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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>keytab — MIT Kerberos Documentation</title> <link rel="stylesheet" href="../_static/agogo.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <link rel="stylesheet" href="../_static/kerb.css" type="text/css" /> <script type="text/javascript"> var DOCUMENTATION_OPTIONS = { URL_ROOT: '../', VERSION: '1.15.1', COLLAPSE_INDEX: false, FILE_SUFFIX: '.html', HAS_SOURCE: true }; </script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <link rel="author" title="About these documents" href="../about.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="top" title="MIT Kerberos Documentation" href="../index.html" /> <link rel="up" title="Kerberos V5 concepts" href="index.html" /> <link rel="next" title="replay cache" href="rcache_def.html" /> <link rel="prev" title="Credential cache" href="ccache_def.html" /> </head> <body> <div class="header-wrapper"> <div class="header"> <h1><a href="../index.html">MIT Kerberos Documentation</a></h1> <div class="rel"> <a href="../index.html" title="Full Table of Contents" accesskey="C">Contents</a> | <a href="ccache_def.html" title="Credential cache" accesskey="P">previous</a> | <a href="rcache_def.html" title="replay cache" accesskey="N">next</a> | <a href="../genindex.html" title="General Index" accesskey="I">index</a> | <a href="../search.html" title="Enter search criteria" accesskey="S">Search</a> | <a href="mailto:krb5-bugs@mit.edu?subject=Documentation__keytab">feedback</a> </div> </div> </div> <div class="content-wrapper"> <div class="content"> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body"> <div class="section" id="keytab"> <span id="keytab-definition"></span><h1>keytab<a class="headerlink" href="#keytab" title="Permalink to this headline">¶</a></h1> <p>A keytab (short for “key table”) stores long-term keys for one or more principals. Keytabs are normally represented by files in a standard format, although in rare cases they can be represented in other ways. Keytabs are used most often to allow server applications to accept authentications from clients, but can also be used to obtain initial credentials for client applications.</p> <p>Keytabs are named using the format <em>type</em><tt class="docutils literal"><span class="pre">:</span></tt><em>value</em>. Usually <em>type</em> is <tt class="docutils literal"><span class="pre">FILE</span></tt> and <em>value</em> is the absolute pathname of the file. Other possible values for <em>type</em> are <tt class="docutils literal"><span class="pre">SRVTAB</span></tt>, which indicates a file in the deprecated Kerberos 4 srvtab format, and <tt class="docutils literal"><span class="pre">MEMORY</span></tt>, which indicates a temporary keytab stored in the memory of the current process.</p> <p>A keytab contains one or more entries, where each entry consists of a timestamp (indicating when the entry was written to the keytab), a principal name, a key version number, an encryption type, and the encryption key itself.</p> <p>A keytab can be displayed using the <a class="reference internal" href="../user/user_commands/klist.html#klist-1"><em>klist</em></a> command with the <tt class="docutils literal"><span class="pre">-k</span></tt> option. Keytabs can be created or appended to by extracting keys from the KDC database using the <a class="reference internal" href="../admin/admin_commands/kadmin_local.html#kadmin-1"><em>kadmin</em></a> <a class="reference internal" href="../admin/admin_commands/kadmin_local.html#ktadd"><em>ktadd</em></a> command. Keytabs can be manipulated using the <a class="reference internal" href="../admin/admin_commands/ktutil.html#ktutil-1"><em>ktutil</em></a> and <a class="reference internal" href="../admin/admin_commands/k5srvutil.html#k5srvutil-1"><em>k5srvutil</em></a> commands.</p> <div class="section" id="default-keytab"> <h2>Default keytab<a class="headerlink" href="#default-keytab" title="Permalink to this headline">¶</a></h2> <p>The default keytab is used by server applications if the application does not request a specific keytab. The name of the default keytab is determined by the following, in decreasing order of preference:</p> <ol class="arabic simple"> <li>The <strong>KRB5_KTNAME</strong> environment variable.</li> <li>The <strong>default_keytab_name</strong> profile variable in <a class="reference internal" href="../admin/conf_files/krb5_conf.html#libdefaults"><em>[libdefaults]</em></a>.</li> <li>The hardcoded default, <tt class="docutils literal"><span class="pre">FILE:/etc/krb5.keytab</span></tt>.</li> </ol> </div> <div class="section" id="default-client-keytab"> <h2>Default client keytab<a class="headerlink" href="#default-client-keytab" title="Permalink to this headline">¶</a></h2> <p>The default client keytab is used, if it is present and readable, to automatically obtain initial credentials for GSSAPI client applications. The principal name of the first entry in the client keytab is used by default when obtaining initial credentials. The name of the default client keytab is determined by the following, in decreasing order of preference:</p> <ol class="arabic simple"> <li>The <strong>KRB5_CLIENT_KTNAME</strong> environment variable.</li> <li>The <strong>default_client_keytab_name</strong> profile variable in <a class="reference internal" href="../admin/conf_files/krb5_conf.html#libdefaults"><em>[libdefaults]</em></a>.</li> <li>The hardcoded default, <tt class="docutils literal"><span class="pre">FILE:/var/kerberos/krb5/user/%{euid}/client.keytab</span></tt>.</li> </ol> </div> </div> </div> </div> </div> </div> <div class="sidebar"> <h2>On this page</h2> <ul> <li><a class="reference internal" href="#">keytab</a><ul> <li><a class="reference internal" href="#default-keytab">Default keytab</a></li> <li><a class="reference internal" href="#default-client-keytab">Default client keytab</a></li> </ul> </li> </ul> <br/> <h2>Table of contents</h2> <ul class="current"> <li class="toctree-l1"><a class="reference internal" href="../user/index.html">For users</a></li> <li class="toctree-l1"><a class="reference internal" href="../admin/index.html">For administrators</a></li> <li class="toctree-l1"><a class="reference internal" href="../appdev/index.html">For application developers</a></li> <li class="toctree-l1"><a class="reference internal" href="../plugindev/index.html">For plugin module developers</a></li> <li class="toctree-l1"><a class="reference internal" href="../build/index.html">Building Kerberos V5</a></li> <li class="toctree-l1 current"><a class="reference internal" href="index.html">Kerberos V5 concepts</a><ul class="current"> <li class="toctree-l2"><a class="reference internal" href="ccache_def.html">Credential cache</a></li> <li class="toctree-l2 current"><a class="current reference internal" href="">keytab</a><ul class="simple"> </ul> </li> <li class="toctree-l2"><a class="reference internal" href="rcache_def.html">replay cache</a></li> <li class="toctree-l2"><a class="reference internal" href="stash_file_def.html">stash file</a></li> <li class="toctree-l2"><a class="reference internal" href="date_format.html">Supported date and time formats</a></li> </ul> </li> <li class="toctree-l1"><a class="reference internal" href="../formats/index.html">Protocols and file formats</a></li> <li class="toctree-l1"><a class="reference internal" href="../mitK5features.html">MIT Kerberos features</a></li> <li class="toctree-l1"><a class="reference internal" href="../build_this.html">How to build this documentation from the source</a></li> <li class="toctree-l1"><a class="reference internal" href="../about.html">Contributing to the MIT Kerberos Documentation</a></li> <li class="toctree-l1"><a class="reference internal" href="../resources.html">Resources</a></li> </ul> <br/> <h4><a href="../index.html">Full Table of Contents</a></h4> <h4>Search</h4> <form class="search" action="../search.html" method="get"> <input type="text" name="q" size="18" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <div class="clearer"></div> </div> </div> <div class="footer-wrapper"> <div class="footer" > <div class="right" ><i>Release: 1.15.1</i><br /> © <a href="../copyright.html">Copyright</a> 1985-2017, MIT. </div> <div class="left"> <a href="../index.html" title="Full Table of Contents" >Contents</a> | <a href="ccache_def.html" title="Credential cache" >previous</a> | <a href="rcache_def.html" title="replay cache" >next</a> | <a href="../genindex.html" title="General Index" >index</a> | <a href="../search.html" title="Enter search criteria" >Search</a> | <a href="mailto:krb5-bugs@mit.edu?subject=Documentation__keytab">feedback</a> </div> </div> </div> </body> </html>