draft-ietf-opsawg-tacacs-yang-09.txt   draft-ietf-opsawg-tacacs-yang-10.txt 
Opsawg B. Wu, Ed. Opsawg B. Wu, Ed.
Internet-Draft G. Zheng Internet-Draft G. Zheng
Intended status: Standards Track M. Wang, Ed. Intended status: Standards Track M. Wang, Ed.
Expires: September 13, 2021 Huawei Expires: October 10, 2021 Huawei
March 12, 2021 April 8, 2021
YANG Data Model for TACACS+ A YANG Module for TACACS+
draft-ietf-opsawg-tacacs-yang-09 draft-ietf-opsawg-tacacs-yang-10
Abstract Abstract
This document defines a TACACS+ client YANG module, that augments the This document defines a Terminal Access Controller Access-Control
System Management data model, defined in RFC 7317, to allow devices System Plus (TACACS+) client YANG module, that augments the System
to make use of TACACS+ servers for centralized Authentication, Management data model, defined in RFC 7317, to allow devices to make
Authorization and Accounting. use of TACACS+ servers for centralized Authentication, Authorization
and Accounting (AAA).
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 Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 13, 2021. This Internet-Draft will expire on October 10, 2021.
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
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3 2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Tree Diagrams . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Tree Diagrams . . . . . . . . . . . . . . . . . . . . . . 3
3. Design of the TACACS+ Data Model . . . . . . . . . . . . . . 3 3. Design of the TACACS+ Data Model . . . . . . . . . . . . . . 3
4. TACACS+ Client Module . . . . . . . . . . . . . . . . . . . . 5 4. TACACS+ Client Module . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 12 5. Security Considerations . . . . . . . . . . . . . . . . . . . 12
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.1. Normative References . . . . . . . . . . . . . . . . . . 13 8.1. Normative References . . . . . . . . . . . . . . . . . . 13
8.2. Informative References . . . . . . . . . . . . . . . . . 14 8.2. Informative References . . . . . . . . . . . . . . . . . 15
Appendix A. Example TACACS+ Authentication Configuration . . . . 14 Appendix A. Example TACACS+ Authentication Configuration . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
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 the [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
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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
Tree diagrams used in this document follow the notation defined in Tree diagrams used in this document follow the notation defined in
[RFC8340]. [RFC8340].
3. Design of the TACACS+ Data Model 3. Design of the TACACS+ Data Model
This model is used to configure TACACS+ client on a device to support This module is used to configure TACACS+ client on a device to
deployment scenarios with centralized authentication, authorization, support deployment scenarios with centralized authentication,
and accounting servers. Authentication is used to validate a user's authorization, and accounting servers. Authentication is used to
username and password, authorization allows the user to access and validate a user's username and password, authorization allows the
execute commands at various command levels assigned to the user, and user to access and execute commands at various command levels
accounting keeps track of the activity of a user who has accessed the assigned to the user, and accounting keeps track of the activity of a
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+ to validate users who attempt to access the router by several
mechanisms, e.g., a command line interface or a web-based user mechanisms, e.g., a command line interface or a web-based user
interface. interface.
The "server" list is directly under the "tacacs-plus" container, The "server" list is directly under the "tacacs-plus" container,
which holds a list of TACACS+ servers and uses server-type to which 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). 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 FIB. For the TACACS+ server located in a Virtual from the local Forwarding Information Base (FIB). For the TACACS+
Private Network(VPN), a VRF instance needs to be specified. server located in a Virtual Private Network (VPN), a VPN Routing and
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 data model for TACACS+ client has the following structure: The YANG module for TACACS+ client has the following structure:
module: ietf-system-tacacs-plus module: ietf-system-tacacs-plus
augment /sys:system: augment /sys:system:
+--rw tacacs-plus +--rw tacacs-plus
+--rw server* [name] +--rw server* [name]
+--rw name string +--rw name string
+--rw server-type? tacacs-plus-server-type +--rw server-type? tacacs-plus-server-type
+--rw address inet:host +--rw address inet:host
+--rw port? inet:port-number +--rw port? inet:port-number
+--rw (encryption) +--rw (encryption)
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+--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@2021-03-12.yang" <CODE BEGINS> file "ietf-system-tacacs-plus@2021-04-08.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 { import ietf-inet-types {
prefix inet; prefix inet;
reference reference
"RFC 6991: Common YANG Data Types"; "RFC 6991: Common YANG Data Types";
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Relating to IETF Documents Relating to IETF Documents
(http://trustee.ietf.org/license-info). (http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see the This version of this YANG module is part of RFC XXXX; see the
RFC itself for full legal notices."; RFC itself for full legal notices.";
// RFC Ed.: update the date below with the date of RFC // RFC Ed.: update the date below with the date of RFC
// publication and remove this note. // publication and remove this note.
// RFC Ed.: replace XXXX with actual RFC number and remove // RFC Ed.: replace XXXX with actual RFC number and remove
// this note. // this note.
revision 2021-03-12 { revision 2021-04-08 {
description description
"Initial revision."; "Initial revision.";
reference reference
"RFC XXXX: A Yang Data Model for TACACS+"; "RFC XXXX: A YANG Module for TACACS+";
} }
typedef tacacs-plus-server-type { typedef tacacs-plus-server-type {
type bits { type bits {
bit authentication { bit authentication {
description description
"Indicates that the TACACS server is providing authentication "Indicates that the TACACS server is providing authentication
services."; services.";
} }
bit authorization { bit authorization {
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leaf shared-secret { leaf shared-secret {
type string { type string {
length "16..max"; length "16..max";
} }
nacm:default-deny-all; nacm:default-deny-all;
description description
"The shared secret, which is known to both the "The shared secret, which is known to both the
TACACS+ client and server. TACACS+ server TACACS+ client and server. TACACS+ server
administrators should configure shared secret of administrators should configure shared secret of
minimum 16 characters length. minimum 16 characters length.
It is highly recommended that shared keys are at least It is highly recommended that this shared secret is
32 characters long."; at least 32 characters long and sufficiently complex
with a mix of different character types
i.e. upper case, lower case, numeric, punctuation.";
reference reference
"RFC 8907: The TACACS+ Protocol"; "RFC 8907: The TACACS+ Protocol";
} }
} }
} }
choice source-type { choice source-type {
description description
"The source address type for outbound TACACS+ packets."; "The source address type for outbound TACACS+ packets.";
case source-ip { case source-ip {
leaf source-ip { leaf source-ip {
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/system/tacacsplus/server: This list contains the data nodes used to /system/tacacsplus/server: This list contains the data nodes used to
control the TACACS+ servers used by the device. Unauthorized control the TACACS+ servers used by the device. Unauthorized
access to this list could cause a complete control over the device access to this list could cause a complete control over the device
by pointing to a compromised TACACS+ server. by pointing to a compromised TACACS+ server.
/system/tacacsplus/server/shared-secret: This leaf controls the key /system/tacacsplus/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 has been restricted using the "default-deny-all" access therefore has been restricted using the "default-deny-all" access
control defined in [RFC8341]. control defined in [RFC8341]. When setting, it is highly
recommended that the leaf is at least 32 characters long and
sufficiently complex with a mix of different character types i.e.
upper case, lower case, numeric, 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 all
of the threats that are present in TACACS+ applications. For a of the threats that are present in TACACS+ applications. For a
discussion of such threats, see Section 9 of the TACACS+ Protocol discussion of such threats, see Section 9 of the TACACS+ Protocol
[RFC8907]. [RFC8907].
6. IANA Considerations 6. IANA Considerations
This document registers a URI in the IETF XML registry [RFC3688]. This document registers a URI in the IETF XML registry [RFC3688].
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"ietf-system:system": { "ietf-system:system": {
"authentication": { "authentication": {
"user-authentication-order": [tacacs-plus, local-users] "user-authentication-order": [tacacs-plus, local-users]
} }
"tacacs-plus": { "tacacs-plus": {
"server": [ "server": [
{ {
"name": "tac_plus1", "name": "tac_plus1",
"server-type": "authentication", "server-type": "authentication",
"address": "192.0.2.2", "address": "192.0.2.2",
"shared-secret": "QaEfThUkO1980100754609236h3TbE8n", "shared-secret": "QaEfThUkO198010075460923+h3TbE8n",
"source-ip": "192.0.2.12", "source-ip": "192.0.2.12",
"timeout": "10" "timeout": "10"
} }
] ]
} }
} }
} }
Authors' Addresses Authors' Addresses
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