module ietf-ssh-client {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-ssh-client";
prefix sshc;
import ietf-netconf-acm {
prefix nacm;
reference
"RFC 8341: Network Configuration Access Control Model";
}
import ietf-crypto-types {
prefix ct;
reference
"RFC AAAA: YANG Data Types and Groupings 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-ssh-common {
prefix sshcmn;
revision-date 2021-06-18; // stable grouping definitions
reference
"RFC EEEE: YANG Groupings for SSH Clients and SSH Servers";
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web:
WG List:
Author: Kent Watsen
Author: Gary Wu ";
description
"This module defines reusable groupings for SSH clients that
can be used as a basis for specific SSH client instances.
Copyright (c) 2021 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 EEEE
(https://www.rfc-editor.org/info/rfcEEEE); 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 2021-06-18 {
description
"Initial version";
reference
"RFC EEEE: YANG Groupings for SSH Clients and SSH Servers";
}
// Features
feature ssh-client-keepalives {
description
"Per socket SSH keepalive parameters are configurable for
SSH clients on the server implementing this feature.";
}
feature client-ident-publickey {
description
"Indicates that the 'publickey' authentication type, per
RFC 4252, is supported for client identification.
The 'publickey' authentication type is required by
RFC 4252, but common implementations enable it to
be disabled.";
reference
"RFC 4252:
The Secure Shell (SSH) Authentication Protocol";
}
feature client-ident-password {
description
"Indicates that the 'password' authentication type, per
RFC 4252, is supported for client identification.";
reference
"RFC 4252:
The Secure Shell (SSH) Authentication Protocol";
}
feature client-ident-hostbased {
description
"Indicates that the 'hostbased' authentication type, per
RFC 4252, is supported for client identification.";
reference
"RFC 4252:
The Secure Shell (SSH) Authentication Protocol";
}
feature client-ident-none {
description
"Indicates that the 'none' authentication type, per
RFC 4252, is supported for client identification.";
reference
"RFC 4252:
The Secure Shell (SSH) Authentication Protocol";
}
// Groupings
grouping ssh-client-grouping {
description
"A reusable grouping for configuring a SSH client without
any consideration for how an underlying TCP session is
established.
Note that this grouping uses fairly typical descendant
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
'ssh-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
"The username and authentication methods for the client.
The authentication methods are unordered. Clients may
initially send any configured method or, per RFC 4252,
Section 5.2, send the 'none' method to prompt the server
to provide a list of productive methods. Whenever a
choice amongst methods arises, implementations SHOULD
use a default ordering that prioritizes automation
over human-interaction.";
leaf username {
type string;
description
"The username of this user. This will be the username
used, for instance, to log into an SSH server.";
}
container public-key {
if-feature "client-ident-publickey";
presence
"Indicates that publickey-based authentication has been
configured. This statement is present so the mandatory
descendent nodes do not imply that this node must be
configured.";
description
"A locally-defined or referenced asymmetric key
pair to be used for client identification.";
reference
"RFC CCCC: A YANG Data Model for a Keystore";
uses ks:local-or-keystore-asymmetric-key-grouping {
refine "local-or-keystore/local/local-definition" {
must 'public-key-format = "ct:ssh-public-key-format"';
}
refine "local-or-keystore/keystore/keystore-reference" {
must 'deref(.)/../ks:public-key-format'
+ ' = "ct:ssh-public-key-format"';
}
}
}
container password {
if-feature "client-ident-password";
presence
"Indicates that password-based authentication has been
configured. This statement is present so the mandatory
descendent nodes do not imply that this node must be
configured.";
description
"A password to be used to authenticate the client's
identity.";
uses ct:password-grouping;
}
container hostbased {
if-feature "client-ident-hostbased";
presence
"Indicates that hostbased authentication is configured.
This statement is present so the mandatory descendent
nodes do not imply that this node must be configured.";
description
"A locally-defined or referenced asymmetric key
pair to be used for host identification.";
reference
"RFC CCCC: A YANG Data Model for a Keystore";
uses ks:local-or-keystore-asymmetric-key-grouping {
refine "local-or-keystore/local/local-definition" {
must 'public-key-format = "ct:ssh-public-key-format"';
}
refine "local-or-keystore/keystore/keystore-reference" {
must 'deref(.)/../ks:public-key-format'
+ ' = "ct:ssh-public-key-format"';
}
}
}
leaf none {
if-feature "client-ident-none";
type empty;
description
"Indicates that 'none' algorithm is used for client
identification.";
}
container certificate {
if-feature "sshcmn:ssh-x509-certs";
presence
"Indicates that certificate-based authentication has been
configured. This statement is present so the mandatory
descendant nodes do not imply that this node must be
configured.";
description
"A locally-defined or referenced certificate
to be used for client identification.";
reference
"RFC CCCC: A YANG Data Model for a Keystore";
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"';
}
}
}
} // container client-identity
container server-authentication {
nacm:default-deny-write;
must 'ssh-host-keys or ca-certs or ee-certs';
description
"Specifies how the SSH client can authenticate SSH servers.
Any combination of authentication methods is additive and
unordered.";
container ssh-host-keys {
presence
"Indicates that the SSH host key have been configured.
This statement is present so the mandatory descendant
nodes do not imply that this node must be configured.";
description
"A bag of SSH host keys used by the SSH client to
authenticate SSH server host keys. A server host key
is authenticated if it is an exact match to a
configured SSH host 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:ssh-public-key-format"';
}
refine
"local-or-truststore/truststore/truststore-reference" {
must 'deref(.)/../*/ts:public-key-format'
+ ' = "ct:ssh-public-key-format"';
}
}
}
container ca-certs {
if-feature "sshcmn:ssh-x509-certs";
presence
"Indicates that the CA certificates have been configured.
This statement is present so the mandatory descendant
nodes do not imply that this node must be configured.";
description
"A set of certificate authority (CA) certificates used by
the SSH client to authenticate SSH servers. A server
is authenticated if its certificate 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 {
if-feature "sshcmn:ssh-x509-certs";
presence
"Indicates that the EE certificates have been configured.
This statement is present so the mandatory descendant
nodes do not imply that this node must be configured.";
description
"A set of end-entity certificates used by the SSH client
to authenticate SSH servers. A server is authenticated
if its certificate is an exact match to a configured
end-entity certificate.";
reference
"RFC BBBB: A YANG Data Model for a Truststore";
uses ts:local-or-truststore-certs-grouping;
}
} // container server-authentication
container transport-params {
nacm:default-deny-write;
if-feature "sshcmn:transport-params";
description
"Configurable parameters of the SSH transport layer.";
uses sshcmn:transport-params-grouping;
} // container transport-parameters
container keepalives {
nacm:default-deny-write;
if-feature "ssh-client-keepalives";
presence
"Indicates that the SSH client proactively tests the
aliveness of the remote SSH server.";
description
"Configures the keep-alive policy, to proactively test
the aliveness of the SSH server. An unresponsive TLS
server is dropped after approximately max-wait *
max-attempts seconds. Per Section 4 of RFC 4254,
the SSH client SHOULD send an SSH_MSG_GLOBAL_REQUEST
message with a purposely nonexistent 'request name'
value (e.g., keepalive@ietf.org) and the 'want reply'
value set to '1'.";
reference
"RFC 4254: The Secure Shell (SSH) Connection Protocol";
leaf max-wait {
type uint16 {
range "1..max";
}
units "seconds";
default "30";
description
"Sets the amount of time in seconds after which if
no data has been received from the SSH server, a
TLS-level message will be sent to test the
aliveness of the SSH 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 SSH server before assuming the SSH server is
no longer alive.";
}
} // container keepalives
} // grouping ssh-client-grouping
}