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309 lines
12 KiB
XML
309 lines
12 KiB
XML
<?xml version="1.0"?>
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<!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
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<?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?>
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<modulesynopsis>
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<name>mod_access</name>
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<description>Provides access control based on client hostname, IP
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address, or other characteristics of the client request.</description>
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<status>Base</status>
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<sourcefile>mod_access.c</sourcefile>
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<identifier>access_module</identifier>
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<summary>
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<p>The directives provided by mod_access are used in <directive
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module="core" type="section">Directory</directive>, <directive
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module="core" type="section">Files</directive>, and <directive
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module="core" type="section">Location</directive> sections as well as
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<code><a href="core.html#accessfilename">.htaccess</a></code>
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files to control access to particular parts of the server. Access
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can be controlled based on the client hostname, IP address, or
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other characteristics of the client request, as captured in <a
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href="../env.html">environment variables</a>. The <directive
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module="mod_access">Allow</directive> and <directive
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module="mod_access">Deny</directive> directives are used to
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specify which clients are or are not allowed access to the server,
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while the <directive module="mod_access">Order</directive>
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directive sets the default access state, and configures how the
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<directive module="mod_access">Allow</directive> and <directive
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module="mod_access">Deny</directive> directives interact with each
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other.</p>
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<p>Both host-based access restrictions and password-based
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authentication may be implemented simultaneously. In that case,
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the <directive module="core">Satisfy</directive> directive is used
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to determine how the two sets of restrictions interact.</p>
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<p>In general, access restriction directives apply to all
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access methods (<code>GET</code>, <code>PUT</code>,
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<code>POST</code>, etc). This is the desired behavior in most
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cases. However, it is possible to restrict some methods, while
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leaving other methods unrestricted, by enclosing the directives
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in a <directive module="core" type="section">Limit</directive> section.</p>
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</summary>
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<seealso><directive module="core">Satisfy</directive></seealso>
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<seealso><directive module="core">Require</directive></seealso>
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<directivesynopsis>
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<name>Allow</name>
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<description>Controls which hosts can access an area of the
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server</description>
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<syntax> Allow from
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all|<em>host</em>|env=<em>env-variable</em>
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[<em>host</em>|env=<em>env-variable</em>] ...</syntax>
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<contextlist><context>directory</context><context>.htaccess</context>
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</contextlist>
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<override>Limit</override>
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<usage>
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<p>The <directive>Allow</directive> directive affects which hosts can
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access an area of the server. Access can be controlled by
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hostname, IP Address, IP Address range, or by other
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characteristics of the client request captured in environment
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variables.</p>
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<p>The first argument to this directive is always
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<code>from</code>. The subsequent arguments can take three
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different forms. If <code>Allow from all</code> is specified, then
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all hosts are allowed access, subject to the configuration of the
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<directive module="mod_access">Deny</directive> and <directive
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module="mod_access">Order</directive> directives as discussed
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below. To allow only particular hosts or groups of hosts to access
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the server, the <em>host</em> can be specified in any of the
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following formats:</p>
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<dl>
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<dt>A (partial) domain-name</dt>
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<dd>Example: <code>Allow from apache.org</code><br />
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Hosts whose names match, or end in, this string are allowed
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access. Only complete components are matched, so the above
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example will match <code>foo.apache.org</code> but it will
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not match <code>fooapache.org</code>. This configuration will
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cause the server to perform a reverse DNS lookup on the
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client IP address, regardless of the setting of the <directive
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module="core">HostnameLookups</directive>
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directive.</dd>
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<dt>A full IP address</dt>
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<dd>Example: <code>Allow from 10.1.2.3</code><br />
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An IP address of a host allowed access</dd>
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<dt>A partial IP address</dt>
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<dd>Example: <code>Allow from 10.1</code><br />
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The first 1 to 3 bytes of an IP address, for subnet
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restriction.</dd>
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<dt>A network/netmask pair</dt>
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<dd>Example: <code>Allow from
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10.1.0.0/255.255.0.0</code><br />
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A network a.b.c.d, and a netmask w.x.y.z. For more
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fine-grained subnet restriction.</dd>
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<dt>A network/nnn CIDR specification</dt>
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<dd>Example: <code>Allow from 10.1.0.0/16</code><br />
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Similar to the previous case, except the netmask consists of
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nnn high-order 1 bits.</dd>
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</dl>
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<p>Note that the last three examples above match exactly the
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same set of hosts.</p>
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<p>IPv6 addresses and IPv6 subnets can be specified as shown
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below:</p>
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<example>
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Allow from fe80::a00:20ff:fea7:ccea<br />
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Allow from fe80::a00:20ff:fea7:ccea/10
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</example>
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<p>The third format of the arguments to the
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<directive>Allow</directive> directive allows access to the server
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to be controlled based on the existence of an <a
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href="../env.html">environment variable</a>. When <code>Allow from
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env=</code><em>env-variable</em> is specified, then the request is
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allowed access if the environment variable <em>env-variable</em>
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exists. The server provides the ability to set environment
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variables in a flexible way based on characteristics of the client
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request using the directives provided by
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<module>mod_setenvif</module>. Therefore, this directive can be
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used to allow access based on such factors as the clients
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<code>User-Agent</code> (browser type), <code>Referer</code>, or
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other HTTP request header fields.</p>
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<example>
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<title>Example:</title>
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SetEnvIf User-Agent ^KnockKnock/2.0 let_me_in<br />
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<Directory /docroot><br />
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Order Deny,Allow<br />
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Deny from all<br />
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Allow from env=let_me_in<br />
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</Directory>
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</example>
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<p>In this case, browsers with a user-agent string beginning
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with <code>KnockKnock/2.0</code> will be allowed access, and all
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others will be denied.</p>
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</usage>
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</directivesynopsis>
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<directivesynopsis>
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<name>Deny</name>
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<description>Controls which hosts are denied access to the
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server</description>
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<syntax> Deny from
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all|<em>host</em>|env=<em>env-variable</em>
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[<em>host</em>|env=<em>env-variable</em>] ...</syntax>
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<contextlist><context>directory</context><context>.htaccess</context>
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</contextlist>
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<override>Limit</override>
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<usage>
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<p>This directive allows access to the server to be restricted
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based on hostname, IP address, or environment variables. The
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arguments for the <directive>Deny</directive> directive are
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identical to the arguments for the <directive
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module="mod_access">Allow</directive> directive.</p>
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</usage>
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</directivesynopsis>
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<directivesynopsis>
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<name>Order</name>
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<description>Controls the default access state and the order in which
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<directive>Allow</directive> and <directive>Deny</directive> are
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evaluated.</description>
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<syntax> Order <em>ordering</em></syntax>
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<default>Order Deny,Allow</default>
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<contextlist><context>directory</context><context>.htaccess</context>
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</contextlist>
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<override>Limit</override>
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<usage>
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<p>The <directive>Order</directive> directive controls the default
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access state and the order in which <directive
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module="mod_access">Allow</directive> and <directive
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module="mod_access">Deny</directive> directives are evaluated.
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<em>Ordering</em> is one of</p>
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<dl>
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<dt>Deny,Allow</dt>
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<dd>The <directive module="mod_access">Deny</directive> directives
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are evaluated before the <directive
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module="mod_access">Allow</directive> directives. Access is
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allowed by default. Any client which does not match a
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<directive module="mod_access">Deny</directive> directive or does
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match an <directive module="mod_access">Allow</directive>
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directive will be allowed access to the server.</dd>
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<dt>Allow,Deny</dt>
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<dd>The <directive module="mod_access">Allow</directive>
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directives are evaluated before the <directive
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module="mod_access">Deny</directive> directives. Access is denied
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by default. Any client which does not match an <directive
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module="mod_access">Allow</directive> directive or does match a
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<directive module="mod_access">Deny</directive> directive will be
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denied access to the server.</dd>
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<dt>Mutual-failure</dt>
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<dd>Only those hosts which appear on the <directive
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module="mod_access">Allow</directive> list and do not appear on
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the <directive module="mod_access">Deny</directive> list are
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granted access. This ordering has the same effect as <code>Order
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Allow,Deny</code> and is deprecated in favor of that
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configuration.</dd>
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</dl>
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<p>Keywords may only be separated by a comma; no whitespace is
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allowed between them. Note that in all cases every <directive
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module="mod_access">Allow</directive> and <directive
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module="mod_access">Deny</directive> statement is evaluated.</p>
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<p>In the following example, all hosts in the apache.org domain
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are allowed access; all other hosts are denied access.</p>
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<example>
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Order Deny,Allow<br />
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Deny from all<br />
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Allow from apache.org<br />
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</example>
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<p>In the next example, all hosts in the apache.org domain are
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allowed access, except for the hosts which are in the
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foo.apache.org subdomain, who are denied access. All hosts not
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in the apache.org domain are denied access because the default
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state is to deny access to the server.</p>
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<example>
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Order Allow,Deny<br />
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Allow from apache.org<br />
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Deny from foo.apache.org<br />
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</example>
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<p>On the other hand, if the <directive>Order</directive> in the last
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example is changed to <code>Deny,Allow</code>, all hosts will
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be allowed access. This happens because, regardless of the
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actual ordering of the directives in the configuration file,
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the <code>Allow from apache.org</code> will be evaluated last
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and will override the <code>Deny from foo.apache.org</code>.
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All hosts not in the <code>apache.org</code> domain will also
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be allowed access because the default state will change to
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<em>allow</em>.</p>
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<p>The presence of an <directive>Order</directive> directive can affect
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access to a part of the server even in the absence of accompanying
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<directive module="mod_access">Allow</directive> and <directive
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module="mod_access">Deny</directive> directives because of its effect
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on the default access state. For example,</p>
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<example>
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<Directory /www><br />
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Order Allow,Deny<br />
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</Directory>
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</example>
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<p>will deny all access to the <code>/www</code> directory
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because the default access state will be set to
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<em>deny</em>.</p>
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<p>The <directive>Order</directive> directive controls the order of access
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directive processing only within each phase of the server's
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configuration processing. This implies, for example, that an
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<directive module="mod_access">Allow</directive> or <directive
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module="mod_access">Deny</directive> directive occurring in a
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<directive module="core" type="section">Location</directive> section will
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always be evaluated after an <directive
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module="mod_access">Allow</directive> or <directive
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module="mod_access">Deny</directive> directive occurring in a
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<directive module="core" type="section">Directory</directive> section or
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<code>.htaccess</code> file, regardless of the setting of the
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<directive>Order</directive> directive. For details on the merging
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of configuration sections, see the documentation on <a
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href="../sections.html">How Directory, Location and Files sections
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work</a>.</p>
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</usage>
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</directivesynopsis>
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</modulesynopsis>
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