auth.html.en revision 2407b76c36f70b3deae5e99eb6f3cf95975c6833
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
This file is generated from xml source: DO NOT EDIT
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
-->
<title>Authentication, Authorization and Access Control - Apache HTTP Server</title>
<link href="/style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
<link href="/style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
<body id="manual-page"><div id="page-header">
<p class="menu"><a href="/mod/">Modules</a> | <a href="/mod/directives.html">Directives</a> | <a href="/faq/">FAQ</a> | <a href="/glossary.html">Glossary</a> | <a href="/sitemap.html">Sitemap</a></p>
<p class="apache">Apache HTTP Server Version 2.3</p>
<div id="path">
<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.3</a> > <a href="./">How-To / Tutorials</a></div><div id="page-content"><div id="preamble"><h1>Authentication, Authorization and Access Control</h1>
<div class="toplang">
<p><span>Available Languages: </span><a href="/en/howto/auth.html" title="English"> en </a> |
</div>
<p>Authentication is any process by which you verify that
someone is who they claim they are. Authorization is any
process by which someone is allowed to be where they want to
go, or to have information that they want to have.</p>
</div>
<div id="quickview"><ul id="toc"><li><img alt="" src="/images/down.gif" /> <a href="#related">Related Modules and Directives</a></li>
<li><img alt="" src="/images/down.gif" /> <a href="#lettingmorethanonepersonin">Letting more than one
person in</a></li>
</ul></div>
<div class="section">
<h2><a name="related" id="related">Related Modules and Directives</a></h2>
<p>There are three types of modules involved in the authentication and
authorization process. You will usually need to choose at least one
module from each group.</p>
<ul>
<li>Authentication type (see the
<ul>
</ul>
</li>
<li>Authentication provider (see the
<code class="directive"><a href="/mod/mod_auth_basic.html#authbasicprovider">AuthBasicProvider</a></code> and
<code class="directive"><a href="/mod/mod_auth_digest.html#authdigestprovider">AuthDigestProvider</a></code> directives)
<ul>
</ul>
</li>
<li>Authorization (see the
<ul>
<li><code class="module"><a href="/mod/mod_authz_groupfile.html">mod_authz_groupfile</a></code></li>
</ul>
</li>
</ul>
<p>In addition to these modules, there are also
<code class="module"><a href="/mod/mod_authz_core.html">mod_authz_core</a></code>. These module implement core
directives that are core to all auth modules.</p>
<p>The module <code class="module"><a href="/mod/mod_authnz_ldap.html">mod_authnz_ldap</a></code> is both an
authentication and authorization provider. The module
<code class="module"><a href="/mod/mod_authz_host.html">mod_authz_host</a></code> provides authorization
and access control based on hostname, IP address or characteristics
of the request, but is not part of the authentication provider
system. For backwards compatibility with the mod_access, there is
a new module <code class="module"><a href="/mod/mod_access_compat.html">mod_access_compat</a></code>.</p>
<p>You probably also want to take a look at the <a href="access.html">Access Control</a> howto, which discusses the
various ways to control access to your server.</p>
<div class="section">
<h2><a name="introduction" id="introduction">Introduction</a></h2>
<p>If you have information on your web site that is sensitive
or intended for only a small group of people, the techniques in
this article will help you make sure that the people that see
those pages are the people that you wanted to see them.</p>
<p>This article covers the "standard" way of protecting parts
of your web site that most of you are going to use.</p>
<div class="note"><h3>Note:</h3>
<p>If your data really needs to be secure, consider using
<code class="module"><a href="/mod/mod_ssl.html">mod_ssl</a></code> in addition to any authentication.</p>
</div>
<div class="section">
<h2><a name="theprerequisites" id="theprerequisites">The Prerequisites</a></h2>
<p>The directives discussed in this article will need to go
either in your main server configuration file (typically in a
<code class="directive"><a href="/mod/core.html#directory"><Directory></a></code> section), or
in per-directory configuration files (<code>.htaccess</code> files).</p>
<p>If you plan to use <code>.htaccess</code> files, you will
need to have a server configuration that permits putting
authentication directives in these files. This is done with the
<code class="directive"><a href="/mod/core.html#allowoverride">AllowOverride</a></code> directive, which
specifies which directives, if any, may be put in per-directory
configuration files.</p>
<p>Since we're talking here about authentication, you will need
an <code class="directive"><a href="/mod/core.html#allowoverride">AllowOverride</a></code> directive like the
following:</p>
<div class="example"><p><code>
AllowOverride AuthConfig
</code></p></div>
<p>Or, if you are just going to put the directives directly in
your main server configuration file, you will of course need to
have write permission to that file.</p>
<p>And you'll need to know a little bit about the directory
structure of your server, in order to know where some files are
kept. This should not be terribly difficult, and I'll try to
make this clear when we come to that point.</p>
<p>You will also need to make sure that the modules
<code class="module"><a href="/mod/mod_authn_core.html">mod_authn_core</a></code> and <code class="module"><a href="/mod/mod_authz_core.html">mod_authz_core</a></code>
have either been built into the httpd binary or loaded by the
httpd.conf configuration file. Both of these modules provide core
directives and functionality that are critical to the configuration
and use of authentication and authorization in the web server.</p>
<div class="section">
<h2><a name="gettingitworking" id="gettingitworking">Getting it working</a></h2>
<p>Here's the basics of password protecting a directory on your
server.</p>
<p>First, you need to create a password file. Exactly how you do
this will vary depending on what authentication provider you have
chosen. More on that later. To start with, we'll use a text password
file.</p>
<p>This file should be
placed somewhere not accessible from the web. This is so that
folks cannot download the password file. For example, if your
might want to put the password file(s) in
<p>To create the file, use the <code class="program"><a href="/programs/htpasswd.html">htpasswd</a></code> utility that
came with Apache. This will be located in the <code>bin</code> directory
of wherever you installed Apache. If you have installed Apache from
a third-party package, it may be in your execution path.</p>
<p>To create the file, type:</p>
<div class="example"><p><code>
</code></p></div>
<p><code class="program"><a href="/programs/htpasswd.html">htpasswd</a></code> will ask you for the password, and
then ask you to type it again to confirm it:</p>
<div class="example"><p><code>
New password: mypassword<br />
Re-type new password: mypassword<br />
Adding password for user rbowen
</code></p></div>
<p>If <code class="program"><a href="/programs/htpasswd.html">htpasswd</a></code> is not in your path, of course
you'll have to type the full path to the file to get it to run.
With a default installation, it's located at
<p>Next, you'll need to configure the server to request a
password and tell the server which users are allowed access.
file or using an <code>.htaccess</code> file. For example, if
you wish to protect the directory
following directives, either placed in the file
<div class="example"><p><code>
AuthType Basic<br />
AuthName "Restricted Files"<br />
# (Following line optional)<br />
AuthBasicProvider file<br />
Require user rbowen
</code></p></div>
<p>Let's examine each of those directives individually. The <code class="directive"><a href="/mod/core.html#authtype">AuthType</a></code> directive selects
that method that is used to authenticate the user. The most
common method is <code>Basic</code>, and this is the method
implemented by <code class="module"><a href="/mod/mod_auth_basic.html">mod_auth_basic</a></code>. It is important to be aware,
however, that Basic authentication sends the password from the client to
the server unencrypted. This method should therefore not be used for
highly sensitive data, unless accompanied by <code class="module"><a href="/mod/mod_ssl.html">mod_ssl</a></code>.
Apache supports one other authentication method:
<code>AuthType Digest</code>. This method is implemented by <code class="module"><a href="/mod/mod_auth_digest.html">mod_auth_digest</a></code> and is much more secure. Most recent
browsers support Digest authentication.</p>
the <dfn>Realm</dfn> to be used in the authentication. The realm serves
two major functions. First, the client often presents this information to
the user as part of the password dialog box. Second, it is used by the
client to determine what password to send for a given authenticated
area.</p>
<p>So, for example, once a client has authenticated in the
<code>"Restricted Files"</code> area, it will automatically
retry the same password for any area on the same server that is
marked with the <code>"Restricted Files"</code> Realm.
Therefore, you can prevent a user from being prompted more than
once for a password by letting multiple restricted areas share
the same realm. Of course, for security reasons, the client
will always need to ask again for the password whenever the
hostname of the server changes.</p>
<p>The <code class="directive"><a href="/mod/mod_auth_basic.html#authbasicprovider">AuthBasicProvider</a></code> is,
in this case, optional, since <code>file</code> is the default value
for this directive. You'll need to use this directive if you are
choosing a different source for authentication, such as
<code class="module"><a href="/mod/mod_authn_dbm.html">mod_authn_dbm</a></code> or <code class="module"><a href="/mod/mod_authn_dbd.html">mod_authn_dbd</a></code>.</p>
<p>The <code class="directive"><a href="/mod/mod_authn_file.html#authuserfile">AuthUserFile</a></code>
directive sets the path to the password file that we just
created with <code class="program"><a href="/programs/htpasswd.html">htpasswd</a></code>. If you have a large number
of users, it can be quite slow to search through a plain text
file to authenticate the user on each request. Apache also has
the ability to store user information in fast database files.
The <code class="module"><a href="/mod/mod_authn_dbm.html">mod_authn_dbm</a></code> module provides the <code class="directive"><a href="/mod/mod_authn_dbm.html#authdbmuserfile">AuthDBMUserFile</a></code> directive. These
files can be created and manipulated with the <code class="program"><a href="/programs/dbmmanage.html">dbmmanage</a></code> program. Many
other types of authentication options are available from third
party modules in the <a href="http://modules.apache.org/">Apache Modules
Database</a>.</p>
directive provides the authorization part of the process by
setting the user that is allowed to access this region of the
server. In the next section, we discuss various ways to use the
<div class="section">
<h2><a name="lettingmorethanonepersonin" id="lettingmorethanonepersonin">Letting more than one
person in</a></h2>
<p>The directives above only let one person (specifically
someone with a username of <code>rbowen</code>) into the
directory. In most cases, you'll want to let more than one
person in. This is where the <code class="directive"><a href="/mod/mod_authz_groupfile.html#authgroupfile">AuthGroupFile</a></code> comes in.</p>
<p>If you want to let more than one person in, you'll need to
create a group file that associates group names with a list of
users in that group. The format of this file is pretty simple,
and you can create it with your favorite editor. The contents
of the file will look like this:</p>
<div class="example"><p><code>
GroupName: rbowen dpitts sungo rshersey
</code></p></div>
<p>That's just a list of the members of the group in a long
line separated by spaces.</p>
<p>To add a user to your already existing password file,
type:</p>
<div class="example"><p><code>
</code></p></div>
<p>You'll get the same response as before, but it will be
appended to the existing file, rather than creating a new file.
(It's the <code>-c</code> that makes it create a new password
file).</p>
<p>Now, you need to modify your <code>.htaccess</code> file to
look like the following:</p>
<div class="example"><p><code>
AuthType Basic<br />
AuthName "By Invitation Only"<br />
# Optional line:
AuthBasicProvider file
Require group GroupName
</code></p></div>
<p>Now, anyone that is listed in the group <code>GroupName</code>,
and has an entry in the <code>password</code> file, will be let in, if
they type the correct password.</p>
<p>There's another way to let multiple users in that is less
specific. Rather than creating a group file, you can just use
the following directive:</p>
<div class="example"><p><code>
Require valid-user
</code></p></div>
<p>Using that rather than the <code>Require user rbowen</code>
line will allow anyone in that is listed in the password file,
and who correctly enters their password. You can even emulate
the group behavior here, by just keeping a separate password
file for each group. The advantage of this approach is that
Apache only has to check one file, rather than two. The
disadvantage is that you have to maintain a bunch of password
files, and remember to reference the right one in the
<code class="directive"><a href="/mod/mod_authn_file.html#authuserfile">AuthUserFile</a></code> directive.</p>
<div class="section">
<h2><a name="possibleproblems" id="possibleproblems">Possible problems</a></h2>
<p>Because of the way that Basic authentication is specified,
your username and password must be verified every time you
request a document from the server. This is even if you're
reloading the same page, and for every image on the page (if
they come from a protected directory). As you can imagine, this
slows things down a little. The amount that it slows things
down is proportional to the size of the password file, because
it has to open up that file, and go down the list of users
until it gets to your name. And it has to do this every time a
page is loaded.</p>
<p>A consequence of this is that there's a practical limit to
how many users you can put in one password file. This limit
will vary depending on the performance of your particular
server machine, but you can expect to see slowdowns once you
get above a few hundred entries, and may wish to consider a
different authentication method at that time.</p>
<div class="section">
<h2><a name="dbmdbd" id="dbmdbd">Alternate password storage</a></h2>
<p>Because storing passwords in plain text files has the above
problems, you may wish to store your passwords somewhere else, such
as in a database.</p>
<p><code class="module"><a href="/mod/mod_authn_dbm.html">mod_authn_dbm</a></code> and <code class="module"><a href="/mod/mod_authn_dbd.html">mod_authn_dbd</a></code>
are two modules which make this possible. Rather than selecting
<code class="directive"><a href="/mod/mod_auth_basic.html#authbasicsource">AuthBasicSource</a></code> file,
instead you can choose <code>dbm</code> or <code>dbd</code> as your
storage format.</p>
<p>To select a dbd file rather than a text file, for example:</p>
<div class="example"><p><code>
AuthName "Private"<br />
AuthType Basic<br />
AuthBasicProvider dbm<br />
Require valid-user
</code></p></div>
<p>Other options are available. Consult the
<code class="module"><a href="/mod/mod_authn_dbm.html">mod_authn_dbm</a></code> documentation for more details.</p>
<div class="section">
<h2><a name="multprovider" id="multprovider">Using multiple providers</a></h2>
<p>With the introduction of the new provider based authentication and
authorization architecture, you are no longer locked into a single
authentication or authorization method. In fact any number of the
providers can be mixed and matched to provide you with exactly the
scheme that meets your needs. In the following example, both the
file and ldap based authentication providers are being used.</p>
<div class="example"><p><code>
AuthName "Private"<br />
AuthType Basic<br />
AuthBasicProvider file ldap<br />
AuthLDAPURL ldap://ldaphost/o=yourorg<br />
Require valid-user
</code></p></div>
<p>In this example the file provider will attempt to authenticate
the user first. If it is unable to authenticate the user, the ldap
provider will be called. This allows the scope of authentication
to be broadened if your organization implements more than
one type of authentication store. Other authentication and authorization
scenarios may include mixing one type of authentication with a
different type of authorization. For example, authenticating against
a password file yet authorizing against and ldap directory.</p>
<p>Just as multiple authentication providers can be implemented, multiple
authorization methods can also be used. In this example both file group
authorization as well as ldap group authorization is being used.</p>
<div class="example"><p><code>
AuthName "Private"<br />
AuthType Basic<br />
AuthBasicProvider file<br />
AuthLDAPURL ldap://ldaphost/o=yourorg
Require group GroupName<br />
Require ldap-group cn=mygroup,o=yourorg
</code></p></div>
<p>To take authorization a little further, the directives
<code class="directive"><a href="/mod/mod_authz_core.html#<satisfyall>"><SatisfyAll></a></code> and
<code class="directive"><a href="/mod/mod_authz_core.html#<satisfyone>"><SatisfyOne></a></code> allow
is handled can be completely controled through the configuration. See
these directives for a complete example on they can be applied.</p>
<div class="section">
<h2><a name="beyond" id="beyond">Beyond just authorization</a></h2>
<p>The way that authorization can be apply is now much more flexible
than just a single check against a single data store. Ordering, logic
and choosing how authorization will be done is now possible.</p>
<p>Controling how and in what order authorization will be applied
has been a bit of a mystery in the past. In Apache 2.2 a provider based
authentication mechanism was introduced to decouple the actual
authentication process from authorization and supporting functionality.
One of the side benefits was that authentication providers could be
configured and called in a specific order which didn't depend on the
load order of the auth module itself. This same provider based mechanism
has been brought forward into authorization as well. What this means is
that the <code class="directive"><a href="/mod/mod_authz_core.html#require">Require</a></code> directive
not only specifies which authorization methods should be used, it also
specifies the order in which they are called. Multiple autorization
methods are called in the same order in which the
<code class="directive"><a href="/mod/mod_authz_core.html#require">Require</a></code> directives appear
in the configuration.</p>
<p>With the introduction of the directives
<code class="directive"><a href="/mod/mod_authz_core.html#<satisfyall>"><SatisfyAll></a></code> and
<code class="directive"><a href="/mod/mod_authz_core.html#<satisfyone>"><SatisfyOne></a></code>, the
configuration also has control over when the
authorization methods are called and what criteria determines when
access is granted. For example the following authorization block would
apply the logic:</p>
<div class="example"><p><code>
# if ((user == "John") ||<br />
# ((Group == "admin")<br />
# && (ldap-group <ldap-object> contains auth'ed_user)<br />
# && ((ldap-attribute dept == "sales")<br />
# || (file-group contains auth'ed_user))))<br />
# then<br />
# auth_granted<br />
# else<br />
# auth_denied<br />
#<br />
<span class="indent">
Authname ...<br />
AuthBasicProvider ...<br />
...<br />
Require user John<br />
<SatisfyAll><br />
<span class="indent">
Require Group admins<br />
Require ldap-group cn=mygroup,o=foo<br />
<SatisfyOne><br />
<span class="indent">
Require ldap-attribute dept="sales"<br />
Require file-group<br />
</span>
</SatisfyOne><br />
</span>
</SatisfyAll><br />
</span>
</Directory>
</code></p></div>
<p>By default all <code class="directive"><a href="/mod/mod_authz_core.html#require">Require</a></code>
directives are handled through and OR operation. In other words, if
any of the specified authorization methods succeed, then authorization
is granted. By enclosing a set of
<code class="directive"><a href="/mod/mod_authz_core.html#require">Require</a></code> directives within
a <code class="directive"><a href="/mod/mod_authz_core.html#<satisfyall>"><SatisfyAll></a></code> block,
the processing switches to an AND operation which requires all authorization
methods to succeed before authorization is granted.</p>
<h3><a name="reqaccessctrl" id="reqaccessctrl">Using 'Require' or 'Reject' for access control</a></h3>
<p>Authentication by username and password is only part of the
story. Frequently you want to let people in based on something
other than who they are. Something such as where they are
coming from.</p>
<p>The authorization providers <code class="directive"><a href="/mod/mod_authz_host.html# all">
ip</a></code> let you allow or deny access based other host based
criteria such as host name or ip address of the machine requesting
a document.</p>
<p>The usage of these providers is specified through the
These directives register the authorization providers
that will be called during the authorization stage of the request
processing. For example:</p>
<div class="example"><p><code>
Require ip <var>address</var>
</code></p></div>
<p>where <var>address</var> is an IP address (or a partial IP
address) or:</p>
<div class="example"><p><code>
Require host <var>domain_name</var>
</code></p></div>
<p>where <var>domain_name</var> is a fully qualified domain name
(or a partial domain name); you may provide multiple addresses or
domain names, if desired.</p>
<p>For example, if you have someone spamming your message
board, and you want to keep them out, you could do the
following:</p>
<div class="example"><p><code>
Reject ip 205.252.46.165
</code></p></div>
<p>Visitors coming from that address will not be able to see
the content covered by this directive. If, instead, you have a
machine name, rather than an IP address, you can use that.</p>
<div class="example"><p><code>
</code></p></div>
<p>And, if you'd like to block access from an entire domain,
you can specify just part of an address or domain name:</p>
<div class="example"><p><code>
<SatisfyAll><br />
<span class="indent">
Reject ip <var>192.101.205</var><br />
</span>
</SatisfyAll>
</code></p></div>
<p>Using the <code class="directive"><a href="/mod/mod_authz_host.html#reject">Reject</a></code> directive
inside of a <code class="directive"><a href="/mod/mod_authz_core.html#<satisfyall>"><SatisfyAll></a></code>
block, will let you be sure that you are actually restricting things to
only the group that you want to let in.</p>
<p>The above example uses the <code class="directive"><a href="/mod/mod_authz_core.html# <satisfyall>">
<SatisfyAll></a></code> block to make sure that all of the
satisfied before granting access. </p>
<h3><a name="filesystem" id="filesystem">Access Control backwards compatibility</a></h3>
<p>One of the side effects of adopting a provider based mechanism for
authentication is that the need for the previous access control directives
<code class="directive"><a href="/mod/mod_access_compat.html#satisfy">Satisfy</a></code> are no longer needed.
However to provide backwards compatibility for older configurations, these
directives have been moved to the <code class="module"><a href="/mod/mod_access_compat.html">mod_access_compat</a></code> module.</p>
<p>One of the problems with these directives was that the line between
authorization and access control was very fuzzy. The
tried to tie these two stages together by hooking itself into the
request processing itself. Now that these directive have been moved to the
<code class="module"><a href="/mod/mod_access_compat.html">mod_access_compat</a></code>, mixing the new authorization directives
with the older access control directives becomes difficult. To address this
issue, the <code class="module"><a href="/mod/mod_authz_default.html">mod_authz_default</a></code> module becomes very important and must
be loaded. The main purpose of the <code class="module"><a href="/mod/mod_authz_default.html">mod_authz_default</a></code> module is
to handle any authorization requests that could not be handled by the
authorization providers. But when the older access control directives are used,
it also links access control with authorization and determines if access
should be granted based on the outcome of each stage. Therefore if the
older directives do not seem to be working properly, it might be because the
<code class="module"><a href="/mod/mod_authz_default.html">mod_authz_default</a></code> module has not been loaded.</p>
<div class="section">
<h2><a name="moreinformation" id="moreinformation">More information</a></h2>
<p>You should also read the documentation for
<code class="module"><a href="/mod/mod_auth_basic.html">mod_auth_basic</a></code> and <code class="module"><a href="/mod/mod_authz_host.html">mod_authz_host</a></code> which
contain some more information about how this all works.
The directive <code class="directive"><a href="/mod/mod_authn_core.html#<authnprovideralias>"><AuthnProviderAlias></a></code>
can also help in simplifying certain authentication configurations.</p>
Control</a> howto, which discusses a number of related topics.</p>
</div></div>
<div class="bottomlang">
<p><span>Available Languages: </span><a href="/en/howto/auth.html" title="English"> en </a> |
</div><div id="footer">
<p class="apache">Copyright 1995-2006 The Apache Software Foundation or its licensors, as applicable.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
<p class="menu"><a href="/mod/">Modules</a> | <a href="/mod/directives.html">Directives</a> | <a href="/faq/">FAQ</a> | <a href="/glossary.html">Glossary</a> | <a href="/sitemap.html">Sitemap</a></p></div>
</body></html>