apache/docs/manual/mod/mod_authz_dbm.xml

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<modulesynopsis metafile="mod_authz_dbm.xml.meta">

<name>mod_authz_dbm</name>
<description>Group authorization using DBM files</description>
<status>Extension</status>
<sourcefile>mod_authz_dbm.c</sourcefile>
<identifier>authz_dbm_module</identifier>
<compatibility>Available in Apache 2.1 and later</compatibility>

<summary>
    <p>This module provides authorization capabilities so that
       authenticated users can be allowed or denied access to portions
       of the web site by group membership. Similar functionality is
       provided by <module>mod_authz_groupfile</module>.</p>
</summary>

<seealso><directive module="core">Require</directive></seealso>
<seealso><directive module="core">Satisfy</directive></seealso>

<directivesynopsis>
<name>AuthDBMGroupFile</name>
<description>Sets the name of the database file containing the list
of user groups for authentication</description>
<syntax>AuthDBMGroupFile <var>file-path</var></syntax>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>The <directive>AuthDBMGroupFile</directive> directive sets the
    name of a DBM file containing the list of user groups for user
    authentication.  <var>File-path</var> is the absolute path to the
    group file.</p>

    <p>The group file is keyed on the username. The value for a
    user is a comma-separated list of the groups to which the users
    belongs. There must be no whitespace within the value, and it
    must never contain any colons.</p>

    <note type="warning"><title>Security</title>
      <p>Make sure that the <directive>AuthDBMGroupFile</directive> is
      stored outside the document tree of the web-server. Do
      <strong>not</strong> put it in the directory that it protects.
      Otherwise, clients will be able to download the
      <directive>AuthDBMGroupFile</directive> unless otherwise
      protected.</p>
    </note>

    <p>Combining Group and Password DBM files: In some cases it is
    easier to manage a single database which contains both the
    password and group details for each user. This simplifies any
    support programs that need to be written: they now only have to
    deal with writing to and locking a single DBM file. This can be
    accomplished by first setting the group and password files to
    point to the same DBM:</p>

    <example>
      AuthDBMGroupFile /www/userbase<br />
      AuthDBMUserFile /www/userbase
    </example>

    <p>The key for the single DBM is the username. The value consists
    of</p>

    <example>
      Encrypted Password : List of Groups [ : (ignored) ]
    </example>

    <p>The password section contains the encrypted
    password as before. This is followed by a colon and the comma
    separated list of groups. Other data may optionally be left in the
    DBM file after another colon; it is ignored by the authentication
    module. This is what www.telescope.org uses for its combined
    password and group database.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>AuthzDBMType</name>
<description>Sets the type of database file that is used to
store passwords</description>
<syntax>AuthzDBMType default|SDBM|GDBM|NDBM|DB</syntax>
<default>AuthzDBMType default</default>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>Sets the type of database file that is used to store the passwords.
    The default database type is determined at compile time.  The
    availability of other types of database files also depends on
    <a href="../install.html#dbm">compile-time settings</a>.</p>

    <p>It is crucial that whatever program you use to create your password
    files is configured to use the same type of database.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>AuthzDBMAuthoritative</name>
<description>Sets whether authorization will be passed on to lower level
modules</description>
<syntax>AuthzDBMAuthoritative On|Off</syntax>
<default>AuthzDBMAuthoritative On</default>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>Setting the <directive>AuthzDBMAuthoritative</directive>
    directive explicitly to <code>Off</code> allows group authorization
    to be passed on to lower level modules (as defined in the
    <code>modules.c</code> file) if there is no group found
    for the the supplied userID. If there are any groups
    specified, the usual checks will be applied and a failure will
    give an Authentication Required reply.</p>

    <p>So if a userID appears in the database of more than one module;
    or if a valid <directive module="core">Require</directive>
    directive applies to more than one module; then the first module
    will verify the credentials; and no access is passed on;
    regardless of the <directive>AuthAuthoritative</directive> setting.</p>

    <p>A common use for this is in conjunction with one of the
    auth providers; such as <module>mod_authn_dbm</module> or
    <module>mod_authn_file</module>. Whereas this DBM module supplies
    the bulk of the user credential checking; a few (administrator) related
    accesses fall through to a lower level with a well protected
    <code>.htpasswd</code> file.</p>

    <p>By default, control is not passed on and an unknown group
    will result in an Authentication Required reply. Not
    setting it thus keeps the system secure and forces an NCSA
    compliant behaviour.</p>

    <note type="warning"><title>Security</title>
      <p>Do consider the implications of allowing a user to
      allow fall-through in his .htaccess file; and verify that this
      is really what you want; Generally it is easier to just secure
      a single <code>.htpasswd</code> file, than it is to secure a
      database which might have more access interfaces.</p>
    </note>
</usage>
</directivesynopsis>

</modulesynopsis>