draft-ietf-opsawg-tacacs-yang-12.txt   rfc9105.txt 
Opsawg B. Wu, Ed. Internet Engineering Task Force (IETF) B. Wu, Ed.
Internet-Draft G. Zheng Request for Comments: 9105 G. Zheng
Intended status: Standards Track M. Wang, Ed. Category: Standards Track M. Wang, Ed.
Expires: November 14, 2021 Huawei ISSN: 2070-1721 Huawei
May 13, 2021 August 2021
A YANG Module for TACACS+ A YANG Data Model for Terminal Access Controller Access-Control System
draft-ietf-opsawg-tacacs-yang-12 Plus (TACACS+)
Abstract Abstract
This document defines a Terminal Access Controller Access-Control This document defines a Terminal Access Controller Access-Control
System Plus (TACACS+) client YANG module, that augments the System System Plus (TACACS+) client YANG module that augments the System
Management data model, defined in RFC 7317, to allow devices to make Management data model, defined in RFC 7317, to allow devices to make
use of TACACS+ servers for centralized Authentication, Authorization use of TACACS+ servers for centralized Authentication, Authorization,
and Accounting (AAA). Though being a standard module, this module and Accounting (AAA). Though being a standard module, this module
does not endorse the security mechanisms of the TACACS+ protocol (RFC does not endorse the security mechanisms of the TACACS+ protocol (RFC
8907) and TACACS+ MUST be used within a secure deployment. 8907), and TACACS+ MUST be used within a secure deployment.
The YANG module in this document conforms to the Network Management The YANG module in this document conforms to the Network Management
Datastore Architecture (NMDA) defined in RFC 8342. Datastore Architecture (NMDA) defined in RFC 8342.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
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 This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on November 14, 2021. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9105.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
2. Conventions used in this document . . . . . . . . . . . . . . 3 2. Conventions Used in This Document
2.1. Tree Diagrams . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Tree Diagrams
3. Design of the TACACS+ Data Model . . . . . . . . . . . . . . 3 3. Design of the TACACS+ Data Model
4. TACACS+ Client Module . . . . . . . . . . . . . . . . . . . . 5 4. TACACS+ Client Module
5. Security Considerations . . . . . . . . . . . . . . . . . . . 12 5. Security Considerations
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 6. IANA Considerations
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 7. References
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 7.1. Normative References
8.1. Normative References . . . . . . . . . . . . . . . . . . 13 7.2. Informative References
8.2. Informative References . . . . . . . . . . . . . . . . . 15 Appendix A. Example TACACS+ Authentication Configuration
Appendix A. Example TACACS+ Authentication Configuration . . . . 15 Acknowledgments
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses
1. Introduction 1. Introduction
This document defines a YANG module that augments the System This document defines a YANG module that augments the System
Management data model defined in the [RFC7317] to support the Management data model defined in [RFC7317] to support the
configuration and management of TACACS+ clients. configuration and management of TACACS+ clients.
TACACS+ [RFC8907] provides device administration for routers, network TACACS+ [RFC8907] provides device administration for routers, network
access servers and other networked devices via one or more access servers, and other networked devices via one or more
centralized servers. centralized servers.
The System Management Model [RFC7317] defines separate functionality The System Management data model [RFC7317] defines separate
to support local and RADIUS authentication: functionality to support local and RADIUS authentication:
o User Authentication Model: Defines a list of usernames with User Authentication Model: Defines a list of usernames with
associated passwords and a configuration leaf to decide the order associated passwords and a configuration leaf to decide the order
in which local or RADIUS authentication is used. in which local or RADIUS authentication is used.
o RADIUS Client Model: Defines a list of RADIUS servers used by a RADIUS Client Model: Defines a list of RADIUS servers used by a
device for centralized user authentication. device for centralized user authentication.
The System Management Model is augmented with the TACACS+ YANG module The System Management data model is augmented with the TACACS+ YANG
defined in this document to allow the use of TACACS+ servers as an module defined in this document to allow the use of TACACS+ servers
alternative to RADIUS servers. as an alternative to RADIUS servers.
The YANG module can be used with network management protocols such as The YANG module can be used with network management protocols such as
NETCONF[RFC6241]. the Network Configuration Protocol (NETCONF) [RFC6241].
The YANG module in this document conforms to the Network Management The YANG module in this document conforms to the Network Management
Datastore Architecture (NMDA) defined in [RFC8342]. Datastore Architecture (NMDA) defined in [RFC8342].
2. Conventions used in this document 2. Conventions Used in This Document
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP14, [RFC2119], [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
The following terms are defined in [RFC6241] and are used in this The following terms are defined in [RFC6241] and are used in this
specification: specification:
o configuration data * configuration data
o state data * state data
The following terms are defined in [RFC7950] and are used in this The following terms are defined in [RFC7950] and are used in this
specification: specification:
o augment * augment
o data model * data model
o data node * data node
The terminology for describing YANG data models is found in The terminology for describing YANG data models is found in
[RFC7950]. [RFC7950].
2.1. Tree Diagrams 2.1. Tree Diagrams
The tree diagram used in this document follows the notation defined The tree diagram used in this document follows the notation defined
in [RFC8340]. in [RFC8340].
3. Design of the TACACS+ Data Model 3. Design of the TACACS+ Data Model
skipping to change at page 4, line 8 skipping to change at line 144
support deployment scenarios with centralized authentication, support deployment scenarios with centralized authentication,
authorization, and accounting servers. Authentication is used to authorization, and accounting servers. Authentication is used to
validate a user's username and password, authorization allows the validate a user's username and password, authorization allows the
user to access and execute commands at various privilege levels user to access and execute commands at various privilege levels
assigned to the user, and accounting keeps track of the activity of a assigned to the user, and accounting keeps track of the activity of a
user who has accessed the device. user who has accessed the device.
The ietf-system-tacacs-plus module augments the "/sys:system" path The ietf-system-tacacs-plus module augments the "/sys:system" path
defined in the ietf-system module with the contents of the "tacacs- defined in the ietf-system module with the contents of the "tacacs-
plus" grouping. Therefore, a device can use local, RADIUS, or plus" grouping. Therefore, a device can use local, RADIUS, or
TACACS+ to validate users who attempt to access the router by several TACACS+ authentication to validate users who attempt to access the
mechanisms, e.g., a command line interface or a web-based user router by several mechanisms, e.g., a command line interface or a
interface. web-based user interface.
The "server" list is directly under the "tacacs-plus" container, The "server" list, which is directly under the "tacacs-plus"
which holds a list of TACACS+ servers and uses server-type to container, holds a list of TACACS+ servers and uses server-type to
distinguish between Authentication, Authorization and Accounting distinguish between Authentication, Authorization, and Accounting
(AAA). The list of servers is for redundancy. (AAA) services. The list of servers is for redundancy.
Most of the parameters in the "server" list are taken directly from Most of the parameters in the "server" list are taken directly from
the TACACS+ protocol [RFC8907], and some are derived from the various the TACACS+ protocol [RFC8907], and some are derived from the various
implementations by network equipment manufacturers. For example, implementations by network equipment manufacturers. For example,
when there are multiple interfaces connected to the TACACS+ client or when there are multiple interfaces connected to the TACACS+ client or
server, the source address of outgoing TACACS+ packets could be server, the source address of outgoing TACACS+ packets could be
specified, or the source address could be specified through the specified, or the source address could be specified through the
interface IP address setting, or derived from the outbound interface interface IP address setting or derived from the outbound interface
from the local Forwarding Information Base (FIB). For the TACACS+ from the local Forwarding Information Base (FIB). For the TACACS+
server located in a Virtual Private Network (VPN), a VPN Routing and server located in a Virtual Private Network (VPN), a VPN Routing and
Forwarding (VRF) instance needs to be specified. Forwarding (VRF) instance needs to be specified.
The "statistics" container under the "server list" is a collection of The "statistics" container under the "server list" is a collection of
read-only counters for sent and received messages from a configured read-only counters for sent and received messages from a configured
server. server.
The YANG module for TACACS+ client has the following structure: The YANG module for TACACS+ client has the following structure:
skipping to change at page 5, line 43 skipping to change at line 208
+--ro errors-received? yang:counter64 +--ro errors-received? yang:counter64
+--ro sessions? yang:counter64 +--ro sessions? yang:counter64
4. TACACS+ Client Module 4. TACACS+ Client Module
This YANG module imports typedefs from [RFC6991]. This module also This YANG module imports typedefs from [RFC6991]. This module also
uses the interface typedef from [RFC8343], the leafref to VRF uses the interface typedef from [RFC8343], the leafref to VRF
instance from [RFC8529], and the "default-deny-all" extension instance from [RFC8529], and the "default-deny-all" extension
statement from [RFC8341]. statement from [RFC8341].
<CODE BEGINS> file "ietf-system-tacacs-plus@2021-05-13.yang" <CODE BEGINS> file "ietf-system-tacacs-plus@2021-08-05.yang"
module ietf-system-tacacs-plus {
module ietf-system-tacacs-plus { yang-version 1.1;
yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-system-tacacs-plus";
namespace "urn:ietf:params:xml:ns:yang:ietf-system-tacacs-plus"; prefix sys-tcs-plus;
prefix sys-tcs-plus;
import ietf-inet-types {
prefix inet;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-yang-types {
prefix yang;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-network-instance {
prefix ni;
reference
"RFC 8529: YANG Data Model for Network Instances";
}
import ietf-interfaces {
prefix if;
reference
"RFC 8343: A YANG Data Model for Interface Management";
}
import ietf-system {
prefix sys;
reference
"RFC 7317: A YANG Data Model for System Management";
}
import ietf-netconf-acm {
prefix nacm;
reference
"RFC 8341: Network Configuration Access Control Model";
}
organization
"IETF Opsawg (Operations and Management Area Working Group)";
contact
"WG Web: <http://tools.ietf.org/wg/opsawg/>
WG List: <mailto:opsawg@ietf.org>
Editor: Bo Wu <lana.wubo@huawei.com>
Editor: Guangying Zheng <zhengguangying@huawei.com>";
description
"This module provides configuration of TACACS+ client.
Copyright (c) 2021 IETF Trust and the persons identified as import ietf-inet-types {
authors of the code. All rights reserved. prefix inet;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-yang-types {
prefix yang;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-network-instance {
prefix ni;
reference
"RFC 8529: YANG Data Model for Network Instances";
}
import ietf-interfaces {
prefix if;
reference
"RFC 8343: A YANG Data Model for Interface Management";
}
import ietf-system {
prefix sys;
reference
"RFC 7317: A YANG Data Model for System Management";
}
import ietf-netconf-acm {
prefix nacm;
reference
"RFC 8341: Network Configuration Access Control Model";
}
Redistribution and use in source and binary forms, with or organization
without modification, is permitted pursuant to, and subject "IETF OPSAWG (Operations and Management Area Working Group)";
to the license terms contained in, the Simplified BSD License contact
set forth in Section 4.c of the IETF Trust's Legal Provisions "WG Web: <http://datatracker.ietf.org/wg/opsawg/>
Relating to IETF Documents WG List: <mailto:opsawg@ietf.org>
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see the Editor: Bo Wu <lana.wubo@huawei.com>
RFC itself for full legal notices. Editor: Guangying Zheng <zhengguangying@huawei.com>";
description
"This module provides configuration of TACACS+ client.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED', NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
'MAY', and 'OPTIONAL' in this document are to be interpreted as 'MAY', and 'OPTIONAL' in this document are to be interpreted as
described in BCP 14 (RFC 2119) (RFC 8174) when, and only when, described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
they appear in all capitals, as shown here."; they appear in all capitals, as shown here.
// RFC Ed.: update the date below with the date of RFC Copyright (c) 2021 IETF Trust and the persons identified as
// publication and remove this note. authors of the code. All rights reserved.
// RFC Ed.: replace XXXX with actual RFC number and remove
// this note.
revision 2021-05-13 { Redistribution and use in source and binary forms, with or
description without modification, is permitted pursuant to, and subject
"Initial revision."; to the license terms contained in, the Simplified BSD License
reference set forth in Section 4.c of the IETF Trust's Legal Provisions
"RFC XXXX: A YANG Module for TACACS+"; Relating to IETF Documents
} (https://trustee.ietf.org/license-info).
typedef tacacs-plus-server-type { This version of this YANG module is part of RFC 9105; see the
type bits { RFC itself for full legal notices.";
bit authentication {
description
"Indicates that the TACACS+ server is providing authentication
services.";
}
bit authorization {
description
"Indicates that the TACACS+ server is providing authorization
services.";
}
bit accounting {
description
"Indicates that the TACACS+ server is providing accounting
services.";
}
}
description
"tacacs-plus-server-type can be set to
authentication/authorization/accounting
or any combination of the three types.";
}
identity tacacs-plus { revision 2021-08-05 {
base sys:authentication-method; description
description "Initial revision.";
"Indicates AAA operation using TACACS+."; reference
reference "RFC 9105: A YANG Data Model for Terminal Access Controller
"RFC 8907: The TACACS+ Protocol"; Access-Control System Plus (TACACS+)";
} }
grouping statistics { typedef tacacs-plus-server-type {
description type bits {
"Grouping for TACACS+ statistics attributes"; bit authentication {
container statistics { description
config false; "Indicates that the TACACS+ server is providing
description authentication services.";
"A collection of server-related statistics objects"; }
leaf connection-opens { bit authorization {
type yang:counter64; description
description "Indicates that the TACACS+ server is providing
"Number of new connection requests sent to the server, e.g., authorization services.";
socket open"; }
} bit accounting {
leaf connection-closes { description
type yang:counter64; "Indicates that the TACACS+ server is providing accounting
description services.";
"Number of connection close requests sent to the server, e.g., }
socket close"; }
} description
leaf connection-aborts { "tacacs-plus-server-type can be set to
type yang:counter64; authentication/authorization/accounting
description or any combination of the three types.";
"Number of aborted connections to the server. These do }
not include connections that are closed gracefully.";
}
leaf connection-failures {
type yang:counter64;
description
"Number of connection failures to the server";
}
leaf connection-timeouts {
type yang:counter64;
description
"Number of connection timeouts to the server";
}
leaf messages-sent {
type yang:counter64;
description
"Number of messages sent to the server";
}
leaf messages-received {
type yang:counter64;
description
"Number of messages received from the server";
}
leaf errors-received {
type yang:counter64;
description
"Number of error messages received from the server";
}
leaf sessions {
type yang:counter64;
description
"Number of TACACS+ sessions completed with the server.
If the Single Connection Mode was NOT enabled, the number of
sessions is the same as the number of 'connection-closes'.
If the Mode was enabled, a single TCP connection may contain
multiple TACACS+ sessions.";
}
}
}
grouping tacacs-plus { identity tacacs-plus {
description base sys:authentication-method;
"Grouping for TACACS+ attributes"; description
container tacacs-plus { "Indicates AAA operation using TACACS+.";
must "not(derived-from-or-self(../sys:authentication" reference
+ "/sys:user-authentication-order, 'tacacs-plus'))" "RFC 8907: The TACACS+ Protocol";
+ " or bit-is-set(server/server-type,'authentication')" { }
error-message "When 'tacacs-plus' is used as a system"
+ " authentication method, a TACACS+ authentication"
+ " server must be configured.";
description
"When 'tacacs-plus' is used as an authentication method,
a TACACS+ server must be configured.";
}
description
"Container for TACACS+ configurations and operations.";
list server {
key "name";
ordered-by user;
description
"List of TACACS+ servers used by the device.";
leaf name {
type string;
description
"An arbitrary name for the TACACS+ server.";
}
leaf server-type {
type tacacs-plus-server-type;
mandatory true;
description
"Server type: authentication/authorization/accounting and
various combinations.";
}
leaf address {
type inet:host;
mandatory true;
description
"The address of the TACACS+ server.";
}
leaf port {
type inet:port-number;
default "49";
description
"The port number of TACACS+ Server port.";
}
choice security {
mandatory true;
description
"Security mechanism between TACACS+ client and server.
This is modelled as a YANG 'choice' so that it can be
augmented by a YANG module in a backwards compatible
manner.";
case obfuscation {
leaf shared-secret {
type string {
length "1..max";
}
nacm:default-deny-all;
description
"The shared secret, which is known to both the
TACACS+ client and server. TACACS+ server
administrators SHOULD configure a shared secret of
minimum 16 characters length.
It is highly recommended that this shared secret is
at least 32 characters long and sufficiently complex
with a mix of different character types
i.e. upper case, lower case, numeric, punctuation.
Note that this security mechanism is best described as
'obfuscation' and not 'encryption' as it does not
provide any meaningful integrity, privacy, or replay
protection.";
reference
"RFC 8907: The TACACS+ Protocol";
}
}
} grouping statistics {
choice source-type { description
description "Grouping for TACACS+ statistics attributes.";
"The source address type for outbound TACACS+ packets."; container statistics {
case source-ip { config false;
leaf source-ip { description
type inet:ip-address; "A collection of server-related statistics objects.";
description leaf connection-opens {
"Specifies source IP address for TACACS+ outbound type yang:counter64;
packets."; description
} "Number of new connection requests sent to the server,
} e.g., socket open.";
case source-interface { }
leaf source-interface { leaf connection-closes {
type if:interface-ref; type yang:counter64;
description description
"Specifies the interface from which the IP address is "Number of connection close requests sent to the server,
derived for use as the source for the outbound TACACS+ e.g., socket close.";
packet"; }
} leaf connection-aborts {
} type yang:counter64;
} description
leaf vrf-instance { "Number of aborted connections to the server. These do
type leafref { not include connections that are closed gracefully.";
path "/ni:network-instances/ni:network-instance/ni:name"; }
} leaf connection-failures {
description type yang:counter64;
"Specifies the VPN Routing and Forwarding (VRF) instance to description
use to communicate with the TACACS+ server."; "Number of connection failures to the server.";
reference }
"RFC 8529: YANG Data Model for Network Instances"; leaf connection-timeouts {
} type yang:counter64;
leaf single-connection { description
type boolean; "Number of connection timeouts to the server.";
default "false"; }
description leaf messages-sent {
"Whether the single connection mode is enabled for the type yang:counter64;
server. By default, the single connection mode is description
disabled."; "Number of messages sent to the server.";
} }
leaf timeout { leaf messages-received {
type uint16 { type yang:counter64;
range "1..max"; description
} "Number of messages received from the server.";
units "seconds"; }
default "5"; leaf errors-received {
description type yang:counter64;
"The number of seconds the device will wait for a description
response from each TACACS+ server before trying with a "Number of error messages received from the server.";
different server."; }
} leaf sessions {
uses statistics; type yang:counter64;
} description
} "Number of TACACS+ sessions completed with the server.
} If the Single Connection Mode was NOT enabled, the number
of sessions is the same as the number of
'connection-closes'. If the Mode was enabled, a single
TCP connection may contain multiple TACACS+ sessions.";
}
}
}
augment "/sys:system" { grouping tacacs-plus {
description description
"Augment the system model with the tacacs-plus model"; "Grouping for TACACS+ attributes.";
uses tacacs-plus; container tacacs-plus {
} must "not(derived-from-or-self(../sys:authentication"
} + "/sys:user-authentication-order, 'tacacs-plus'))"
+ " or bit-is-set(server/server-type,'authentication')" {
error-message "When 'tacacs-plus' is used as a system"
+ " authentication method, a TACACS+"
+ " authentication server must be configured.";
description
"When 'tacacs-plus' is used as an authentication method,
a TACACS+ server must be configured.";
}
description
"Container for TACACS+ configurations and operations.";
list server {
key "name";
ordered-by user;
description
"List of TACACS+ servers used by the device.";
leaf name {
type string;
description
"An arbitrary name for the TACACS+ server.";
}
leaf server-type {
type tacacs-plus-server-type;
mandatory true;
description
"Server type: authentication/authorization/accounting and
various combinations.";
}
leaf address {
type inet:host;
mandatory true;
description
"The address of the TACACS+ server.";
}
leaf port {
type inet:port-number;
default "49";
description
"The port number of TACACS+ Server port.";
}
choice security {
mandatory true;
description
"Security mechanism between TACACS+ client and server.
This is modeled as a YANG 'choice' so that it can be
augmented by a YANG module in a backwards-compatible
manner.";
case obfuscation {
leaf shared-secret {
type string {
length "1..max";
}
nacm:default-deny-all;
description
"The shared secret, which is known to both the
TACACS+ client and server. TACACS+ server
administrators SHOULD configure a shared secret with
a minimum length of 16 characters.
It is highly recommended that this shared secret is
at least 32 characters long and sufficiently complex
with a mix of different character types,
i.e., upper case, lower case, numeric, and
punctuation. Note that this security mechanism is
best described as 'obfuscation' and not 'encryption'
as it does not provide any meaningful integrity,
privacy, or replay protection.";
reference
"RFC 8907: The TACACS+ Protocol";
}
}
}
choice source-type {
description
"The source address type for outbound TACACS+ packets.";
case source-ip {
leaf source-ip {
type inet:ip-address;
description
"Specifies source IP address for TACACS+ outbound
packets.";
}
}
case source-interface {
leaf source-interface {
type if:interface-ref;
description
"Specifies the interface from which the IP address
is derived for use as the source for the outbound
TACACS+ packet.";
}
}
}
leaf vrf-instance {
type leafref {
path "/ni:network-instances/ni:network-instance/ni:name";
}
description
"Specifies the VPN Routing and Forwarding (VRF) instance
to use to communicate with the TACACS+ server.";
reference
"RFC 8529: YANG Data Model for Network Instances";
}
leaf single-connection {
type boolean;
default "false";
description
"Indicates whether the Single Connection Mode is enabled
for the server. By default, the Single Connection Mode
is disabled.";
}
leaf timeout {
type uint16 {
range "1..max";
}
units "seconds";
default "5";
description
"The number of seconds the device will wait for a
response from each TACACS+ server before trying with a
different server.";
}
uses statistics;
}
}
}
augment "/sys:system" {
description
"Augments the system model with the tacacs-plus model.";
uses tacacs-plus;
}
}
<CODE ENDS> <CODE ENDS>
5. Security Considerations 5. Security Considerations
The YANG module defined in this document is designed to be accessed The YANG module specified in this document defines a schema for data
via network management protocols such as NETCONF [RFC6241] or that is designed to be accessed via network management protocols such
RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer
layer, and the mandatory-to-implement secure transport is Secure is the secure transport layer, and the mandatory-to-implement secure
Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer
mandatory-to-implement secure transport is TLS [RFC8446]. is HTTPS, and the mandatory-to-implement secure transport is TLS
[RFC8446].
The NETCONF access control model [RFC8341] provides the means to The Network Configuration Access Control Model (NACM) [RFC8341]
restrict access for particular NETCONF or RESTCONF users to a provides the means to restrict access for particular NETCONF or
preconfigured subset of all available NETCONF or RESTCONF protocol RESTCONF users to a preconfigured subset of all available NETCONF or
operations and content. RESTCONF protocol operations and content.
There are a number of data nodes defined in this YANG module that are There are a number of data nodes defined in this YANG module that are
writable/creatable/deletable (i.e., config true, which is the writable/creatable/deletable (i.e., config true, which is the
default). These data nodes may be considered sensitive or vulnerable default). These data nodes may be considered sensitive or vulnerable
in some network environments. Write operations (e.g., edit-config) in some network environments. Write operations (e.g., edit-config)
to these data nodes without proper protection can have a negative to these data nodes without proper protection can have a negative
effect on network operations. These are the subtrees and data nodes effect on network operations. These are the subtrees and data nodes
and their sensitivity/vulnerability: and their sensitivity/vulnerability:
/system/tacacsplus/server: This list contains the data nodes used to /system/tacacs-plus/server: This list contains the data nodes used
control the TACACS+ servers used by the device. Unauthorized to control the TACACS+ servers used by the device. Unauthorized
access to this list could enable an attacker to assume complete access to this list could enable an attacker to assume complete
control over the device by pointing to a compromised TACACS+ control over the device by pointing to a compromised TACACS+
server ,or to modify the counters to hide attacks against the server, or to modify the counters to hide attacks against the
device. device.
/system/tacacsplus/server/shared-secret: This leaf controls the key /system/tacacs-plus/server/shared-secret: This leaf controls the key
known to both the TACACS+ client and server. Unauthorized access known to both the TACACS+ client and server. Unauthorized access
to this leaf could make the device vulnerable to attacks, to this leaf could make the device vulnerable to attacks;
therefore it has been restricted using the "default-deny-all" therefore, it has been restricted using the "default-deny-all"
access control defined in [RFC8341]. When setting, it is highly access control defined in [RFC8341]. When setting, it is highly
recommended that the leaf is at least 32 characters long and recommended that the leaf is at least 32 characters long and
sufficiently complex with a mix of different character types i.e. sufficiently complex with a mix of different character types,
upper case, lower case, numeric, punctuation. i.e., upper case, lower case, numeric, and punctuation.
This document describes the use of TACACS+ for purposes of This document describes the use of TACACS+ for purposes of
authentication, authorization and accounting, it is vulnerable to all authentication, authorization, and accounting; it is vulnerable to
of the threats that are present in TACACS+ applications. For a all of the threats that are present in TACACS+ applications. For a
discussion of such threats, see Section 10 of the TACACS+ Protocol discussion of such threats, see Section 10 of the TACACS+ protocol
[RFC8907]. [RFC8907].
6. IANA Considerations 6. IANA Considerations
This document registers a URI in the IETF XML registry [RFC3688]. IANA has registered the following URI in the "ns" subregistry within
Following the format in [RFC3688], the following registration is the "IETF XML Registry" [RFC3688]:
requested to be made:
URI: urn:ietf:params:xml:ns:yang:ietf-system-tacacs-plus
Registrant Contact: The IESG.
XML: N/A, the requested URI is an XML namespace.
This document registers a YANG module in the YANG Module Names
registry [RFC7950].
Name: ietf-system-tacacs-plus URI: urn:ietf:params:xml:ns:yang:ietf-system-tacacs-plus
Namespace: urn:ietf:params:xml:ns:yang:ietf-system-tacacs-plus Registrant Contact: The IESG.
Prefix: sys-tcs-plus XML: N/A, the requested URI is an XML namespace.
Reference: RFC XXXX (RFC Ed.: replace XXXX with actual
RFC number and remove this note.)
7. Acknowledgments IANA has registered the following YANG module in the "YANG Module
Names" registry [RFC7950]:
The authors wish to thank Alex Campbell, John Heasley, Ebben Aries, Name: ietf-system-tacacs-plus
Alan DeKok, Joe Clarke, Joe Clarke, Tom Petch, Robert Wilton, and Maintained by IANA: N
many others for their helpful comments and suggestions. Namespace: urn:ietf:params:xml:ns:yang:ietf-system-tacacs-plus
Prefix: sys-tcs-plus
Reference: RFC 9105
8. References 7. References
8.1. Normative References 7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>. <https://www.rfc-editor.org/info/rfc6241>.
skipping to change at page 15, line 14 skipping to change at line 644
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>. <https://www.rfc-editor.org/info/rfc8446>.
[RFC8529] Berger, L., Hopps, C., Lindem, A., Bogdanovic, D., and X. [RFC8529] Berger, L., Hopps, C., Lindem, A., Bogdanovic, D., and X.
Liu, "YANG Data Model for Network Instances", RFC 8529, Liu, "YANG Data Model for Network Instances", RFC 8529,
DOI 10.17487/RFC8529, March 2019, DOI 10.17487/RFC8529, March 2019,
<https://www.rfc-editor.org/info/rfc8529>. <https://www.rfc-editor.org/info/rfc8529>.
[RFC8907] Dahm, T., Ota, A., Medway Gash, D., Carrel, D., and L. [RFC8907] Dahm, T., Ota, A., Medway Gash, D.C., Carrel, D., and L.
Grant, "The Terminal Access Controller Access-Control Grant, "The Terminal Access Controller Access-Control
System Plus (TACACS+) Protocol", RFC 8907, System Plus (TACACS+) Protocol", RFC 8907,
DOI 10.17487/RFC8907, September 2020, DOI 10.17487/RFC8907, September 2020,
<https://www.rfc-editor.org/info/rfc8907>. <https://www.rfc-editor.org/info/rfc8907>.
8.2. Informative References 7.2. Informative References
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004, DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>. <https://www.rfc-editor.org/info/rfc3688>.
Appendix A. Example TACACS+ Authentication Configuration Appendix A. Example TACACS+ Authentication Configuration
The following shows an example where a TACACS+ authentication server The following shows an example where a TACACS+ authentication server
instance is configured. instance is configured.
skipping to change at page 16, line 5 skipping to change at line 681
"address": "192.0.2.2", "address": "192.0.2.2",
"shared-secret": "QaEfThUkO198010075460923+h3TbE8n", "shared-secret": "QaEfThUkO198010075460923+h3TbE8n",
"source-ip": "192.0.2.12", "source-ip": "192.0.2.12",
"timeout": "10" "timeout": "10"
} }
] ]
} }
} }
} }
Acknowledgments
The authors wish to thank Alex Campbell, John Heasley, Ebben Aries,
Alan DeKok, Joe Clarke, Tom Petch, Robert Wilton, and many others for
their helpful comments and suggestions.
Authors' Addresses Authors' Addresses
Bo Wu (editor) Bo Wu (editor)
Huawei Technologies, Co., Huawei Technologies, Co., Ltd
Ltd Yuhua District
101 Software Avenue, Yuhua District 101 Software Avenue
Nanjing, Jiangsu 210012 Nanjing
Jiangsu, 210012
China China
Email: lana.wubo@huawei.com Email: lana.wubo@huawei.com
Guangying Zheng Guangying Zheng
Huawei Technologies, Co., Huawei Technologies, Co., Ltd
Ltd Yuhua District
101 Software Avenue, Yuhua District 101 Software Avenue
Nanjing, Jiangsu 210012 Nanjing
Jiangsu, 210012
China China
Email: zhengguangying@huawei.com Email: zhengguangying@huawei.com
Michael Wang (editor) Michael Wang (editor)
Huawei Technologies, Co., Huawei Technologies, Co., Ltd
Ltd Yuhua District
101 Software Avenue, Yuhua District 101 Software Avenue
Nanjing 210012 Nanjing
210012
China China
Email: wangzitao@huawei.com Email: wangzitao@huawei.com
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