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<?xml version="1.0" encoding='UTF-8'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
	"http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd">

<refentry id="pam_pwhistory">

  <refmeta>
    <refentrytitle>pam_pwhistory</refentrytitle>
    <manvolnum>8</manvolnum>
    <refmiscinfo class="sectdesc">Linux-PAM Manual</refmiscinfo>
  </refmeta>

  <refnamediv id="pam_pwhistory-name">
    <refname>pam_pwhistory</refname>
    <refpurpose>PAM module to remember last passwords</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis id="pam_pwhistory-cmdsynopsis">
      <command>pam_pwhistory.so</command>
      <arg choice="opt">
        debug
      </arg>
      <arg choice="opt">
        use_authtok
      </arg>
      <arg choice="opt">
        enforce_for_root
      </arg>
      <arg choice="opt">
        remember=<replaceable>N</replaceable>
      </arg>
      <arg choice="opt">
        retry=<replaceable>N</replaceable>
      </arg>
      <arg choice="opt">
        authtok_type=<replaceable>STRING</replaceable>
      </arg>

    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1 id="pam_pwhistory-description">

    <title>DESCRIPTION</title>

    <para>
      This module saves the last passwords for each user in order
      to force password change history and keep the user from
      alternating between the same password too frequently.
    </para>
    <para>
      This module does not work together with kerberos. In general,
      it does not make much sense to use this module in conjunction
      with NIS or LDAP, since the old passwords are stored on the
      local machine and are not available on another machine for
      password history checking.
    </para>
  </refsect1>

  <refsect1 id="pam_pwhistory-options">
    <title>OPTIONS</title>
    <variablelist>
      <varlistentry>
        <term>
          <option>debug</option>
        </term>
        <listitem>
          <para>
            Turns on debugging via
            <citerefentry>
              <refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum>
            </citerefentry>.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          <option>use_authtok</option>
        </term>
        <listitem>
          <para>
           When password changing enforce the module to use the new password
           provided by a previously stacked <option>password</option>
           module (this is used in the example of the stacking of the
           <command>pam_cracklib</command> module documented below).
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          <option>enforce_for_root</option>
        </term>
        <listitem>
          <para>
            If this option is set, the check is enforced for root, too.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          <option>remember=<replaceable>N</replaceable></option>
        </term>
        <listitem>
          <para>
            The last <replaceable>N</replaceable> passwords for each
            user are saved in <filename>/etc/security/opasswd</filename>.
            The default is <emphasis>10</emphasis>. Value of
            <emphasis>0</emphasis> makes the module to keep the existing
            contents of the <filename>opasswd</filename> file unchanged.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
          <term>
            <option>retry=<replaceable>N</replaceable></option>
          </term>
          <listitem>
            <para>
              Prompt user at most <replaceable>N</replaceable> times
              before returning with error. The default is
              <emphasis>1</emphasis>.
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            <option>authtok_type=<replaceable>STRING</replaceable></option>
          </term>
          <listitem>
            <para>
              See <citerefentry>
	<refentrytitle>pam_get_authtok</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry> for more details.
            </para>
          </listitem>
        </varlistentry>

    </variablelist>
  </refsect1>

  <refsect1 id="pam_pwhistory-types">
    <title>MODULE TYPES PROVIDED</title>
    <para>
      Only the <option>password</option> module type is provided.
    </para>
  </refsect1>

  <refsect1 id='pam_pwhistory-return_values'>
    <title>RETURN VALUES</title>
    <variablelist>
      <varlistentry>
      <term>PAM_AUTHTOK_ERR</term>
        <listitem>
          <para>
            No new password was entered, the user aborted password
            change or new password couldn't be set.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>PAM_IGNORE</term>
        <listitem>
          <para>
            Password history was disabled.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>PAM_MAXTRIES</term>
        <listitem>
          <para>
            Password was rejected too often.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>PAM_USER_UNKNOWN</term>
        <listitem>
          <para>
            User is not known to system.
          </para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1 id='pam_pwhistory-examples'>
    <title>EXAMPLES</title>
    <para>
      An example password section would be:
      <programlisting>
#%PAM-1.0
password     required       pam_pwhistory.so
password     required       pam_unix.so        use_authtok
      </programlisting>
    </para>
    <para>
     In combination with <command>pam_cracklib</command>:
      <programlisting>
#%PAM-1.0
password     required       pam_cracklib.so    retry=3
password     required       pam_pwhistory.so   use_authtok
password     required       pam_unix.so        use_authtok
      </programlisting>
    </para>
  </refsect1>

  <refsect1 id="pam_pwhistory-files">
    <title>FILES</title>
    <variablelist>
      <varlistentry>
        <term><filename>/etc/security/opasswd</filename></term>
        <listitem>
          <para>File with password history</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1 id='pam_pwhistory-see_also'>
    <title>SEE ALSO</title>
    <para>
      <citerefentry>
	<refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum>
      </citerefentry>,
      <citerefentry>
	<refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>
      <citerefentry>
	<refentrytitle>pam_get_authtok</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>
    </para>
  </refsect1>

  <refsect1 id='pam_pwhistory-author'>
    <title>AUTHOR</title>
      <para>
        pam_pwhistory was written by Thorsten Kukuk &lt;kukuk@thkukuk.de&gt;
      </para>
  </refsect1>

</refentry>