draft-ietf-opsawg-tacacs-yang-03.txt   draft-ietf-opsawg-tacacs-yang-04.txt 
Network Working Group G. Zheng Network Working Group G. Zheng
Internet-Draft M. Wang Internet-Draft M. Wang
Intended status: Standards Track B. Wu Intended status: Standards Track B. Wu
Expires: October 21, 2020 Huawei Expires: November 9, 2020 Huawei
April 19, 2020 May 8, 2020
Yang data model for TACACS+ Yang data model for TACACS+
draft-ietf-opsawg-tacacs-yang-03 draft-ietf-opsawg-tacacs-yang-04
Abstract Abstract
This document defines YANG modules that augment the System Management This document defines YANG modules that augment the System Management
data model defined in the RFC 7317 with TACACS+ client model. The data model defined in the RFC 7317 with TACACS+ client model. The
data model of Terminal Access Controller Access Control System Plus data model of Terminal Access Controller Access Control System Plus
(TACACS+) client allows the configuration of TACACS+ servers for (TACACS+) client allows the configuration of TACACS+ servers for
centralized Authentication, Authorization and Accounting. centralized Authentication, Authorization and Accounting.
The YANG modules in this document conforms to the Network Management The YANG modules in this document conforms to the Network Management
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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 October 21, 2020. This Internet-Draft will expire on November 9, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 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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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 Data Model . . . . . . . . . . . . . . . . . . 3 3. Design of the Data Model . . . . . . . . . . . . . . . . . . 3
4. TACACS+ Client Module . . . . . . . . . . . . . . . . . . . . 5 4. TACACS+ Client Module . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.1. Normative References . . . . . . . . . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . 13
8.2. Informative References . . . . . . . . . . . . . . . . . 13 8.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. TACACS+ Authentication Configuration . . . . . . . . 14 Appendix A. Example Tacacs+ Authentication Configuration . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction 1. Introduction
This document defines YANG modules that augment the System Management This document defines YANG modules that augment the System Management
data model defined in the [RFC7317] with TACACS+ client model. data model defined in the [RFC7317] with TACACS+ client model.
TACACS+ provides Device Administration for routers, network access TACACS+ provides Device Administration for routers, network access
servers and other networked computing devices via one or more servers and other networked computing devices via one or more
centralized servers which is defined in the TACACS+ Protocol. centralized servers which is defined in the TACACS+ Protocol.
[I-D.ietf-opsawg-tacacs] [I-D.ietf-opsawg-tacacs]
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This model is used to configure TACACS+ client on the device to This model is used to configure TACACS+ client on the device to
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 name and password, authorization allows the user to validate a user's name and password, authorization allows the user to
access and execute commands at various command levels assigned to the access and execute commands at various command levels assigned to the
user and accounting keeps track of the activity of a user who has user and accounting keeps track of the activity of a user who has
accessed the device. accessed the device.
The ietf-system-tacacsplus module is intended to augment the The ietf-system-tacacsplus module is intended to augment the
"/sys:system" path defined in the ietf-system module with "/sys:system" path defined in the ietf-system module with the
"tacacsplus" grouping. Therefore, a device can use local, Remote contents of the"tacacsplus" grouping. Therefore, a device can use
Authentication Dial In User Service (RADIUS), or Terminal Access local, Remote Authentication Dial In User Service (RADIUS), or
Controller Access Control System Plus (TACACS+) to validate users who Terminal Access Controller Access Control System Plus (TACACS+) to
attempt to access the router by several mechanisms, e.g. a command validate users who attempt to access the router by several
line interface or a web-based user interface. mechanisms, e.g. a command line interface or a web-based user
interface.
The "server" list is directly under the "tacacsplus" container, which The "server" list is directly under the "tacacsplus" container, which
holds a list of TACACS+ servers and uses server-type to distinguish holds a list of TACACS+ servers and uses server-type to distinguish
between the three protocols. The list of servers is for redundancy. between the three protocols. 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 [I-D.ietf-opsawg-tacacs], and some are derived the TACACS+ protocol [I-D.ietf-opsawg-tacacs], and some are derived
from the various implementations by network equipment manufacturers. from the various implementations by network equipment manufacturers.
For example, when there are multiple interfaces connected to the For example, when there are multiple interfaces connected to the
TACACS+ client or server, the source address of outgoing TACACS+ TACACS+ client or server, the source address of outgoing TACACS+
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include the amount of data a user has sent and/or received during a include the amount of data a user has sent and/or received during a
session. session.
The data model for TACACS+ client has the following structure: The data model for TACACS+ client has the following structure:
module: ietf-system-tacacsplus module: ietf-system-tacacsplus
augment /sys:system: augment /sys:system:
+--rw tacacsplus {tacacsplus}? +--rw tacacsplus {tacacsplus}?
+--rw server* [name] +--rw server* [name]
+--rw name string +--rw name string
+--rw server-type? enumeration +--rw server-type? tcsplus-server-type
+--rw address inet:host +--rw address inet:host
+--rw port? inet:port-number +--rw port? inet:port-number
+--rw shared-secret string +--rw shared-secret string
+--rw (source-type)? +--rw (source-type)?
| +--:(source-ip) | +--:(source-ip)
| | +--rw source-ip? inet:ip-address | | +--rw source-ip? inet:ip-address
| +--:(source-interface) | +--:(source-interface)
| +--rw source-interface? if:interface-ref | +--rw source-interface? if:interface-ref
+--rw vrf-instance? +--rw vrf-instance?
| -> /ni:network-instances/network-instance/name | -> /ni:network-instances/network-instance/name
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+--ro connection-aborts? yang:counter64 +--ro connection-aborts? yang:counter64
+--ro connection-failures? yang:counter64 +--ro connection-failures? yang:counter64
+--ro connection-timeouts? yang:counter64 +--ro connection-timeouts? yang:counter64
+--ro messages-sent? yang:counter64 +--ro messages-sent? yang:counter64
+--ro messages-received? yang:counter64 +--ro messages-received? yang:counter64
+--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
<CODE BEGINS> file "ietf-system-tacacsplus@2020-04-20.yang" <CODE BEGINS> file "ietf-system-tacacsplus@2020-05-09.yang"
module ietf-system-tacacsplus { module ietf-system-tacacsplus {
yang-version 1.1; yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-system-tacacsplus"; namespace "urn:ietf:params:xml:ns:yang:ietf-system-tacacsplus";
prefix sys-tcsplus; prefix sys-tcsplus;
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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"RFC 8341: Network Configuration Access Control Model"; "RFC 8341: Network Configuration Access Control Model";
} }
organization organization
"IETF Opsawg (Operations and Management Area Working Group)"; "IETF Opsawg (Operations and Management Area Working Group)";
contact contact
"WG Web: <http://tools.ietf.org/wg/opsawg/> "WG Web: <http://tools.ietf.org/wg/opsawg/>
WG List: <mailto:opsawg@ietf.org> WG List: <mailto:opsawg@ietf.org>
Editor: Bo Wu <lana.wubo@huawei.com> Editor: Bo Wu <lana.wubo@huawei.com>
: Guangying Zheng <zhengguangying@huawei.com>"; Editor: Guangying Zheng <zhengguangying@huawei.com>";
description description
"This module provides configuration of TACACS+ client. "This module provides configuration of TACACS+ client.
Copyright (c) 2020 IETF Trust and the persons identified as Copyright (c) 2020 IETF Trust and the persons identified as
authors of the code. All rights reserved. authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions set forth in Section 4.c of the IETF Trust's Legal Provisions
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.";
revision 2020-04-20 { revision 2020-05-09 {
description description
"Initial revision."; "Initial revision.";
reference reference
"RFC XXXX: A Yang Data Model for TACACS+"; "RFC XXXX: A Yang Data Model for TACACS+";
} }
typedef tcsplus-server-type {
type bits {
bit authentication {
description
"When set, the server is an authentication server.";
}
bit authorization {
description
"When set, the server is an authorization server.";
}
bit accounting {
description
"When set, the server is an accounting server.";
}
}
description
"server-type can be set to authentication/authorization/accounting
or any combination of the three types. When all three types are
supported, all the three bits are set.";
}
feature tacacsplus { feature tacacsplus {
description description
"Indicates that the device can be configured as a TACACS+ "Indicates that the device can be configured as a TACACS+
client."; client.";
reference reference
"draft-ietf-opsawg-tacacs-18: The TACACS+ Protocol"; "draft-ietf-opsawg-tacacs-18: The TACACS+ Protocol";
} }
identity tacacsplus { identity tacacsplus {
base sys:authentication-method; base sys:authentication-method;
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"Number of messages received by the server"; "Number of messages received by the server";
} }
leaf errors-received { leaf errors-received {
type yang:counter64; type yang:counter64;
description description
"Number of error messages received from the server"; "Number of error messages received from the server";
} }
leaf sessions { leaf sessions {
type yang:counter64; type yang:counter64;
description description
"Total Number of sessions. A single-connection tacacs+ "Number of TACACS+ sessions completed with the server.
connection may be >1 sessions."; 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 tacacsplus { grouping tacacsplus {
description description
"Grouping for TACACS+ attributes"; "Grouping for TACACS+ attributes";
container tacacsplus { container tacacsplus {
if-feature "tacacsplus"; if-feature "tacacsplus";
must "not(derived-from-or-self(../sys:authentication" must "not(derived-from-or-self(../sys:authentication"
+ "/sys:user-authentication-order, 'tacacsplus')) or server" { + "/sys:user-authentication-order, 'tacacsplus')) or server" {
error-message "When 'tacacsplus' is used as a sysytem" error-message "When 'tacacsplus' is used as a system"
+ " authentication method, a TACACS+ server" + " authentication method, a TACACS+ server"
+ " must be configured."; + " must be configured.";
description description
"When 'tacacsplus' is used as an authentication method, "When 'tacacsplus' is used as an authentication method,
a TACACS+ server must be configured."; a TACACS+ server must be configured.";
} }
description description
"Container for TACACS+ configurations and operations."; "Container for TACACS+ configurations and operations.";
list server { list server {
key "name"; key "name";
ordered-by user; ordered-by user;
description description
"List of TACACS+ servers used by the device."; "List of TACACS+ servers used by the device.";
leaf name { leaf name {
type string; type string;
description description
"An arbitrary name for the TACACS+ server."; "An arbitrary name for the TACACS+ server.";
} }
leaf server-type { leaf server-type {
type enumeration { type tcsplus-server-type;
enum authentication {
description
"The server is an authentication server.";
}
enum authorization {
description
"The server is an authorization server.";
}
enum accounting {
description
"The server is an accounting server.";
}
enum all {
description
"The group of all types of TACACS+ servers.";
}
}
description description
"Server type: authentication/authorization/accounting/all."; "Server type: authentication/authorization/accounting and
various combinations.
When all three types are supported, all the three bits
are set.";
} }
leaf address { leaf address {
type inet:host; type inet:host;
mandatory true; mandatory true;
description description
"The address of the TACACS+ server."; "The address of the TACACS+ server.";
} }
leaf port { leaf port {
type inet:port-number; type inet:port-number;
default "49"; default "49";
description description
"The port number of TACACS+ Server port."; "The port number of TACACS+ Server port.";
} }
leaf shared-secret { leaf shared-secret {
type string; type string {
length "16..max";
}
mandatory true; mandatory true;
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 administrators TACACS+ client and server. TACACS+ server administrators
should configure secret keys of minimum should configure shared secret of minimum 16 characters
16 characters length."; length.
It is highly recommended that shared keys are at least 32
characters long.";
reference reference
"TACACS+ protocol:"; "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 {
type inet:ip-address; type inet:ip-address;
description description
"Specifies source IP address for TACACS+ outbound "Specifies source IP address for TACACS+ outbound
packets."; packets.";
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response from each TACACS+ server before trying with a response from each TACACS+ server before trying with a
different server."; different server.";
} }
uses statistics; uses statistics;
} }
} }
} }
augment "/sys:system" { augment "/sys:system" {
description description
"Augment the system model with authorization and accounting "Augment the system model with the tacacsplus model";
attributes
Augment the system model with the tacacsplus model";
uses tacacsplus; uses tacacsplus;
} }
} }
<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 defined in this document is designed to be accessed
via network management protocols such as NETCONF [RFC6241] or via network management protocols such as NETCONF [RFC6241] or
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The NETCONF access control model [RFC8341] provides the means to The NETCONF access control model [RFC8341] provides the means to
restrict access for particular NETCONF or RESTCONF users to a restrict access for particular NETCONF or RESTCONF users to a
preconfigured subset of all available NETCONF or RESTCONF protocol preconfigured subset of all available NETCONF or RESTCONF protocol
operations and content. 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. effect on network operations. These are the subtrees and data nodes
and their sensitivity/vulnerability:
/system/tacacsplus/server: This list contains the objects used to
control the TACACS+ servers used by the device. Unauthorized
access to this list could cause a user management failure on the
device .
/system/tacacsplus/server/shared-secret: This leaf controls the
key known to both the TACACS+ client and server. Unauthorized
access to this leaf could cause the device vulnerable to attacks.
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
[I-D.ietf-opsawg-tacacs]. [I-D.ietf-opsawg-tacacs].
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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registry [RFC7950]. registry [RFC7950].
Name: ietf-system-tacacsplus Name: ietf-system-tacacsplus
Namespace: urn:ietf:params:xml:ns:yang: ietf-tacacsplus Namespace: urn:ietf:params:xml:ns:yang: ietf-tacacsplus
Prefix: sys-tcsplus Prefix: sys-tcsplus
Reference: RFC XXXX Reference: RFC XXXX
7. Acknowledgments 7. Acknowledgments
The authors wish to thank Alex Campbell, John Heasley, Ebben Aries, The authors wish to thank Alex Campbell, John Heasley, Ebben Aries,
Alan DeKok, Joe Clarke, and many others for their helpful comments Alan DeKok, Joe Clarke, Joe Clarke, Tom Petch, and many others for
and suggestions. their helpful comments and suggestions.
8. References 8. References
8.1. Normative References 8.1. Normative References
[I-D.ietf-opsawg-tacacs] [I-D.ietf-opsawg-tacacs]
Dahm, T., Ota, A., dcmgash@cisco.com, d., Carrel, D., and Dahm, T., Ota, A., dcmgash@cisco.com, d., Carrel, D., and
L. Grant, "The TACACS+ Protocol", draft-ietf-opsawg- L. Grant, "The TACACS+ Protocol", draft-ietf-opsawg-
tacacs-18 (work in progress), March 2020. tacacs-18 (work in progress), March 2020.
skipping to change at page 14, line 5 skipping to change at page 14, line 25
[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>.
8.2. Informative References 8.2. 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. TACACS+ Authentication Configuration Appendix A. Example Tacacs+ Authentication Configuration
The system management model defines two authentication configuration
options, "local-users" and "radius", and use "user-authentication-
order" to control the authentication methods. As defined in
[RFC7317], the current system authentication methods model is as
follows:
+--rw system The following shows an example where a tacacs+ authentication server
+--rw authentication instance is configured.
+--rw user-authentication-order* identityref
...
This draft defines the "tacacsplus" extension and therefore needs to {
be configured in the same way. The 'tacacsplus' identity is defined "ietf-system:system": {
to control whether or not TACACS+ authentication should be used. "authentication": {
"user-authentication-order": [tacacsplus, local-users]
}
"tacacsplus": {
"server": [
{
"name": "tac_plus1",
"server-type": "authentication"
"address": "10.10.10.2",
"shared-secret": "QaEfThUkO1980100754609236h3TbE8n",
"source-ip": "10.10.10.12"
"single-connection": "false"
"timeout": "10"
}
]
}
}
}
Authors' Addresses Authors' Addresses
Guangying Zheng Guangying Zheng
Huawei Huawei
101 Software Avenue, Yuhua District 101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012 Nanjing, Jiangsu 210012
China China
Email: zhengguangying@huawei.com Email: zhengguangying@huawei.com
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