RFC 7317
A YANG Data Model for System Management
Hey bestie, it's RFC 7317! 🎀✨
Okay so this one is a YANG data model for System Management 💅. The authors are A. Bierman from YumaWorks and M. Bjorklund from Tail-f Systems. It's a Standards Track doc (ISSN 2070-1721), dated August 2014. The title block doesn't list any Obsoletes or Updates, so it doesn't replace or patch anything else 🦋.
Its whole vibe is making the common stuff on a NETCONF-managed device (the system name, the clock, who can log in, the DNS resolver) configurable in a standard way. Yes, that's iconic 👑.
Abstract
This doc defines a YANG data model for configuring and identifying common system properties on a device running a Network Configuration Protocol (NETCONF) server. It also covers system identification, time-of-day management, user management, DNS resolver config, and a few protocol operations for system management 🌸.
Status of This Memo
This is an Internet Standards Track document 💜.
It's a product of the Internet Engineering Task Force (IETF) and represents the consensus of the IETF community. It went through public review and got approved for publication by the Internet Engineering Steering Group (IESG). If you want more on Internet Standards, check Section 2 of RFC 5741 🧚.
For the current status, errata, and how to send feedback, go to http://www.rfc-editor.org/info/rfc7317 🔥.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved 🌈.
This doc is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) as in effect on the publication date. Read those carefully, because they spell out your rights and restrictions. Code Components pulled from this doc must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions, and they come without warranty as described in the Simplified BSD License 🫶.
Table of Contents
1. Introduction ....................................................2
1.1. Terminology ................................................3
1.2. Tree Diagrams ..............................................3
2. Objectives ......................................................4
2.1. System Identification ......................................4
2.2. System Time Management .....................................4
2.3. User Authentication ........................................4
2.4. DNS Resolver ...............................................5
2.5. System Control .............................................5
3. System Data Model ...............................................5
3.1. System Identification ......................................5
3.2. System Time Management .....................................6
3.3. DNS Resolver Model .........................................7
3.4. RADIUS Client Model ........................................7
3.5. User Authentication Model ..................................8
3.5.1. SSH Public Key Authentication .......................8
3.5.2. Local User Password Authentication ..................9
3.5.3. RADIUS Password Authentication ......................9
3.6. System Control .............................................9
4. Relationship to the SNMPv2-MIB .................................10
5. IANA Crypt Hash YANG Module ....................................10
6. System YANG Module .............................................13
7. IANA Considerations ............................................31
8. Security Considerations ........................................31
9. References .....................................................33
9.1. Normative References ......................................33
9.2. Informative References ....................................351. Introduction ✨
This doc defines a YANG [RFC6020] data model for configuring and identifying some common properties on a device that runs a Network Configuration Protocol (NETCONF) server 💖.
Devices managed by NETCONF (and maybe other mechanisms too) have common properties that need to be configured and monitored in a standard way. That's the whole point 🎀.
The "ietf-system" YANG module defined here gives you these features:
- configuration and monitoring of system identification
- configuration and monitoring of system time-of-day
- configuration of user authentication
- configuration of local users
- configuration of the DNS resolver
- system control operations (shutdown, restart, setting time)
1.1. 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] 🔥.
These terms are defined in [RFC6241] and aren't redefined here:
- client
- configuration data
- server
- state data
These terms are defined in [RFC6020] and aren't redefined here:
- augment
- data model
1.2. Tree Diagrams
The doc uses a simplified graphical view of the data model. Here's what the symbols mean 🦋:
- Brackets "[" and "]" enclose list keys.
- Abbreviations before data node names:
rwmeans configuration (read-write), andromeans state data (read-only). - Symbols after data node names:
?means an optional node,!means a presence container, and*denotes a list and leaf-list. - Parentheses enclose choice and case nodes, and case nodes are also marked with a colon (":").
- Ellipsis ("...") stands for contents of subtrees that aren't shown.
2. Objectives 🌸
2.1. System Identification
Lots of common properties are used to identify devices, operating systems, software versions, and so on. These need to be supported in the system data module. They're defined as operational state data, and the info the server returns is meant to be specific to the device vendor 🧚.
There are also some user-configurable admin strings, like the system location and description 💅.
2.2. System Time Management
Managing the date and time the system uses needs to be supported. Using one or more NTP servers to set the system date and time automatically needs to be possible. Support for the Time Zone Database [RFC6557] also needs to be there. It should be possible to configure the system to use NTP 🕰️.
2.3. User Authentication
The authentication mechanism needs to support password authentication over RADIUS, so deployments with centralized authentication servers work 🔐. For setups without a centralized server, or where the device can't reach it, local users need to be supported too 💖.
Since the mandatory transport protocol for NETCONF is Secure Shell (SSH) [RFC6242], the authentication model needs to support SSH's "publickey" and "password" authentication methods [RFC4252] 🗝️.
The model for authentication config should be flexible enough to support authentication methods defined by other standards docs or by vendors. It should be possible to configure the system authentication properties 🎀.
2.4. DNS Resolver
Configuring the DNS resolver in the system that holds the NETCONF server is required, so you can control how domain names get resolved 🌐.
2.5. System Control
A few operations are needed for common tasks, like restarting the device or setting the system date and time 🔄.
3. System Data Model 💜
3.1. System Identification
The system identification data model has this structure:
+--rw system
| +--rw contact? string
| +--rw hostname? inet:domain-name
| +--rw location? string
+--ro system-state
+--ro platform
+--ro os-name? string
+--ro os-release? string
+--ro os-version? string
+--ro machine? string3.2. System Time Management
The system time management data model has this structure:
+--rw system
| +--rw clock
| | +--rw (timezone)?
| | +--:(timezone-name)
| | | +--rw timezone-name? timezone-name
| | +--:(timezone-utc-offset)
| | +--rw timezone-utc-offset? int16
| +--rw ntp!
| +--rw enabled? boolean
| +--rw server* [name]
| +--rw name string
| +--rw (transport)
| | +--:(udp)
| | +--rw udp
| | +--rw address inet:host
| | +--rw port? inet:port-number
| +--rw association-type? enumeration
| +--rw iburst? boolean
| +--rw prefer? boolean
+--ro system-state
+--ro clock
+--ro current-datetime? yang:date-and-time
+--ro boot-datetime? yang:date-and-timeNew "case" statements can be added in future revisions of this data model, or through augmentation by some other data model 🦋.
3.3. DNS Resolver Model
The DNS resolver config data model has this structure:
+--rw system
+--rw dns-resolver
+--rw search* inet:domain-name
+--rw server* [name]
| +--rw name string
| +--rw (transport)
| +--:(udp-and-tcp)
| +--udp-and-tcp
| +--rw address inet:ip-address
| +--rw port? inet:port-number
+--rw options
+--rw timeout? uint8
+--rw attempts? uint8New "case" statements can be added in future revisions of this data model, or through augmentation by some other data model 🌈.
3.4. RADIUS Client Model
The RADIUS client config data model has this structure:
+--rw system
+--rw radius
+--rw server* [name]
| +--rw name string
| +--rw (transport)
| | +--:(udp)
| | +--rw udp
| | +--rw address inet:host
| | +--rw authentication-port? inet:port-number
| | +--rw shared-secret string
| +--rw authentication-type? identityref
+--rw options
+--rw timeout? uint8
+--rw attempts? uint8New "case" statements can be added in future revisions of this data model, or through augmentation by some other data model ⭐.
Part 2 is next: section 3.5 (User Authentication Model) and onward 🧚💖
3.5. User Authentication Model ✨
okay so bestie, this is where auth gets SPICY 🔥 NETCONF has three authentication methods, and yes, I checked twice 💅
publickeyfor local users over SSHpasswordfor local users over any secure transportpasswordfor RADIUS users over any secure transport
Other standards docs or vendors can add more methods later, so this list isn't the final boss 🫶
This document defines two optional YANG features, local-users and radius-authentication. The server advertises them to say "yep, I can do local users on the device" and "yep, I can use RADIUS for auth" 🌸
The auth parameters here are mainly for configuring NETCONF users, but they MAY also be used by other interfaces, like a command line interface or a web-based user interface 🧚
Here's the data model structure, bestie 🎀
+--rw system
+--rw authentication
+--rw user-authentication-order* identityref
+--rw user* [name]
+--rw name string
+--rw password? ianach:crypt-hash
+--rw authorized-key* [name]
+--rw name string
+--rw algorithm string
+--rw key-data binary3.5.1. SSH Public Key Authentication 🔑
If the NETCONF server advertises the local-users feature, you can configure local users and their SSH public keys in the /system/authentication/user list. Cute, right? 🦋
Public key auth is requested by the SSH client. If local-users is supported, then when a NETCONF client starts an SSH session toward the server using the "publickey" authentication "method name" [RFC4252], the SSH server looks up the user name from the SSH auth request in the /system/authentication/user list and verifies the key as described in [RFC4253]. It's giving secure handshake vibes 💜
3.5.2. Local User Password Authentication 🔐
If the NETCONF server advertises the local-users feature, you can configure local users and their passwords in the /system/authentication/user list 💖
For NETCONF transport protocols that support password auth, the leaf-list user-authentication-order controls whether local user password auth gets used or not. Main character energy for that leaf-list ✨
In SSH, the client is the one who requests password auth. Other NETCONF transport protocols MAY also support password authentication 🌈
When local user password auth is requested, the NETCONF transport looks up the user name the client sent in the /system/authentication/user list and verifies the password 🔥
3.5.3. RADIUS Password Authentication 📡
If the NETCONF server advertises the radius-authentication feature, the device can authenticate users using RADIUS. Lowkey iconic 👑
For NETCONF transport protocols that support password auth, the leaf-list user-authentication-order controls whether RADIUS password auth gets used or not. Same energy as before, just with RADIUS 🫶
In SSH, the client requests password auth. Other NETCONF transport protocols MAY also support password authentication 🍓
3.6. System Control 🔄
These are the operations defined:
set-current-datetime
system-restart
system-shutdownTwo protocol operations let you restart or shut down the system 💀 The system-restart operation restarts the entire system, not just the NETCONF server. The system-shutdown operation powers off the entire system. So be careful with those, bestie 🙈
4. Relationship to the SNMPv2-MIB 💫
If a device implements the SNMPv2-MIB [RFC3418], there are two objects that MAY be mapped by the implementation. Check the YANG module definition in Section 6 for details 🦋 The table below shows which YANG data nodes match up with objects in the SNMPv2-MIB.
+----------------+-------------------+
| YANG data node | SNMPv2-MIB object |
+----------------+-------------------+
| contact | sysContact |
| location | sysLocation |
+----------------+-------------------+
YANG Interface Configuration Data Nodes and
Related SNMPv2-MIB Objects5. IANA Crypt Hash YANG Module 🧂
This YANG module references [RFC1321], [IEEE-1003.1-2008], and [FIPS.180-4.2012]. Lots of citations, but they're all cute 🌸
<CODE BEGINS> file "iana-crypt-hash@2014-08-06.yang"
module iana-crypt-hash {
namespace "urn:ietf:params:xml:ns:yang:iana-crypt-hash";
prefix ianach;
organization "IANA";
contact
" Internet Assigned Numbers Authority
Postal: ICANN
12025 Waterfront Drive, Suite 300
Los Angeles, CA 90094-2536
United States
Tel: +1 310 301 5800
E-Mail: iana@iana.org>";
description
"This YANG module defines a type for storing passwords
using a hash function and features to indicate which hash
functions are supported by an implementation.
The latest revision of this YANG module can be obtained from
the IANA web site.
Requests for new values should be made to IANA via
email (iana@iana.org).
Copyright (c) 2014 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
(http://trustee.ietf.org/license-info).
The initial version of this YANG module is part of RFC 7317;
see the RFC itself for full legal notices.";
revision 2014-08-06 {
description
"Initial revision.";
reference
"RFC 7317: A YANG Data Model for System Management";
}
typedef crypt-hash {
type string {
pattern
'$0$.*'
+ '|$1$[a-zA-Z0-9./]{1,8}$[a-zA-Z0-9./]{22}'
+ '|$5$(rounds=\d+$)?[a-zA-Z0-9./]{1,16}$[a-zA-Z0-9./]{43}'
+ '|$6$(rounds=\d+$)?[a-zA-Z0-9./]{1,16}$[a-zA-Z0-9./]{86}';
}
description
"The crypt-hash type is used to store passwords using
a hash function. The algorithms for applying the hash
function and encoding the result are implemented in
various UNIX systems as the function crypt(3).
A value of this type matches one of the forms:
$0$<clear text password>
$<id>$<salt>$<password hash>
$<id>$<parameter>$<salt>$<password hash>
The '$0$' prefix signals that the value is clear text. When
such a value is received by the server, a hash value is
calculated, and the string '$<id>$<salt>$' or
$<id>$<parameter>$<salt>$ is prepended to the result. This
value is stored in the configuration data store.
If a value starting with '$<id>$', where <id> is not '0', is
received, the server knows that the value already represents a
hashed value and stores it 'as is' in the data store.
When a server needs to verify a password given by a user, it
finds the stored password hash string for that user, extracts
the salt, and calculates the hash with the salt and given
password as input. If the calculated hash value is the same
as the stored value, the password given by the client is
accepted.
This type defines the following hash functions:
id | hash function | feature
---+---------------+-------------------
1 | MD5 | crypt-hash-md5
5 | SHA-256 | crypt-hash-sha-256
6 | SHA-512 | crypt-hash-sha-512
The server indicates support for the different hash functions
by advertising the corresponding feature.";
reference
"IEEE Std 1003.1-2008 - crypt() function
RFC 1321: The MD5 Message-Digest Algorithm
FIPS.180-4.2012: Secure Hash Standard (SHS)";
}
feature crypt-hash-md5 {
description
"Indicates that the device supports the MD5
hash function in 'crypt-hash' values.";
reference "RFC 1321: The MD5 Message-Digest Algorithm";
}
feature crypt-hash-sha-256 {
description
"Indicates that the device supports the SHA-256
hash function in 'crypt-hash' values.";
reference "FIPS.180-4.2012: Secure Hash Standard (SHS)";
}
feature crypt-hash-sha-512 {
description
"Indicates that the device supports the SHA-512
hash function in 'crypt-hash' values.";
reference "FIPS.180-4.2012: Secure Hash Standard (SHS)";
}
}
<CODE ENDS>6. System YANG Module 🎀
This YANG module imports YANG extensions from [RFC6536] and imports YANG types from [RFC6991]. It also references [RFC1035], [RFC2865], [RFC3418], [RFC5607], [RFC5966], and [RFC6557]. Lots of imports, bestie, but that's how we build the good stuff 💅
<CODE BEGINS> file "ietf-system@2014-08-06.yang"
module ietf-system {
namespace "urn:ietf:params:xml:ns:yang:ietf-system";
prefix "sys";
import ietf-yang-types {
prefix yang;
}
import ietf-inet-types {
prefix inet;
}
import ietf-netconf-acm {
prefix nacm;
}
import iana-crypt-hash {
prefix ianach;
}
organization
"IETF NETMOD (NETCONF Data Modeling Language) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netmod/>
WG List: <mailto:netmod@ietf.org>
WG Chair: Thomas Nadeau
<mailto:tnadeau@lucidvision.com>
WG Chair: Juergen Schoenwaelder
<mailto:j.schoenwaelder@jacobs-university.de>
Editor: Andy Bierman
<mailto:andy@yumaworks.com>
Editor: Martin Bjorklund
<mailto:mbj@tail-f.com>";
description
"This module contains a collection of YANG definitions for the
configuration and identification of some common system
properties within a device containing a NETCONF server. This
includes data node definitions for system identification,
time-of-day management, user management, DNS resolver
configuration, and some protocol operations for system
management.
Copyright (c) 2014 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
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC 7317; see
the RFC itself for full legal notices.";
revision 2014-08-06 {
description
"Initial revision.";
reference
"RFC 7317: A YANG Data Model for System Management";
}
/*
* Typedefs
*/
typedef timezone-name {
type string;
description
"A time zone name as used by the Time Zone Database,
sometimes referred to as the 'Olson Database'.
The exact set of valid values is an implementation-specific
matter. Client discovery of the exact set of time zone names
for a particular server is out of scope.";
reference
"RFC 6557: Procedures for Maintaining the Time Zone Database";
}
/*
* Features
*/feature radius { description "Indicates that the device can be configured as a RADIUS client."; reference "RFC 2865: Remote Authentication Dial In User Service (RADIUS)"; }
feature authentication { description "Indicates that the device supports configuration of user authentication."; }
feature local-users { if-feature authentication; description "Indicates that the device supports configuration of local user authentication."; } feature radius-authentication { if-feature radius; if-feature authentication; description "Indicates that the device supports configuration of user authentication over RADIUS."; reference "RFC 2865: Remote Authentication Dial In User Service (RADIUS) RFC 5607: Remote Authentication Dial-In User Service (RADIUS) Authorization for Network Access Server (NAS) Management"; }
feature ntp { description "Indicates that the device can be configured to use one or more NTP servers to set the system date and time."; }
feature ntp-udp-port { if-feature ntp; description "Indicates that the device supports the configuration of the UDP port for NTP servers.
This is a 'feature', since many implementations do not support any port other than the default port."; }
feature timezone-name { description "Indicates that the local time zone on the device can be configured to use the TZ database to set the time zone and manage daylight saving time."; reference "RFC 6557: Procedures for Maintaining the Time Zone Database"; }
feature dns-udp-tcp-port { description "Indicates that the device supports the configuration of the UDP and TCP port for DNS servers.
This is a 'feature', since many implementations do not support any port other than the default port."; } /*
- Identities */
identity authentication-method { description "Base identity for user authentication methods."; }
identity radius { base authentication-method; description "Indicates user authentication using RADIUS."; reference "RFC 2865: Remote Authentication Dial In User Service (RADIUS) RFC 5607: Remote Authentication Dial-In User Service (RADIUS) Authorization for Network Access Server (NAS) Management"; }
identity local-users { base authentication-method; description "Indicates password-based authentication of locally configured users."; }
identity radius-authentication-type { description "Base identity for RADIUS authentication types."; }
identity radius-pap { base radius-authentication-type; description "The device requests Password Authentication Protocol (PAP) authentication from the RADIUS server."; reference "RFC 2865: Remote Authentication Dial In User Service (RADIUS)"; } identity radius-chap { base radius-authentication-type; description "The device requests Challenge Handshake Authentication Protocol (CHAP) authentication from the RADIUS server."; reference "RFC 2865: Remote Authentication Dial In User Service (RADIUS)"; }
/*
- Configuration data nodes */
container system { description "System group configuration.";
leaf contact { type string; description "The administrator contact information for the system.
A server implementation MAY map this leaf to the sysContact MIB object. Such an implementation needs to use some mechanism to handle the differences in size and characters allowed between this leaf and sysContact. The definition of such a mechanism is outside the scope of this document."; reference "RFC 3418: Management Information Base (MIB) for the Simple Network Management Protocol (SNMP) SNMPv2-MIB.sysContact"; } leaf hostname { type inet:domain-name; description "The name of the host. This name can be a single domain label or the fully qualified domain name of the host."; } leaf location { type string; description "The system location.
A server implementation MAY map this leaf to the sysLocation MIB object. Such an implementation needs to use some mechanism to handle the differences in size and characters allowed between this leaf and sysLocation. The definition of such a mechanism is outside the scope of this document.";
reference "RFC 3418: Management Information Base (MIB) for the Simple Network Management Protocol (SNMP) SNMPv2-MIB.sysLocation"; }
container clock { description "Configuration of the system date and time properties.";
choice timezone { description "The system time zone information.";
case timezone-name { if-feature timezone-name; leaf timezone-name { type timezone-name; description "The TZ database name to use for the system, such as 'Europe/Stockholm'."; } } case timezone-utc-offset { leaf timezone-utc-offset { type int16 { range "-1500 .. 1500"; } units "minutes"; description "The number of minutes to add to UTC time to identify the time zone for this system. For example, 'UTC - 8:00 hours' would be represented as '-480'. Note that automatic daylight saving time adjustment is not provided if this object is used."; } } } }
container ntp { if-feature ntp; presence "Enables the NTP client unless the 'enabled' leaf (which defaults to 'true') is set to 'false'"; description "Configuration of the NTP client.";
leaf enabled { type boolean; default true; description "Indicates that the system should attempt to synchronize the system clock with an NTP server from the 'ntp/server' list."; } list server { key name; description "List of NTP servers to use for system clock synchronization. If '/system/ntp/enabled' is 'true', then the system will attempt to contact and utilize the specified NTP servers.";
leaf name { type string; description "An arbitrary name for the NTP server."; } choice transport { mandatory true; description "The transport-protocol-specific parameters for this server.";
case udp { container udp { description "Contains UDP-specific configuration parameters for NTP."; leaf address { type inet:host; mandatory true; description "The address of the NTP server."; } leaf port { if-feature ntp-udp-port; type inet:port-number; default 123; description "The port number of the NTP server."; } } } } leaf association-type { type enumeration { enum server { description "Use client association mode. This device will not provide synchronization to the configured NTP server."; } enum peer { description "Use symmetric active association mode. This device may provide synchronization to the configured NTP server."; } enum pool { description "Use client association mode with one or more of the NTP servers found by DNS resolution of the domain name given by the 'address' leaf. This device will not provide synchronization to the servers."; } } default server; description "The desired association type for this NTP server."; } leaf iburst { type boolean; default false; description "Indicates whether this server should enable burst synchronization or not."; } leaf prefer { type boolean; default false; description "Indicates whether this server should be preferred or not."; } } }
container dns-resolver { description "Configuration of the DNS resolver.";
leaf-list search { type inet:domain-name; ordered-by user; description "An ordered list of domains to search when resolving a host name."; } list server { key name; ordered-by user; description "List of the DNS servers that the resolver should query.
When the resolver is invoked by a calling application, it sends the query to the first name server in this list. If no response has been received within 'timeout' seconds, the resolver continues with the next server in the list. If no response is received from any server, the resolver continues with the first server again. When the resolver has traversed the list 'attempts' times without receiving any response, it gives up and returns an error to the calling application.
Implementations MAY limit the number of entries in this list.";
leaf name { type string; description "An arbitrary name for the DNS server."; } choice transport { mandatory true; description "The transport-protocol-specific parameters for this server.";
case udp-and-tcp { container udp-and-tcp { description "Contains UDP- and TCP-specific configuration parameters for DNS."; reference "RFC 1035: Domain Names - Implementation and Specification RFC 5966: DNS Transport over TCP - Implementation Requirements";
okay bestie, we're picking up right in the middle of the DNS resolver stuff 💅🎀
leaf address {
type inet:ip-address;
mandatory true;
description
"The address of the DNS server.";
}
leaf port {
if-feature dns-udp-tcp-port;
type inet:port-number;
default 53;
description
"The UDP and TCP port number of the DNS server.";
}
}
}
}
}
container options {
description
"Resolver options. The set of available options has been
limited to those that are generally available across
different resolver implementations and generally useful.";
leaf timeout {
type uint8 {
range "1..max";
}
units "seconds";
default "5";
description
"The amount of time the resolver will wait for a
response from each remote name server before
retrying the query via a different name server.";
}
leaf attempts {
type uint8 {
range "1..max";
}
default "2";
description
"The number of times the resolver will send a query to
all of its name servers before giving up and returning
an error to the calling application.";
}
}
}so the resolver's options container is basically its patience settings 🧚 it waits 5 seconds per server by default, tries 2 rounds, then gives up and tells the app "nope" 🙈
now the RADIUS client 🔐✨ it's giving "list of servers, try them in order, go back to the start if everyone's ghosting you" 💀
container radius {
if-feature radius;
description
"Configuration of the RADIUS client.";
list server {
key name;
ordered-by user;
description
"List of RADIUS servers used by the device.
When the RADIUS client is invoked by a calling
application, it sends the query to the first server in
this list. If no response has been received within
'timeout' seconds, the client continues with the next
server in the list. If no response is received from any
server, the client continues with the first server again.
When the client has traversed the list 'attempts' times
without receiving any response, it gives up and returns an
error to the calling application.";
leaf name {
type string;
description
"An arbitrary name for the RADIUS server.";
}
choice transport {
mandatory true;
description
"The transport-protocol-specific parameters for this
server.";
case udp {
container udp {
description
"Contains UDP-specific configuration parameters
for RADIUS.";
leaf address {
type inet:host;
mandatory true;
description
"The address of the RADIUS server.";
}
leaf authentication-port {
type inet:port-number;
default "1812";
description
"The port number of the RADIUS server.";
}
leaf shared-secret {
type string;
mandatory true;
nacm:default-deny-all;
description
"The shared secret, which is known to both the
RADIUS client and server.";
reference
"RFC 2865: Remote Authentication Dial In User
Service (RADIUS)";
}
}
}
}
leaf authentication-type {
type identityref {
base radius-authentication-type;
}
default radius-pap;
description
"The authentication type requested from the RADIUS
server.";
}
}
container options {
description
"RADIUS client options.";
leaf timeout {
type uint8 {
range "1..max";
}
units "seconds";
default "5";
description
"The number of seconds the device will wait for a
response from each RADIUS server before trying with a
different server.";
}
leaf attempts {
type uint8 {
range "1..max";
}
default "2";
description
"The number of times the device will send a query to
all of its RADIUS servers before giving up.";
}
}
}the big vibe here is the server list is ordered, the first one gets the first shot, and the shared-secret is the bit that's known to both the client and the server 🤫 and yes, it's locked down with nacm:default-deny-all 🔒 very not-for-everyone energy
okay the authentication subtree is where it gets spicy 🌶️👑 the methods get tried in order, and if they all flop, the user is denied, periodt 😤
container authentication {
nacm:default-deny-write;
if-feature authentication;
description
"The authentication configuration subtree.";
leaf-list user-authentication-order {
type identityref {
base authentication-method;
}
must '(. != "sys:radius" or ../../radius/server)' {
error-message
"When 'radius' is used, a RADIUS server"
+ " must be configured.";
description
"When 'radius' is used as an authentication method,
a RADIUS server must be configured.";
}
ordered-by user;
description
"When the device authenticates a user with a password,
it tries the authentication methods in this leaf-list in
order. If authentication with one method fails, the next
method is used. If no method succeeds, the user is
denied access.
An empty user-authentication-order leaf-list still allows
authentication of users using mechanisms that do not
involve a password.
If the 'radius-authentication' feature is advertised by
the NETCONF server, the 'radius' identity can be added to
this list.
If the 'local-users' feature is advertised by the
NETCONF server, the 'local-users' identity can be
added to this list.";
}
list user {
if-feature local-users;
key name;
description
"The list of local users configured on this device.";
leaf name {
type string;
description
"The user name string identifying this entry.";
}
leaf password {
type ianach:crypt-hash;
description
"The password for this entry.";
}
list authorized-key {
key name;
description
"A list of public SSH keys for this user. These keys
are allowed for SSH authentication, as described in
RFC 4253.";
reference
"RFC 4253: The Secure Shell (SSH) Transport Layer
Protocol";
leaf name {
type string;
description
"An arbitrary name for the SSH key.";
}
leaf algorithm {
type string;
mandatory true;
description
"The public key algorithm name for this SSH key.
Valid values are the values in the IANA 'Secure Shell
(SSH) Protocol Parameters' registry, Public Key
Algorithm Names.";
reference
"IANA 'Secure Shell (SSH) Protocol Parameters'
registry, Public Key Algorithm Names";
}
leaf key-data {
type binary;
mandatory true;
description
"The binary public key data for this SSH key, as
specified by RFC 4253, Section 6.6, i.e.:
string certificate or public key format
identifier
byte[n] key/certificate data.";
reference
"RFC 4253: The Secure Shell (SSH) Transport Layer
Protocol";
}
}
}
}
}
/*
* Operational state data nodes
*/
container system-state {
config false;
description
"System group operational state.";
container platform {
description
"Contains vendor-specific information for
identifying the system platform and operating system.";
reference
"IEEE Std 1003.1-2008 - sys/utsname.h";
leaf os-name {
type string;
description
"The name of the operating system in use -
for example, 'Linux'.";
reference
"IEEE Std 1003.1-2008 - utsname.sysname";
}
leaf os-release {
type string;
description
"The current release level of the operating
system in use. This string MAY indicate
the OS source code revision.";
reference
"IEEE Std 1003.1-2008 - utsname.release";
}
leaf os-version {
type string;
description
"The current version level of the operating
system in use. This string MAY indicate
the specific OS build date and target variant
information.";
reference
"IEEE Std 1003.1-2008 - utsname.version";
}
leaf machine {
type string;
description
"A vendor-specific identifier string representing
the hardware in use.";
reference
"IEEE Std 1003.1-2008 - utsname.machine";
}
}
container clock {
description
"Monitoring of the system date and time properties.";
leaf current-datetime {
type yang:date-and-time;
description
"The current system date and time.";
}
leaf boot-datetime {
type yang:date-and-time;
description
"The system date and time when the system last restarted.";
}
}
}
rpc set-current-datetime {
nacm:default-deny-all;
description
"Set the /system-state/clock/current-datetime leaf
to the specified value.
If the system is using NTP (i.e., /system/ntp/enabled
is set to 'true'), then this operation will fail with
error-tag 'operation-failed' and error-app-tag value of
'ntp-active'.";
input {
leaf current-datetime {
type yang:date-and-time;
mandatory true;
description
"The current system date and time.";
}
}
}
rpc system-restart {
nacm:default-deny-all;
description
"Request that the entire system be restarted immediately.
A server SHOULD send an rpc reply to the client before
restarting the system.";
}
rpc system-shutdown {
nacm:default-deny-all;
description
"Request that the entire system be shut down immediately.
A server SHOULD send an rpc reply to the client before
shutting down the system.";
}
}
<CODE ENDS>the system-state bit is the read-only side of things 👀 it's where you peek at the OS name, release, version and machine, plus the clock and when the box last booted 🕰️
and the RPCs are the "do it now" buttons 🔥 set-current-datetime won't play nice if NTP is switched on (it'll fail with ntp-active), and the restart and shutdown ones come with a little note about replying first 💌 all three are locked with nacm:default-deny-all 🔐 main character security energy 💜
7. IANA Considerations ✨
Okay so IANA is getting a brand new YANG module called "iana-crypt-hash" 🎀. It's based on what's in Section 5, and it's what lets new hash algorithms get added to the type "crypt-hash" later on. The registration procedure is Expert Review, as defined by [RFC5226] 💅.
This doc registers two URIs in the "IETF XML Registry" [RFC3688] 🦋. Following the format in RFC 3688, the registrations look like this:
URI: urn:ietf:params:xml:ns:yang:iana-crypt-hash
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
URI: urn:ietf:params:xml:ns:yang:ietf-system
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.It also registers two YANG modules in the "YANG Module Names" registry [RFC6020] 🌸:
name: iana-crypt-hash
namespace: urn:ietf:params:xml:ns:yang:iana-crypt-hash
prefix: ianach
reference: RFC 7317
name: ietf-system
namespace: urn:ietf:params:xml:ns:yang:ietf-system
prefix: sys
reference: RFC 73178. Security Considerations 🔐
Okay bestie, this section is SERIOUS 😭 so read it carefully. The YANG modules in this memo are designed to be accessed through the NETCONF protocol [RFC6241]. The lowest NETCONF layer is the secure transport layer, and the mandatory to implement secure transport is SSH [RFC6242]. The NETCONF access control model [RFC6536] gives you a way to restrict particular NETCONF users to a preconfigured subset of all the NETCONF protocol operations and content available 🧚.
There are a bunch of data nodes in the "ietf-system" YANG module that are writable, creatable, and deletable (that's config true, which is the default). These may be considered sensitive or vulnerable in some network environments. Write operations (like edit-config) to these data nodes without proper protection can have a negative effect on network operations 💀. Here are the subtrees and data nodes, along with their sensitivity and vulnerability:
/system/clock/timezone: This choice contains the objects used to control the time zone used by the device./system/ntp: This container contains the objects used to control the Network Time Protocol servers used by the device./system/dns-resolver: This container contains the objects used to control the Domain Name System servers used by the device./system/radius: This container contains the objects used to control the Remote Authentication Dial-In User Service servers used by the device./system/authentication/user-authentication-order: This leaf controls how user login attempts are authenticated by the device./system/authentication/user: This list contains the local users enabled on the system.
Some of the readable data nodes in the "ietf-system" YANG module may also be considered sensitive or vulnerable in some network environments 👀. So it's really important to control read access to these data nodes (for example, via get, get-config or notification). Here are the subtrees and data nodes and their sensitivity and vulnerability:
/system/platform: This container has objects that may help identify the specific NETCONF server and/or operating system implementation used on the device./system/authentication/user: This list has objects that may help identify the specific user names and password information in use on the device.
Some of the RPC operations in the "ietf-system" YANG module may be considered sensitive or vulnerable too 🚨. It's important to control access to these operations. Here they are and why they matter:
set-current-datetime: Changes the current date and time on the device.system-restart: Reboots the device.system-shutdown: Shuts down the device.
Since this document describes the use of RADIUS for authentication, it is vulnerable to all of the threats present in other RADIUS applications 😬. For a discussion of those threats, see [RFC2865] and [RFC3162], and Section 4 of [RFC3579].
This document provides configuration parameters for SSH's "publickey" and "password" authentication mechanisms 🔑. Section 9.4 of [RFC4251] and Section 11 of [RFC4252] discuss security considerations for these mechanisms.
The "iana-crypt-hash" YANG module defines a type "crypt-hash" that can be used to store MD5 hashes. [RFC6151] discusses security considerations for MD5. The usage of MD5 is NOT RECOMMENDED 🙅♀️.
9. References 📚
9.1. Normative References
[FIPS.180-4.2012] National Institute of Standards and Technology, "Secure Hash Standard (SHS)", FIPS PUB 180-4, March 2012, <http://csrc.nist.gov/publications/fips/fips180-4/fips-180-4.pdf>.
[IEEE-1003.1-2008] Institute of Electrical and Electronics Engineers, "POSIX.1-2008", IEEE Standard 1003.1, March 2008.
[RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987.
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321, April 1992.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, "Remote Authentication Dial In User Service (RADIUS)", RFC 2865, June 2000.
[RFC3162] Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6", RFC 3162, August 2001.
[RFC3418] Presuhn, R., "Management Information Base (MIB) for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3418, December 2002.
[RFC4251] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) Protocol Architecture", RFC 4251, January 2006.
[RFC4252] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) Authentication Protocol", RFC 4252, January 2006.
[RFC4253] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) Transport Layer Protocol", RFC 4253, January 2006.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008.
[RFC5607] Nelson, D. and G. Weber, "Remote Authentication Dial-In User Service (RADIUS) Authorization for Network Access Server (NAS) Management", RFC 5607, July 2009.
[RFC5966] Bellis, R., "DNS Transport over TCP - Implementation Requirements", RFC 5966, August 2010.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, October 2010.
[RFC6151] Turner, S. and L. Chen, "Updated Security Considerations for the MD5 Message-Digest and the HMAC-MD5 Algorithms", RFC 6151, March 2011.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, June 2011.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, June 2011.
[RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration Protocol (NETCONF) Access Control Model", RFC 6536, March 2012.
[RFC6991] Schoenwaelder, J., "Common YANG Data Types", RFC 6991, July 2013.
9.2. Informative References
[RFC3579] Aboba, B. and P. Calhoun, "RADIUS (Remote Authentication Dial In User Service) Support For Extensible Authentication Protocol (EAP)", RFC 3579, September 2003.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004.
[RFC6557] Lear, E. and P. Eggert, "Procedures for Maintaining the Time Zone Database", BCP 175, RFC 6557, February 2012.
Authors' Addresses 🎀
Andy Bierman YumaWorks
EMail: andy@yumaworks.com
Martin Bjorklund Tail-f Systems
EMail: mbj@tail-f.com
📦 where this page comes from
- ietf: rfc7317 2014-08
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms