docs/manual/programs/htpasswd.xml

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<manualpage metafile="htpasswd.xml.meta">
<parentdocument href="./">Programs</parentdocument>

<title>htpasswd - Manage user files for basic authentication</title>

<summary>
    <p><program>htpasswd</program> is used to create and update the flat-files used to
    store usernames and password for basic authentication of HTTP users. If
    <program>htpasswd</program> cannot access a file, such as not being able to write
    to the output file or not being able to read the file in order to update it,
    it returns an error status and makes no changes.</p>

    <p>Resources available from the Apache HTTP server can be restricted to
    just the users listed in the files created by <program>htpasswd</program>. This
    program can only manage usernames and passwords stored in a flat-file. It
    can hash and display password information for use in other types of data
    stores, though. To use a DBM database see <program>dbmmanage</program> or
    <program>htdbm</program>.</p>

    <p><program>htpasswd</program> hashes passwords using either bcrypt, a
    version of MD5 modified for Apache, SHA-1, or the system's
    <code>crypt()</code> routine. SHA-2-based hashes (SHA-256 and
    SHA-512) are supported for <code>crypt()</code>.  Files managed by
    <program>htpasswd</program> may contain a mixture of different encoding
    types of passwords; some user records may have bcrypt or
    MD5-hashed passwords while others in the same file may have
    passwords hashed with <code>crypt()</code>.</p>

    <p>This manual page only lists the command line arguments. For details of
    the directives necessary to configure user authentication in
    <program>httpd</program> see the Apache manual, which is part of the
    Apache distribution or can be found at <a href="http://httpd.apache.org"
    >http://httpd.apache.org/</a>.</p>
</summary>
<seealso><program>httpd</program></seealso>
<seealso><program>htdbm</program></seealso>
<seealso>The scripts in support/SHA1 which come with the
distribution.</seealso>

<section id="synopsis"><title>Synopsis</title>
    <p><code><strong>htpasswd</strong>
    [ -<strong>c</strong> ]
    [ -<strong>i</strong> ]
    [ -<strong>m</strong> |
      -<strong>B</strong> |
      -<strong>2</strong> | 
      -<strong>5</strong> | 
      -<strong>d</strong> |
      -<strong>s</strong> |
      -<strong>p</strong> ]
    [ -<strong>r</strong> <var>rounds</var> ]
    [ -<strong>C</strong> <var>cost</var> ]
    [ -<strong>D</strong> ]
    [ -<strong>v</strong> ]  <var>passwdfile</var> <var>username</var></code></p>

    <p><code><strong>htpasswd</strong> -<strong>b</strong>
    [ -<strong>c</strong> ]
    [ -<strong>m</strong> |
      -<strong>B</strong> |
      -<strong>2</strong> | 
      -<strong>5</strong> | 
      -<strong>d</strong> |
      -<strong>s</strong> |
      -<strong>p</strong> ]
    [ -<strong>r</strong> <var>rounds</var> ]
    [ -<strong>C</strong> <var>cost</var> ]
    [ -<strong>D</strong> ]
    [ -<strong>v</strong> ]  <var>passwdfile</var> <var>username</var>
    <var>password</var></code></p>

    <p><code><strong>htpasswd</strong> -<strong>n</strong>
    [ -<strong>i</strong> ]
    [ -<strong>m</strong> |
      -<strong>B</strong> |
      -<strong>2</strong> | 
      -<strong>5</strong> | 
      -<strong>d</strong> |
      -<strong>s</strong> |
      -<strong>p</strong> ]
    [ -<strong>r</strong> <var>rounds</var> ]
    [ -<strong>C</strong> <var>cost</var> ] <var>username</var></code></p>

    <p><code><strong>htpasswd</strong> -<strong>nb</strong>
    [ -<strong>m</strong> |
      -<strong>B</strong> | 
      -<strong>2</strong> | 
      -<strong>5</strong> | 
      -<strong>d</strong> |
      -<strong>s</strong> |
      -<strong>p</strong> ]
    [ -<strong>r</strong> <var>rounds</var> ]
    [ -<strong>C</strong> <var>cost</var> ] <var>username</var>
    <var>password</var></code></p>
</section>

<section id="options"><title>Options</title>
    <dl>
    <dt><code>-b</code></dt>
    <dd>Use batch mode; <em>i.e.</em>, get the password from the command line
    rather than prompting for it. This option should be used with extreme care,
    since <strong>the password is clearly visible</strong> on the command
    line. For script use see the <code>-i</code> option.<br />
    Available in 2.4.4 and later.</dd>

    <dt><code>-i</code></dt>
    <dd>Read the password from stdin without verification (for script usage).</dd>

    <dt><code>-c</code></dt>
    <dd>Create the <var>passwdfile</var>. If <var>passwdfile</var> already
    exists, it is rewritten and truncated. This option cannot be combined with
    the <code>-n</code> option.</dd>

    <dt><code>-n</code></dt>
    <dd>Display the results on standard output rather than updating a file.
    This is useful for generating password records acceptable to Apache for
    inclusion in non-text data stores. This option changes the syntax of the
    command line, since the <var>passwdfile</var> argument (usually the first
    one) is omitted. It cannot be combined with the <code>-c</code> option.</dd>

    <dt><code>-m</code></dt>
    <dd>Use MD5 hashing for passwords. This is the default (since version
    2.2.18).</dd>

    <dt><code>-2</code></dt>
    <dd>Use SHA-256 <code>crypt()</code> based hashes for passwords.  This is
    supported on most Unix platforms.</dd>

    <dt><code>-5</code></dt>
    <dd>Use SHA-512 <code>crypt()</code> based hashes for passwords.  This is
    supported on most Unix platforms.</dd>

    <dt><code>-B</code></dt>
    <dd>Use bcrypt hashing for passwords. This is currently considered to
    be very secure.</dd>

    <dt><code>-C</code></dt>
    <dd>This flag is only allowed in combination with <code>-B</code> (bcrypt
    hashing). It sets the computing time used for the bcrypt algorithm
    (higher is more secure but slower, default: 5, valid: 4 to 17).</dd>

    <dt><code>-r</code></dt>
    <dd>This flag is only allowed in combination with <code>-2</code>
    or <code>-5</code>. It sets the number of hash rounds used for the
    SHA-2 algorithms (higher is more secure but slower; the default is
    5,000).</dd>

    <dt><code>-d</code></dt>
    <dd>Use <code>crypt()</code> hashing for passwords. This is not
    supported by the <program>httpd</program> server on Windows and
    NetWare. This algorithm limits the password length to 8 characters.
    This algorithm is <strong>insecure</strong> by today's standards.
    It used to be the default algorithm until version 2.2.17.</dd>

    <dt><code>-s</code></dt>
    <dd>Use SHA-1 (160-bit) hashing for passwords. Facilitates migration
    from/to Netscape servers using the LDAP Directory Interchange
    Format (ldif).  This algorithm is <strong>insecure</strong> by
    today's standards.</dd>

    <dt><code>-p</code></dt>
    <dd>Use plaintext passwords. Though <program>htpasswd</program> will support
    creation on all platforms, the <program>httpd</program> daemon will
    only accept plain text passwords on Windows and NetWare.</dd>

    <dt><code>-D</code></dt>
    <dd>Delete user. If the username exists in the specified htpasswd file, it
    will be deleted.</dd>

    <dt><code>-v</code></dt>
    <dd>Verify password. Verify that the given password matches the password
    of the user stored in the specified htpasswd file.<br />
    Available in 2.4.5 and later.</dd>

    <dt><code><var>passwdfile</var></code></dt>
    <dd>Name of the file to contain the user name and password. If
    <code>-c</code> is given, this file is created if it does not already exist,
    or rewritten and truncated if it does exist.</dd>

    <dt><code><var>username</var></code></dt>
    <dd>The username to create or update in <var>passwdfile</var>. If
    <var>username</var> does not exist in this file, an entry is added. If it
    does exist, the password is changed.</dd>

    <dt><code><var>password</var></code></dt>
    <dd>The plaintext password to be hashed and stored  in the file. Only
    used with the <code>-b</code> flag.</dd>
    </dl>
</section>

<section id="exit"><title>Exit Status</title>
    <p><program>htpasswd</program> returns a zero status ("true") if the username and
    password have been successfully added or updated in the
    <var>passwdfile</var>. <program>htpasswd</program> returns <code>1</code> if it
    encounters some problem accessing files, <code>2</code> if there was a
    syntax problem with the command line, <code>3</code> if the password was
    entered interactively and the verification entry didn't match,
    <code>4</code> if its operation was interrupted, <code>5</code> if a value
    is too long (username, filename, password, or final computed record),
    <code>6</code> if the username contains illegal characters (see the
    <a href="#restrictions">Restrictions section</a>), and <code>7</code>
    if the file is not a valid password file.</p>
</section>

<section id="examples"><title>Examples</title>
    <example>
      htpasswd /usr/local/etc/apache/.htpasswd-users jsmith
    </example>

    <p>Adds or modifies the password for user <code>jsmith</code>. The user
    is prompted for the password. The password will be hashed using the
    modified Apache MD5 algorithm. If the file does not exist,
    <program>htpasswd</program> will do nothing except return an error.</p>

    <example>
      htpasswd -c /home/doe/public_html/.htpasswd jane
    </example>

    <p>Creates a new file and stores a record in it for user <code>jane</code>.
    The user is prompted for the password. If the file exists and cannot be
    read, or cannot be written, it is not altered and <program>htpasswd</program>
    will display a message and return an error status.</p>

    <example>
      htpasswd -db /usr/web/.htpasswd-all jones Pwd4Steve
    </example>

    <p>Encrypts the password from the command line (<code>Pwd4Steve</code>)
    using the <code>crypt()</code> algorithm, and stores it in the specified
    file.</p>
</section>

<section id="security"><title>Security Considerations</title>
    <p>Web password files such as those managed by <program>htpasswd</program> should
    <em>not</em> be within the Web server's URI space -- that is, they should
    not be fetchable with a browser.</p>

    <p>This program is not safe as a setuid executable. Do <em>not</em> make it
    setuid.</p>

    <p>The use of the <code>-b</code> option is discouraged, since when it is
    used the plaintext password appears on the command line.</p>

    <p>When using the <code>crypt()</code> algorithm, note that only the first
    8 characters of the password are used  to form the password. If the supplied
    password is longer, the extra characters will be silently discarded.</p>

    <p>The SHA-1 hashing format does not use salting: for a given
    password, there is only one hashed representation. The
    <code>crypt()</code> and MD5 formats permute the representation by
    prepending a random salt string, to make dictionary attacks
    against the passwords more difficult.</p>

    <p>The SHA-1 and <code>crypt()</code> formats are insecure by
    today's standards.</p>

    <p>The SHA-2-based <code>crypt()</code> formats (SHA-256 and
    SHA-512) are supported on most modern Unix systems, and follow the
    specification at <a
    href="https://www.akkadia.org/drepper/SHA-crypt.txt">https://www.akkadia.org/drepper/SHA-crypt.txt</a>.</p>
    
</section>

<section id="restrictions"><title>Restrictions</title>
    <p>On the Windows platform, passwords hashed with
    <program>htpasswd</program> are limited to no more than <code>255</code>
    characters in length. Longer passwords will be truncated to 255
    characters.</p>

    <p>The MD5 algorithm used by <program>htpasswd</program> is specific to the Apache
    software; passwords hashed using it will not be usable with other Web
    servers.</p>

    <p>Usernames are limited to <code>255</code> bytes and may not include the
    character <code>:</code>.</p>

    <p>The cost of computing a bcrypt password hash value increases
    with the number of rounds specified by the <code>-C</code> option.
    The <code>apr-util</code> library enforces a maximum number of
    rounds of 17 in version <code>1.6.0</code> and later.</p>
</section>

<section id="files"><title>Files</title>

<p>The password file path is specified as an argument on the command line
and may be located anywhere on the filesystem.</p>

<dl>
<dt><var>passwdfile</var></dt>
<dd>The flat-file containing usernames and passwords.
May contain empty lines and comment lines beginning with the hash
character (<code>#</code>).</dd>
</dl>

</section>

</manualpage>