<?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='shadow.5'>
  <!-- $Id: shadow.5.xml,v 1.9 2005/06/16 17:27:33 kloczek Exp $ -->
  <refmeta>
    <refentrytitle>shadow</refentrytitle>
    <manvolnum>5</manvolnum>
  </refmeta>
  <refnamediv id='name'>
    <refname>shadow</refname>
    <refpurpose>encrypted password file</refpurpose>
  </refnamediv>
  
  <refsect1 id='description'>
    <title>DESCRIPTION</title>
    <para><emphasis remap='I'>shadow</emphasis> contains the encrypted
      password information for user's accounts
      and optional the password aging information. Included is:
    </para>
    <itemizedlist mark='bullet'>
      <listitem>
        <para>login name</para>
      </listitem>
      <listitem>
        <para>encrypted password</para>
      </listitem>
      <listitem>
        <para>days since Jan 1, 1970 that password was last changed</para>
      </listitem>
      <listitem>
        <para>days before password may be changed</para>
      </listitem>
      <listitem>
        <para>days after which password must be changed</para>
      </listitem>
      <listitem>
        <para>days before password is to expire that user is warned</para>
      </listitem>
      <listitem>
        <para>days after password expires that account is disabled</para>
      </listitem>
      <listitem>
        <para>days since Jan 1, 1970 that account is disabled</para>
      </listitem>
      <listitem>
        <para>a reserved field</para>
      </listitem>
    </itemizedlist>
    
    <para>The password field must be filled. The encrypted password consists
      of 13 to 24 characters from the 64 characters alphabet a thru z, A
      thru Z, 0 thru 9, \. and /. Optionally it can start with a "$"
      character. This means the encrypted password was generated using
      another (not DES) algorithm. For example if it starts with "$1$" it
      means the MD5-based algorithm was used.
    </para>
    
    <para>
      Refer to 
      <citerefentry>
        <refentrytitle>crypt</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>
      for details on how this string is interpreted.
    </para>
    
    <para>The date of the last password change is given as the number of
      days since Jan 1, 1970. The password may not be changed again until
      the proper number of days have passed, and must be changed after the
      maximum number of days. If the minimum number of days required is
      greater than the maximum number of day allowed, this password may not
      be changed by the user.
    </para>
    
    <para>An account is considered to be inactive and is disabled if the
      password is not changed within the specified number of days after the
      password expires. An account will also be disabled on the specified
      day regardless of other password expiration information.
    </para>
    
    <para>This information supersedes any password or password age
      information present in <filename>/etc/passwd</filename>.
    </para>
    
    <para>This file must not be readable by regular users if password
      security is to be maintained.
    </para>
  </refsect1>
  
  <refsect1 id='files'>
    <title>FILES</title>
    <variablelist>
      <varlistentry>
        <term><filename>/etc/passwd</filename></term>
        <listitem>user account information</listitem>
      </varlistentry>
      <varlistentry>
        <term><filename>/etc/shadow</filename></term>
        <listitem>secure user account information</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>
  
  <refsect1 id='see_also'>
    <title>SEE ALSO</title>
    <para><citerefentry>
        <refentrytitle>chage</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>login</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>passwd</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>su</refentrytitle><manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>passwd</refentrytitle><manvolnum>5</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>pwconv</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>pwunconv</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>sulogin</refentrytitle><manvolnum>8</manvolnum>
      </citerefentry>
    </para>
  </refsect1>
  
  <refsect1 id='author'>
    <title>AUTHOR</title>
    <para>Julianne Frances Haugh (jockgrrl@ix.netcom.com)</para>
  </refsect1>
</refentry>
