| +--rw idle-timeout? uint16
+--rw reconnect-strategy
+--rw start-with? enumeration
+--rw max-attempts? uint8
3.2. Example Usage
The following example illustrates configuring a RESTCONF server to
listen for RESTCONF client connections, as well as configuring call-
home to one RESTCONF client.
This example is consistent with the examples presented in Section 3.2
of [I-D.ietf-netconf-keystore].
[Note: '\' line wrapping for formatting only]
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netconf/tls
11.22.33.44
ct:rsa2048
base64encodedvalue==
base64encodedvalue==
base64encodedvalue==
explicitly-trusted-client-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
config-manager
east-data-center
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22.33.44.55
ct:rsa2048
base64encodedvalue==
base64encodedvalue==
base64encodedvalue==
explicitly-trusted-client-ca-certs
explicitly-trusted-client-certs\
pinned-client-certs>
1
11:0A:05:11:00
x509c2n:san-any
2
B3:4F:A1:8C:54
x509c2n:specified
scooby-doo
west-data-center
33.44.55.66
ct:rsa2048
base64encodedvalue==
base64encodedvalue==
base64encodedvalue==
explicitly-trusted-client-ca-certs
explicitly-trusted-client-certs\
pinned-client-certs>
1
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11:0A:05:11:00
x509c2n:san-any
2
B3:4F:A1:8C:54
x509c2n:specified
scooby-doo
300
60
last-connected
3
3.3. YANG Module
This YANG module has normative references to [RFC6991], [RFC7407],
[RFC8040], [RFC8071], and [I-D.ietf-netconf-tls-client-server].
file "ietf-restconf-server@2018-10-22.yang"
module ietf-restconf-server {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-restconf-server";
prefix "rcs";
import ietf-yang-types {
prefix yang;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-inet-types {
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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-tls-server {
prefix ts;
revision-date 2018-10-22; // stable grouping definitions
reference
"RFC ZZZZ: YANG Groupings for TLS Clients and TLS Servers";
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web:
WG List:
Author: Kent Watsen
Author: Gary Wu
Author: Juergen Schoenwaelder
";
description
"This module contains a collection of YANG definitions for
configuring RESTCONF servers.
Copyright (c) 2017 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).
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This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
revision "2018-10-22" {
description
"Initial version";
reference
"RFC XXXX: RESTCONF Client and Server Models";
}
// Features
feature listen {
description
"The 'listen' feature indicates that the RESTCONF server
supports opening a port to accept RESTCONF client connections
using at least one transport (e.g., TLS, etc.).";
}
feature tls-listen {
if-feature listen;
description
"The 'tls-listen' feature indicates that the RESTCONF server
supports opening a port to listen for incoming RESTCONF
client connections. This feature exists as TLS might not
be a mandatory to implement transport in the future.";
reference
"RFC 8040: RESTCONF Protocol";
}
feature call-home {
description
"The 'call-home' feature indicates that the RESTCONF
server supports initiating RESTCONF call home connections
to RESTCONF clients using at least one transport (e.g.,
TLS, etc.).";
reference
"RFC 8071: NETCONF Call Home and RESTCONF Call Home";
}
feature tls-call-home {
if-feature call-home;
description
"The 'tls-call-home' feature indicates that the RESTCONF
server supports initiating connections to RESTCONF clients.
This feature exists as TLS might not be a mandatory to
implement transport in the future.";
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reference
"RFC 8071: NETCONF Call Home and RESTCONF Call Home";
}
container restconf-server {
uses restconf-server-grouping;
description
"Top-level container for RESTCONF server configuration.";
}
grouping restconf-server-grouping {
description
"Top-level grouping for RESTCONF server configuration.";
container listen {
if-feature listen;
presence "Enables server to listen for TCP connections";
description "Configures listen behavior";
list endpoint {
key name;
min-elements 1;
description
"List of endpoints to listen for RESTCONF connections.";
leaf name {
type string;
description
"An arbitrary name for the RESTCONF listen endpoint.";
}
choice transport {
mandatory true;
description
"Selects between available transports. This is a
'choice' statement so as to support additional
transport options to be augmented in.";
case tls {
if-feature tls-listen;
container tls {
description
"TLS-specific listening configuration for inbound
connections.";
leaf address {
type inet:ip-address;
description
"The IP address to listen on for incoming
connections. The RESTCONF server will listen
on all configured interfaces if no value is
specified. INADDR_ANY (0.0.0.0) or INADDR6_ANY
(0:0:0:0:0:0:0:0 a.k.a. ::) MUST be used when
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the server is to listen on all IPv4 or IPv6
addresses, respectively.";
}
leaf port {
type inet:port-number;
default 443;
description
"The local port number to listen on. If no value
is specified, the IANA-assigned port value for
'https' (443) is used.";
}
uses ts:tls-server-grouping {
refine "client-auth" {
must 'pinned-ca-certs or pinned-client-certs';
description
"RESTCONF servers MUST be able to validate
clients.";
}
augment "client-auth" {
description
"Augments in the cert-to-name structure,
so the RESTCONF server can map TLS-layer
client certificates to RESTCONF usernames.";
container cert-maps {
uses x509c2n:cert-to-name;
description
"The cert-maps container is used by a TLS-
based RESTCONF server to map the RESTCONF
client's presented X.509 certificate to
a RESTCONF username. If no matching and
valid cert-to-name list entry can be found,
then the RESTCONF server MUST close the
connection, and MUST NOT accept RESTCONF
messages over it.";
reference
"RFC 7407: A YANG Data Model for SNMP
Configuration.";
}
}
}
} // end tls container
} // end tls case
} // end transport
} // end endpoint
} // end listen
container call-home {
if-feature call-home;
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presence "Enables server to initiate TCP connections";
description "Configures call-home behavior";
list restconf-client {
key name;
min-elements 1;
description
"List of RESTCONF clients the RESTCONF server is to
initiate call-home connections to in parallel.";
leaf name {
type string;
description
"An arbitrary name for the remote RESTCONF client.";
}
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 RESTCONF
client. Defining more than one enables high-
availability.";
leaf name {
type string;
description
"An arbitrary name for this endpoint.";
}
choice transport {
mandatory true;
description
"Selects between available transports. This is a
'choice' statement so as to support additional
transport options to be augmented in.";
case tls {
if-feature tls-call-home;
container tls {
description
"Specifies TLS-specific call-home transport
configuration.";
leaf address {
type inet:host;
mandatory true;
description
"The IP address or hostname of the endpoint.
If a domain name is configured, then the
DNS resolution should happen on each usage
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attempt. If the DNS resolution results in
multiple IP addresses, the IP addresses will
be tried according to local preference order
until a connection has been established or
until all IP addresses have failed.";
}
leaf port {
type inet:port-number;
default 4336;
description
"The IP port for this endpoint. The RESTCONF
server will use the IANA-assigned well-known
port for 'restconf-ch-tls' (4336) if no value
is specified.";
}
uses ts:tls-server-grouping {
refine "client-auth" {
must 'pinned-ca-certs or pinned-client-certs';
description
"RESTCONF servers MUST be able to validate
clients.";
}
augment "client-auth" {
description
"Augments in the cert-to-name structure,
so the RESTCONF server can map TLS-layer
client certificates to RESTCONF usernames.";
container cert-maps {
uses x509c2n:cert-to-name;
description
"The cert-maps container is used by a
TLS-based RESTCONF server to map the
RESTCONF client's presented X.509
certificate to a RESTCONF username. If
no matching and valid cert-to-name list
entry can be found, then the RESTCONF
server MUST close the connection, and
MUST NOT accept RESTCONF messages over
it.";
reference
"RFC 7407: A YANG Data Model for SNMP
Configuration.";
}
}
}
}
}
} // end transport
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} // end endpoint
} // end endpoints
container connection-type {
description
"Indicates the RESTCONF client's preference for how the
RESTCONF server's connection is maintained.";
choice connection-type {
mandatory true;
description
"Selects between available connection types.";
case persistent-connection {
container persistent {
presence
"Indicates that a persistent connection is to be
maintained.";
description
"Maintain a persistent connection to the RESTCONF
client. If the connection goes down, immediately
start trying to reconnect to it, using the
reconnection strategy.
This connection type minimizes any RESTCONF
client to RESTCONF server data-transfer delay,
albeit at the expense of holding resources
longer.";
container keep-alives {
description
"Configures the keep-alive policy, to
proactively test the aliveness of the TLS
client. An unresponsive TLS client will
be dropped after approximately (max-attempts
* max-wait) seconds.";
reference
"RFC 8071: NETCONF Call Home and RESTCONF
Call Home, Section 4.1, item S7";
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 TLS client, a TLS-level message will
be sent to test the aliveness of the TLS
client.";
}
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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 TLS client before assuming
the TLS client is no longer alive.";
}
}
}
}
case periodic-connection {
container periodic {
presence
"Indicates that a periodic connection is to be
maintained.";
description
"Periodically connect to the RESTCONF client. The
RESTCONF client should close the underlying TLS
connection upon completing planned activities.
This connection type increases resource
utilization, albeit with increased delay in
RESTCONF client to RESTCONF client interactions.";
leaf period {
type uint16;
units "minutes";
default 60;
description
"Duration of time between periodic connections.";
}
leaf anchor-time {
type yang:date-and-time {
// constrained to minute-level granularity
pattern '\d{4}-\d{2}-\d{2}T\d{2}:\d{2}'
+ '(Z|[\+\-]\d{2}:\d{2})';
}
description
"Designates a timestamp before or after which a
series of periodic connections are determined.
The periodic connections occur at a whole
multiple interval from the anchor time. For
example, for an anchor time is 15 minutes past
midnight and a period interval of 24 hours, then
a periodic connection will occur 15 minutes past
midnight everyday.";
}
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leaf idle-timeout {
type uint16;
units "seconds";
default 120; // two minutes
description
"Specifies the maximum number of seconds that
the underlying TLS session may remain idle.
A TLS 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.";
}
}
}
}
}
container reconnect-strategy {
description
"The reconnection strategy directs how a RESTCONF server
reconnects to a RESTCONF client after discovering its
connection to the client has dropped, even if due to a
reboot. The RESTCONF 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. RESTCONF
servers SHOULD be able to remember the last
endpoint connected to across reboots.";
}
enum random-selection {
description
"Indicates that reconnections should start with
a random endpoint.";
}
}
default first-listed;
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description
"Specifies which of the RESTCONF client's endpoints
the RESTCONF server should start with when trying
to connect to the RESTCONF client.";
}
leaf max-attempts {
type uint8 {
range "1..max";
}
default 3;
description
"Specifies the number times the RESTCONF server tries
to connect to a specific endpoint before moving on to
the next endpoint in the list (round robin).";
}
}
}
}
}
}
4. Security Considerations
The YANG module defined in this document uses a grouping defined in
[I-D.ietf-netconf-tls-client-server]. Please see the Security
Considerations section in that document for concerns related that
grouping.
The YANG module defined in this document is designed to be accessed
via YANG based management protocols, such as NETCONF [RFC6241] and
RESTCONF [RFC8040]. Both of these protocols have mandatory-to-
implement secure transport layers (e.g., SSH, TLS) with mutual
authentication.
The NETCONF access control model (NACM) [RFC8341] provides the means
to restrict access for particular users to a pre-configured subset of
all available protocol operations and content.
There are a number of data nodes defined in this YANG module that are
writable/creatable/deletable (i.e., config true, which is the
default). These data nodes may be considered sensitive or vulnerable
in some network environments. Write operations (e.g., edit-config)
to these data nodes without proper protection can have a negative
effect on network operations. These are the subtrees and data nodes
and their sensitivity/vulnerability:
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/: The entire data trees defined by the modules defined in this
draft are sensitive to write operations. For instance, the
addition or removal of references to keys, certificates,
trusted anchors, etc., can dramatically alter the implemented
security policy. However, no NACM annotations are applied as
the data SHOULD be editable by users other than a designated
'recovery session'.
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:
NONE
Some of the RPC operations in this YANG module may be considered
sensitive or vulnerable in some network environments. It is thus
important to control access to these operations. These are the
operations and their sensitivity/vulnerability:
NONE
5. IANA Considerations
5.1. The IETF XML Registry
This document registers two URIs in the "ns" subregistry of the IETF
XML Registry [RFC3688]. Following the format in [RFC3688], the
following registrations are requested:
URI: urn:ietf:params:xml:ns:yang:ietf-restconf-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-restconf-server
Registrant Contact: The NETCONF WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
5.2. 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-restconf-client
namespace: urn:ietf:params:xml:ns:yang:ietf-restconf-client
prefix: ncc
reference: RFC XXXX
name: ietf-restconf-server
namespace: urn:ietf:params:xml:ns:yang:ietf-restconf-server
prefix: ncs
reference: RFC XXXX
6. References
6.1. Normative References
[I-D.ietf-netconf-keystore]
Watsen, K., "YANG Data Model for a Centralized Keystore
Mechanism", draft-ietf-netconf-keystore-06 (work in
progress), September 2018.
[I-D.ietf-netconf-tls-client-server]
Watsen, K. and G. Wu, "YANG Groupings for TLS Clients and
TLS Servers", draft-ietf-netconf-tls-client-server-07
(work in progress), September 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
.
[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, .
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
.
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[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
.
[RFC8071] Watsen, K., "NETCONF Call Home and RESTCONF Call Home",
RFC 8071, DOI 10.17487/RFC8071, February 2017,
.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, .
6.2. Informative References
[I-D.ietf-netconf-netconf-client-server]
Watsen, K., "NETCONF Client and Server Models", draft-
ietf-netconf-netconf-client-server-07 (work in progress),
September 2018.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
.
[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,
.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
.
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Appendix A. Change Log
A.1. 00 to 01
o Renamed "keychain" to "keystore".
A.2. 01 to 02
o Filled in previously missing 'ietf-restconf-client' module.
o Updated the ietf-restconf-server module to accomodate new grouping
'ietf-tls-server-grouping'.
A.3. 02 to 03
o Refined use of tls-client-grouping to add a must statement
indicating that the TLS client must specify a client-certificate.
o Changed restconf-client??? to be a grouping (not a container).
A.4. 03 to 04
o Added RFC 8174 to Requirements Language Section.
o Replaced refine statement in ietf-restconf-client to add a
mandatory true.
o Added refine statement in ietf-restconf-server to add a must
statement.
o Now there are containers and groupings, for both the client and
server models.
o Now tree diagrams reference ietf-netmod-yang-tree-diagrams
o Updated examples to inline key and certificates (no longer a
leafref to keystore)
A.5. 04 to 05
o Now tree diagrams reference ietf-netmod-yang-tree-diagrams
o Updated examples to inline key and certificates (no longer a
leafref to keystore)
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A.6. 05 to 06
o Fixed change log missing section issue.
o Updated examples to match latest updates to the crypto-types,
trust-anchors, and keystore drafts.
o Reduced line length of the YANG modules to fit within 69 columns.
A.7. 06 to 07
o removed "idle-timeout" from "persistent" connection config.
o Added "random-selection" for reconnection-strategy's "starts-with"
enum.
o Replaced "connection-type" choice default (persistent) with
"mandatory true".
o Reduced the periodic-connection's "idle-timeout" from 5 to 2
minutes.
o Replaced reconnect-timeout with period/anchor-time combo.
A.8. 07 to 08
o Modified examples to be compatible with new crypto-types algs
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, Balazs Kovacs, David
Lamparter, Alan Luchuk, Ladislav Lhotka, Radek Krejci, Tom Petch,
Juergen Schoenwaelder, Phil Shafer, Sean Turner, and Bert Wijnen.
Author's Address
Kent Watsen
Juniper Networks
EMail: kwatsen@juniper.net
Watsen Expires April 25, 2019 [Page 39]