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<!DOCTYPE html>
<html lang="en" class="RFC">
<head>
<meta charset="utf-8">
<meta content="Common,Latin" name="scripts">
<meta content="initial-scale=1.0" name="viewport">
<title>RFC 9105: A YANG Data Model for Terminal Access Controller Access-Control System Plus (TACACS+)</title>
<meta content="Bo Wu" name="author">
<meta content="Guangying Zheng" name="author">
<meta content="Michael Wang" name="author">
<meta content="
       This document defines a Terminal Access Controller Access-Control
      System Plus (TACACS+) client YANG module that augments the System
      Management data model, defined in RFC 7317, to allow devices to make use
      of TACACS+ servers for centralized Authentication, Authorization, and
      Accounting (AAA). Though being a standard module, this module does not
      endorse the security mechanisms of the TACACS+ protocol (RFC 8907), and
      TACACS+  MUST  be used within a secure deployment. 
       The YANG module in this document conforms to the Network Management
      Datastore Architecture (NMDA) defined in RFC 8342. 
    " name="description">
<meta content="xml2rfc 3.9.1" name="generator">
<meta content="Authentication" name="keyword">
<meta content="Authorization" name="keyword">
<meta content="Accounting" name="keyword">
<meta content="Authentication, Authorization, and Accounting" name="keyword">
<meta content="AAA" name="keyword">
<meta content="(AAA)" name="keyword">
<meta content="9105" name="rfc.number">
<!-- Generator version information:
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    appdirs 1.4.4
    ConfigArgParse 1.2.3
    google-i18n-address 2.3.5
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<link href="rfc9105.xml" rel="alternate" type="application/rfc+xml">
<link href="#copyright" rel="license">
<style type="text/css">/*

  NOTE: Changes at the bottom of this file overrides some earlier settings.

  Once the style has stabilized and has been adopted as an official RFC style,
  this can be consolidated so that style settings occur only in one place, but
  for now the contents of this file consists first of the initial CSS work as
  provided to the RFC Formatter (xml2rfc) work, followed by itemized and
  commented changes found necssary during the development of the v3
  formatters.

*/

/* fonts */
@import url('https://fonts.googleapis.com/css?family=Noto+Sans'); /* Sans-serif */
@import url('https://fonts.googleapis.com/css?family=Noto+Serif'); /* Serif (print) */
@import url('https://fonts.googleapis.com/css?family=Roboto+Mono'); /* Monospace */

@viewport {
  zoom: 1.0;
  width: extend-to-zoom;
}
@-ms-viewport {
  width: extend-to-zoom;
  zoom: 1.0;
}
/* general and mobile first */
html {
}
body {
  max-width: 90%;
  margin: 1.5em auto;
  color: #222;
  background-color: #fff;
  font-size: 14px;
  font-family: 'Noto Sans', Arial, Helvetica, sans-serif;
  line-height: 1.6;
  scroll-behavior: smooth;
}
.ears {
  display: none;
}

/* headings */
#title, h1, h2, h3, h4, h5, h6 {
  margin: 1em 0 0.5em;
  font-weight: bold;
  line-height: 1.3;
}
#title {
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  padding: 1em 0 0.5em;
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.author {
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}
h1 {
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h2 {
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h3 {
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h4 {
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h5, h6 {
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#n-copyright-notice {
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/* general structure */
p {
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}
div, span {
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div {
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.alignRight.art-text pre {
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.alignRight {
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.alignRight > *:first-child {
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  float: right;
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}
.alignRight > *:nth-child(2) {
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}
svg {
  display: block;
}
.alignCenter.art-text {
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  padding: 1em 1em 0;
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}
.alignCenter.art-text pre {
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.alignCenter {
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.alignCenter > *:first-child {
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  */
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}

/* lists */
ol, ul {
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ol ol, ul ul, ol ul, ul ol {
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}
li {
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.ulCompact li {
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}
ul.empty, .ulEmpty {
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ul.empty li, .ulEmpty li {
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ul.ulBare, li.ulBare {
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ul.compact, .ulCompact,
ol.compact, .olCompact {
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  margin: 0 0 0 2em;
}

/* definition lists */
dl {
}
dl > dt {
  float: left;
  margin-right: 1em;
}
/* 
dl.nohang > dt {
  float: none;
}
*/
dl > dd {
  margin-bottom: .8em;
  min-height: 1.3em;
}
dl.compact > dd, .dlCompact > dd {
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}
dl > dd > dl {
  margin-top: 0.5em;
  margin-bottom: 0em;
}

/* links */
a {
  text-decoration: none;
}
a[href] {
  color: #22e; /* Arlen: WCAG 2019 */
}
a[href]:hover {
  background-color: #f2f2f2;
}
figcaption a[href],
a[href].selfRef {
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}
/* XXX probably not this:
a.selfRef:hover {
  background-color: transparent;
  cursor: default;
} */

/* Figures */
tt, code, pre, code {
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}
pre {
  border: 1px solid #eee;
  margin: 0;
  padding: 1em;
}
img {
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}
figure {
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}
figure blockquote {
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}
figcaption {
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}
@media screen {
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}

/* aside, blockquote */
aside, blockquote {
  margin-left: 0;
  padding: 1.2em 2em;
}
blockquote {
  background-color: #f9f9f9;
  color: #111; /* Arlen: WCAG 2019 */
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  margin: 1em 0;
}
cite {
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  font-style: italic;
}

/* tables */
table {
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  border: 1px solid #eee;
}
th, td {
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th {
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tr:nth-child(2n+1) > td {
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table caption {
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}
table p {
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}

/* pilcrow */
a.pilcrow {
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  text-decoration: none;
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  -o-user-select:none;
  -moz-user-select: none;
  -khtml-user-select: none;
  -webkit-user-select: none;
  -webkit-touch-callout: none;
}
@media screen {
  aside:hover > a.pilcrow,
  p:hover > a.pilcrow,
  blockquote:hover > a.pilcrow,
  div:hover > a.pilcrow,
  li:hover > a.pilcrow,
  pre:hover > a.pilcrow {
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  a.pilcrow:hover {
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}

/* misc */
hr {
  border: 0;
  border-top: 1px solid #eee;
}
.bcp14 {
  font-variant: small-caps;
}

.role {
  font-variant: all-small-caps;
}

/* info block */
#identifiers {
  margin: 0;
  font-size: 0.9em;
}
#identifiers dt {
  width: 3em;
  clear: left;
}
#identifiers dd {
  float: left;
  margin-bottom: 0;
}
#identifiers .authors .author {
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}
#identifiers .authors .org {
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}

/* The prepared/rendered info at the very bottom of the page */
.docInfo {
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  font-style: italic;
  margin-top: 2em;
}
.docInfo .prepared {
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}
.docInfo .prepared {
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}

/* table of contents */
#toc  {
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  margin-bottom: 1em;
}
nav.toc ul {
  margin: 0 0.5em 0 0;
  padding: 0;
  list-style: none;
}
nav.toc li {
  line-height: 1.3em;
  margin: 0.75em 0;
  padding-left: 1.2em;
  text-indent: -1.2em;
}
/* references */
.references dt {
  text-align: right;
  font-weight: bold;
  min-width: 7em;
}
.references dd {
  margin-left: 8em;
  overflow: auto;
}

.refInstance {
  margin-bottom: 1.25em;
}

.references .ascii {
  margin-bottom: 0.25em;
}

/* index */
.index ul {
  margin: 0 0 0 1em;
  padding: 0;
  list-style: none;
}
.index ul ul {
  margin: 0;
}
.index li {
  margin: 0;
  text-indent: -2em;
  padding-left: 2em;
  padding-bottom: 5px;
}
.indexIndex {
  margin: 0.5em 0 1em;
}
.index a {
  font-weight: 700;
}
/* make the index two-column on all but the smallest screens */
@media (min-width: 600px) {
  .index ul {
    -moz-column-count: 2;
    -moz-column-gap: 20px;
  }
  .index ul ul {
    -moz-column-count: 1;
    -moz-column-gap: 0;
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}

/* authors */
address.vcard {
  font-style: normal;
  margin: 1em 0;
}

address.vcard .nameRole {
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  margin-left: 0;
}
address.vcard .label {
  font-family: "Noto Sans",Arial,Helvetica,sans-serif;
  margin: 0.5em 0;
}
address.vcard .type {
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}
.alternative-contact {
  margin: 1.5em 0 1em;
}
hr.addr {
  border-top: 1px dashed;
  margin: 0;
  color: #ddd;
  max-width: calc(100% - 16px);
}

/* temporary notes */
.rfcEditorRemove::before {
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  top: 0.2em;
  right: 0.2em;
  padding: 0.2em;
  content: "The RFC Editor will remove this note";
  color: #9e2a00; /* Arlen: WCAG 2019 */
  background-color: #ffd; /* Arlen: WCAG 2019 */
}
.rfcEditorRemove {
  position: relative;
  padding-top: 1.8em;
  background-color: #ffd; /* Arlen: WCAG 2019 */
  border-radius: 3px;
}
.cref {
  background-color: #ffd; /* Arlen: WCAG 2019 */
  padding: 2px 4px;
}
.crefSource {
  font-style: italic;
}
/* alternative layout for smaller screens */
@media screen and (max-width: 1023px) {
  body {
    padding-top: 2em;
  }
  #title {
    padding: 1em 0;
  }
  h1 {
    font-size: 24px;
  }
  h2 {
    font-size: 20px;
    margin-top: -18px;  /* provide offset for in-page anchors */
    padding-top: 38px;
  }
  #identifiers dd {
    max-width: 60%;
  }
  #toc {
    position: fixed;
    z-index: 2;
    top: 0;
    right: 0;
    padding: 0;
    margin: 0;
    background-color: inherit;
    border-bottom: 1px solid #ccc;
  }
  #toc h2 {
    margin: -1px 0 0 0;
    padding: 4px 0 4px 6px;
    padding-right: 1em;
    min-width: 190px;
    font-size: 1.1em;
    text-align: right;
    background-color: #444;
    color: white;
    cursor: pointer;
  }
  #toc h2::before { /* css hamburger */
    float: right;
    position: relative;
    width: 1em;
    height: 1px;
    left: -164px;
    margin: 6px 0 0 0;
    background: white none repeat scroll 0 0;
    box-shadow: 0 4px 0 0 white, 0 8px 0 0 white;
    content: "";
  }
  #toc nav {
    display: none;
    padding: 0.5em 1em 1em;
    overflow: auto;
    height: calc(100vh - 48px);
    border-left: 1px solid #ddd;
  }
}

/* alternative layout for wide screens */
@media screen and (min-width: 1024px) {
  body {
    max-width: 724px;
    margin: 42px auto;
    padding-left: 1.5em;
    padding-right: 29em;
  }
  #toc {
    position: fixed;
    top: 42px;
    right: 42px;
    width: 25%;
    margin: 0;
    padding: 0 1em;
    z-index: 1;
  }
  #toc h2 {
    border-top: none;
    border-bottom: 1px solid #ddd;
    font-size: 1em;
    font-weight: normal;
    margin: 0;
    padding: 0.25em 1em 1em 0;
  }
  #toc nav {
    display: block;
    height: calc(90vh - 84px);
    bottom: 0;
    padding: 0.5em 0 0;
    overflow: auto;
  }
  img { /* future proofing */
    max-width: 100%;
    height: auto;
  }
}

/* pagination */
@media print {
  body {

    width: 100%;
  }
  p {
    orphans: 3;
    widows: 3;
  }
  #n-copyright-notice {
    border-bottom: none;
  }
  #toc, #n-introduction {
    page-break-before: always;
  }
  #toc {
    border-top: none;
    padding-top: 0;
  }
  figure, pre {
    page-break-inside: avoid;
  }
  figure {
    overflow: scroll;
  }
  h1, h2, h3, h4, h5, h6 {
    page-break-after: avoid;
  }
  h2+*, h3+*, h4+*, h5+*, h6+* {
    page-break-before: avoid;
  }
  pre {
    white-space: pre-wrap;
    word-wrap: break-word;
    font-size: 10pt;
  }
  table {
    border: 1px solid #ddd;
  }
  td {
    border-top: 1px solid #ddd;
  }
}

/* This is commented out here, as the string-set: doesn't
   pass W3C validation currently */
/*
.ears thead .left {
  string-set: ears-top-left content();
}

.ears thead .center {
  string-set: ears-top-center content();
}

.ears thead .right {
  string-set: ears-top-right content();
}

.ears tfoot .left {
  string-set: ears-bottom-left content();
}

.ears tfoot .center {
  string-set: ears-bottom-center content();
}

.ears tfoot .right {
  string-set: ears-bottom-right content();
}
*/

@page :first {
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  @top-left {
    content: normal;
    border: none;
  }
  @top-center {
    content: normal;
    border: none;
  }
  @top-right {
    content: normal;
    border: none;
  }
}

@page {
  size: A4;
  margin-bottom: 45mm;
  padding-top: 20px;
  /* The follwing is commented out here, but set appropriately by in code, as
     the content depends on the document */
  /*
  @top-left {
    content: 'Internet-Draft';
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-left {
    content: string(ears-top-left);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-center {
    content: string(ears-top-center);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-right {
    content: string(ears-top-right);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @bottom-left {
    content: string(ears-bottom-left);
    vertical-align: top;
    border-top: solid 1px #ccc;
  }
  @bottom-center {
    content: string(ears-bottom-center);
    vertical-align: top;
    border-top: solid 1px #ccc;
  }
  @bottom-right {
      content: '[Page ' counter(page) ']';
      vertical-align: top;
      border-top: solid 1px #ccc;
  }
  */

}

/* Changes introduced to fix issues found during implementation */
/* Make sure links are clickable even if overlapped by following H* */
a {
  z-index: 2;
}
/* Separate body from document info even without intervening H1 */
section {
  clear: both;
}


/* Top align author divs, to avoid names without organization dropping level with org names */
.author {
  vertical-align: top;
}

/* Leave room in document info to show Internet-Draft on one line */
#identifiers dt {
  width: 8em;
}

/* Don't waste quite as much whitespace between label and value in doc info */
#identifiers dd {
  margin-left: 1em;
}

/* Give floating toc a background color (needed when it's a div inside section */
#toc {
  background-color: white;
}

/* Make the collapsed ToC header render white on gray also when it's a link */
@media screen and (max-width: 1023px) {
  #toc h2 a,
  #toc h2 a:link,
  #toc h2 a:focus,
  #toc h2 a:hover,
  #toc a.toplink,
  #toc a.toplink:hover {
    color: white;
    background-color: #444;
    text-decoration: none;
  }
}

/* Give the bottom of the ToC some whitespace */
@media screen and (min-width: 1024px) {
  #toc {
    padding: 0 0 1em 1em;
  }
}

/* Style section numbers with more space between number and title */
.section-number {
  padding-right: 0.5em;
}

/* prevent monospace from becoming overly large */
tt, code, pre, code {
  font-size: 95%;
}

/* Fix the height/width aspect for ascii art*/
pre.sourcecode,
.art-text pre {
  line-height: 1.12;
}


/* Add styling for a link in the ToC that points to the top of the document */
a.toplink {
  float: right;
  margin-right: 0.5em;
}

/* Fix the dl styling to match the RFC 7992 attributes */
dl > dt,
dl.dlParallel > dt {
  float: left;
  margin-right: 1em;
}
dl.dlNewline > dt {
  float: none;
}

/* Provide styling for table cell text alignment */
table td.text-left,
table th.text-left {
  text-align: left;
}
table td.text-center,
table th.text-center {
  text-align: center;
}
table td.text-right,
table th.text-right {
  text-align: right;
}

/* Make the alternative author contact informatio look less like just another
   author, and group it closer with the primary author contact information */
.alternative-contact {
  margin: 0.5em 0 0.25em 0;
}
address .non-ascii {
  margin: 0 0 0 2em;
}

/* With it being possible to set tables with alignment
  left, center, and right, { width: 100%; } does not make sense */
table {
  width: auto;
}

/* Avoid reference text that sits in a block with very wide left margin,
   because of a long floating dt label.*/
.references dd {
  overflow: visible;
}

/* Control caption placement */
caption {
  caption-side: bottom;
}

/* Limit the width of the author address vcard, so names in right-to-left
   script don't end up on the other side of the page. */

address.vcard {
  max-width: 30em;
  margin-right: auto;
}

/* For address alignment dependent on LTR or RTL scripts */
address div.left {
  text-align: left;
}
address div.right {
  text-align: right;
}

/* Provide table alignment support.  We can't use the alignX classes above
   since they do unwanted things with caption and other styling. */
table.right {
 margin-left: auto;
 margin-right: 0;
}
table.center {
 margin-left: auto;
 margin-right: auto;
}
table.left {
 margin-left: 0;
 margin-right: auto;
}

/* Give the table caption label the same styling as the figcaption */
caption a[href] {
  color: #222;
}

@media print {
  .toplink {
    display: none;
  }

  /* avoid overwriting the top border line with the ToC header */
  #toc {
    padding-top: 1px;
  }

  /* Avoid page breaks inside dl and author address entries */
  .vcard {
    page-break-inside: avoid;
  }

}
/* Tweak the bcp14 keyword presentation */
.bcp14 {
  font-variant: small-caps;
  font-weight: bold;
  font-size: 0.9em;
}
/* Tweak the invisible space above H* in order not to overlay links in text above */
 h2 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 31px;
 }
 h3 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 24px;
 }
 h4 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 24px;
 }
/* Float artwork pilcrow to the right */
@media screen {
  .artwork a.pilcrow {
    display: block;
    line-height: 0.7;
    margin-top: 0.15em;
  }
}
/* Make pilcrows on dd visible */
@media screen {
  dd:hover > a.pilcrow {
    visibility: visible;
  }
}
/* Make the placement of figcaption match that of a table's caption
   by removing the figure's added bottom margin */
.alignLeft.art-text,
.alignCenter.art-text,
.alignRight.art-text {
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<table class="ears">
<thead><tr>
<td class="left">RFC 9105</td>
<td class="center">TACACS+ YANG Data Model</td>
<td class="right">August 2021</td>
</tr></thead>
<tfoot><tr>
<td class="left">Wu, et al.</td>
<td class="center">Standards Track</td>
<td class="right">[Page]</td>
</tr></tfoot>
</table>
<div id="external-metadata" class="document-information"></div>
<div id="internal-metadata" class="document-information">
<dl id="identifiers">
<dt class="label-stream">Stream:</dt>
<dd class="stream">Internet Engineering Task Force (IETF)</dd>
<dt class="label-rfc">RFC:</dt>
<dd class="rfc"><a href="https://www.rfc-editor.org/rfc/rfc9105" class="eref">9105</a></dd>
<dt class="label-category">Category:</dt>
<dd class="category">Standards Track</dd>
<dt class="label-published">Published:</dt>
<dd class="published">
<time datetime="2021-08" class="published">August 2021</time>
    </dd>
<dt class="label-issn">ISSN:</dt>
<dd class="issn">2070-1721</dd>
<dt class="label-authors">Authors:</dt>
<dd class="authors">
<div class="author">
      <div class="author-name">B. Wu, <span class="editor">Ed.</span>
</div>
<div class="org">Huawei</div>
</div>
<div class="author">
      <div class="author-name">G. Zheng</div>
<div class="org">Huawei</div>
</div>
<div class="author">
      <div class="author-name">M. Wang, <span class="editor">Ed.</span>
</div>
<div class="org">Huawei</div>
</div>
</dd>
</dl>
</div>
<h1 id="rfcnum">RFC 9105</h1>
<h1 id="title">A YANG Data Model for Terminal Access Controller Access-Control System Plus (TACACS+)</h1>
<section id="section-abstract">
      <h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">This document defines a Terminal Access Controller Access-Control
      System Plus (TACACS+) client YANG module that augments the System
      Management data model, defined in RFC 7317, to allow devices to make use
      of TACACS+ servers for centralized Authentication, Authorization, and
      Accounting (AAA). Though being a standard module, this module does not
      endorse the security mechanisms of the TACACS+ protocol (RFC 8907), and
      TACACS+ <span class="bcp14">MUST</span> be used within a secure deployment.<a href="#section-abstract-1" class="pilcrow">¶</a></p>
<p id="section-abstract-2">The YANG module in this document conforms to the Network Management
      Datastore Architecture (NMDA) defined in RFC 8342.<a href="#section-abstract-2" class="pilcrow">¶</a></p>
</section>
<div id="status-of-memo">
<section id="section-boilerplate.1">
        <h2 id="name-status-of-this-memo">
<a href="#name-status-of-this-memo" class="section-name selfRef">Status of This Memo</a>
        </h2>
<p id="section-boilerplate.1-1">
            This is an Internet Standards Track document.<a href="#section-boilerplate.1-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-2">
            This document is a product of the Internet Engineering Task Force
            (IETF).  It represents the consensus of the IETF community.  It has
            received public review and has been approved for publication by
            the Internet Engineering Steering Group (IESG).  Further
            information on Internet Standards is available in Section 2 of 
            RFC 7841.<a href="#section-boilerplate.1-2" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-3">
            Information about the current status of this document, any
            errata, and how to provide feedback on it may be obtained at
            <span><a href="https://www.rfc-editor.org/info/rfc9105">https://www.rfc-editor.org/info/rfc9105</a></span>.<a href="#section-boilerplate.1-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="copyright">
<section id="section-boilerplate.2">
        <h2 id="name-copyright-notice">
<a href="#name-copyright-notice" class="section-name selfRef">Copyright Notice</a>
        </h2>
<p id="section-boilerplate.2-1">
            Copyright (c) 2021 IETF Trust and the persons identified as the
            document authors. All rights reserved.<a href="#section-boilerplate.2-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.2-2">
            This document is subject to BCP 78 and the IETF Trust's Legal
            Provisions Relating to IETF Documents
            (<span><a href="https://trustee.ietf.org/license-info">https://trustee.ietf.org/license-info</a></span>) in effect on the date of
            publication of this document. Please review these documents
            carefully, as they describe your rights and restrictions with
            respect to this document. Code Components extracted from this
            document must include Simplified BSD License text as described in
            Section 4.e of the Trust Legal Provisions and are provided without
            warranty as described in the Simplified BSD License.<a href="#section-boilerplate.2-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="toc">
<section id="section-toc.1">
        <a href="#" onclick="scroll(0,0)" class="toplink">▲</a><h2 id="name-table-of-contents">
<a href="#name-table-of-contents" class="section-name selfRef">Table of Contents</a>
        </h2>
<nav class="toc"><ul class="toc ulBare compact ulEmpty">
<li class="toc ulBare compact ulEmpty" id="section-toc.1-1.1">
            <p id="section-toc.1-1.1.1" class="keepWithNext"><a href="#section-1" class="xref">1</a>.  <a href="#name-introduction" class="xref">Introduction</a></p>
</li>
          <li class="toc ulBare compact ulEmpty" id="section-toc.1-1.2">
            <p id="section-toc.1-1.2.1" class="keepWithNext"><a href="#section-2" class="xref">2</a>.  <a href="#name-conventions-used-in-this-do" class="xref">Conventions Used in This Document</a></p>
<ul class="ulBare ulEmpty toc compact">
<li class="ulBare ulEmpty toc compact" id="section-toc.1-1.2.2.1">
                <p id="section-toc.1-1.2.2.1.1" class="keepWithNext"><a href="#section-2.1" class="xref">2.1</a>.  <a href="#name-tree-diagrams" class="xref">Tree Diagrams</a></p>
</li>
            </ul>
</li>
          <li class="toc ulBare compact ulEmpty" id="section-toc.1-1.3">
            <p id="section-toc.1-1.3.1"><a href="#section-3" class="xref">3</a>.  <a href="#name-design-of-the-tacacs-data-m" class="xref">Design of the TACACS+ Data Model</a></p>
</li>
          <li class="toc ulBare compact ulEmpty" id="section-toc.1-1.4">
            <p id="section-toc.1-1.4.1"><a href="#section-4" class="xref">4</a>.  <a href="#name-tacacs-client-module" class="xref">TACACS+ Client Module</a></p>
</li>
          <li class="toc ulBare compact ulEmpty" id="section-toc.1-1.5">
            <p id="section-toc.1-1.5.1"><a href="#section-5" class="xref">5</a>.  <a href="#name-security-considerations" class="xref">Security Considerations</a></p>
</li>
          <li class="toc ulBare compact ulEmpty" id="section-toc.1-1.6">
            <p id="section-toc.1-1.6.1"><a href="#section-6" class="xref">6</a>.  <a href="#name-iana-considerations" class="xref">IANA Considerations</a></p>
</li>
          <li class="toc ulBare compact ulEmpty" id="section-toc.1-1.7">
            <p id="section-toc.1-1.7.1"><a href="#section-7" class="xref">7</a>.  <a href="#name-references" class="xref">References</a></p>
<ul class="ulBare ulEmpty toc compact">
<li class="ulBare ulEmpty toc compact" id="section-toc.1-1.7.2.1">
                <p id="section-toc.1-1.7.2.1.1"><a href="#section-7.1" class="xref">7.1</a>.  <a href="#name-normative-references" class="xref">Normative References</a></p>
</li>
              <li class="ulBare ulEmpty toc compact" id="section-toc.1-1.7.2.2">
                <p id="section-toc.1-1.7.2.2.1"><a href="#section-7.2" class="xref">7.2</a>.  <a href="#name-informative-references" class="xref">Informative References</a></p>
</li>
            </ul>
</li>
          <li class="toc ulBare compact ulEmpty" id="section-toc.1-1.8">
            <p id="section-toc.1-1.8.1"><a href="#appendix-A" class="xref">Appendix A</a>.  <a href="#name-example-tacacs-authenticati" class="xref">Example TACACS+ Authentication Configuration</a></p>
</li>
          <li class="toc ulBare compact ulEmpty" id="section-toc.1-1.9">
            <p id="section-toc.1-1.9.1"><a href="#appendix-B" class="xref"></a><a href="#name-acknowledgments" class="xref">Acknowledgments</a></p>
</li>
          <li class="toc ulBare compact ulEmpty" id="section-toc.1-1.10">
            <p id="section-toc.1-1.10.1"><a href="#appendix-C" class="xref"></a><a href="#name-authors-addresses" class="xref">Authors' Addresses</a></p>
</li>
        </ul>
</nav>
</section>
</div>
<section id="section-1">
      <h2 id="name-introduction">
<a href="#section-1" class="section-number selfRef">1. </a><a href="#name-introduction" class="section-name selfRef">Introduction</a>
      </h2>
<p id="section-1-1">This document defines a YANG module that augments the System
      Management data model defined in <span>[<a href="#RFC7317" class="xref">RFC7317</a>]</span> to support
      the configuration and management of TACACS+ clients.<a href="#section-1-1" class="pilcrow">¶</a></p>
<p id="section-1-2">TACACS+ <span>[<a href="#RFC8907" class="xref">RFC8907</a>]</span> provides device
      administration for routers, network access servers, and other networked
      devices via one or more centralized servers.<a href="#section-1-2" class="pilcrow">¶</a></p>
<p id="section-1-3"><span><a href="#RFC7317" class="xref">The System Management data model</a> [<a href="#RFC7317" class="xref">RFC7317</a>]</span> defines
      separate functionality to support local and RADIUS authentication:<a href="#section-1-3" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-1-4">
        <dt id="section-1-4.1">User Authentication Model: </dt>
        <dd style="margin-left: 1.5em" id="section-1-4.2">Defines a list of usernames with associated passwords and a configuration
leaf to decide the order in which local or RADIUS authentication is used.<a href="#section-1-4.2" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-1-4.3">RADIUS Client Model: </dt>
        <dd style="margin-left: 1.5em" id="section-1-4.4">Defines a list of RADIUS servers used by a device for centralized user
authentication.<a href="#section-1-4.4" class="pilcrow">¶</a>
</dd>
      <dd class="break"></dd>
</dl>
<p id="section-1-5">The System Management data model is augmented with the TACACS+ YANG module
      defined in this document to allow the use of TACACS+ servers as an
      alternative to RADIUS servers.<a href="#section-1-5" class="pilcrow">¶</a></p>
<p id="section-1-6">The YANG module can be used with network management protocols such as
      the Network Configuration Protocol (NETCONF) <span>[<a href="#RFC6241" class="xref">RFC6241</a>]</span>.<a href="#section-1-6" class="pilcrow">¶</a></p>
<p id="section-1-7">The YANG module in this document conforms to the Network Management
      Datastore Architecture (NMDA) defined in <span>[<a href="#RFC8342" class="xref">RFC8342</a>]</span>.<a href="#section-1-7" class="pilcrow">¶</a></p>
</section>
<section id="section-2">
      <h2 id="name-conventions-used-in-this-do">
<a href="#section-2" class="section-number selfRef">2. </a><a href="#name-conventions-used-in-this-do" class="section-name selfRef">Conventions Used in This Document</a>
      </h2>
<p id="section-2-1">
    The key words "<span class="bcp14">MUST</span>", "<span class="bcp14">MUST NOT</span>",
    "<span class="bcp14">REQUIRED</span>", "<span class="bcp14">SHALL</span>", "<span class="bcp14">SHALL NOT</span>", "<span class="bcp14">SHOULD</span>", "<span class="bcp14">SHOULD NOT</span>",
    "<span class="bcp14">RECOMMENDED</span>", "<span class="bcp14">NOT RECOMMENDED</span>",
    "<span class="bcp14">MAY</span>", and "<span class="bcp14">OPTIONAL</span>" in this document are
    to be interpreted as described in BCP 14 <span>[<a href="#RFC2119" class="xref">RFC2119</a>]</span>
        <span>[<a href="#RFC8174" class="xref">RFC8174</a>]</span> when, and only when, they appear in all capitals,
    as shown here.<a href="#section-2-1" class="pilcrow">¶</a></p>
<p id="section-2-2">The following terms are defined in <span>[<a href="#RFC6241" class="xref">RFC6241</a>]</span> and are
      used in this specification:<a href="#section-2-2" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-2-3.1">configuration data<a href="#section-2-3.1" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-3.2">state data<a href="#section-2-3.2" class="pilcrow">¶</a>
</li>
      </ul>
<p id="section-2-4">The following terms are defined in <span>[<a href="#RFC7950" class="xref">RFC7950</a>]</span> and are
      used in this specification:<a href="#section-2-4" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-2-5.1">augment<a href="#section-2-5.1" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-5.2">data model<a href="#section-2-5.2" class="pilcrow">¶</a>
</li>
        <li class="normal" id="section-2-5.3">data node<a href="#section-2-5.3" class="pilcrow">¶</a>
</li>
      </ul>
<p id="section-2-6">The terminology for describing YANG data models is found in
      <span>[<a href="#RFC7950" class="xref">RFC7950</a>]</span>.<a href="#section-2-6" class="pilcrow">¶</a></p>
<div id="tree-diagrams">
<section id="section-2.1">
        <h3 id="name-tree-diagrams">
<a href="#section-2.1" class="section-number selfRef">2.1. </a><a href="#name-tree-diagrams" class="section-name selfRef">Tree Diagrams</a>
        </h3>
<p id="section-2.1-1">The tree diagram used in this document follows the notation defined
        in <span>[<a href="#RFC8340" class="xref">RFC8340</a>]</span>.<a href="#section-2.1-1" class="pilcrow">¶</a></p>
</section>
</div>
</section>
<section id="section-3">
      <h2 id="name-design-of-the-tacacs-data-m">
<a href="#section-3" class="section-number selfRef">3. </a><a href="#name-design-of-the-tacacs-data-m" class="section-name selfRef">Design of the TACACS+ Data Model</a>
      </h2>
<p id="section-3-1">This module is used to configure a TACACS+ client on a device to
      support deployment scenarios with centralized authentication,
      authorization, and accounting servers. Authentication is used to
      validate a user's username and password, authorization allows the user
      to access and execute commands at various privilege levels assigned to
      the user, and accounting keeps track of the activity of a user who has
      accessed the device.<a href="#section-3-1" class="pilcrow">¶</a></p>
<p id="section-3-2">The ietf-system-tacacs-plus module augments the "/sys:system" path
      defined in the ietf-system module with the contents of the "tacacs-plus"
      grouping. Therefore, a device can use local, RADIUS, or TACACS+ authentication to
      validate users who attempt to access the router by several mechanisms,
      e.g., a command line interface or a web-based user interface.<a href="#section-3-2" class="pilcrow">¶</a></p>
<p id="section-3-3">The "server" list, which is directly under the "tacacs-plus" container,
      holds a list of TACACS+ servers and uses server-type to
      distinguish between Authentication, Authorization, and Accounting (AAA) services.
      The list of servers is for redundancy.<a href="#section-3-3" class="pilcrow">¶</a></p>
<p id="section-3-4">Most of the parameters in the "server" list are taken directly from
      the <span><a href="#RFC8907" class="xref">TACACS+ protocol</a> [<a href="#RFC8907" class="xref">RFC8907</a>]</span>,
      and some are derived from the various implementations by network
      equipment manufacturers. For example, when there are multiple interfaces
      connected to the TACACS+ client or server, the source address of
      outgoing TACACS+ packets could be specified, or the source address could
      be specified through the interface IP address setting or derived from
      the outbound interface from the local Forwarding Information Base
      (FIB). For the TACACS+ server located in a Virtual Private Network
      (VPN), a VPN Routing and Forwarding (VRF) instance needs to be
      specified.<a href="#section-3-4" class="pilcrow">¶</a></p>
<p id="section-3-5">The "statistics" container under the "server list" is a collection of
      read-only counters for sent and received messages from a configured
      server.<a href="#section-3-5" class="pilcrow">¶</a></p>
<p id="section-3-6">The YANG module for TACACS+ client has the following structure:<a href="#section-3-6" class="pilcrow">¶</a></p>
<div id="section-3-7">
<pre class="sourcecode lang-yangtree">
module: ietf-system-tacacs-plus
  augment /sys:system:
    +--rw tacacs-plus
       +--rw server* [name]
          +--rw name                      string
          +--rw server-type               tacacs-plus-server-type
          +--rw address                   inet:host
          +--rw port?                     inet:port-number
          +--rw (security)
          |  +--:(obfuscation)
          |     +--rw shared-secret?      string
          +--rw (source-type)?
          |  +--:(source-ip)
          |  |  +--rw source-ip?          inet:ip-address
          |  +--:(source-interface)
          |     +--rw source-interface?   if:interface-ref
          +--rw vrf-instance?
          |       -&gt; /ni:network-instances/network-instance/name
          +--rw single-connection?        boolean
          +--rw timeout?                  uint16
          +--ro statistics
             +--ro connection-opens?      yang:counter64
             +--ro connection-closes?     yang:counter64
             +--ro connection-aborts?     yang:counter64
             +--ro connection-failures?   yang:counter64
             +--ro connection-timeouts?   yang:counter64
             +--ro messages-sent?         yang:counter64
             +--ro messages-received?     yang:counter64
             +--ro errors-received?       yang:counter64
             +--ro sessions?              yang:counter64
</pre><a href="#section-3-7" class="pilcrow">¶</a>
</div>
</section>
<section id="section-4">
      <h2 id="name-tacacs-client-module">
<a href="#section-4" class="section-number selfRef">4. </a><a href="#name-tacacs-client-module" class="section-name selfRef">TACACS+ Client Module</a>
      </h2>
<p id="section-4-1">This YANG module imports typedefs from <span>[<a href="#RFC6991" class="xref">RFC6991</a>]</span>. This
      module also uses the interface typedef from <span>[<a href="#RFC8343" class="xref">RFC8343</a>]</span>,
      the leafref to VRF instance from <span>[<a href="#RFC8529" class="xref">RFC8529</a>]</span>, and the
      "default-deny-all" extension statement from <span>[<a href="#RFC8341" class="xref">RFC8341</a>]</span>.<a href="#section-4-1" class="pilcrow">¶</a></p>
<div id="section-4-2">
<pre class="sourcecode lang-yang">&lt;CODE BEGINS&gt; file "ietf-system-tacacs-plus@2021-08-05.yang"

module ietf-system-tacacs-plus {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-system-tacacs-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:   &lt;http://datatracker.ietf.org/wg/opsawg/&gt;
     WG List:  &lt;mailto:opsawg@ietf.org&gt;

     Editor: Bo Wu &lt;lana.wubo@huawei.com&gt;
     Editor: Guangying Zheng &lt;zhengguangying@huawei.com&gt;";
  description
    "This module provides configuration of TACACS+ client.

     The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
     NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
     'MAY', and 'OPTIONAL' in this document are to be interpreted as
     described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
     they appear in all capitals, as shown here.

     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Simplified BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (https://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC 9105; see the
     RFC itself for full legal notices.";

  revision 2021-08-05 {
    description
      "Initial revision.";
    reference
      "RFC 9105: A YANG Data Model for Terminal Access Controller
       Access-Control System Plus (TACACS+)";
  }

  typedef tacacs-plus-server-type {
    type bits {
      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 {
    base sys:authentication-method;
    description
      "Indicates AAA operation using TACACS+.";
    reference
      "RFC 8907: The TACACS+ Protocol";
  }

  grouping statistics {
    description
      "Grouping for TACACS+ statistics attributes.";
    container statistics {
      config false;
      description
        "A collection of server-related statistics objects.";
      leaf connection-opens {
        type yang:counter64;
        description
          "Number of new connection requests sent to the server,
           e.g., socket open.";
      }
      leaf connection-closes {
        type yang:counter64;
        description
          "Number of connection close requests sent to the server,
           e.g., socket close.";
      }
      leaf connection-aborts {
        type yang:counter64;
        description
          "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 {
    description
      "Grouping for TACACS+ attributes.";
    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;
  }
}

&lt;CODE ENDS&gt;</pre><a href="#section-4-2" class="pilcrow">¶</a>
</div>
</section>
<section id="section-5">
      <h2 id="name-security-considerations">
<a href="#section-5" class="section-number selfRef">5. </a><a href="#name-security-considerations" class="section-name selfRef">Security Considerations</a>
      </h2>
<p id="section-5-1">The YANG module specified in this document defines a schema for data
      that is designed to be accessed via network management protocols such as
      NETCONF <span>[<a href="#RFC6241" class="xref">RFC6241</a>]</span> or RESTCONF <span>[<a href="#RFC8040" class="xref">RFC8040</a>]</span>. The lowest NETCONF layer is the
      secure transport layer, and the mandatory-to-implement secure transport
      is Secure Shell (SSH) <span>[<a href="#RFC6242" class="xref">RFC6242</a>]</span>. The
      lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure
      transport is TLS <span>[<a href="#RFC8446" class="xref">RFC8446</a>]</span>.<a href="#section-5-1" class="pilcrow">¶</a></p>
<p id="section-5-2">The Network Configuration Access Control Model (NACM) <span>[<a href="#RFC8341" class="xref">RFC8341</a>]</span> provides the means to restrict
      access for particular NETCONF or RESTCONF users to a preconfigured
      subset of all available NETCONF or RESTCONF protocol operations and
      content.<a href="#section-5-2" class="pilcrow">¶</a></p>
<p id="section-5-3">There are a number of data nodes defined in this YANG module that are
      writable/creatable/deletable (i.e., config true, which is the default).
      These data nodes may be considered sensitive or vulnerable in some
      network environments. Write operations (e.g., edit-config) to these data
      nodes without proper protection can have a negative effect on network
      operations. These are the subtrees and data nodes and their
      sensitivity/vulnerability:<a href="#section-5-3" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5-4">
        <dt id="section-5-4.1">/system/tacacs-plus/server:</dt>
        <dd style="margin-left: 1.5em" id="section-5-4.2">This list contains the data
          nodes used to control the TACACS+ servers used by the device.
          Unauthorized access to this list could enable an attacker to assume
          complete control over the device by pointing to a compromised
          TACACS+ server, or to modify the counters to hide attacks against
          the device.<a href="#section-5-4.2" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-5-4.3">/system/tacacs-plus/server/shared-secret:</dt>
        <dd style="margin-left: 1.5em" id="section-5-4.4">This leaf controls the key known to both the TACACS+ client and
        server.  Unauthorized access to this leaf could make the device
        vulnerable to attacks; therefore, it has been restricted using the
        "default-deny-all" access control defined in <span>[<a href="#RFC8341" class="xref">RFC8341</a>]</span>. 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, and punctuation.<a href="#section-5-4.4" class="pilcrow">¶</a>
</dd>
      <dd class="break"></dd>
</dl>
<p id="section-5-5">This document describes the use of TACACS+ for purposes of
      authentication, authorization, and accounting; it is vulnerable to all
      of the threats that are present in TACACS+ applications. For a
      discussion of such threats, see <span><a href="https://www.rfc-editor.org/rfc/rfc8907#section-10" class="relref">Section 10</a> of the TACACS+
     protocol [<a href="#RFC8907" class="xref">RFC8907</a>]</span>.<a href="#section-5-5" class="pilcrow">¶</a></p>
</section>
<section id="section-6">
      <h2 id="name-iana-considerations">
<a href="#section-6" class="section-number selfRef">6. </a><a href="#name-iana-considerations" class="section-name selfRef">IANA Considerations</a>
      </h2>
<p id="section-6-1">IANA has registered the following URI in the "ns" subregistry within the "IETF XML Registry" <span>[<a href="#RFC3688" class="xref">RFC3688</a>]</span>:<a href="#section-6-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel dlCompact" id="section-6-2">
        <dt id="section-6-2.1">URI:</dt>
        <dd style="margin-left: 1.5em" id="section-6-2.2">urn:ietf:params:xml:ns:yang:ietf-system-tacacs-plus<a href="#section-6-2.2" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-6-2.3">Registrant Contact: </dt>
        <dd style="margin-left: 1.5em" id="section-6-2.4">The IESG.<a href="#section-6-2.4" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-6-2.5">XML: </dt>
        <dd style="margin-left: 1.5em" id="section-6-2.6">N/A, the requested URI is an XML namespace.<a href="#section-6-2.6" class="pilcrow">¶</a>
</dd>
      <dd class="break"></dd>
</dl>
<p id="section-6-3">IANA has registered the following YANG module in the "YANG Module Names"
      registry <span>[<a href="#RFC7950" class="xref">RFC7950</a>]</span>:<a href="#section-6-3" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel dlCompact" id="section-6-4">
        <dt id="section-6-4.1">Name: </dt>
        <dd style="margin-left: 1.5em" id="section-6-4.2">ietf-system-tacacs-plus<a href="#section-6-4.2" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-6-4.3">Maintained by IANA: </dt>
        <dd style="margin-left: 1.5em" id="section-6-4.4">N<a href="#section-6-4.4" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-6-4.5">Namespace: </dt>
        <dd style="margin-left: 1.5em" id="section-6-4.6">urn:ietf:params:xml:ns:yang:ietf-system-tacacs-plus<a href="#section-6-4.6" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-6-4.7">Prefix: </dt>
        <dd style="margin-left: 1.5em" id="section-6-4.8">sys-tcs-plus<a href="#section-6-4.8" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
<dt id="section-6-4.9">Reference: </dt>
        <dd style="margin-left: 1.5em" id="section-6-4.10">RFC 9105<a href="#section-6-4.10" class="pilcrow">¶</a>
</dd>
      <dd class="break"></dd>
</dl>
</section>
<section id="section-7">
      <h2 id="name-references">
<a href="#section-7" class="section-number selfRef">7. </a><a href="#name-references" class="section-name selfRef">References</a>
      </h2>
<section id="section-7.1">
        <h3 id="name-normative-references">
<a href="#section-7.1" class="section-number selfRef">7.1. </a><a href="#name-normative-references" class="section-name selfRef">Normative References</a>
        </h3>
<dl class="references">
<dt id="RFC2119">[RFC2119]</dt>
        <dd>
<span class="refAuthor">Bradner, S.</span>, <span class="refTitle">"Key words for use in RFCs to Indicate Requirement Levels"</span>, <span class="seriesInfo">BCP 14</span>, <span class="seriesInfo">RFC 2119</span>, <span class="seriesInfo">DOI 10.17487/RFC2119</span>, <time datetime="1997-03" class="refDate">March 1997</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc2119">https://www.rfc-editor.org/info/rfc2119</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6241">[RFC6241]</dt>
        <dd>
<span class="refAuthor">Enns, R., Ed.</span>, <span class="refAuthor">Bjorklund, M., Ed.</span>, <span class="refAuthor">Schoenwaelder, J., Ed.</span>, and <span class="refAuthor">A. Bierman, Ed.</span>, <span class="refTitle">"Network Configuration Protocol (NETCONF)"</span>, <span class="seriesInfo">RFC 6241</span>, <span class="seriesInfo">DOI 10.17487/RFC6241</span>, <time datetime="2011-06" class="refDate">June 2011</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6241">https://www.rfc-editor.org/info/rfc6241</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6242">[RFC6242]</dt>
        <dd>
<span class="refAuthor">Wasserman, M.</span>, <span class="refTitle">"Using the NETCONF Protocol over Secure Shell (SSH)"</span>, <span class="seriesInfo">RFC 6242</span>, <span class="seriesInfo">DOI 10.17487/RFC6242</span>, <time datetime="2011-06" class="refDate">June 2011</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6242">https://www.rfc-editor.org/info/rfc6242</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6991">[RFC6991]</dt>
        <dd>
<span class="refAuthor">Schoenwaelder, J., Ed.</span>, <span class="refTitle">"Common YANG Data Types"</span>, <span class="seriesInfo">RFC 6991</span>, <span class="seriesInfo">DOI 10.17487/RFC6991</span>, <time datetime="2013-07" class="refDate">July 2013</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6991">https://www.rfc-editor.org/info/rfc6991</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7317">[RFC7317]</dt>
        <dd>
<span class="refAuthor">Bierman, A.</span> and <span class="refAuthor">M. Bjorklund</span>, <span class="refTitle">"A YANG Data Model for System Management"</span>, <span class="seriesInfo">RFC 7317</span>, <span class="seriesInfo">DOI 10.17487/RFC7317</span>, <time datetime="2014-08" class="refDate">August 2014</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7317">https://www.rfc-editor.org/info/rfc7317</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7950">[RFC7950]</dt>
        <dd>
<span class="refAuthor">Bjorklund, M., Ed.</span>, <span class="refTitle">"The YANG 1.1 Data Modeling Language"</span>, <span class="seriesInfo">RFC 7950</span>, <span class="seriesInfo">DOI 10.17487/RFC7950</span>, <time datetime="2016-08" class="refDate">August 2016</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7950">https://www.rfc-editor.org/info/rfc7950</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8040">[RFC8040]</dt>
        <dd>
<span class="refAuthor">Bierman, A.</span>, <span class="refAuthor">Bjorklund, M.</span>, and <span class="refAuthor">K. Watsen</span>, <span class="refTitle">"RESTCONF Protocol"</span>, <span class="seriesInfo">RFC 8040</span>, <span class="seriesInfo">DOI 10.17487/RFC8040</span>, <time datetime="2017-01" class="refDate">January 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8040">https://www.rfc-editor.org/info/rfc8040</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8174">[RFC8174]</dt>
        <dd>
<span class="refAuthor">Leiba, B.</span>, <span class="refTitle">"Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words"</span>, <span class="seriesInfo">BCP 14</span>, <span class="seriesInfo">RFC 8174</span>, <span class="seriesInfo">DOI 10.17487/RFC8174</span>, <time datetime="2017-05" class="refDate">May 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8174">https://www.rfc-editor.org/info/rfc8174</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8340">[RFC8340]</dt>
        <dd>
<span class="refAuthor">Bjorklund, M.</span> and <span class="refAuthor">L. Berger, Ed.</span>, <span class="refTitle">"YANG Tree Diagrams"</span>, <span class="seriesInfo">BCP 215</span>, <span class="seriesInfo">RFC 8340</span>, <span class="seriesInfo">DOI 10.17487/RFC8340</span>, <time datetime="2018-03" class="refDate">March 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8340">https://www.rfc-editor.org/info/rfc8340</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8341">[RFC8341]</dt>
        <dd>
<span class="refAuthor">Bierman, A.</span> and <span class="refAuthor">M. Bjorklund</span>, <span class="refTitle">"Network Configuration Access Control Model"</span>, <span class="seriesInfo">STD 91</span>, <span class="seriesInfo">RFC 8341</span>, <span class="seriesInfo">DOI 10.17487/RFC8341</span>, <time datetime="2018-03" class="refDate">March 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8341">https://www.rfc-editor.org/info/rfc8341</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8342">[RFC8342]</dt>
        <dd>
<span class="refAuthor">Bjorklund, M.</span>, <span class="refAuthor">Schoenwaelder, J.</span>, <span class="refAuthor">Shafer, P.</span>, <span class="refAuthor">Watsen, K.</span>, and <span class="refAuthor">R. Wilton</span>, <span class="refTitle">"Network Management Datastore Architecture (NMDA)"</span>, <span class="seriesInfo">RFC 8342</span>, <span class="seriesInfo">DOI 10.17487/RFC8342</span>, <time datetime="2018-03" class="refDate">March 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8342">https://www.rfc-editor.org/info/rfc8342</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8343">[RFC8343]</dt>
        <dd>
<span class="refAuthor">Bjorklund, M.</span>, <span class="refTitle">"A YANG Data Model for Interface Management"</span>, <span class="seriesInfo">RFC 8343</span>, <span class="seriesInfo">DOI 10.17487/RFC8343</span>, <time datetime="2018-03" class="refDate">March 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8343">https://www.rfc-editor.org/info/rfc8343</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8446">[RFC8446]</dt>
        <dd>
<span class="refAuthor">Rescorla, E.</span>, <span class="refTitle">"The Transport Layer Security (TLS) Protocol Version 1.3"</span>, <span class="seriesInfo">RFC 8446</span>, <span class="seriesInfo">DOI 10.17487/RFC8446</span>, <time datetime="2018-08" class="refDate">August 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8446">https://www.rfc-editor.org/info/rfc8446</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8529">[RFC8529]</dt>
        <dd>
<span class="refAuthor">Berger, L.</span>, <span class="refAuthor">Hopps, C.</span>, <span class="refAuthor">Lindem, A.</span>, <span class="refAuthor">Bogdanovic, D.</span>, and <span class="refAuthor">X. Liu</span>, <span class="refTitle">"YANG Data Model for Network Instances"</span>, <span class="seriesInfo">RFC 8529</span>, <span class="seriesInfo">DOI 10.17487/RFC8529</span>, <time datetime="2019-03" class="refDate">March 2019</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8529">https://www.rfc-editor.org/info/rfc8529</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8907">[RFC8907]</dt>
      <dd>
<span class="refAuthor">Dahm, T.</span>, <span class="refAuthor">Ota, A.</span>, <span class="refAuthor">Medway Gash, D.C.</span>, <span class="refAuthor">Carrel, D.</span>, and <span class="refAuthor">L. Grant</span>, <span class="refTitle">"The Terminal Access Controller Access-Control System Plus (TACACS+) Protocol"</span>, <span class="seriesInfo">RFC 8907</span>, <span class="seriesInfo">DOI 10.17487/RFC8907</span>, <time datetime="2020-09" class="refDate">September 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8907">https://www.rfc-editor.org/info/rfc8907</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
<section id="section-7.2">
        <h3 id="name-informative-references">
<a href="#section-7.2" class="section-number selfRef">7.2. </a><a href="#name-informative-references" class="section-name selfRef">Informative References</a>
        </h3>
<dl class="references">
<dt id="RFC3688">[RFC3688]</dt>
      <dd>
<span class="refAuthor">Mealling, M.</span>, <span class="refTitle">"The IETF XML Registry"</span>, <span class="seriesInfo">BCP 81</span>, <span class="seriesInfo">RFC 3688</span>, <span class="seriesInfo">DOI 10.17487/RFC3688</span>, <time datetime="2004-01" class="refDate">January 2004</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3688">https://www.rfc-editor.org/info/rfc3688</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
</section>
<section id="appendix-A">
      <h2 id="name-example-tacacs-authenticati">
<a href="#appendix-A" class="section-number selfRef">Appendix A. </a><a href="#name-example-tacacs-authenticati" class="section-name selfRef">Example TACACS+ Authentication Configuration</a>
      </h2>
<p id="appendix-A-1">The following shows an example where a TACACS+ authentication server
      instance is configured.<a href="#appendix-A-1" class="pilcrow">¶</a></p>
<div id="appendix-A-2">
<pre class="sourcecode">   {
     "ietf-system:system": {
       "authentication": {
         "user-authentication-order": [tacacs-plus, local-users]
       }
       "tacacs-plus": {
         "server": [
           {
             "name": "tac_plus1",
             "server-type": "authentication",
             "address": "192.0.2.2",
             "shared-secret": "QaEfThUkO198010075460923+h3TbE8n",
             "source-ip": "192.0.2.12",
             "timeout": "10"
           }
         ]
       }
     }
   }</pre><a href="#appendix-A-2" class="pilcrow">¶</a>
</div>
</section>
<section id="appendix-B">
      <h2 id="name-acknowledgments">
<a href="#name-acknowledgments" class="section-name selfRef">Acknowledgments</a>
      </h2>
<p id="appendix-B-1">The authors wish to thank <span class="contact-name">Alex Campbell</span>,
      <span class="contact-name">John Heasley</span>, <span class="contact-name">Ebben Aries</span>,
      <span class="contact-name">Alan DeKok</span>, <span class="contact-name">Joe Clarke</span>,
      <span class="contact-name">Tom Petch</span>, <span class="contact-name">Robert Wilton</span>,
      and many others for their helpful comments and suggestions.<a href="#appendix-B-1" class="pilcrow">¶</a></p>
</section>
<div id="authors-addresses">
<section id="appendix-C">
      <h2 id="name-authors-addresses">
<a href="#name-authors-addresses" class="section-name selfRef">Authors' Addresses</a>
      </h2>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Bo Wu (<span class="role">editor</span>)</span></div>
<div dir="auto" class="left"><span class="org">Huawei Technologies, Co., Ltd</span></div>
<div dir="auto" class="left"><span class="extended-address">Yuhua District</span></div>
<div dir="auto" class="left"><span class="street-address">101 Software Avenue</span></div>
<div dir="auto" class="left"><span class="locality">Nanjing</span></div>
<div dir="auto" class="left">
<span class="region">Jiangsu</span>, <span class="postal-code">210012</span>
</div>
<div dir="auto" class="left"><span class="country-name">China</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:lana.wubo@huawei.com" class="email">lana.wubo@huawei.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Guangying Zheng</span></div>
<div dir="auto" class="left"><span class="org">Huawei Technologies, Co., Ltd</span></div>
<div dir="auto" class="left"><span class="extended-address">Yuhua District</span></div>
<div dir="auto" class="left"><span class="street-address">101 Software Avenue</span></div>
<div dir="auto" class="left"><span class="locality">Nanjing</span></div>
<div dir="auto" class="left">
<span class="region">Jiangsu</span>, <span class="postal-code">210012</span>
</div>
<div dir="auto" class="left"><span class="country-name">China</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:zhengguangying@huawei.com" class="email">zhengguangying@huawei.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Michael Wang (<span class="role">editor</span>)</span></div>
<div dir="auto" class="left"><span class="org">Huawei Technologies, Co., Ltd</span></div>
<div dir="auto" class="left"><span class="extended-address">Yuhua District</span></div>
<div dir="auto" class="left"><span class="street-address">101 Software Avenue</span></div>
<div dir="auto" class="left"><span class="locality">Nanjing</span></div>
<div dir="auto" class="left"><span class="postal-code">210012</span></div>
<div dir="auto" class="left"><span class="country-name">China</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:wangzitao@huawei.com" class="email">wangzitao@huawei.com</a>
</div>
</address>
</section>
</div>
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