mod_access.html.en

Apache HTTP Server 是一个功能强大的灵活的与HTTP/1.1相兼容的web服务器.这里给出的是Apache HTTP服务器的源码。

    <p>The third format of the arguments to the
    <code class="directive">Allow</code> directive allows access to the server
    to be controlled based on the existence of an <a href="../env.html">environment variable</a>. When <code>Allow from
    env=<var>env-variable</var></code> is specified, then the request is
    allowed access if the environment variable <var>env-variable</var>
    exists. The server provides the ability to set environment
    variables in a flexible way based on characteristics of the client
    request using the directives provided by
    <code class="module"><a href="../mod/mod_setenvif.html">mod_setenvif</a></code>.  Therefore, this directive can be
    used to allow access based on such factors as the clients
    <code>User-Agent</code> (browser type), <code>Referer</code>, or
    other HTTP request header fields.</p>

    <div class="example"><h3>Example:</h3><p><code>
      SetEnvIf User-Agent ^KnockKnock/2\.0 let_me_in<br />
      &lt;Directory /docroot&gt;<br />
      <span class="indent">
        Order Deny,Allow<br />
        Deny from all<br />
        Allow from env=let_me_in<br />
      </span>
      &lt;/Directory&gt;
    </code></p></div>

    <p>In this case, browsers with a user-agent string beginning
    with <code>KnockKnock/2.0</code> will be allowed access, and all
    others will be denied.</p>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="Deny" id="Deny">Deny</a> <a name="deny" id="deny">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls which hosts are denied access to the
server</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code> Deny from all|<var>host</var>|env=<var>env-variable</var>
[<var>host</var>|env=<var>env-variable</var>] ...</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Limit</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_access</td></tr>
</table>
    <p>This directive allows access to the server to be restricted
    based on hostname, IP address, or environment variables. The
    arguments for the <code class="directive">Deny</code> directive are
    identical to the arguments for the <code class="directive"><a href="#allow">Allow</a></code> directive.</p>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="Order" id="Order">Order</a> <a name="order" id="order">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls the default access state and the order in which
<code class="directive">Allow</code> and <code class="directive">Deny</code> are
evaluated.</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code> Order <var>ordering</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Order Deny,Allow</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Limit</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_access</td></tr>
</table>

    <p>The <code class="directive">Order</code> directive controls the default
    access state and the order in which <code class="directive"><a href="#allow">Allow</a></code> and <code class="directive"><a href="#deny">Deny</a></code> directives are evaluated.
    <var>Ordering</var> is one of</p>

    <dl>
      <dt><code>Deny,Allow</code></dt>

      <dd>The <code class="directive"><a href="#deny">Deny</a></code> directives
      are evaluated before the <code class="directive"><a href="#allow">Allow</a></code> directives. Access is
      allowed by default.  Any client which does not match a
      <code class="directive"><a href="#deny">Deny</a></code> directive or does
      match an <code class="directive"><a href="#allow">Allow</a></code>
      directive will be allowed access to the server.</dd>

      <dt><code>Allow,Deny</code></dt>

      <dd>The <code class="directive"><a href="#allow">Allow</a></code>
      directives are evaluated before the <code class="directive"><a href="#deny">Deny</a></code> directives. Access is denied
      by default. Any client which does not match an <code class="directive"><a href="#allow">Allow</a></code> directive or does match a
      <code class="directive"><a href="#deny">Deny</a></code> directive will be
      denied access to the server.</dd>

      <dt><code>Mutual-failure</code></dt>

      <dd>Only those hosts which appear on the <code class="directive"><a href="#allow">Allow</a></code> list and do not appear on
      the <code class="directive"><a href="#deny">Deny</a></code> list are
      granted access. This ordering has the same effect as <code>Order
      Allow,Deny</code> and is deprecated in favor of that
      configuration.</dd>
    </dl>

    <p>Keywords may only be separated by a comma; <em>no whitespace</em> is
    allowed between them. Note that in all cases every <code class="directive"><a href="#allow">Allow</a></code> and <code class="directive"><a href="#deny">Deny</a></code> statement is evaluated.</p>

    <p>In the following example, all hosts in the apache.org domain
    are allowed access; all other hosts are denied access.</p>

    <div class="example"><p><code>
      Order Deny,Allow<br />
      Deny from all<br />
      Allow from apache.org
    </code></p></div>

    <p>In the next example, all hosts in the apache.org domain are
    allowed access, except for the hosts which are in the
    foo.apache.org subdomain, who are denied access. All hosts not
    in the apache.org domain are denied access because the default
    state is to deny access to the server.</p>

    <div class="example"><p><code>
      Order Allow,Deny<br />
      Allow from apache.org<br />
      Deny from foo.apache.org
    </code></p></div>

    <p>On the other hand, if the <code class="directive">Order</code> in the last
    example is changed to <code>Deny,Allow</code>, all hosts will
    be allowed access. This happens because, regardless of the
    actual ordering of the directives in the configuration file,
    the <code>Allow from apache.org</code> will be evaluated last
    and will override the <code>Deny from foo.apache.org</code>.
    All hosts not in the <code>apache.org</code> domain will also
    be allowed access because the default state will change to
    <var>allow</var>.</p>

    <p>The presence of an <code class="directive">Order</code> directive can affect
    access to a part of the server even in the absence of accompanying
    <code class="directive"><a href="#allow">Allow</a></code> and <code class="directive"><a href="#deny">Deny</a></code> directives because of its effect
    on the default access state.  For example,</p>

    <div class="example"><p><code>
      &lt;Directory /www&gt;<br />
      <span class="indent">
        Order Allow,Deny<br />
      </span>
      &lt;/Directory&gt;
    </code></p></div>

    <p>will deny all access to the <code>/www</code> directory
    because the default access state will be set to
    <var>deny</var>.</p>

    <p>The <code class="directive">Order</code> directive controls the order of access
    directive processing only within each phase of the server's
    configuration processing. This implies, for example, that an
    <code class="directive"><a href="#allow">Allow</a></code> or <code class="directive"><a href="#deny">Deny</a></code> directive occurring in a
    <code class="directive"><a href="../mod/core.html#location">&lt;Location&gt;</a></code> section will
    always be evaluated after an <code class="directive"><a href="#allow">Allow</a></code> or <code class="directive"><a href="#deny">Deny</a></code> directive occurring in a
    <code class="directive"><a href="../mod/core.html#directory">&lt;Directory&gt;</a></code> section or
    <code>.htaccess</code> file, regardless of the setting of the
    <code class="directive">Order</code> directive. For details on the merging
    of configuration sections, see the documentation on <a href="../sections.html">How Directory, Location and Files sections
    work</a>.</p>

</div>
</div>
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