NETCONF Working Group K. Watsen
Internet-Draft Watsen Networks
Intended status: Standards Track G. Wu
Expires: November 21, 2020 Cisco Systems
May 20, 2020
YANG Groupings for TLS Clients and TLS Servers
draft-ietf-netconf-tls-client-server-19
Abstract
This document defines three YANG modules: the first defines groupings
for a generic TLS client, the second defines groupings for a generic
TLS server, and the third defines common identities and groupings
used by both the client and the server. It is intended that these
groupings will be used by applications using the TLS protocol.
Editorial Note (To be removed by RFC Editor)
This draft contains 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.
Artwork in this document contains shorthand references to drafts in
progress. Please apply the following replacements:
o "AAAA" --> the assigned RFC value for draft-ietf-netconf-crypto-
types
o "BBBB" --> the assigned RFC value for draft-ietf-netconf-trust-
anchors
o "CCCC" --> the assigned RFC value for draft-ietf-netconf-keystore
o "DDDD" --> the assigned RFC value for draft-ietf-netconf-tcp-
client-server
o "FFFF" --> the assigned RFC value for this draft
Artwork in this document contains placeholder values for the date of
publication of this draft. Please apply the following replacement:
o "2020-05-20" --> the publication date of this draft
The following Appendix section is to be removed prior to publication:
Watsen & Wu Expires November 21, 2020 [Page 1]
Internet-Draft Groupings for TLS Clients and Servers May 2020
o Appendix A. Change Log
Note to Reviewers (To be removed by RFC Editor)
This document presents a YANG module or modules that is/are part of a
collection of drafts that work together to produce the ultimate goal
of the NETCONF WG: to define configuration modules for NETCONF client
and servers, and RESTCONF client and servers.
The relationship between the various drafts in the collection is
presented in the below diagram.
crypto-types
^ ^
/ \
/ \
trust-anchors keystore
^ ^ ^ ^
| +---------+ | |
| | | |
| +------------+ |
tcp-client-server | / | |
^ ^ ssh-client-server | |
| | ^ tls-client-server
| | | ^ ^ http-client-server
| | | | | ^
| | | +-----+ +---------+ |
| | | | | |
| +-----------|--------|--------------+ | |
| | | | | |
+-----------+ | | | | |
| | | | | |
| | | | | |
netconf-client-server restconf-client-server
Full draft names and link to drafts:
o draft-ietf-netconf-crypto-types (html [1])
o draft-ietf-netconf-trust-anchors (html [2])
o draft-ietf-netconf-keystore (html [3])
o draft-ietf-netconf-tcp-client-server (html [4])
o draft-ietf-netconf-ssh-client-server (html [5])
Watsen & Wu Expires November 21, 2020 [Page 2]
Internet-Draft Groupings for TLS Clients and Servers May 2020
o draft-ietf-netconf-tls-client-server (html [6])
o draft-ietf-netconf-http-client-server (html [7])
o draft-ietf-netconf-netconf-client-server (html [8])
o draft-ietf-netconf-restconf-client-server (html [9])
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 https://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 November 21, 2020.
Copyright Notice
Copyright (c) 2020 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 . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. The TLS Client Model . . . . . . . . . . . . . . . . . . . . 5
3.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 6
3.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 10
Watsen & Wu Expires November 21, 2020 [Page 3]
Internet-Draft Groupings for TLS Clients and Servers May 2020
4. The TLS Server Model . . . . . . . . . . . . . . . . . . . . 17
4.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 17
4.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 18
4.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 22
5. The TLS Common Model . . . . . . . . . . . . . . . . . . . . 29
5.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 30
5.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 31
5.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 31
6. Security Considerations . . . . . . . . . . . . . . . . . . . 40
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 41
7.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 41
7.2. The YANG Module Names Registry . . . . . . . . . . . . . 42
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 42
8.1. Normative References . . . . . . . . . . . . . . . . . . 42
8.2. Informative References . . . . . . . . . . . . . . . . . 44
8.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 46
A.1. 00 to 01 . . . . . . . . . . . . . . . . . . . . . . . . 46
A.2. 01 to 02 . . . . . . . . . . . . . . . . . . . . . . . . 46
A.3. 02 to 03 . . . . . . . . . . . . . . . . . . . . . . . . 46
A.4. 03 to 04 . . . . . . . . . . . . . . . . . . . . . . . . 46
A.5. 04 to 05 . . . . . . . . . . . . . . . . . . . . . . . . 47
A.6. 05 to 06 . . . . . . . . . . . . . . . . . . . . . . . . 47
A.7. 06 to 07 . . . . . . . . . . . . . . . . . . . . . . . . 47
A.8. 07 to 08 . . . . . . . . . . . . . . . . . . . . . . . . 47
A.9. 08 to 09 . . . . . . . . . . . . . . . . . . . . . . . . 47
A.10. 09 to 10 . . . . . . . . . . . . . . . . . . . . . . . . 47
A.11. 10 to 11 . . . . . . . . . . . . . . . . . . . . . . . . 48
A.12. 11 to 12 . . . . . . . . . . . . . . . . . . . . . . . . 48
A.13. 12 to 13 . . . . . . . . . . . . . . . . . . . . . . . . 48
A.14. 12 to 13 . . . . . . . . . . . . . . . . . . . . . . . . 48
A.15. 13 to 14 . . . . . . . . . . . . . . . . . . . . . . . . 49
A.16. 14 to 15 . . . . . . . . . . . . . . . . . . . . . . . . 49
A.17. 15 to 16 . . . . . . . . . . . . . . . . . . . . . . . . 49
A.18. 16 to 17 . . . . . . . . . . . . . . . . . . . . . . . . 49
A.19. 17 to 18 . . . . . . . . . . . . . . . . . . . . . . . . 49
A.20. 18 to 19 . . . . . . . . . . . . . . . . . . . . . . . . 50
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 50
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 50
1. Introduction
This document defines three YANG 1.1 [RFC7950] modules: the first
defines a grouping for a generic TLS client, the second defines a
grouping for a generic TLS server, and the third defines identities
and groupings common to both the client and the server (TLS is
defined in [RFC5246]). It is intended that these groupings will be
used by applications using the TLS protocol. For instance, these
Watsen & Wu Expires November 21, 2020 [Page 4]
Internet-Draft Groupings for TLS Clients and Servers May 2020
groupings could be used to help define the data model for an HTTPS
[RFC2818] server or a NETCONF over TLS [RFC7589] based server.
The client and server YANG modules in this document each define one
grouping, which is focused on just TLS-specific configuration, and
specifically avoids any transport-level configuration, such as what
ports to listen-on or connect-to. This affords applications the
opportunity to define their own strategy for how the underlying TCP
connection is established. For instance, applications supporting
NETCONF Call Home [RFC8071] could use the "ssh-server-grouping"
grouping for the TLS parts it provides, while adding data nodes for
the TCP-level call-home configuration.
2. 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.
3. The TLS Client Model
3.1. Tree Diagram
This section provides a tree diagram [RFC8340] for the "ietf-tls-
client" module that does not have groupings expanded.
Watsen & Wu Expires November 21, 2020 [Page 5]
Internet-Draft Groupings for TLS Clients and Servers May 2020
========== NOTE: '\' line wrapping per BCP XXX (RFC XXXX) ===========
module: ietf-tls-client
grouping tls-client-grouping
+-- client-identity
| +-- (auth-type)?
| +--:(certificate) {x509-certificate-auth}?
| | +-- certificate
| | +---u ks:local-or-keystore-end-entity-cert-with-key-\
grouping
| +--:(raw-public-key) {raw-public-key-auth}?
| | +-- raw-private-key
| | +---u ks:local-or-keystore-asymmetric-key-grouping
| +--:(psk) {psk-auth}?
| +-- psk
| +---u ks:local-or-keystore-symmetric-key-grouping
+-- server-authentication
| +-- ca-certs! {x509-certificate-auth}?
| | +---u ts:local-or-truststore-certs-grouping
| +-- ee-certs! {x509-certificate-auth}?
| | +---u ts:local-or-truststore-certs-grouping
| +-- raw-public-keys! {raw-public-key-auth}?
| | +---u ts:local-or-truststore-public-keys-grouping
| +-- psks! {psk-auth}?
+-- hello-params {tls-client-hello-params-config}?
| +---u tlscmn:hello-params-grouping
+-- keepalives {tls-client-keepalives}?
+-- peer-allowed-to-send? empty
+-- test-peer-aliveness!
+-- max-wait? uint16
+-- max-attempts? uint8
3.2. Example Usage
This section presents two examples showing the "tls-client-grouping"
grouping populated with some data. These examples are effectively
the same except the first configures the client identity using a
local key while the second uses a key configured in a keystore. Both
examples are consistent with the examples presented in Section 2 of
[I-D.ietf-netconf-trust-anchors] and Section 3.2 of
[I-D.ietf-netconf-keystore].
The following example configures the client identity using a local
key:
========== NOTE: '\' line wrapping per BCP XXX (RFC XXXX) ===========
Watsen & Wu Expires November 21, 2020 [Page 6]
Internet-Draft Groupings for TLS Clients and Servers May 2020
ct:subject-public-key-info-format
base64encodedvalue==
ct:rsa-private-key-format
base64encodedvalue==
base64encodedvalue==
base64encodedvalue==
base64encodedvalue==
base64encodedvalue==
Watsen & Wu Expires November 21, 2020 [Page 7]
Internet-Draft Groupings for TLS Clients and Servers May 2020
base64encodedvalue==
base64encodedvalue==
base64encodedvalue==
corp-fw1
ct:subject-public-key-info-format
base64encodedvalue==
corp-fw1
ct:subject-public-key-info-format
base64encodedvalue==
30
3
The following example configures the client identity using a key from
the keystore:
Watsen & Wu Expires November 21, 2020 [Page 8]
Internet-Draft Groupings for TLS Clients and Servers May 2020
========== NOTE: '\' line wrapping per BCP XXX (RFC XXXX) ===========
rsa-asymmetric-key
ex-rsa-cert
trusted-server-ca-certs
trusted-server-ee-certs
Raw Public Keys for TLS Servers
30
3
Watsen & Wu Expires November 21, 2020 [Page 9]
Internet-Draft Groupings for TLS Clients and Servers May 2020
3.3. YANG Module
This YANG module has normative references to
[I-D.ietf-netconf-trust-anchors] and [I-D.ietf-netconf-keystore].
file "ietf-tls-client@2020-05-20.yang"
module ietf-tls-client {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-tls-client";
prefix tlsc;
import ietf-netconf-acm {
prefix nacm;
reference
"RFC 8341: Network Configuration Access Control Model";
}
import ietf-crypto-types {
prefix ct;
reference
"RFC AAAA: Common YANG Data Types for Cryptography";
}
import ietf-truststore {
prefix ts;
reference
"RFC BBBB: A YANG Data Model for a Truststore";
}
import ietf-keystore {
prefix ks;
reference
"RFC CCCC: A YANG Data Model for a Keystore";
}
import ietf-tls-common {
prefix tlscmn;
revision-date 2020-05-20; // stable grouping definitions
reference
"RFC FFFF: YANG Groupings for TLS Clients and TLS Servers";
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web:
Watsen & Wu Expires November 21, 2020 [Page 10]
Internet-Draft Groupings for TLS Clients and Servers May 2020
WG List:
Author: Kent Watsen
Author: Gary Wu ";
description
"This module defines reusable groupings for TLS clients that
can be used as a basis for specific TLS client instances.
Copyright (c) 2020 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
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC FFFF
(https://www.rfc-editor.org/info/rfcFFFF); see the RFC
itself for full legal notices.
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 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here.";
revision 2020-05-20 {
description
"Initial version";
reference
"RFC FFFF: YANG Groupings for TLS Clients and TLS Servers";
}
// Features
feature tls-client-hello-params-config {
description
"TLS hello message parameters are configurable on a TLS
client.";
}
feature tls-client-keepalives {
description
"Per socket TLS keepalive parameters are configurable for
TLS clients on the server implementing this feature.";
Watsen & Wu Expires November 21, 2020 [Page 11]
Internet-Draft Groupings for TLS Clients and Servers May 2020
}
feature x509-certificate-auth {
description
"Indicates that the client supports authenticating servers
using X.509 certificates.";
}
feature raw-public-key-auth {
description
"Indicates that the client supports authenticating servers
using ray public keys.";
}
feature psk-auth {
description
"Indicates that the client supports authenticating servers
using PSKs (pre-shared or pairwise-symmetric keys).";
}
// Groupings
grouping tls-client-grouping {
description
"A reusable grouping for configuring a TLS client without
any consideration for how an underlying TCP session is
established.
Note that this grouping uses fairly typical descendent
node names such that a stack of 'uses' statements will
have name conflicts. It is intended that the consuming
data model will resolve the issue (e.g., by wrapping
the 'uses' statement in a container called
'tls-client-parameters'). This model purposely does
not do this itself so as to provide maximum flexibility
to consuming models.";
container client-identity {
nacm:default-deny-write;
description
"Identity credentials the TLS client MAY present when
establishing a connection to a TLS server. If not
configured, then client authentication is presumed to
occur a protocol layer above TLS. When configured,
and requested by the TLS server when establishing a
TLS session, these credentials are passed in the
Watsen & Wu Expires November 21, 2020 [Page 12]
Internet-Draft Groupings for TLS Clients and Servers May 2020
Certificate message defined in Section 7.4.2 of
RFC 5246.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2
RFC CCCC: A YANG Data Model for a Keystore";
choice auth-type {
description
"A choice amongst available authentication types.";
case certificate {
if-feature x509-certificate-auth;
container certificate {
description
"Specifies the client identity using a certificate.";
uses
ks:local-or-keystore-end-entity-cert-with-key-grouping{
refine "local-or-keystore/local/local-definition" {
must 'public-key-format'
+ ' = "ct:subject-public-key-info-format"';
}
refine "local-or-keystore/keystore/keystore-reference"
+ "/asymmetric-key" {
must 'deref(.)/../ks:public-key-format'
+ ' = "ct:subject-public-key-info-format"';
}
}
}
}
case raw-public-key {
if-feature raw-public-key-auth;
container raw-private-key {
description
"Specifies the client identity using a raw
private key.";
uses ks:local-or-keystore-asymmetric-key-grouping {
refine "local-or-keystore/local/local-definition" {
must 'public-key-format'
+ ' = "ct:subject-public-key-info-format"';
}
refine "local-or-keystore/keystore"
+ "/keystore-reference" {
must 'deref(.)/../ks:public-key-format'
+ ' = "ct:subject-public-key-info-format"';
}
}
}
}
case psk {
Watsen & Wu Expires November 21, 2020 [Page 13]
Internet-Draft Groupings for TLS Clients and Servers May 2020
if-feature psk-auth;
container psk {
description
"Specifies the client identity using a PSK (pre-shared
or pairwise-symmetric key). Note that, when the PSK is
configured as a Keystore reference, the key's 'name'
node MAY be used as the PSK's ID when used by the TLS
protocol.";
uses ks:local-or-keystore-symmetric-key-grouping {
augment "local-or-keystore/local/local-definition" {
if-feature "ks:local-definitions-supported";
description
"Adds an 'id' value when the PSK is used by TLS.";
leaf id {
type string; // FIXME: is this the right type?
description
"The key id used in the TLS protocol for PSKs.";
}
}
}
}
}
}
} // container client-identity
container server-authentication {
nacm:default-deny-write;
must 'ca-certs or server-certs';
description
"Specifies how the TLS client can authenticate TLS servers.
Any combination of credentials is additive and unordered.
Note that no configuration is required for PSK (pre-shared
or pairwise-symmetric key) based authentication as the key
is necessarily the same as configured in the '../client-
identity' node.";
container ca-certs {
if-feature "x509-certificate-auth";
presence
"Indicates that the TLS client can authenticate TLS servers
using configured certificate authority certificates.";
description
"A set of certificate authority (CA) certificates used by
the TLS client to authenticate TLS server certificates.
A server certificate is authenticated if it has a valid
chain of trust to a configured CA certificate.";
reference
"RFC BBBB: A YANG Data Model for a Truststore";
Watsen & Wu Expires November 21, 2020 [Page 14]
Internet-Draft Groupings for TLS Clients and Servers May 2020
uses ts:local-or-truststore-certs-grouping;
}
container ee-certs { // FIXME: plural too much?
if-feature "x509-certificate-auth";
presence
"Indicates that the TLS client can authenticate TLS
servers using configured server certificates.";
description
"A set of server certificates (i.e., end entity
certificates) used by the TLS client to authenticate
certificates presented by TLS servers. A server
certificate is authenticated if it is an exact
match to a configured server certificate.";
reference
"RFC BBBB: A YANG Data Model for a Truststore";
uses ts:local-or-truststore-certs-grouping;
}
container raw-public-keys {
if-feature "raw-public-key-auth";
presence
"Indicates that the TLS client can authenticate TLS
servers using configured server certificates.";
description
"A set of raw public keys used by the TLS client to
authenticate raw public keys presented by the TLS
server. A raw public key is authenticated if it
is an exact match to a configured raw public key.";
reference
"RFC BBBB: A YANG Data Model for a Truststore";
uses ts:local-or-truststore-public-keys-grouping {
refine "local-or-truststore/local/local-definition"
+ "/public-key" {
must 'public-key-format'
+ ' = "ct:subject-public-key-info-format"';
}
refine "local-or-truststore/truststore"
+ "/truststore-reference" {
must 'deref(.)/../*/ts:public-key-format'
+ ' = "ct:subject-public-key-info-format"';
}
}
}
container psks {
if-feature "psk-auth";
presence
"Indicates that the TLS client can authenticate TLS servers
using a configure PSK (pre-shared or pairwise-symmetric
key).";
Watsen & Wu Expires November 21, 2020 [Page 15]
Internet-Draft Groupings for TLS Clients and Servers May 2020
description
"No configuration is required since the PSK value is the
same as PSK value configured in the 'client-identity'
node.";
}
} // container server-authentication
container hello-params {
nacm:default-deny-write;
if-feature "tls-client-hello-params-config";
uses tlscmn:hello-params-grouping;
description
"Configurable parameters for the TLS hello message.";
} // container hello-params
container keepalives {
nacm:default-deny-write;
if-feature "tls-client-keepalives";
description
"Configures the keepalive policy for the TLS client.";
leaf peer-allowed-to-send {
type empty;
description
"Indicates that the remote TLS server is allowed to send
HeartbeatRequest messages, as defined by RFC 6520
to this TLS client.";
reference
"RFC 6520: Transport Layer Security (TLS) and Datagram
Transport Layer Security (DTLS) Heartbeat Extension";
}
container test-peer-aliveness {
presence
"Indicates that the TLS client proactively tests the
aliveness of the remote TLS server.";
description
"Configures the keep-alive policy to proactively test
the aliveness of the TLS server. An unresponsive
TLS server is dropped after approximately max-wait
* max-attempts seconds. The TLS client MUST send
HeartbeatRequest messages, as defined by RFC 6520.";
reference
"RFC 6520: Transport Layer Security (TLS) and Datagram
Transport Layer Security (DTLS) Heartbeat Extension";
leaf max-wait {
type uint16 {
range "1..max";
}
units "seconds";
Watsen & Wu Expires November 21, 2020 [Page 16]
Internet-Draft Groupings for TLS Clients and Servers May 2020
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.";
}
}
}
} // grouping tls-client-grouping
} // module ietf-tls-client
4. The TLS Server Model
4.1. Tree Diagram
This section provides a tree diagram [RFC8340] for the "ietf-tls-
server" module that does not have groupings expanded.
Watsen & Wu Expires November 21, 2020 [Page 17]
Internet-Draft Groupings for TLS Clients and Servers May 2020
========== NOTE: '\' line wrapping per BCP XXX (RFC XXXX) ===========
module: ietf-tls-server
grouping tls-server-grouping
+-- server-identity
| +-- (auth-type)
| +--:(certificate) {x509-certificate-auth}?
| | +-- certificate
| | +---u ks:local-or-keystore-end-entity-cert-with-key-\
grouping
| +--:(raw-private-key) {raw-public-key-auth}?
| | +-- raw-private-key
| | +---u ks:local-or-keystore-asymmetric-key-grouping
| +--:(psk) {psk-auth}?
| +-- psk
| +---u ks:local-or-keystore-symmetric-key-grouping
+-- client-authentication! {client-auth-config-supported}?
| +-- ca-certs! {x509-certificate-auth}?
| | +---u ts:local-or-truststore-certs-grouping
| +-- ee-certs! {x509-certificate-auth}?
| | +---u ts:local-or-truststore-certs-grouping
| +-- raw-public-keys! {raw-public-key-auth}?
| | +---u ts:local-or-truststore-public-keys-grouping
| +-- psks! {psk-auth}?
+-- hello-params {tls-server-hello-params-config}?
| +---u tlscmn:hello-params-grouping
+-- keepalives {tls-server-keepalives}?
+-- peer-allowed-to-send? empty
+-- test-peer-aliveness!
+-- max-wait? uint16
+-- max-attempts? uint8
4.2. Example Usage
This section presents two examples showing the "tls-server-grouping"
grouping populated with some data. These examples are effectively
the same except the first configures the server identity using a
local key while the second uses a key configured in a keystore. Both
examples are consistent with the examples presented in Section 2 of
[I-D.ietf-netconf-trust-anchors] and Section 3.2 of
[I-D.ietf-netconf-keystore].
The following example configures the server identity using a local
key:
========== NOTE: '\' line wrapping per BCP XXX (RFC XXXX) ===========
Watsen & Wu Expires November 21, 2020 [Page 18]
Internet-Draft Groupings for TLS Clients and Servers May 2020
ct:subject-public-key-info-format
base64encodedvalue==
ct:rsa-private-key-format
base64encodedvalue==
base64encodedvalue==
base64encodedvalue==
base64encodedvalue==
base64encodedvalue==
Watsen & Wu Expires November 21, 2020 [Page 19]
Internet-Draft Groupings for TLS Clients and Servers May 2020
base64encodedvalue==
base64encodedvalue==
base64encodedvalue==
User A
ct:subject-public-key-info-format
base64encodedvalue==
User B
ct:subject-public-key-info-format
base64encodedvalue==
The following example configures the server identity using a key from
the keystore:
Watsen & Wu Expires November 21, 2020 [Page 20]
Internet-Draft Groupings for TLS Clients and Servers May 2020
========== NOTE: '\' line wrapping per BCP XXX (RFC XXXX) ===========
rsa-asymmetric-key
ex-rsa-cert
trusted-client-ca-certs
trusted-client-ee-certs
Raw Public Keys for TLS Clients
Watsen & Wu Expires November 21, 2020 [Page 21]
Internet-Draft Groupings for TLS Clients and Servers May 2020
4.3. YANG Module
This YANG module has a normative references to [RFC5246],
[I-D.ietf-netconf-trust-anchors] and [I-D.ietf-netconf-keystore].
file "ietf-tls-server@2020-05-20.yang"
module ietf-tls-server {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-tls-server";
prefix tlss;
import ietf-netconf-acm {
prefix nacm;
reference
"RFC 8341: Network Configuration Access Control Model";
}
import ietf-crypto-types {
prefix ct;
reference
"RFC AAAA: Common YANG Data Types for Cryptography";
}
import ietf-truststore {
prefix ts;
reference
"RFC BBBB: A YANG Data Model for a Truststore";
}
import ietf-keystore {
prefix ks;
reference
"RFC CCCC: A YANG Data Model for a Keystore";
}
import ietf-tls-common {
prefix tlscmn;
revision-date 2020-05-20; // stable grouping definitions
reference
"RFC FFFF: YANG Groupings for TLS Clients and TLS Servers";
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web:
Watsen & Wu Expires November 21, 2020 [Page 22]
Internet-Draft Groupings for TLS Clients and Servers May 2020
WG List:
Author: Kent Watsen
Author: Gary Wu ";
description
"This module defines reusable groupings for TLS servers that
can be used as a basis for specific TLS server instances.
Copyright (c) 2020 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
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC FFFF
(https://www.rfc-editor.org/info/rfcFFFF); see the RFC
itself for full legal notices.
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 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here.";
revision 2020-05-20 {
description
"Initial version";
reference
"RFC FFFF: YANG Groupings for TLS Clients and TLS Servers";
}
// Features
feature tls-server-hello-params-config {
description
"TLS hello message parameters are configurable on a TLS
server.";
}
feature tls-server-keepalives {
description
"Per socket TLS keepalive parameters are configurable for
TLS servers on the server implementing this feature.";
Watsen & Wu Expires November 21, 2020 [Page 23]
Internet-Draft Groupings for TLS Clients and Servers May 2020
}
feature client-auth-config-supported {
description
"Indicates that the configuration for how to authenticate
clients can be configured herein, as opposed to in an
application specific location. That is, to support the
consuming data models that prefer to place client
authentication with client definitions, rather then
in a data model principally concerned with configuring
the transport.";
}
feature x509-certificate-auth {
description
"Indicates that the server supports authenticating clients
using X.509 certificates.";
}
feature raw-public-key-auth {
description
"Indicates that the server supports authenticating clients
using ray public keys.";
}
feature psk-auth {
description
"Indicates that the server supports authenticating clients
using PSKs (pre-shared or pairwise-symmetric keys).";
}
// Groupings
grouping tls-server-grouping {
description
"A reusable grouping for configuring a TLS server without
any consideration for how underlying TCP sessions are
established.
Note that this grouping uses fairly typical descendent
node names such that a stack of 'uses' statements will
have name conflicts. It is intended that the consuming
data model will resolve the issue (e.g., by wrapping
the 'uses' statement in a container called
'tls-server-parameters'). This model purposely does
not do this itself so as to provide maximum flexibility
Watsen & Wu Expires November 21, 2020 [Page 24]
Internet-Draft Groupings for TLS Clients and Servers May 2020
to consuming models.";
container server-identity {
nacm:default-deny-write;
description
"A locally-defined or referenced end-entity certificate,
including any configured intermediate certificates, the
TLS server will present when establishing a TLS connection
in its Certificate message, as defined in Section 7.4.2
in RFC 5246.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2
RFC CCCC: A YANG Data Model for a Keystore";
choice auth-type {
mandatory true;
description
"A choice amongst authentication types.";
case certificate {
if-feature x509-certificate-auth;
container certificate {
description
"Specifies the server identity using a certificate.";
uses
ks:local-or-keystore-end-entity-cert-with-key-grouping{
refine "local-or-keystore/local/local-definition" {
must 'public-key-format'
+ ' = "ct:subject-public-key-info-format"';
}
refine "local-or-keystore/keystore/keystore-reference"
+ "/asymmetric-key" {
must 'deref(.)/../ks:public-key-format'
+ ' = "ct:subject-public-key-info-format"';
}
}
}
}
case raw-private-key {
if-feature raw-public-key-auth;
container raw-private-key {
description
"Specifies the server identity using a raw
private key.";
uses ks:local-or-keystore-asymmetric-key-grouping {
refine "local-or-keystore/local/local-definition" {
must 'public-key-format'
+ ' = "ct:subject-public-key-info-format"';
Watsen & Wu Expires November 21, 2020 [Page 25]
Internet-Draft Groupings for TLS Clients and Servers May 2020
}
refine "local-or-keystore/keystore/keystore-reference"{
must 'deref(.)/../ks:public-key-format'
+ ' = "ct:subject-public-key-info-format"';
}
}
}
}
case psk {
if-feature psk-auth;
container psk {
description
"Specifies the server identity using a PSK (pre-shared
or pairwise-symmetric key). Note that, when the PSK is
configured as a Keystore reference, the key's 'name'
node MAY be used as the PSK's ID when used by the TLS
protocol.";
uses ks:local-or-keystore-symmetric-key-grouping {
augment "local-or-keystore/local/local-definition" {
if-feature "ks:local-definitions-supported";
description
"An 'id' value for when the PSK is used by TLS.";
leaf id {
type string; // FIXME: is this the right type?
description
"The key id used in the TLS protocol for PSKs.";
}
}
}
}
}
}
} // container server-identity
container client-authentication {
if-feature "client-auth-config-supported";
nacm:default-deny-write;
presence
"Indicates that client authentication is supported (i.e.,
that the server will request clients send certificates).
If not configured, the TLS server SHOULD NOT request the
TLS clients provide authentication credentials.";
description
"Specifies how the TLS server can authenticate TLS clients.
Any combination of credentials is additive and unordered.
Note that no configuration is required for PSK (pre-shared
or pairwise-symmetric key) based authentication as the key
Watsen & Wu Expires November 21, 2020 [Page 26]
Internet-Draft Groupings for TLS Clients and Servers May 2020
is necessarily the same as configured in the '../server-
identity' node.";
container ca-certs {
if-feature "x509-certificate-auth";
presence
"Indicates that the TLS server can authenticate TLS clients
using configured certificate authority certificates.";
description
"A set of certificate authority (CA) certificates used by
the TLS server to authenticate TLS client certificates. A
client certificate is authenticated if it has a valid
chain of trust to a configured CA certificate.";
reference
"RFC BBBB: A YANG Data Model for a Truststore";
uses ts:local-or-truststore-certs-grouping;
}
container ee-certs { // FIXME: plural too much?
if-feature "x509-certificate-auth";
presence
"Indicates that the TLS server can authenticate TLS
clients using configured client certificates.";
description
"A set of client certificates (i.e., end entity
certificates) used by the TLS server to authenticate
certificates presented by TLS clients. A client
certificate is authenticated if it is an exact
match to a configured client certificate.";
reference
"RFC BBBB: A YANG Data Model for a Truststore";
uses ts:local-or-truststore-certs-grouping;
}
container raw-public-keys {
if-feature "raw-public-key-auth";
presence
"Indicates that the TLS server can authenticate TLS
clients using raw public keys.";
description
"A set of raw public keys used by the TLS server to
authenticate raw public keys presented by the TLS
client. A raw public key is authenticated if it
is an exact match to a configured raw public key.";
reference
"RFC BBBB: A YANG Data Model for a Truststore";
uses ts:local-or-truststore-public-keys-grouping {
refine "local-or-truststore/local/local-definition"
+ "/public-key" {
must 'public-key-format'
+ ' = "ct:subject-public-key-info-format"';
Watsen & Wu Expires November 21, 2020 [Page 27]
Internet-Draft Groupings for TLS Clients and Servers May 2020
}
refine "local-or-truststore/truststore"
+ "/truststore-reference" {
must 'deref(.)/../*/ts:public-key-format'
+ ' = "ct:subject-public-key-info-format"';
}
}
}
container psks {
if-feature "psk-auth";
presence
"Indicates that the TLS server can authenticate the TLS
client using its PSK (pre-shared or pairwise-symmetric
key).";
description
"No configuration is required since the PSK value is the
same as PSK value configured in the 'client-identity'
node.";
}
} // container client-authentication
container hello-params {
nacm:default-deny-write;
if-feature "tls-server-hello-params-config";
uses tlscmn:hello-params-grouping;
description
"Configurable parameters for the TLS hello message.";
} // container hello-params
container keepalives {
nacm:default-deny-write;
if-feature "tls-server-keepalives";
description
"Configures the keepalive policy for the TLS server.";
leaf peer-allowed-to-send {
type empty;
description
"Indicates that the remote TLS client is allowed to send
HeartbeatRequest messages, as defined by RFC 6520
to this TLS server.";
reference
"RFC 6520: Transport Layer Security (TLS) and Datagram
Transport Layer Security (DTLS) Heartbeat Extension";
}
container test-peer-aliveness {
presence
"Indicates that the TLS server proactively tests the
aliveness of the remote TLS client.";
Watsen & Wu Expires November 21, 2020 [Page 28]
Internet-Draft Groupings for TLS Clients and Servers May 2020
description
"Configures the keep-alive policy to proactively test
the aliveness of the TLS client. An unresponsive
TLS client is dropped after approximately max-wait
* max-attempts seconds.";
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.";
}
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.";
}
}
} // container keepalives
} // grouping tls-server-grouping
} // module ietf-tls-server
5. The TLS Common Model
The TLS common model presented in this section contains identities
and groupings common to both TLS clients and TLS servers. The
"hello-params-grouping" grouping can be used to configure the list of
TLS algorithms permitted by the TLS client or TLS server. The lists
of algorithms are ordered such that, if multiple algorithms are
permitted by the client, the algorithm that appears first in its list
that is also permitted by the server is used for the TLS transport
layer connection. The ability to restrict the algorithms allowed is
provided in this grouping for TLS clients and TLS servers that are
capable of doing so and may serve to make TLS clients and TLS servers
compliant with local security policies. This model supports both
TLS1.2 [RFC5246] and TLS 1.3 [RFC8446].
Watsen & Wu Expires November 21, 2020 [Page 29]
Internet-Draft Groupings for TLS Clients and Servers May 2020
TLS 1.2 and TLS 1.3 have different ways defining their own supported
cryptographic algorithms, see TLS and DTLS IANA registries page
(https://www.iana.org/assignments/tls-parameters/tls-
parameters.xhtml):
o TLS 1.2 defines four categories of registries for cryptographic
algorithms: TLS Cipher Suites, TLS SignatureAlgorithm, TLS
HashAlgorithm, TLS Supported Groups. TLS Cipher Suites plays the
role of combining all of them into one set, as each value of the
set represents a unique and feasible combination of all the
cryptographic algorithms, and thus the other three registry
categories do not need to be considered here. In this document,
the TLS common model only chooses those TLS1.2 algorithms in TLS
Cipher Suites which are marked as recommended:
TLS_DHE_RSA_WITH_AES_128_GCM_SHA256,
TLS_DHE_RSA_WITH_AES_256_GCM_SHA384,
TLS_DHE_PSK_WITH_AES_128_GCM_SHA256,
TLS_DHE_PSK_WITH_AES_256_GCM_SHA384, and so on. All chosen
algorithms are enumerated in Table 1-1 below;
o TLS 1.3 defines its supported algorithms differently. Firstly, it
defines three categories of registries for cryptographic
algorithms: TLS Cipher Suites, TLS SignatureScheme, TLS Supported
Groups. Secondly, all three of these categories are useful, since
they represent different parts of all the supported algorithms
respectively. Thus, all of these registries categories are
considered here. In this draft, the TLS common model chooses only
those TLS1.3 algorithms specified in B.4, 4.2.3, 4.2.7 of
[RFC8446].
Thus, in order to support both TLS1.2 and TLS1.3, the cipher-suites
part of the "hello-params-grouping" grouping should include three
parameters for configuring its permitted TLS algorithms, which are:
TLS Cipher Suites, TLS SignatureScheme, TLS Supported Groups. Note
that TLS1.2 only uses TLS Cipher Suites.
Features are defined for algorithms that are OPTIONAL or are not
widely supported by popular implementations. Note that the list of
algorithms is not exhaustive.
5.1. Tree Diagram
The following tree diagram [RFC8340] provides an overview of the data
model for the "ietf-tls-common" module.
Watsen & Wu Expires November 21, 2020 [Page 30]
Internet-Draft Groupings for TLS Clients and Servers May 2020
module: ietf-tls-common
grouping hello-params-grouping
+-- tls-versions
| +-- tls-version* identityref
+-- cipher-suites
+-- cipher-suite* identityref
5.2. Example Usage
This section shows how it would appear if the "hello-params-grouping"
grouping were populated with some data.
tlscmn:tls-1.1
tlscmn:tls-1.2
tlscmn:dhe-rsa-with-aes-128-cbc-sha
tlscmn:rsa-with-aes-128-cbc-sha
tlscmn:rsa-with-3des-ede-cbc-sha
5.3. YANG Module
This YANG module has a normative references to [RFC4346], [RFC5246],
[RFC5288], [RFC5289], and [RFC8422].
This YANG module has a informative references to [RFC2246],
[RFC4346], [RFC5246], and [RFC8446].
file "ietf-tls-common@2020-05-20.yang"
module ietf-tls-common {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-tls-common";
prefix tlscmn;
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web:
WG List:
Watsen & Wu Expires November 21, 2020 [Page 31]
Internet-Draft Groupings for TLS Clients and Servers May 2020
Author: Kent Watsen
Author: Gary Wu ";
description
"This module defines a common features, identities, and
groupings for Transport Layer Security (TLS).
Copyright (c) 2020 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
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC
itself for full legal notices.
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 (RFC 2119)
(RFC 8174) when, and only when, they appear in all
capitals, as shown here.";
revision 2020-05-20 {
description
"Initial version";
reference
"RFC XXXX: YANG Groupings for TLS Clients and TLS Servers";
}
// Features
feature tls-1_0 {
description
"TLS Protocol Version 1.0 is supported.";
reference
"RFC 2246: The TLS Protocol Version 1.0";
}
feature tls-1_1 {
description
"TLS Protocol Version 1.1 is supported.";
reference
Watsen & Wu Expires November 21, 2020 [Page 32]
Internet-Draft Groupings for TLS Clients and Servers May 2020
"RFC 4346: The Transport Layer Security (TLS) Protocol
Version 1.1";
}
feature tls-1_2 {
description
"TLS Protocol Version 1.2 is supported.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2";
}
feature tls-1_3 {
description
"TLS Protocol Version 1.2 is supported.";
reference
"RFC 8446: The Transport Layer Security (TLS) Protocol
Version 1.3";
}
feature tls-ecc {
description
"Elliptic Curve Cryptography (ECC) is supported for TLS.";
reference
"RFC 8422: Elliptic Curve Cryptography (ECC) Cipher Suites
for Transport Layer Security (TLS)";
}
feature tls-dhe {
description
"Ephemeral Diffie-Hellman key exchange is supported for TLS.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2";
}
feature tls-3des {
description
"The Triple-DES block cipher is supported for TLS.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2";
}
feature tls-gcm {
description
"The Galois/Counter Mode authenticated encryption mode is
supported for TLS.";
Watsen & Wu Expires November 21, 2020 [Page 33]
Internet-Draft Groupings for TLS Clients and Servers May 2020
reference
"RFC 5288: AES Galois Counter Mode (GCM) Cipher Suites for
TLS";
}
feature tls-sha2 {
description
"The SHA2 family of cryptographic hash functions is supported
for TLS.";
reference
"FIPS PUB 180-4: Secure Hash Standard (SHS)";
}
// Identities
identity tls-version-base {
description
"Base identity used to identify TLS protocol versions.";
}
identity tls-1.0 {
if-feature "tls-1_0";
base tls-version-base;
description
"TLS Protocol Version 1.0.";
reference
"RFC 2246: The TLS Protocol Version 1.0";
}
identity tls-1.1 {
if-feature "tls-1_1";
base tls-version-base;
description
"TLS Protocol Version 1.1.";
reference
"RFC 4346: The Transport Layer Security (TLS) Protocol
Version 1.1";
}
identity tls-1.2 {
if-feature "tls-1_2";
base tls-version-base;
description
"TLS Protocol Version 1.2.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2";
}
Watsen & Wu Expires November 21, 2020 [Page 34]
Internet-Draft Groupings for TLS Clients and Servers May 2020
identity cipher-suite-base {
description
"Base identity used to identify TLS cipher suites.";
}
identity rsa-with-aes-128-cbc-sha {
base cipher-suite-base;
description
"Cipher suite TLS_RSA_WITH_AES_128_CBC_SHA.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2";
}
identity rsa-with-aes-256-cbc-sha {
base cipher-suite-base;
description
"Cipher suite TLS_RSA_WITH_AES_256_CBC_SHA.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2";
}
identity rsa-with-aes-128-cbc-sha256 {
if-feature "tls-sha2";
base cipher-suite-base;
description
"Cipher suite TLS_RSA_WITH_AES_128_CBC_SHA256.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2";
}
identity rsa-with-aes-256-cbc-sha256 {
if-feature "tls-sha2";
base cipher-suite-base;
description
"Cipher suite TLS_RSA_WITH_AES_256_CBC_SHA256.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2";
}
identity dhe-rsa-with-aes-128-cbc-sha {
if-feature "tls-dhe";
base cipher-suite-base;
description
"Cipher suite TLS_DHE_RSA_WITH_AES_128_CBC_SHA.";
Watsen & Wu Expires November 21, 2020 [Page 35]
Internet-Draft Groupings for TLS Clients and Servers May 2020
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2";
}
identity dhe-rsa-with-aes-256-cbc-sha {
if-feature "tls-dhe";
base cipher-suite-base;
description
"Cipher suite TLS_DHE_RSA_WITH_AES_256_CBC_SHA.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2";
}
identity dhe-rsa-with-aes-128-cbc-sha256 {
if-feature "tls-dhe and tls-sha2";
base cipher-suite-base;
description
"Cipher suite TLS_DHE_RSA_WITH_AES_128_CBC_SHA256.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2";
}
identity dhe-rsa-with-aes-256-cbc-sha256 {
if-feature "tls-dhe and tls-sha2";
base cipher-suite-base;
description
"Cipher suite TLS_DHE_RSA_WITH_AES_256_CBC_SHA256.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2";
}
identity ecdhe-ecdsa-with-aes-128-cbc-sha256 {
if-feature "tls-ecc and tls-sha2";
base cipher-suite-base;
description
"Cipher suite TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256.";
reference
"RFC 5289: TLS Elliptic Curve Cipher Suites with
SHA-256/384 and AES Galois Counter Mode (GCM)";
}
identity ecdhe-ecdsa-with-aes-256-cbc-sha384 {
if-feature "tls-ecc and tls-sha2";
base cipher-suite-base;
Watsen & Wu Expires November 21, 2020 [Page 36]
Internet-Draft Groupings for TLS Clients and Servers May 2020
description
"Cipher suite TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384.";
reference
"RFC 5289: TLS Elliptic Curve Cipher Suites with
SHA-256/384 and AES Galois Counter Mode (GCM)";
}
identity ecdhe-rsa-with-aes-128-cbc-sha256 {
if-feature "tls-ecc and tls-sha2";
base cipher-suite-base;
description
"Cipher suite TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256.";
reference
"RFC 5289: TLS Elliptic Curve Cipher Suites with
SHA-256/384 and AES Galois Counter Mode (GCM)";
}
identity ecdhe-rsa-with-aes-256-cbc-sha384 {
if-feature "tls-ecc and tls-sha2";
base cipher-suite-base;
description
"Cipher suite TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384.";
reference
"RFC 5289: TLS Elliptic Curve Cipher Suites with
SHA-256/384 and AES Galois Counter Mode (GCM)";
}
identity ecdhe-ecdsa-with-aes-128-gcm-sha256 {
if-feature "tls-ecc and tls-gcm and tls-sha2";
base cipher-suite-base;
description
"Cipher suite TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256.";
reference
"RFC 5289: TLS Elliptic Curve Cipher Suites with
SHA-256/384 and AES Galois Counter Mode (GCM)";
}
identity ecdhe-ecdsa-with-aes-256-gcm-sha384 {
if-feature "tls-ecc and tls-gcm and tls-sha2";
base cipher-suite-base;
description
"Cipher suite TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384.";
reference
"RFC 5289: TLS Elliptic Curve Cipher Suites with
SHA-256/384 and AES Galois Counter Mode (GCM)";
}
identity ecdhe-rsa-with-aes-128-gcm-sha256 {
Watsen & Wu Expires November 21, 2020 [Page 37]
Internet-Draft Groupings for TLS Clients and Servers May 2020
if-feature "tls-ecc and tls-gcm and tls-sha2";
base cipher-suite-base;
description
"Cipher suite TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256.";
reference
"RFC 5289: TLS Elliptic Curve Cipher Suites with
SHA-256/384 and AES Galois Counter Mode (GCM)";
}
identity ecdhe-rsa-with-aes-256-gcm-sha384 {
if-feature "tls-ecc and tls-gcm and tls-sha2";
base cipher-suite-base;
description
"Cipher suite TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384.";
reference
"RFC 5289: TLS Elliptic Curve Cipher Suites with
SHA-256/384 and AES Galois Counter Mode (GCM)";
}
identity rsa-with-3des-ede-cbc-sha {
if-feature "tls-3des";
base cipher-suite-base;
description
"Cipher suite TLS_RSA_WITH_3DES_EDE_CBC_SHA.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2";
}
identity ecdhe-rsa-with-3des-ede-cbc-sha {
if-feature "tls-ecc and tls-3des";
base cipher-suite-base;
description
"Cipher suite TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA.";
reference
"RFC 8422: Elliptic Curve Cryptography (ECC) Cipher Suites
for Transport Layer Security (TLS)";
}
identity ecdhe-rsa-with-aes-128-cbc-sha {
if-feature "tls-ecc";
base cipher-suite-base;
description
"Cipher suite TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA.";
reference
"RFC 8422: Elliptic Curve Cryptography (ECC) Cipher Suites
for Transport Layer Security (TLS)";
}
Watsen & Wu Expires November 21, 2020 [Page 38]
Internet-Draft Groupings for TLS Clients and Servers May 2020
identity ecdhe-rsa-with-aes-256-cbc-sha {
if-feature "tls-ecc";
base cipher-suite-base;
description
"Cipher suite TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA.";
reference
"RFC 8422: Elliptic Curve Cryptography (ECC) Cipher Suites
for Transport Layer Security (TLS)";
}
// Groupings
grouping hello-params-grouping {
description
"A reusable grouping for TLS hello message parameters.";
reference
"RFC 5246: The Transport Layer Security (TLS) Protocol
Version 1.2";
container tls-versions {
description
"Parameters regarding TLS versions.";
leaf-list tls-version {
type identityref {
base tls-version-base;
}
description
"Acceptable TLS protocol versions.
If this leaf-list is not configured (has zero elements)
the acceptable TLS protocol versions are implementation-
defined.";
}
}
container cipher-suites {
description
"Parameters regarding cipher suites.";
leaf-list cipher-suite {
type identityref {
base cipher-suite-base;
}
ordered-by user;
description
"Acceptable cipher suites in order of descending
preference. The configured host key algorithms should
be compatible with the algorithm used by the configured
private key. Please see Section 5 of RFC XXXX for
valid combinations.
Watsen & Wu Expires November 21, 2020 [Page 39]
Internet-Draft Groupings for TLS Clients and Servers May 2020
If this leaf-list is not configured (has zero elements)
the acceptable cipher suites are implementation-
defined.";
reference
"RFC XXXX: YANG Groupings for TLS Clients and TLS Servers";
}
}
}
}
6. Security Considerations
The YANG modules defined in this document are 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.
Since the modules in this document only define groupings, these
considerations are primarily for the designers of other modules that
use these groupings.
There are a number of data nodes defined in the YANG modules 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 subtree defined by the grouping statement in both
the "ietf-ssh-client" and "ietf-ssh-server" modules is
sensitive to write operations. For instance, the addition or
removal of references to keys, certificates, trusted anchors,
etc., or even the modification of transport or keepalive
parameters can dramatically alter the implemented security
policy. For this reason, this node is protected the NACM
extension "default-deny-write".
Some of the readable data nodes in the YANG modules 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
Watsen & Wu Expires November 21, 2020 [Page 40]
Internet-Draft Groupings for TLS Clients and Servers May 2020
notification) to these data nodes. These are the subtrees and data
nodes and their sensitivity/vulnerability:
/tls-client-parameters/client-identity/: This subtree in the
"ietf-tls-client" module contains nodes that are additionally
sensitive to read operations such that, in normal use cases,
they should never be returned to a client. Some of these nodes
(i.e., public-key/local-definition/private-key and certificate/
local-definition/private-key) are already protected by the NACM
extension "default-deny-all" set in the "grouping" statements
defined in [I-D.ietf-netconf-crypto-types].
/tls-server-parameters/server-identity/: This subtree in the
"ietf-tls-server" module contains nodes that are additionally
sensitive to read operations such that, in normal use cases,
they should never be returned to a client. All of these nodes
(i.e., host-key/public-key/local-definition/private-key and
host-key/certificate/local-definition/private-key) are already
protected by the NACM extension "default-deny-all" set in the
"grouping" statements defined in
[I-D.ietf-netconf-crypto-types].
Some of the 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:
*: The groupings defined in this document include "action"
statements that come from groupings defined in
[I-D.ietf-netconf-crypto-types]. Please consult that document
for the security considerations of the "action" statements
defined by the "grouping" statements defined in this document.
7. IANA Considerations
7.1. The IETF XML Registry
This document registers three URIs in the "ns" subregistry of the
IETF XML Registry [RFC3688]. Following the format in [RFC3688], the
following registrations are requested:
Watsen & Wu Expires November 21, 2020 [Page 41]
Internet-Draft Groupings for TLS Clients and Servers May 2020
URI: urn:ietf:params:xml:ns:yang:ietf-tls-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-tls-server
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-tls-common
Registrant Contact: The NETCONF WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
7.2. The YANG Module Names Registry
This document registers three YANG modules in the YANG Module Names
registry [RFC6020]. Following the format in [RFC6020], the following
registrations are requested:
name: ietf-tls-client
namespace: urn:ietf:params:xml:ns:yang:ietf-tls-client
prefix: tlsc
reference: RFC FFFF
name: ietf-tls-server
namespace: urn:ietf:params:xml:ns:yang:ietf-tls-server
prefix: tlss
reference: RFC FFFF
name: ietf-tls-common
namespace: urn:ietf:params:xml:ns:yang:ietf-tls-common
prefix: tlscmn
reference: RFC FFFF
8. References
8.1. Normative References
[I-D.ietf-netconf-crypto-types]
Watsen, K. and H. Wang, "Common YANG Data Types for
Cryptography", draft-ietf-netconf-crypto-types-14 (work in
progress), March 2020.
[I-D.ietf-netconf-keystore]
Watsen, K., "A YANG Data Model for a Keystore", draft-
ietf-netconf-keystore-16 (work in progress), March 2020.
Watsen & Wu Expires November 21, 2020 [Page 42]
Internet-Draft Groupings for TLS Clients and Servers May 2020
[I-D.ietf-netconf-trust-anchors]
Watsen, K., "A YANG Data Model for a Truststore", draft-
ietf-netconf-trust-anchors-09 (work in progress), March
2020.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
.
[RFC5288] Salowey, J., Choudhury, A., and D. McGrew, "AES Galois
Counter Mode (GCM) Cipher Suites for TLS", RFC 5288,
DOI 10.17487/RFC5288, August 2008,
.
[RFC5289] Rescorla, E., "TLS Elliptic Curve Cipher Suites with SHA-
256/384 and AES Galois Counter Mode (GCM)", RFC 5289,
DOI 10.17487/RFC5289, August 2008,
.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
.
[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,
.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, .
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
.
Watsen & Wu Expires November 21, 2020 [Page 43]
Internet-Draft Groupings for TLS Clients and Servers May 2020
[RFC8422] Nir, Y., Josefsson, S., and M. Pegourie-Gonnard, "Elliptic
Curve Cryptography (ECC) Cipher Suites for Transport Layer
Security (TLS) Versions 1.2 and Earlier", RFC 8422,
DOI 10.17487/RFC8422, August 2018,
.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
.
8.2. Informative References
[RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
RFC 2246, DOI 10.17487/RFC2246, January 1999,
.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000,
.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
.
[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.1", RFC 4346,
DOI 10.17487/RFC4346, April 2006,
.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
.
[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,
.
[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,
.
Watsen & Wu Expires November 21, 2020 [Page 44]
Internet-Draft Groupings for TLS Clients and Servers May 2020
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
.
8.3. URIs
[1] https://tools.ietf.org/html/draft-ietf-netconf-crypto-types
[2] https://tools.ietf.org/html/draft-ietf-netconf-trust-anchors
[3] https://tools.ietf.org/html/draft-ietf-netconf-keystore
[4] https://tools.ietf.org/html/draft-ietf-netconf-tcp-client-server
[5] https://tools.ietf.org/html/draft-ietf-netconf-ssh-client-server
[6] https://tools.ietf.org/html/draft-ietf-netconf-tls-client-server
[7] https://tools.ietf.org/html/draft-ietf-netconf-http-client-server
[8] https://tools.ietf.org/html/draft-ietf-netconf-netconf-client-
server
[9] https://tools.ietf.org/html/draft-ietf-netconf-restconf-client-
server
Watsen & Wu Expires November 21, 2020 [Page 45]
Internet-Draft Groupings for TLS Clients and Servers May 2020
Appendix A. Change Log
A.1. 00 to 01
o Noted that '0.0.0.0' and '::' might have special meanings.
o Renamed "keychain" to "keystore".
A.2. 01 to 02
o Removed the groupings containing transport-level configuration.
Now modules contain only the transport-independent groupings.
o Filled in previously incomplete 'ietf-tls-client' module.
o Added cipher suites for various algorithms into new 'ietf-tls-
common' module.
A.3. 02 to 03
o Added a 'must' statement to container 'server-auth' asserting that
at least one of the various auth mechanisms must be specified.
o Fixed description statement for leaf 'trusted-ca-certs'.
A.4. 03 to 04
o Updated title to "YANG Groupings for TLS Clients and TLS Servers"
o Updated leafref paths to point to new keystore path
o Changed the YANG prefix for ietf-tls-common from 'tlscom' to
'tlscmn'.
o Added TLS protocol verions 1.0 and 1.1.
o Made author lists consistent
o Now tree diagrams reference ietf-netmod-yang-tree-diagrams
o Updated YANG to use typedefs around leafrefs to common keystore
paths
o Now inlines key and certificates (no longer a leafref to keystore)
Watsen & Wu Expires November 21, 2020 [Page 46]
Internet-Draft Groupings for TLS Clients and Servers May 2020
A.5. 04 to 05
o Merged changes from co-author.
A.6. 05 to 06
o Updated to use trust anchors from trust-anchors draft (was
keystore draft)
o Now Uses new keystore grouping enabling asymmetric key to be
either locally defined or a reference to the keystore.
A.7. 06 to 07
o factored the tls-[client|server]-groupings into more reusable
groupings.
o added if-feature statements for the new "x509-certificates"
feature defined in draft-ietf-netconf-trust-anchors.
A.8. 07 to 08
o Added a number of compatibility matrices to Section 5 (thanks
Frank!)
o Clarified that any configured "cipher-suite" values need to be
compatible with the configured private key.
A.9. 08 to 09
o Updated examples to reflect update to groupings defined in the
keystore draft.
o Add TLS keepalives features and groupings.
o Prefixed top-level TLS grouping nodes with 'tls-' and support
mashups.
o Updated copyright date, boilerplate template, affiliation, and
folding algorithm.
A.10. 09 to 10
o Reformatted the YANG modules.
Watsen & Wu Expires November 21, 2020 [Page 47]
Internet-Draft Groupings for TLS Clients and Servers May 2020
A.11. 10 to 11
o Collapsed all the inner groupings into the top-level grouping.
o Added a top-level "demux container" inside the top-level grouping.
o Added NACM statements and updated the Security Considerations
section.
o Added "presence" statements on the "keepalive" containers, as was
needed to address a validation error that appeared after adding
the "must" statements into the NETCONF/RESTCONF client/server
modules.
o Updated the boilerplate text in module-level "description"
statement to match copyeditor convention.
A.12. 11 to 12
o In server model, made 'client-authentication' a 'presence' node
indicating that the server supports client authentication.
o In the server model, added a 'required-or-optional' choice to
'client-authentication' to better support protocols such as
RESTCONF.
o In the server model, added a 'local-or-external' choice to
'client-authentication' to better support consuming data models
that prefer to keep client auth with client definitions than in a
model principally concerned with the "transport".
o In both models, removed the "demux containers", floating the
nacm:default-deny-write to each descendent node, and adding a note
to model designers regarding the potential need to add their own
demux containers.
o Fixed a couple references (section 2 --> section 3)
A.13. 12 to 13
o Updated to reflect changes in trust-anchors drafts (e.g., s/trust-
anchors/truststore/g + s/pinned.//)
A.14. 12 to 13
o Removed 'container' under 'client-identity' to match server model.
o Updated examples to reflect change grouping in keystore module.
Watsen & Wu Expires November 21, 2020 [Page 48]
Internet-Draft Groupings for TLS Clients and Servers May 2020
A.15. 13 to 14
o Removed the "certificate" container from "client-identity" in the
ietf-tls-client module.
o Updated examples to reflect ietf-crypto-types change (e.g.,
identities --> enumerations)
A.16. 14 to 15
o Updated "server-authentication" and "client-authentication" nodes
from being a leaf of type "ts:certificates-ref" to a container
that uses "ts:local-or-truststore-certs-grouping".
A.17. 15 to 16
o Removed unnecessary if-feature statements in the -client and
-server modules.
o Cleaned up some description statements in the -client and -server
modules.
o Fixed a canonical ordering issue in ietf-tls-common detected by
new pyang.
A.18. 16 to 17
o Removed choice local-or-external by removing the 'external' case
and flattening the 'local' case and adding a "client-auth-config-
supported" feature.
o Removed choice required-or-optional.
o Updated examples to include the "*-key-format" nodes.
o Augmented-in "must" expressions ensuring that locally-defined
public-key-format are "ct:ssh-public-key-format" (must expr for
ref'ed keys are TBD).
A.19. 17 to 18
o Removed the unused "external-client-auth-supported" feature.
o Made client-indentity optional, as there may be over-the-top auth
instead.
o Added augment to uses of local-or-keystore-symmetric-key-grouping
for a psk "id" node.
Watsen & Wu Expires November 21, 2020 [Page 49]
Internet-Draft Groupings for TLS Clients and Servers May 2020
o Added missing presence container "psks" to ietf-tls-server's
"client-authentication" container.
o Updated examples to reflect new "bag" addition to truststore.
o Removed feature-limited caseless 'case' statements to improve tree
diagram rendering.
o Refined truststore/keystore groupings to ensure the key formats
"must" be particular values.
o Switched to using truststore's new "public-key" bag (instead of
separate "ssh-public-key" and "raw-public-key" bags.
o Updated client/server examples to cover ALL cases (local/ref x
cert/raw-key/psk).
A.20. 18 to 19
o Updated the "keepalives" containers in part to address Michal
Vasko's request to align with RFC 8071, and in part to better
align to RFC 6520.
o Removed algorithm-mapping tables from the "TLS Common Model"
section
o Removed the 'algorithm' node from the examples.
o Renamed both "client-certs" and "server-certs" to "ee-certs"
o Added a "Note to Reviewers" note to first page.
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, Radek Krejci,
David Lamparter, Ladislav Lhotka, Alan Luchuk, Tom Petch, Juergen
Schoenwaelder, Phil Shafer, Sean Turner, Michal Vasko, Bert Wijnen,
and Liang Xia.
Authors' Addresses
Kent Watsen
Watsen Networks
EMail: kent+ietf@watsen.net
Watsen & Wu Expires November 21, 2020 [Page 50]
Internet-Draft Groupings for TLS Clients and Servers May 2020
Gary Wu
Cisco Systems
EMail: garywu@cisco.com
Watsen & Wu Expires November 21, 2020 [Page 51]