2.4.x-mod_md/docs/manual/mod/mod_auth_basic.xml

<?xml version="1.0"?>
<!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
<?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?>
<!-- $LastChangedRevision$ -->

<!--
 Licensed to the Apache Software Foundation (ASF) under one or more
 contributor license agreements.  See the NOTICE file distributed with
 this work for additional information regarding copyright ownership.
 The ASF licenses this file to You under the Apache License, Version 2.0
 (the "License"); you may not use this file except in compliance with
 the License.  You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
-->

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

<name>mod_auth_basic</name>
<description>Basic HTTP authentication</description>
<status>Base</status>
<sourcefile>mod_auth_basic.c</sourcefile>
<identifier>auth_basic_module</identifier>
<compatibility>Available in Apache 2.1 and later</compatibility>

<summary>
    <p>This module allows the use of HTTP Basic Authentication to
    restrict access by looking up users in the given providers.
    HTTP Digest Authentication is provided by
    <module>mod_auth_digest</module>.  This module should
    usually be combined with at least one authentication module
    such as <module>mod_authn_file</module> and one authorization
    module such as <module>mod_authz_user</module>.</p>
</summary>
<seealso><directive module="mod_authn_core">AuthName</directive></seealso>
<seealso><directive module="mod_authn_core">AuthType</directive></seealso>
<seealso><directive module="mod_authz_core">Require</directive></seealso>
<seealso><a href="../howto/auth.html">Authentication howto</a></seealso>

<directivesynopsis>
<name>AuthBasicProvider</name>
<description>Sets the authentication provider(s) for this location</description>
<syntax>AuthBasicProvider <var>provider-name</var>
[<var>provider-name</var>] ...</syntax>
<default>AuthBasicProvider file</default>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>The <directive>AuthBasicProvider</directive> directive sets
    which provider is used to authenticate the users for this location.
    The default <code>file</code> provider is implemented
    by the <module>mod_authn_file</module> module.  Make sure
    that the chosen provider module is present in the server.</p>
    <example><title>Example</title>
    <highlight language="config">
&lt;Location "/secure"&gt;
    AuthType basic
    AuthName "private area"
    AuthBasicProvider  dbm
    AuthDBMType        SDBM
    AuthDBMUserFile    "/www/etc/dbmpasswd"
    Require            valid-user
&lt;/Location&gt;
    </highlight>
    </example>
    <p> Providers are queried in order until a provider finds a match
    for the requested username, at which point this sole provider will
    attempt to check the password.  A failure to verify the password does
    not result in control being passed on to subsequent providers.</p>

    <p>Providers are implemented by <module>mod_authn_dbm</module>,
    <module>mod_authn_file</module>, <module>mod_authn_dbd</module>,
    <module>mod_authnz_ldap</module> and <module>mod_authn_socache</module>.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>AuthBasicAuthoritative</name>
<description>Sets whether authorization and authentication are passed to
lower level modules</description>
<syntax>AuthBasicAuthoritative On|Off</syntax>
<default>AuthBasicAuthoritative On</default>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>Normally, each authorization module listed in <directive
    module="mod_auth_basic">AuthBasicProvider</directive> will attempt
    to verify the user, and if the user is not found in any provider,
    access will be denied. Setting the
    <directive>AuthBasicAuthoritative</directive> directive explicitly
    to <code>Off</code> allows for both authentication and
    authorization to be passed on to other non-provider-based modules
    if there is <strong>no userID</strong> or <strong>rule</strong>
    matching the supplied userID.  This should only be necessary when
    combining <module>mod_auth_basic</module> with third-party modules
    that are not configured with the <directive
    module="mod_auth_basic">AuthBasicProvider</directive>
    directive.  When using such modules, the order of processing
    is determined in the modules' source code and is not configurable.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>AuthBasicFake</name>
<description>Fake basic authentication using the given expressions for
username and password</description>
<syntax>AuthBasicFake off|username [password]</syntax>
<default>none</default>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>
<compatibility>Apache HTTP Server 2.4.5 and later</compatibility>
<usage>
    <p>The username and password specified are combined into an
    Authorization header, which is passed to the server or service
    behind the webserver. Both the username and password fields are
    interpreted using the <a href="../expr.html">expression parser</a>,
    which allows both the username and password to be set based on
    request parameters.</p>

    <p>If the password is not specified, the default value "password"
    will be used. To disable fake basic authentication for an URL
    space, specify "AuthBasicFake off".</p>

    <p>In this example, we pass a fixed username and password to a
    backend server.</p>

    <example><title>Fixed Example</title>
    <highlight language="config">
&lt;Location "/demo"&gt;
    AuthBasicFake demo demopass
&lt;/Location&gt;
    </highlight>
    </example>

    <p>In this example, we pass the email address extracted from a client
    certificate, extending the functionality of the FakeBasicAuth option
    within the <directive module="mod_ssl">SSLOptions</directive>
    directive. Like the FakeBasicAuth option, the password is set to the
    fixed string "password".</p>

    <example><title>Certificate Example</title>
    <highlight language="config">
&lt;Location "/secure"&gt;
    AuthBasicFake "%{SSL_CLIENT_S_DN_Email}"
&lt;/Location&gt;
    </highlight>
    </example>

    <p>Extending the above example, we generate a password by hashing the
    email address with a fixed passphrase, and passing the hash to the
    backend server. This can be used to gate into legacy systems that do
    not support client certificates.</p>

    <example><title>Password Example</title>
    <highlight language="config">
&lt;Location "/secure"&gt;
    AuthBasicFake "%{SSL_CLIENT_S_DN_Email}" "%{sha1:passphrase-%{SSL_CLIENT_S_DN_Email}}"
&lt;/Location&gt;
    </highlight>
    </example>

    <example><title>Exclusion Example</title>
    <highlight language="config">
&lt;Location "/public"&gt;
    AuthBasicFake off
&lt;/Location&gt;
    </highlight>
    </example>

</usage>
</directivesynopsis>

<directivesynopsis>
<name>AuthBasicUseDigestAlgorithm</name>
<description>Check passwords against the authentication providers as if
Digest Authentication was in force instead of Basic Authentication.
</description>
<syntax>AuthBasicUseDigestAlgorithm MD5|Off</syntax>
<default>AuthBasicUseDigestAlgorithm Off</default>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>
<compatibility>Apache HTTP Server 2.4.7 and later</compatibility>

<usage>
    <p>Normally, when using Basic Authentication, the providers listed in
    <directive module="mod_auth_basic">AuthBasicProvider</directive>
    attempt to verify a user by checking their data stores for
    a matching username and associated password.  The stored passwords
    are usually encrypted, but not necessarily so; each provider may
    choose its own storage scheme for passwords.</p>

    <p>When using <directive
    module="mod_auth_digest">AuthDigestProvider</directive> and Digest
    Authentication, providers perform a similar check to find a matching
    username in their data stores.  However, unlike in the Basic
    Authentication case, the value associated with each stored username
    must be an encrypted string composed from the username, realm name,
    and password.  (See
    <a href="http://tools.ietf.org/html/rfc2617#section-3.2.2.2">
    RFC 2617, Section 3.2.2.2</a> for more details on the format used
    for this encrypted string.)</p>

    <p>As a consequence of the difference in the stored values between
    Basic and Digest Authentication, converting from Digest
    Authentication to Basic Authentication generally requires that all
    users be assigned new passwords, as their existing passwords cannot
    be recovered from the password storage scheme imposed on those
    providers which support Digest Authentication.</p>

    <p>Setting the <directive
    module="mod_auth_basic">AuthBasicUseDigestAlgorithm</directive> directive
    to <code>MD5</code> will cause the user's Basic Authentication password
    to be checked using the same encrypted format as for Digest
    Authentication.  First a string composed from the username, realm name,
    and password is hashed with MD5; then the username and this encrypted
    string are passed to the providers listed in
    <directive module="mod_auth_basic">AuthBasicProvider</directive>
    as if
    <directive module="mod_authn_core">AuthType</directive>
    was set to <code>Digest</code> and Digest Authentication was in force.
    </p>

    <p>Through the use of <directive
    module="mod_auth_basic">AuthBasicUseDigestAlgorithm</directive>
    a site may switch from Digest to Basic Authentication without
    requiring users to be assigned new passwords.</p>

    <note>
      The inverse process of switching from Basic to Digest
      Authentication without assigning new passwords is generally
      not possible.  Only if the Basic Authentication passwords
      have been stored in plain text or with a reversable encryption
      scheme will it be possible to recover them and generate a
      new data store following the Digest Authentication password
      storage scheme.
    </note>

    <note>
      Only providers which support Digest Authentication will be able
      to authenticate users when <directive
      module="mod_auth_basic">AuthBasicUseDigestAlgorithm</directive>
      is set to <code>MD5</code>.  Use of other providers will result
      in an error response and the client will be denied access.
    </note>
</usage>
</directivesynopsis>

</modulesynopsis>