NETCONF Client and Server ModelsWatsen Networkskent+ietf@watsen.net
Operations
NETCONF Working GroupThis 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.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:
I-D.ietf-netconf-keystoreI-D.ietf-netconf-ssh-client-serverI-D.ietf-netconf-tls-client-serverArtwork in this document contains shorthand references to drafts in
progress. Please apply the following replacements:
XXXX --> the assigned RFC value for this draftYYYY --> the assigned RFC value for I-D.ietf-netconf-ssh-client-serverZZZZ --> the assigned RFC value for I-D.ietf-netconf-tls-client-serverAAAA --> the assigned RFC value for I-D.ietf-netconf-tcp-client-serverArtwork in this document contains placeholder values for the date of publication of this
draft. Please apply the following replacement:
2019-03-09 --> the publication date of this draftThe following Appendix section is to be removed prior to publication:
Appendix A. Change LogThis 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 NETCONF over
SSH and NETCONF over TLS
and NETCONF Call Home connections .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
when, and only when, they appear in all capitals, as shown here.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
and
respectively.All private keys and trusted certificates are held in the
keystore model defined in .YANG feature statements are used to enable implementations to advertise
which parts of the model the NETCONF client supports.The following tree diagram
provides an overview of the data model for the "ietf-netconf-client" module.
Just the container is displayed below, but there is also a reusable grouping
called "netconf-client-grouping" that the container is using.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 3.2 of .corp-fw1corp-fw1.example.comcorp-fw1.example.com15330foobarct:rsa2048base64encodedvalue==base64encodedvalue==explicitly-trusted-server-ca-certs
explicitly-trusted-server-certs
303corp-fw2.example.comcorp-fw2.example.com15330foobarct:rsa2048base64encodedvalue==base64encodedvalue==explicitly-trusted-server-ca-certs
explicitly-trusted-server-certs
303last-connectedIntranet-facing listener192.0.2.7foobarct:rsa2048base64encodedvalue==base64encodedvalue==explicitly-trusted-server-ca-certs
explicitly-trusted-server-certs
explicitly-trusted-ssh-host-keys
]]>This YANG module has normative references to ,
, , ,
,
, and
. file "ietf-netconf-client@2019-03-09.yang"
module ietf-netconf-client {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-client";
prefix "ncc";
import ietf-yang-types {
prefix yang;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-tcp-client {
prefix tcpc;
reference
"RFC AAAA: YANG Groupings for TCP Clients and TCP Servers";
}
import ietf-tcp-server {
prefix tcps;
reference
"RFC AAAA: YANG Groupings for TCP Clients and TCP Servers";
}
import ietf-ssh-client {
prefix sshc;
revision-date 2019-03-09; // stable grouping definitions
reference
"RFC YYYY: YANG Groupings for SSH Clients and SSH Servers";
}
import ietf-tls-client {
prefix tlsc;
revision-date 2019-03-09; // 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 ";
description
"This module contains a collection of YANG definitions for
configuring NETCONF clients.
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.
Copyright (c) 2019 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 "2019-03-09" {
description
"Initial version";
reference
"RFC XXXX: NETCONF Client and Server Models";
}
// Features
feature initiate {
description
"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 8071: 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 8071: NETCONF Call Home and RESTCONF Call Home";
}
// Groupings
grouping netconf-client-grouping {
description
"Top-level grouping for NETCONF client configuration.";
container initiate {
if-feature initiate;
presence "Enables client to initiate TCP connections";
description
"Configures client initiating underlying TCP connections.";
list netconf-server {
key name;
min-elements 1;
description
"List of NETCONF servers the NETCONF client is to
initiate connections to in parallel.";
leaf name {
type string;
description
"An arbitrary name for the NETCONF server.";
}
container endpoints {
description
"Container for the list of endpoints.";
list endpoint {
key name;
min-elements 1;
ordered-by user;
description
"A user-ordered list of endpoints that the NETCONF
client will attempt to connect to in the specified
sequence. Defining more than one enables
high-availability.";
leaf name {
type string;
description
"An arbitrary name for the endpoint.";
}
choice transport {
mandatory true;
description
"Selects between available transports.";
case ssh {
if-feature ssh-initiate;
container ssh {
description
"Specifies IP and SSH specific configuration
for the connection.";
uses tcpc:tcp-client-grouping {
refine "remote-port" {
default 830;
description
"The NETCONF client will attempt to connect
to the IANA-assigned well-known port value
for 'netconf-ssh' (443) if no value is
specified.";
}
}
uses sshc:ssh-client-grouping;
} // container ssh
} // case ssh
case tls {
if-feature tls-initiate;
container tls {
description
"Specifies IP and TLS specific configuration
for the connection.";
uses tcpc:tcp-client-grouping {
refine "remote-port" {
default 6513;
description
"The NETCONF client will attempt to connect
to the IANA-assigned well-known port value
for 'netconf-tls' (6513) if no value is
specified.";
}
}
uses tlsc:tls-client-grouping {
refine "tls-client-identity/auth-type" {
mandatory true;
description
"NETCONF/TLS clients MUST pass some
authentication credentials.";
}
}
} // container tls
} // case tls
} // choice transport
} // list endpoint
} // container endpoints
container connection-type {
description
"Indicates the NETCONF client's preference for how the
NETCONF 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 NETCONF
server. If the connection goes down, immediately
start trying to reconnect to it, using the
reconnection strategy.
This connection type minimizes any NETCONF server
to NETCONF client data-transfer delay, albeit at
the expense of holding resources longer.";
}
}
case periodic-connection {
container periodic {
presence
"Indicates that a periodic connection is to be
maintained.";
description
"Periodically connect to the NETCONF server. The
NETCONF server should close the connection upon
completing planned activities.
This connection type increases resource
utilization, albeit with increased delay in
NETCONF server to NETCONF 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.";
}
leaf idle-timeout {
type uint16;
units "seconds";
default 120; // two minutes
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 NETCONF client will
never drop a session because it is idle.";
}
}
}
}
}
container reconnect-strategy {
description
"The reconnection strategy directs how a NETCONF client
reconnects to a NETCONF server, after discovering its
connection to the server has dropped, even if due to a
reboot. The NETCONF 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
"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
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 NETCONF server's endpoints
the NETCONF client should start with when trying
to connect to the NETCONF server.";
}
leaf max-attempts {
type uint8 {
range "1..max";
}
default 3;
description
"Specifies the number times the NETCONF client tries
to connect to a specific endpoint before moving on
to the next endpoint in the list (round robin).";
}
}
} // netconf-server
} // 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
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;
min-elements 1;
description
"List of endpoints to listen for NETCONF connections.";
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 tcps:tcp-server-grouping {
refine "local-port" {
default 4334;
description
"The NETCONF client will listen on the IANA-
assigned well-known port for 'netconf-ch-ssh'
(4334) if no value is specified.";
}
}
uses sshc:ssh-client-grouping;
}
}
case tls {
if-feature tls-listen;
container tls {
description
"TLS-specific listening configuration for inbound
connections.";
uses tcps:tcp-server-grouping {
refine "local-port" {
default 4334;
description
"The NETCONF client will listen on the IANA-
assigned well-known port for 'netconf-ch-ssh'
(4334) if no value is specified.";
}
}
uses tlsc:tls-client-grouping {
refine "tls-client-identity/auth-type" {
mandatory true;
description
"NETCONF/TLS clients MUST pass some
authentication credentials.";
}
}
}
}
} // transport
} // endpoint
} // listen
} // netconf-client
// Protocol accessible node, for servers that 'implement'
// this module.
container netconf-client {
uses netconf-client-grouping;
description
"Top-level container for NETCONF client configuration.";
}
}
]]>The NETCONF server model presented in this section supports servers
both listening for connections as well as initiating call-home
connections.This model supports both the SSH and TLS transport
protocols, using the SSH server and TLS server groupings defined in
and
respectively.All private keys and trusted certificates are held in the
keystore model defined in .YANG feature statements are used to enable implementations to advertise
which parts of the model the NETCONF server supports.The following tree diagram
provides an overview of the data model for the "ietf-netconf-server" module.
Just the container is displayed below, but there is also a reusable grouping
called "netconf-server-grouping" that the container is using.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 3.2 of .netconf/ssh192.0.2.7deployment-specific-certificatect:rsa2048base64encodedvalue==base64encodedvalue==explicitly-trusted-client-ca-certs
explicitly-trusted-client-certs
netconf/tls192.0.2.7ct:rsa2048base64encodedvalue==base64encodedvalue==base64encodedvalue==explicitly-trusted-client-ca-certs
explicitly-trusted-client-certs
111:0A:05:11:00x509c2n:san-any2B3:4F:A1:8C:54x509c2n:specifiedscooby-dooconfig-mgreast-data-centereast.config-mgr.example.com
deployment-specific-certificatect:rsa2048base64encodedvalue==base64encodedvalue==explicitly-trusted-client-ca-certs
explicitly-trusted-client-certs
west-data-centerwest.config-mgr.example.com
deployment-specific-certificatect:rsa2048base64encodedvalue==base64encodedvalue==explicitly-trusted-client-ca-certs
explicitly-trusted-client-certs
30060last-connected3data-collectoreast-data-centereast.analytics.example.com
ct:rsa2048base64encodedvalue==base64encodedvalue==base64encodedvalue==explicitly-trusted-client-ca-certs
explicitly-trusted-client-certs
111:0A:05:11:00x509c2n:san-any2B3:4F:A1:8C:54x509c2n:specifiedscooby-doo15330303west-data-centerwest.analytics.example.com
ct:rsa2048base64encodedvalue==base64encodedvalue==base64encodedvalue==explicitly-trusted-client-ca-certs
explicitly-trusted-client-certs
111:0A:05:11:00x509c2n:san-any2B3:4F:A1:8C:54x509c2n:specifiedscooby-doo15330303first-listed3
]]>This YANG module has normative references to ,
, , ,
, ,
, and
.This YANG module imports YANG types from ,
and YANG groupings from ,
and . file "ietf-netconf-server@2019-03-09.yang"
module ietf-netconf-server {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-server";
prefix "ncs";
import ietf-yang-types {
prefix yang;
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-tcp-client {
prefix tcpc;
reference
"RFC AAAA: YANG Groupings for TCP Clients and TCP Servers";
}
import ietf-tcp-server {
prefix tcps;
reference
"RFC AAAA: YANG Groupings for TCP Clients and TCP Servers";
}
import ietf-ssh-server {
prefix sshs;
revision-date 2019-03-09; // stable grouping definitions
reference
"RFC YYYY: YANG Groupings for SSH Clients and SSH Servers";
}
import ietf-tls-server {
prefix tlss;
revision-date 2019-03-09; // 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 NETCONF servers.
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.
Copyright (c) 2019 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 "2019-03-09" {
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)";
}
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 8071: 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 8071: 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 8071: NETCONF Call Home and RESTCONF Call Home";
}
// Groupings
grouping netconf-server-grouping {
description
"Top-level grouping for NETCONF server configuration.";
container listen {
if-feature listen;
presence "Enables server to listen for TCP connections";
description "Configures listen behavior";
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;
min-elements 1;
description
"List of endpoints to listen for NETCONF connections.";
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 tcps:tcp-server-grouping {
refine "local-port" {
default 830;
description
"The NETCONF server will listen on the IANA-
assigned well-known port value for 'netconf-ssh'
(830) if no value is specified.";
}
}
uses sshs:ssh-server-grouping;
}
}
case tls {
if-feature tls-listen;
container tls {
description
"TLS-specific listening configuration for inbound
connections.";
uses tcps:tcp-server-grouping {
refine "local-port" {
default 6513;
description
"The NETCONF server will listen on the IANA-
assigned well-known port value for 'netconf-tls'
(6513) if no value is specified.";
}
}
uses tlss:tls-server-grouping {
refine "tls-client-auth" {
must 'pinned-ca-certs or pinned-client-certs';
description
"NETCONF/TLS servers MUST validate client
certiticates.";
}
augment "tls-client-auth" {
description
"Augments in the cert-to-name structure.";
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";
}
}
}
}
}
}
}
}
container call-home {
if-feature call-home;
presence "Enables server to initiate TCP connections";
description "Configures call-home behavior";
list netconf-client {
key name;
min-elements 1;
description
"List of NETCONF clients the NETCONF server is to
initiate call-home connections to in parallel.";
leaf name {
type string;
description
"An arbitrary name for the remote NETCONF client.";
}
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
NETCONF server 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.";
case ssh {
if-feature ssh-call-home;
container ssh {
description
"Specifies SSH-specific call-home transport
configuration.";
uses tcpc:tcp-client-grouping {
refine "remote-port" {
default 4334;
description
"The NETCONF server will attempt to connect
to the IANA-assigned well-known port for
'netconf-ch-tls' (4334) if no value is
specified.";
}
}
uses sshs:ssh-server-grouping;
}
}
case tls {
if-feature tls-call-home;
container tls {
description
"Specifies TLS-specific call-home transport
configuration.";
uses tcpc:tcp-client-grouping {
refine "remote-port" {
default 4335;
description
"The NETCONF server will attempt to connect
to the IANA-assigned well-known port for
'netconf-ch-tls' (4335) if no value is
specified.";
}
}
uses tlss:tls-server-grouping {
refine "tls-client-auth" {
must 'pinned-ca-certs or pinned-client-certs';
description
"NETCONF/TLS servers MUST validate client
certiticates.";
}
augment "tls-client-auth" {
description
"Augments in the cert-to-name structure.";
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";
}
}
}
}
} // tls
} // choice
} // endpoint
} // endpoints
container connection-type {
description
"Indicates the NETCONF server's preference for how the
NETCONF 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 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.";
} // container persistent
} // case persistent-connection
case periodic-connection {
container periodic {
presence
"Indicates that a periodic connection is to be
maintained.";
description
"Periodically connect to the NETCONF client. The
NETCONF client should close the underlying TLS
connection upon completing planned activities.
This connection type increases resource
utilization, albeit with increased delay in
NETCONF client to NETCONF 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.";
}
leaf idle-timeout {
type uint16;
units "seconds";
default 120; // two minutes
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.";
}
} // container periodic
} // case periodic-connection
} // choice connection-type
} // container connection-type
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.";
}
enum random-selection {
description
"Indicates that reconnections should start with
a random endpoint.";
}
}
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 next endpoint in the list (round robin).";
}
} // container reconnect-strategy
} // list netconf-client
} // container call-home
} // grouping netconf-server-grouping
// Protocol accessible node, for servers that *implement*
// this module.
container netconf-server {
uses netconf-server-grouping;
description
"Top-level container for NETCONF server configuration.";
}
}
]]>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:The YANG module should support all current NETCONF
transports, namely NETCONF over SSH ,
NETCONF over TLS , 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.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.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.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.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
(), 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.The following objectives only pertain to call home connections.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
server to initiate call home connections, it should be able to do
so to more than one client.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.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.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.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.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
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.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).The YANG module defined in this document uses groupings defined in
and
. Please see the Security
Considerations section in those documents for concerns related those groupings.The YANG module defined in this document is designed to be accessed via YANG
based management protocols, such as NETCONF and
RESTCONF . Both of these protocols have mandatory-to-implement
secure transport layers (e.g., SSH, TLS) with mutual authentication.The NETCONF access control model (NACM) 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:
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:
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:
This document registers two URIs in the "ns" subregistry of the IETF XML
Registry . Following the format in
, the following registrations are
requested:This document registers two YANG modules in the
YANG Module Names registry .
Following the format in , the
the following registrations are requested:Renamed "keychain" to "keystore".Added to ietf-netconf-client ability to connected to a cluster
of endpoints, including a reconnection-strategy.Added to ietf-netconf-client the ability to configure connection-type
and also keep-alive strategy.Updated both modules to accommodate new groupings in the ssh/tls
drafts.Refined use of tls-client-grouping to add a must statement
indicating that the TLS client must specify a client-certificate.Changed 'netconf-client' to be a grouping (not a container).Added RFC 8174 to Requirements Language Section.Replaced refine statement in ietf-netconf-client
to add a mandatory true.Added refine statement in ietf-netconf-server
to add a must statement.Now there are containers and groupings, for both the
client and server models.Now tree diagrams reference ietf-netmod-yang-tree-diagramsUpdated examples to inline key and certificates (no longer
a leafref to keystore)Fixed change log missing section issue.Updated examples to match latest updates to the crypto-types,
trust-anchors, and keystore drafts.Reduced line length of the YANG modules to fit within 69 columns.Removed "idle-timeout" from "persistent" connection config.Added "random-selection" for reconnection-strategy's "starts-with" enum.Replaced "connection-type" choice default (persistent) with "mandatory true".Reduced the periodic-connection's "idle-timeout" from 5 to 2 minutes.Replaced reconnect-timeout with period/anchor-time combo.Modified examples to be compatible with new crypto-types algsCorrected use of "mandatory true" for "address" leafs.Updated examples to reflect update to groupings defined in the keystore draft.Updated to use groupings defined in new TCP and HTTP drafts.Updated copyright date, boilerplate template, affiliation, and folding algorithm.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, Ramkumar Dhanapal,
Mehmet Ersue, Balázs Kovács, David Lamparter, Alan Luchuk, Ladislav Lhotka,
Radek Krejci, Tom Petch, Juergen Schoenwaelder, Phil Shafer, Sean Turner, and
Bert Wijnen.