<!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="X-UA-Compatible" content="IE=Edge" />
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>PKINIT configuration — 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" type="text/css" href="../_static/kerb.css" />
<script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></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>
<script type="text/javascript" src="../_static/language_data.js"></script>
<link rel="author" title="About these documents" href="../about.html" />
<link rel="index" title="Index" href="../genindex.html" />
<link rel="search" title="Search" href="../search.html" />
<link rel="copyright" title="Copyright" href="../copyright.html" />
<link rel="next" title="OTP Preauthentication" href="otp.html" />
<link rel="prev" title="Backups of secure hosts" href="backup_host.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="backup_host.html" title="Backups of secure hosts"
accesskey="P">previous</a> |
<a href="otp.html" title="OTP Preauthentication"
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__PKINIT configuration">feedback</a>
</div>
</div>
</div>
<div class="content-wrapper">
<div class="content">
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body" role="main">
<div class="section" id="pkinit-configuration">
<span id="pkinit"></span><h1>PKINIT configuration<a class="headerlink" href="#pkinit-configuration" title="Permalink to this headline">¶</a></h1>
<p>PKINIT is a preauthentication mechanism for Kerberos 5 which uses
X.509 certificates to authenticate the KDC to clients and vice versa.
PKINIT can also be used to enable anonymity support, allowing clients
to communicate securely with the KDC or with application servers
without authenticating as a particular client principal.</p>
<div class="section" id="creating-certificates">
<h2>Creating certificates<a class="headerlink" href="#creating-certificates" title="Permalink to this headline">¶</a></h2>
<p>PKINIT requires an X.509 certificate for the KDC and one for each
client principal which will authenticate using PKINIT. For anonymous
PKINIT, a KDC certificate is required, but client certificates are
not. A commercially issued server certificate can be used for the KDC
certificate, but generally cannot be used for client certificates.</p>
<p>The instruction in this section describe how to establish a
certificate authority and create standard PKINIT certificates. Skip
this section if you are using a commercially issued server certificate
as the KDC certificate for anonymous PKINIT, or if you are configuring
a client to use an Active Directory KDC.</p>
<div class="section" id="generating-a-certificate-authority-certificate">
<h3>Generating a certificate authority certificate<a class="headerlink" href="#generating-a-certificate-authority-certificate" title="Permalink to this headline">¶</a></h3>
<p>You can establish a new certificate authority (CA) for use with a
PKINIT deployment with the commands:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">openssl</span> <span class="n">genrsa</span> <span class="o">-</span><span class="n">out</span> <span class="n">cakey</span><span class="o">.</span><span class="n">pem</span> <span class="mi">2048</span>
<span class="n">openssl</span> <span class="n">req</span> <span class="o">-</span><span class="n">key</span> <span class="n">cakey</span><span class="o">.</span><span class="n">pem</span> <span class="o">-</span><span class="n">new</span> <span class="o">-</span><span class="n">x509</span> <span class="o">-</span><span class="n">out</span> <span class="n">cacert</span><span class="o">.</span><span class="n">pem</span> <span class="o">-</span><span class="n">days</span> <span class="mi">3650</span>
</pre></div>
</div>
<p>The second command will ask for the values of several certificate
fields. These fields can be set to any values. You can adjust the
expiration time of the CA certificate by changing the number after
<code class="docutils literal notranslate"><span class="pre">-days</span></code>. Since the CA certificate must be deployed to client
machines each time it changes, it should normally have an expiration
time far in the future; however, expiration times after 2037 may cause
interoperability issues in rare circumstances.</p>
<p>The result of these commands will be two files, cakey.pem and
cacert.pem. cakey.pem will contain a 2048-bit RSA private key, which
must be carefully protected. cacert.pem will contain the CA
certificate, which must be placed in the filesytems of the KDC and
each client host. cakey.pem will be required to create KDC and client
certificates.</p>
</div>
<div class="section" id="generating-a-kdc-certificate">
<h3>Generating a KDC certificate<a class="headerlink" href="#generating-a-kdc-certificate" title="Permalink to this headline">¶</a></h3>
<p>A KDC certificate for use with PKINIT is required to have some unusual
fields, which makes generating them with OpenSSL somewhat complicated.
First, you will need a file containing the following:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>[kdc_cert]
basicConstraints=CA:FALSE
keyUsage=nonRepudiation,digitalSignature,keyEncipherment,keyAgreement
extendedKeyUsage=1.3.6.1.5.2.3.5
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer
issuerAltName=issuer:copy
subjectAltName=otherName:1.3.6.1.5.2.2;SEQUENCE:kdc_princ_name
[kdc_princ_name]
realm=EXP:0,GeneralString:${ENV::REALM}
principal_name=EXP:1,SEQUENCE:kdc_principal_seq
[kdc_principal_seq]
name_type=EXP:0,INTEGER:1
name_string=EXP:1,SEQUENCE:kdc_principals
[kdc_principals]
princ1=GeneralString:krbtgt
princ2=GeneralString:${ENV::REALM}
</pre></div>
</div>
<p>If the above contents are placed in extensions.kdc, you can generate
and sign a KDC certificate with the following commands:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">openssl</span> <span class="n">genrsa</span> <span class="o">-</span><span class="n">out</span> <span class="n">kdckey</span><span class="o">.</span><span class="n">pem</span> <span class="mi">2048</span>
<span class="n">openssl</span> <span class="n">req</span> <span class="o">-</span><span class="n">new</span> <span class="o">-</span><span class="n">out</span> <span class="n">kdc</span><span class="o">.</span><span class="n">req</span> <span class="o">-</span><span class="n">key</span> <span class="n">kdckey</span><span class="o">.</span><span class="n">pem</span>
<span class="n">env</span> <span class="n">REALM</span><span class="o">=</span><span class="n">YOUR_REALMNAME</span> <span class="n">openssl</span> <span class="n">x509</span> <span class="o">-</span><span class="n">req</span> <span class="o">-</span><span class="ow">in</span> <span class="n">kdc</span><span class="o">.</span><span class="n">req</span> \
<span class="o">-</span><span class="n">CAkey</span> <span class="n">cakey</span><span class="o">.</span><span class="n">pem</span> <span class="o">-</span><span class="n">CA</span> <span class="n">cacert</span><span class="o">.</span><span class="n">pem</span> <span class="o">-</span><span class="n">out</span> <span class="n">kdc</span><span class="o">.</span><span class="n">pem</span> <span class="o">-</span><span class="n">days</span> <span class="mi">365</span> \
<span class="o">-</span><span class="n">extfile</span> <span class="n">extensions</span><span class="o">.</span><span class="n">kdc</span> <span class="o">-</span><span class="n">extensions</span> <span class="n">kdc_cert</span> <span class="o">-</span><span class="n">CAcreateserial</span>
<span class="n">rm</span> <span class="n">kdc</span><span class="o">.</span><span class="n">req</span>
</pre></div>
</div>
<p>The second command will ask for the values of certificate fields,
which can be set to any values. In the third command, substitute your
KDC’s realm name for YOUR_REALMNAME. You can adjust the certificate’s
expiration date by changing the number after <code class="docutils literal notranslate"><span class="pre">-days</span></code>. Remember to
create a new KDC certificate before the old one expires.</p>
<p>The result of this operation will be in two files, kdckey.pem and
kdc.pem. Both files must be placed in the KDC’s filesystem.
kdckey.pem, which contains the KDC’s private key, must be carefully
protected.</p>
<p>If you examine the KDC certificate with <code class="docutils literal notranslate"><span class="pre">openssl</span> <span class="pre">x509</span> <span class="pre">-in</span> <span class="pre">kdc.pem</span>
<span class="pre">-text</span> <span class="pre">-noout</span></code>, OpenSSL will not know how to display the KDC principal
name in the Subject Alternative Name extension, so it will appear as
<code class="docutils literal notranslate"><span class="pre">othername:<unsupported></span></code>. This is normal and does not mean
anything is wrong with the KDC certificate.</p>
</div>
<div class="section" id="generating-client-certificates">
<h3>Generating client certificates<a class="headerlink" href="#generating-client-certificates" title="Permalink to this headline">¶</a></h3>
<p>PKINIT client certificates also must have some unusual certificate
fields. To generate a client certificate with OpenSSL for a
single-component principal name, you will need an extensions file
(different from the KDC extensions file above) containing:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>[client_cert]
basicConstraints=CA:FALSE
keyUsage=digitalSignature,keyEncipherment,keyAgreement
extendedKeyUsage=1.3.6.1.5.2.3.4
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer
issuerAltName=issuer:copy
subjectAltName=otherName:1.3.6.1.5.2.2;SEQUENCE:princ_name
[princ_name]
realm=EXP:0,GeneralString:${ENV::REALM}
principal_name=EXP:1,SEQUENCE:principal_seq
[principal_seq]
name_type=EXP:0,INTEGER:1
name_string=EXP:1,SEQUENCE:principals
[principals]
princ1=GeneralString:${ENV::CLIENT}
</pre></div>
</div>
<p>If the above contents are placed in extensions.client, you can
generate and sign a client certificate with the following commands:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">openssl</span> <span class="n">genrsa</span> <span class="o">-</span><span class="n">out</span> <span class="n">clientkey</span><span class="o">.</span><span class="n">pem</span> <span class="mi">2048</span>
<span class="n">openssl</span> <span class="n">req</span> <span class="o">-</span><span class="n">new</span> <span class="o">-</span><span class="n">key</span> <span class="n">clientkey</span><span class="o">.</span><span class="n">pem</span> <span class="o">-</span><span class="n">out</span> <span class="n">client</span><span class="o">.</span><span class="n">req</span>
<span class="n">env</span> <span class="n">REALM</span><span class="o">=</span><span class="n">YOUR_REALMNAME</span> <span class="n">CLIENT</span><span class="o">=</span><span class="n">YOUR_PRINCNAME</span> <span class="n">openssl</span> <span class="n">x509</span> \
<span class="o">-</span><span class="n">CAkey</span> <span class="n">cakey</span><span class="o">.</span><span class="n">pem</span> <span class="o">-</span><span class="n">CA</span> <span class="n">cacert</span><span class="o">.</span><span class="n">pem</span> <span class="o">-</span><span class="n">req</span> <span class="o">-</span><span class="ow">in</span> <span class="n">client</span><span class="o">.</span><span class="n">req</span> \
<span class="o">-</span><span class="n">extensions</span> <span class="n">client_cert</span> <span class="o">-</span><span class="n">extfile</span> <span class="n">extensions</span><span class="o">.</span><span class="n">client</span> \
<span class="o">-</span><span class="n">days</span> <span class="mi">365</span> <span class="o">-</span><span class="n">out</span> <span class="n">client</span><span class="o">.</span><span class="n">pem</span>
<span class="n">rm</span> <span class="n">client</span><span class="o">.</span><span class="n">req</span>
</pre></div>
</div>
<p>Normally, the first two commands should be run on the client host, and
the resulting client.req file transferred to the certificate authority
host for the third command. As in the previous steps, the second
command will ask for the values of certificate fields, which can be
set to any values. In the third command, substitute your realm’s name
for YOUR_REALMNAME and the client’s principal name (without realm) for
YOUR_PRINCNAME. You can adjust the certificate’s expiration date by
changing the number after <code class="docutils literal notranslate"><span class="pre">-days</span></code>.</p>
<p>The result of this operation will be two files, clientkey.pem and
client.pem. Both files must be present on the client’s host;
clientkey.pem, which contains the client’s private key, must be
protected from access by others.</p>
<p>As in the KDC certificate, OpenSSL will display the client principal
name as <code class="docutils literal notranslate"><span class="pre">othername:<unsupported></span></code> in the Subject Alternative Name
extension of a PKINIT client certificate.</p>
<p>If the client principal name contains more than one component
(e.g. <code class="docutils literal notranslate"><span class="pre">host/example.com@REALM</span></code>), the <code class="docutils literal notranslate"><span class="pre">[principals]</span></code> section of
<code class="docutils literal notranslate"><span class="pre">extensions.client</span></code> must be altered to contain multiple entries.
(Simply setting <code class="docutils literal notranslate"><span class="pre">CLIENT</span></code> to <code class="docutils literal notranslate"><span class="pre">host/example.com</span></code> would generate a
certificate for <code class="docutils literal notranslate"><span class="pre">host\/example.com@REALM</span></code> which would not match the
multi-component principal name.) For a two-component principal, the
section should read:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>[principals]
princ1=GeneralString:${ENV::CLIENT1}
princ2=GeneralString:${ENV::CLIENT2}
</pre></div>
</div>
<p>The environment variables <code class="docutils literal notranslate"><span class="pre">CLIENT1</span></code> and <code class="docutils literal notranslate"><span class="pre">CLIENT2</span></code> must then be set
to the first and second components when running <code class="docutils literal notranslate"><span class="pre">openssl</span> <span class="pre">x509</span></code>.</p>
</div>
</div>
<div class="section" id="configuring-the-kdc">
<h2>Configuring the KDC<a class="headerlink" href="#configuring-the-kdc" title="Permalink to this headline">¶</a></h2>
<p>The KDC must have filesystem access to the KDC certificate (kdc.pem)
and the KDC private key (kdckey.pem). Configure the following
relation in the KDC’s <a class="reference internal" href="conf_files/kdc_conf.html#kdc-conf-5"><span class="std std-ref">kdc.conf</span></a> file, either in the
<a class="reference internal" href="conf_files/kdc_conf.html#kdcdefaults"><span class="std std-ref">[kdcdefaults]</span></a> section or in a <a class="reference internal" href="conf_files/kdc_conf.html#kdc-realms"><span class="std std-ref">[realms]</span></a> subsection (with
appropriate pathnames):</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">pkinit_identity</span> <span class="o">=</span> <span class="n">FILE</span><span class="p">:</span><span class="o">/</span><span class="n">var</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">krb5kdc</span><span class="o">/</span><span class="n">kdc</span><span class="o">.</span><span class="n">pem</span><span class="p">,</span><span class="o">/</span><span class="n">var</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">krb5kdc</span><span class="o">/</span><span class="n">kdckey</span><span class="o">.</span><span class="n">pem</span>
</pre></div>
</div>
<p>If any clients will authenticate using regular (as opposed to
anonymous) PKINIT, the KDC must also have filesystem access to the CA
certificate (cacert.pem), and the following configuration (with the
appropriate pathname):</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">pkinit_anchors</span> <span class="o">=</span> <span class="n">FILE</span><span class="p">:</span><span class="o">/</span><span class="n">var</span><span class="o">/</span><span class="n">lib</span><span class="o">/</span><span class="n">krb5kdc</span><span class="o">/</span><span class="n">cacert</span><span class="o">.</span><span class="n">pem</span>
</pre></div>
</div>
<p>Because of the larger size of requests and responses using PKINIT, you
may also need to allow TCP access to the KDC:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">kdc_tcp_listen</span> <span class="o">=</span> <span class="mi">88</span>
</pre></div>
</div>
<p>Restart the <a class="reference internal" href="admin_commands/krb5kdc.html#krb5kdc-8"><span class="std std-ref">krb5kdc</span></a> daemon to pick up the configuration
changes.</p>
<p>The principal entry for each PKINIT-using client must be configured to
require preauthentication. Ensure this with the command:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">kadmin</span> <span class="o">-</span><span class="n">q</span> <span class="s1">'modprinc +requires_preauth YOUR_PRINCNAME'</span>
</pre></div>
</div>
<p>Starting with release 1.12, it is possible to remove the long-term
keys of a principal entry, which can save some space in the database
and help to clarify some PKINIT-related error conditions by not asking
for a password:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">kadmin</span> <span class="o">-</span><span class="n">q</span> <span class="s1">'purgekeys -all YOUR_PRINCNAME'</span>
</pre></div>
</div>
<p>These principal options can also be specified at principal creation
time as follows:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">kadmin</span> <span class="o">-</span><span class="n">q</span> <span class="s1">'add_principal +requires_preauth -nokey YOUR_PRINCNAME'</span>
</pre></div>
</div>
<p>By default, the KDC requires PKINIT client certificates to have the
standard Extended Key Usage and Subject Alternative Name attributes
for PKINIT. Starting in release 1.16, it is possible to authorize
client certificates based on the subject or other criteria instead of
the standard PKINIT Subject Alternative Name, by setting the
<strong>pkinit_cert_match</strong> string attribute on each client principal entry.
For example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">kadmin</span> <span class="n">set_string</span> <span class="n">user</span><span class="nd">@REALM</span> <span class="n">pkinit_cert_match</span> <span class="s2">"<SUBJECT>CN=user@REALM$"</span>
</pre></div>
</div>
<p>The <strong>pkinit_cert_match</strong> string attribute follows the syntax used by
the <a class="reference internal" href="conf_files/krb5_conf.html#krb5-conf-5"><span class="std std-ref">krb5.conf</span></a> <strong>pkinit_cert_match</strong> relation. To allow the
use of non-PKINIT client certificates, it will also be necessary to
disable key usage checking using the <strong>pkinit_eku_checking</strong> relation;
for example:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="p">[</span><span class="n">kdcdefaults</span><span class="p">]</span>
<span class="n">pkinit_eku_checking</span> <span class="o">=</span> <span class="n">none</span>
</pre></div>
</div>
</div>
<div class="section" id="configuring-the-clients">
<h2>Configuring the clients<a class="headerlink" href="#configuring-the-clients" title="Permalink to this headline">¶</a></h2>
<p>Client hosts must be configured to trust the issuing authority for the
KDC certificate. For a newly established certificate authority, the
client host must have filesystem access to the CA certificate
(cacert.pem) and the following relation in <a class="reference internal" href="conf_files/krb5_conf.html#krb5-conf-5"><span class="std std-ref">krb5.conf</span></a> in the
appropriate <a class="reference internal" href="conf_files/krb5_conf.html#realms"><span class="std std-ref">[realms]</span></a> subsection (with appropriate pathnames):</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">pkinit_anchors</span> <span class="o">=</span> <span class="n">FILE</span><span class="p">:</span><span class="o">/</span><span class="n">etc</span><span class="o">/</span><span class="n">krb5</span><span class="o">/</span><span class="n">cacert</span><span class="o">.</span><span class="n">pem</span>
</pre></div>
</div>
<p>If the KDC certificate is a commercially issued server certificate,
the issuing certificate is most likely included in a system directory.
You can specify it by filename as above, or specify the whole
directory like so:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">pkinit_anchors</span> <span class="o">=</span> <span class="n">DIR</span><span class="p">:</span><span class="o">/</span><span class="n">etc</span><span class="o">/</span><span class="n">ssl</span><span class="o">/</span><span class="n">certs</span>
</pre></div>
</div>
<p>A commercially issued server certificate will usually not have the
standard PKINIT principal name or Extended Key Usage extensions, so
the following additional configuration is required:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">pkinit_eku_checking</span> <span class="o">=</span> <span class="n">kpServerAuth</span>
<span class="n">pkinit_kdc_hostname</span> <span class="o">=</span> <span class="n">hostname</span><span class="o">.</span><span class="n">of</span><span class="o">.</span><span class="n">kdc</span><span class="o">.</span><span class="n">certificate</span>
</pre></div>
</div>
<p>Multiple <strong>pkinit_kdc_hostname</strong> relations can be configured to
recognize multiple KDC certificates. If the KDC is an Active
Directory domain controller, setting <strong>pkinit_kdc_hostname</strong> is
necessary, but it should not be necessary to set
<strong>pkinit_eku_checking</strong>.</p>
<p>To perform regular (as opposed to anonymous) PKINIT authentication, a
client host must have filesystem access to a client certificate
(client.pem), and the corresponding private key (clientkey.pem).
Configure the following relations in the client host’s
<a class="reference internal" href="conf_files/krb5_conf.html#krb5-conf-5"><span class="std std-ref">krb5.conf</span></a> file in the appropriate <a class="reference internal" href="conf_files/krb5_conf.html#realms"><span class="std std-ref">[realms]</span></a> subsection
(with appropriate pathnames):</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">pkinit_identities</span> <span class="o">=</span> <span class="n">FILE</span><span class="p">:</span><span class="o">/</span><span class="n">etc</span><span class="o">/</span><span class="n">krb5</span><span class="o">/</span><span class="n">client</span><span class="o">.</span><span class="n">pem</span><span class="p">,</span><span class="o">/</span><span class="n">etc</span><span class="o">/</span><span class="n">krb5</span><span class="o">/</span><span class="n">clientkey</span><span class="o">.</span><span class="n">pem</span>
</pre></div>
</div>
<p>If the KDC and client are properly configured, it should now be
possible to run <code class="docutils literal notranslate"><span class="pre">kinit</span> <span class="pre">username</span></code> without entering a password.</p>
</div>
<div class="section" id="anonymous-pkinit">
<span id="id1"></span><h2>Anonymous PKINIT<a class="headerlink" href="#anonymous-pkinit" title="Permalink to this headline">¶</a></h2>
<p>Anonymity support in Kerberos allows a client to obtain a ticket
without authenticating as any particular principal. Such a ticket can
be used as a FAST armor ticket, or to securely communicate with an
application server anonymously.</p>
<p>To configure anonymity support, you must generate or otherwise procure
a KDC certificate and configure the KDC host, but you do not need to
generate any client certificates. On the KDC, you must set the
<strong>pkinit_identity</strong> variable to provide the KDC certificate, but do
not need to set the <strong>pkinit_anchors</strong> variable or store the issuing
certificate if you won’t have any client certificates to verify. On
client hosts, you must set the <strong>pkinit_anchors</strong> variable (and
possibly <strong>pkinit_kdc_hostname</strong> and <strong>pkinit_eku_checking</strong>) in order
to trust the issuing authority for the KDC certificate, but do not
need to set the <strong>pkinit_identities</strong> variable.</p>
<p>Anonymity support is not enabled by default. To enable it, you must
create the principal <code class="docutils literal notranslate"><span class="pre">WELLKNOWN/ANONYMOUS</span></code> using the command:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">kadmin</span> <span class="o">-</span><span class="n">q</span> <span class="s1">'addprinc -randkey WELLKNOWN/ANONYMOUS'</span>
</pre></div>
</div>
<p>Some Kerberos deployments include application servers which lack
proper access control, and grant some level of access to any user who
can authenticate. In such an environment, enabling anonymity support
on the KDC would present a security issue. If you need to enable
anonymity support for TGTs (for use as FAST armor tickets) without
enabling anonymous authentication to application servers, you can set
the variable <strong>restrict_anonymous_to_tgt</strong> to <code class="docutils literal notranslate"><span class="pre">true</span></code> in the
appropriate <a class="reference internal" href="conf_files/kdc_conf.html#kdc-realms"><span class="std std-ref">[realms]</span></a> subsection of the KDC’s
<a class="reference internal" href="conf_files/kdc_conf.html#kdc-conf-5"><span class="std std-ref">kdc.conf</span></a> file.</p>
<p>To obtain anonymous credentials on a client, run <code class="docutils literal notranslate"><span class="pre">kinit</span> <span class="pre">-n</span></code>, or
<code class="docutils literal notranslate"><span class="pre">kinit</span> <span class="pre">-n</span> <span class="pre">@REALMNAME</span></code> to specify a realm. The resulting tickets
will have the client name <code class="docutils literal notranslate"><span class="pre">WELLKNOWN/ANONYMOUS@WELLKNOWN:ANONYMOUS</span></code>.</p>
</div>
<div class="section" id="freshness-tokens">
<h2>Freshness tokens<a class="headerlink" href="#freshness-tokens" title="Permalink to this headline">¶</a></h2>
<p>Freshness tokens can ensure that the client has recently had access to
its certificate private key. If freshness tokens are not required by
the KDC, a client program with temporary possession of the private key
can compose requests for future timestamps and use them later.</p>
<p>In release 1.17 and later, freshness tokens are supported by the
client and are sent by the KDC when the client indicates support for
them. Because not all clients support freshness tokens yet, they are
not required by default. To check if freshness tokens are supported
by a realm’s clients, look in the KDC logs for the lines:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">PKINIT</span><span class="p">:</span> <span class="n">freshness</span> <span class="n">token</span> <span class="n">received</span> <span class="kn">from</span> <span class="o"><</span><span class="n">client</span> <span class="n">principal</span><span class="o">></span>
<span class="n">PKINIT</span><span class="p">:</span> <span class="n">no</span> <span class="n">freshness</span> <span class="n">token</span> <span class="n">received</span> <span class="kn">from</span> <span class="o"><</span><span class="n">client</span> <span class="n">principal</span><span class="o">></span>
</pre></div>
</div>
<p>To require freshness tokens for all clients in a realm (except for
clients authenticating anonymously), set the
<strong>pkinit_require_freshness</strong> variable to <code class="docutils literal notranslate"><span class="pre">true</span></code> in the appropriate
<a class="reference internal" href="conf_files/kdc_conf.html#kdc-realms"><span class="std std-ref">[realms]</span></a> subsection of the KDC’s <a class="reference internal" href="conf_files/kdc_conf.html#kdc-conf-5"><span class="std std-ref">kdc.conf</span></a> file. To
test that this option is in effect, run <code class="docutils literal notranslate"><span class="pre">kinit</span> <span class="pre">-X</span> <span class="pre">disable_freshness</span></code>
and verify that authentication is unsuccessful.</p>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="sidebar">
<h2>On this page</h2>
<ul>
<li><a class="reference internal" href="#">PKINIT configuration</a><ul>
<li><a class="reference internal" href="#creating-certificates">Creating certificates</a><ul>
<li><a class="reference internal" href="#generating-a-certificate-authority-certificate">Generating a certificate authority certificate</a></li>
<li><a class="reference internal" href="#generating-a-kdc-certificate">Generating a KDC certificate</a></li>
<li><a class="reference internal" href="#generating-client-certificates">Generating client certificates</a></li>
</ul>
</li>
<li><a class="reference internal" href="#configuring-the-kdc">Configuring the KDC</a></li>
<li><a class="reference internal" href="#configuring-the-clients">Configuring the clients</a></li>
<li><a class="reference internal" href="#anonymous-pkinit">Anonymous PKINIT</a></li>
<li><a class="reference internal" href="#freshness-tokens">Freshness tokens</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 current"><a class="reference internal" href="index.html">For administrators</a><ul class="current">
<li class="toctree-l2"><a class="reference internal" href="install.html">Installation guide</a></li>
<li class="toctree-l2"><a class="reference internal" href="conf_files/index.html">Configuration Files</a></li>
<li class="toctree-l2"><a class="reference internal" href="realm_config.html">Realm configuration decisions</a></li>
<li class="toctree-l2"><a class="reference internal" href="database.html">Database administration</a></li>
<li class="toctree-l2"><a class="reference internal" href="dbtypes.html">Database types</a></li>
<li class="toctree-l2"><a class="reference internal" href="lockout.html">Account lockout</a></li>
<li class="toctree-l2"><a class="reference internal" href="conf_ldap.html">Configuring Kerberos with OpenLDAP back-end</a></li>
<li class="toctree-l2"><a class="reference internal" href="appl_servers.html">Application servers</a></li>
<li class="toctree-l2"><a class="reference internal" href="host_config.html">Host configuration</a></li>
<li class="toctree-l2"><a class="reference internal" href="backup_host.html">Backups of secure hosts</a></li>
<li class="toctree-l2 current"><a class="current reference internal" href="#">PKINIT configuration</a></li>
<li class="toctree-l2"><a class="reference internal" href="otp.html">OTP Preauthentication</a></li>
<li class="toctree-l2"><a class="reference internal" href="spake.html">SPAKE Preauthentication</a></li>
<li class="toctree-l2"><a class="reference internal" href="dictionary.html">Addressing dictionary attack risks</a></li>
<li class="toctree-l2"><a class="reference internal" href="princ_dns.html">Principal names and DNS</a></li>
<li class="toctree-l2"><a class="reference internal" href="enctypes.html">Encryption types</a></li>
<li class="toctree-l2"><a class="reference internal" href="https.html">HTTPS proxy configuration</a></li>
<li class="toctree-l2"><a class="reference internal" href="auth_indicator.html">Authentication indicators</a></li>
<li class="toctree-l2"><a class="reference internal" href="admin_commands/index.html">Administration programs</a></li>
<li class="toctree-l2"><a class="reference internal" href="../mitK5defaults.html">MIT Kerberos defaults</a></li>
<li class="toctree-l2"><a class="reference internal" href="env_variables.html">Environment variables</a></li>
<li class="toctree-l2"><a class="reference internal" href="troubleshoot.html">Troubleshooting</a></li>
<li class="toctree-l2"><a class="reference internal" href="advanced/index.html">Advanced topics</a></li>
<li class="toctree-l2"><a class="reference internal" href="various_envs.html">Various links</a></li>
</ul>
</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"><a class="reference internal" href="../basic/index.html">Kerberos V5 concepts</a></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: 1.17</i><br />
© <a href="../copyright.html">Copyright</a> 1985-2019, MIT.
</div>
<div class="left">
<a href="../index.html" title="Full Table of Contents"
>Contents</a> |
<a href="backup_host.html" title="Backups of secure hosts"
>previous</a> |
<a href="otp.html" title="OTP Preauthentication"
>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__PKINIT configuration">feedback</a>
</div>
</div>
</div>
</body>
</html>
