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

<name>mod_authz_host</name>

<description>Group authorizations based on host (name or IP

address)</description>

<status>Base</status>

<sourcefile>mod_authz_host.c</sourcefile>

<identifier>authz_host_module</identifier>

<compatibility>Available in Apache 2.1 and later</compatibility>

<summary>

<p>The directives provided by <module>mod_authz_host</module> are

used in <directive module="core" type="section">Directory</directive>,

<directive module="core" type="section">Files</directive>, and

<directive module="core" type="section">Location</directive> sections

as well as <code><a href="core.html#accessfilename">.htaccess</a>

</code> files to control access to particular parts of the server.

Access can be controlled based on the client hostname, IP address, or

other characteristics of the client request, as captured in <a

href="/env.html">environment variables</a>. The <directive

module="mod_authz_host">Allow</directive> and <directive

module="mod_authz_host">Deny</directive> directives are used to

specify which clients are or are not allowed access to the server,

while the <directive module="mod_authz_host">Order</directive>

directive sets the default access state, and configures how the

<directive module="mod_authz_host">Allow</directive> and <directive

module="mod_authz_host">Deny</directive> directives interact with each

other.</p>

<p>Both host-based access restrictions and password-based

authentication may be implemented simultaneously. In that case,

the <directive module="core">Satisfy</directive> directive is used

to determine how the two sets of restrictions interact.</p>

<p>In general, access restriction directives apply to all

access methods (<code>GET</code>, <code>PUT</code>,

<code>POST</code>, etc). This is the desired behavior in most

cases. However, it is possible to restrict some methods, while

leaving other methods unrestricted, by enclosing the directives

in a <directive module="core" type="section">Limit</directive> section.</p>

</summary>

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

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

<directivesynopsis>

<name>Allow</name>

<description>Controls which hosts can access an area of the

server</description>

<syntax> Allow from all|<var>host</var>|env=<var>env-variable</var>

[<var>host</var>|env=<var>env-variable</var>] ...</syntax>

<contextlist><context>directory</context><context>.htaccess</context>

</contextlist>

<override>Limit</override>

<usage>

<p>The <directive>Allow</directive> directive affects which hosts can

access an area of the server. Access can be controlled by

hostname, IP Address, IP Address range, or by other

characteristics of the client request captured in environment

variables.</p>

<p>The first argument to this directive is always

<code>from</code>. The subsequent arguments can take three

different forms. If <code>Allow from all</code> is specified, then

all hosts are allowed access, subject to the configuration of the

<directive module="mod_authz_host">Deny</directive> and <directive

module="mod_authz_host">Order</directive> directives as discussed

below. To allow only particular hosts or groups of hosts to access

the server, the <em>host</em> can be specified in any of the

following formats:</p>

<dl>

<dt>A (partial) domain-name</dt>

<dd>

<example><title>Example:</title>

Allow from apache.org

</example>

<p>Hosts whose names match, or end in, this string are allowed

access. Only complete components are matched, so the above

example will match <code>foo.apache.org</code> but it will not

match <code>fooapache.org</code>. This configuration will cause

Apache to perform a double reverse DNS lookup on the client IP

address, regardless of the setting of the <directive

module="core">HostnameLookups</directive> directive. It will do

a reverse DNS lookup on the IP address to find the associated

hostname, and then do a forward lookup on the hostname to assure

that it matches the original IP address. Only if the forward

and reverse DNS are consistent and the hostname matches will

access be allowed.</p></dd>

<dt>A full IP address</dt>

<dd>

<example><title>Example:</title>

Allow from 10.1.2.3

</example>

<p>An IP address of a host allowed access</p></dd>

<dt>A partial IP address</dt>

<dd>

<example><title>Example:</title>

Allow from 10.1

</example>

<p>The first 1 to 3 bytes of an IP address, for subnet

restriction.</p></dd>

<dt>A network/netmask pair</dt>

<dd>

<example><title>Example:</title>

Allow from 10.1.0.0/255.255.0.0

</example>

<p>A network a.b.c.d, and a netmask w.x.y.z. For more

fine-grained subnet restriction.</p></dd>

<dt>A network/nnn CIDR specification</dt>

<dd>

<example><title>Example:</title>

Allow from 10.1.0.0/16

</example>

<p>Similar to the previous case, except the netmask consists of

nnn high-order 1 bits.</p></dd>

</dl>

<p>Note that the last three examples above match exactly the

same set of hosts.</p>

<p>IPv6 addresses and IPv6 subnets can be specified as shown

below:</p>

<example>

Allow from fe80::a00:20ff:fea7:ccea<br />

Allow from fe80::a00:20ff:fea7:ccea/10

</example>

<p>The third format of the arguments to the

<directive>Allow</directive> 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

<module>mod_setenvif</module>. 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>

<example><title>Example:</title>

SetEnvIf User-Agent ^KnockKnock/2\.0 let_me_in<br />

&lt;Directory /docroot&gt;<br />

<indent>

Order Deny,Allow<br />

Deny from all<br />

Allow from env=let_me_in<br />

</indent>

&lt;/Directory&gt;

</example>

<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>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>Deny</name>

<description>Controls which hosts are denied access to the

server</description>

<syntax> Deny from all|<var>host</var>|env=<var>env-variable</var>

[<var>host</var>|env=<var>env-variable</var>] ...</syntax>

<contextlist><context>directory</context><context>.htaccess</context>

</contextlist>

<override>Limit</override>

<usage>

<p>This directive allows access to the server to be restricted

based on hostname, IP address, or environment variables. The

arguments for the <directive>Deny</directive> directive are

identical to the arguments for the <directive

module="mod_authz_host">Allow</directive> directive.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>Order</name>

<description>Controls the default access state and the order in which

<directive>Allow</directive> and <directive>Deny</directive> are

evaluated.</description>

<syntax> Order <var>ordering</var></syntax>

<default>Order Deny,Allow</default>

<contextlist><context>directory</context><context>.htaccess</context>

</contextlist>

<override>Limit</override>

<usage>

<p>The <directive>Order</directive> directive controls the default

access state and the order in which <directive

module="mod_authz_host">Allow</directive> and <directive

module="mod_authz_host">Deny</directive> directives are evaluated.

<var>Ordering</var> is one of</p>

<dl>

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

<dd>The <directive module="mod_authz_host">Deny</directive> directives

are evaluated before the <directive

module="mod_authz_host">Allow</directive> directives. Access is

allowed by default. Any client which does not match a

<directive module="mod_authz_host">Deny</directive> directive or does

match an <directive module="mod_authz_host">Allow</directive>

directive will be allowed access to the server.</dd>

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

<dd>The <directive module="mod_authz_host">Allow</directive>

directives are evaluated before the <directive

module="mod_authz_host">Deny</directive> directives. Access is denied

by default. Any client which does not match an <directive

module="mod_authz_host">Allow</directive> directive or does match a

<directive module="mod_authz_host">Deny</directive> directive will be

denied access to the server.</dd>

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

<dd>Only those hosts which appear on the <directive

module="mod_authz_host">Allow</directive> list and do not appear on

the <directive module="mod_authz_host">Deny</directive> 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 <directive

module="mod_authz_host">Allow</directive> and <directive

module="mod_authz_host">Deny</directive> 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>

<example>

Order Deny,Allow<br />

Deny from all<br />

Allow from apache.org

</example>

<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>

<example>

Order Allow,Deny<br />

Allow from apache.org<br />

Deny from foo.apache.org

</example>

<p>On the other hand, if the <directive>Order</directive> 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

<em>allow</em>.</p>

<p>The presence of an <directive>Order</directive> directive can affect

access to a part of the server even in the absence of accompanying

<directive module="mod_authz_host">Allow</directive> and <directive

module="mod_authz_host">Deny</directive> directives because of its effect

on the default access state. For example,</p>

<example>

&lt;Directory /www&gt;<br />

<indent>

Order Allow,Deny<br />

</indent>

&lt;/Directory&gt;

</example>

<p>will deny all access to the <code>/www</code> directory

because the default access state will be set to

<em>deny</em>.</p>

<p>The <directive>Order</directive> directive controls the order of access

directive processing only within each phase of the server's

configuration processing. This implies, for example, that an

<directive module="mod_authz_host">Allow</directive> or <directive

module="mod_authz_host">Deny</directive> directive occurring in a

<directive module="core" type="section">Location</directive> section will

always be evaluated after an <directive

module="mod_authz_host">Allow</directive> or <directive

module="mod_authz_host">Deny</directive> directive occurring in a

<directive module="core" type="section">Directory</directive> section or

<code>.htaccess</code> file, regardless of the setting of the

<directive>Order</directive> 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>

</usage>

</directivesynopsis>

</modulesynopsis>