<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<HTML>
<HEAD>
<TITLE>Apache module mod_access</TITLE>
</HEAD>

<!-- Background white, links blue (unvisited), navy (visited), red (active) -->
<BODY
 BGCOLOR="#FFFFFF"
 TEXT="#000000"
 LINK="#0000FF"
 VLINK="#000080"
 ALINK="#FF0000"
>
<!--#include virtual="header.html" -->

<H1 ALIGN="CENTER">Module mod_access</H1>
<P>
This module provides access control based on client hostname, IP
address, or other characteristics of the client request.
</P>

<P><A
HREF="module-dict.html#Status"
REL="Help"
><STRONG>Status:</STRONG></A> Base
<BR>
<A
HREF="module-dict.html#SourceFile"
REL="Help"
><STRONG>Source File:</STRONG></A> mod_access.c
<BR>
<A
HREF="module-dict.html#ModuleIdentifier"
REL="Help"
><STRONG>Module Identifier:</STRONG></A> access_module
</P>

<h2>Summary</h2>

<p>The directives provided by mod_access are used in <CODE><A
HREF="core.html#directory">&lt;Directory&gt;</A>, <A
HREF="core.html#files">&lt;Files&gt;</A>,</code> and <code> <A
HREF="core.html#location">&lt;Location&gt;</A></code> 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
<code>Allow</code> and <code>Deny</code> directives are used
to specify which clients are or are not allowed access to the
server, while the <code>Order</code> directive sets the
default access state, and configures how the <code>Allow</code>
and <code>Deny</code> directives interact with each other.</p>

<p>Both host-based access restrictions and password-based
authentication may be implemented simultaneously.  In 
that case, the <a href="core.html#satsify">Satisfy</a> 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 <a
href="core.html#limit">&lt;Limit&gt;</a> section.</p>

<H2>Directives</H2>

<UL>
<LI><A HREF="#allow">Allow</A>
<LI><A HREF="#deny">Deny</A>
<LI><A HREF="#order">Order</A>
</UL>

<P>See also <A HREF="core.html#satisfy">Satisfy</A>
    and <A HREF="core.html#require">Require</A>.

<HR>


<H2><A NAME="allow">Allow</a> <a name="allowfromenv">directive</A></H2>
<P>
<!--%plaintext &lt;?INDEX {\tt Allow} directive&gt; -->
<A
 HREF="directive-dict.html#Syntax"
 REL="Help"
><STRONG>Syntax:</STRONG></A> Allow from 
   all|<EM>host</em>|env=<em>variablename</em> 
   [<em>host</em>|env=<em>variablename</em>] ...<BR>
<A
 HREF="directive-dict.html#Context"
 REL="Help"
><STRONG>Context:</STRONG></A> directory, .htaccess<BR>
<A
 HREF="directive-dict.html#Override"
 REL="Help"
><STRONG>Override:</STRONG></A> Limit<BR>
<A
 HREF="directive-dict.html#Status"
 REL="Help"
><STRONG>Status:</STRONG></A> Base<BR>
<A
 HREF="directive-dict.html#Module"
 REL="Help"
><STRONG>Module:</STRONG></A> mod_access
</P>

<P>
The <code>Allow</code> 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 <code>Deny</code> and
<code>Order</code> 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: <code>Allow from
apache.org</code><br> 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 the
server to perform a reverse DNS lookup on the client IP address,
regardless of the setting of the <a
href="core.html#hostnamelookups">HostNameLookups</a> directive.</dd>

<DT>A full IP address</dt>
<DD>Example: <code>Allow from 10.1.2.3</code><br>
An IP address of a host allowed access</dd>

<DT>A partial IP address</dt>
<dd>Example: <code>Allow from 10.1</code><br>
The first 1 to 3 bytes of an IP address, for subnet restriction.</dd>

<DT>A network/netmask pair</dt>
<dd>Example: <code>Allow from 10.1.0.0/255.255.0.0</code><br>
 A network a.b.c.d, and a netmask w.x.y.z.  For more fine-grained subnet
    restriction.</dd>

<DT>A network/nnn CIDR specification</dt> <dd>Example: <code>Allow
from 10.1.0.0/16</code><br> Similar to the previous case, except the
netmask consists of nnn high-order 1 bits.</dd>
</DL>

<p>Note that the last three examples above match exactly the
same set of hosts.</p>

<p>The third format of the arguments to the <code>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=</code><em>variablename</em> is specified, then
the request is allowed access if the environment variable
<em>variablename</em> 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 <a
href="mod_setenvif.html">mod_setenvif</a>.  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>

<P>
Example:
</P>
<BLOCKQUOTE><PRE>
SetEnvIf User-Agent ^KnockKnock/2.0 let_me_in
&lt;Directory /docroot&gt;
    Order Deny,Allow
    Deny from all
    Allow from env=let_me_in
&lt;/Directory&gt;
</PRE></BLOCKQUOTE>

<p>In this case, browsers with a user-agent string beginning with
<TT>KnockKnock/2.0</TT> will be allowed access, and all others will be
denied.</p>
<P>
See also <a href="#deny">Deny</a>, <A HREF="#order">Order</A>
and <A HREF="mod_setenvif.html#SetEnvIf">SetEnvIf</A>.
</P>
<HR>

<H2><A NAME="deny">Deny</a> <a name="denyfromenv">directive</A></H2>
<P>
<!--%plaintext &lt;?INDEX {\tt Deny} directive&gt; -->
<A
 HREF="directive-dict.html#Syntax"
 REL="Help"
><STRONG>Syntax:</STRONG></A> Deny from 
   all|<EM>host</em>|env=<em>variablename</em> 
   [<em>host</em>|env=<em>variablename</em>] ...<BR>
<A
 HREF="directive-dict.html#Context"
 REL="Help"
><STRONG>Context:</STRONG></A> directory, .htaccess<BR>
<A
 HREF="directive-dict.html#Override"
 REL="Help"
><STRONG>Override:</STRONG></A> Limit<BR>
<A
 HREF="directive-dict.html#Status"
 REL="Help"
><STRONG>Status:</STRONG></A> Base<BR>
<A
 HREF="directive-dict.html#Module"
 REL="Help"
><STRONG>Module:</STRONG></A> mod_access
</P>

<p>This directive allows access to the server to be restricted based
on hostname, IP address, or environment variables.  The arguments for
the <code>Deny</code> directive are identical to the arguments for the
<a href="#allow">Allow</a> directive.</p>

<p>See also <a href="#allow">Allow</a>, <A HREF="#order">Order</A>
and <A HREF="mod_setenvif.html#SetEnvIf">SetEnvIf</A>.</p>
<HR>

<H2><A NAME="order">Order directive</A></H2>
<P>
<!--%plaintext &lt;?INDEX {\tt Order} directive&gt; -->
<A
 HREF="directive-dict.html#Syntax"
 REL="Help"
><STRONG>Syntax:</STRONG></A> Order <EM>ordering</EM><BR>
<A
 HREF="directive-dict.html#Default"
 REL="Help"
><STRONG>Default:</STRONG></A> <CODE>Order Deny,Allow</CODE><BR>
<A
 HREF="directive-dict.html#Context"
 REL="Help"
><STRONG>Context:</STRONG></A> directory, .htaccess<BR>
<A
 HREF="directive-dict.html#Override"
 REL="Help"
><STRONG>Override:</STRONG></A> Limit<BR>
<A
 HREF="directive-dict.html#Status"
 REL="Help"
><STRONG>Status:</STRONG></A> Base<BR>
<A
 HREF="directive-dict.html#Module"
 REL="Help"
><STRONG>Module:</STRONG></A> mod_access
</P>
<P>
The <CODE>Order</CODE> directive controls the default access state and
the order in which <A HREF="#allow">Allow</A> and <A
HREF="#deny">Deny</A> directives are evaluated. <EM>Ordering</EM> is
one of
</P>
<DL>
<DT>Deny,Allow</dt> <DD>The <CODE>Deny</CODE> directives are evaluated
before the <CODE>Allow</CODE> directives.  Access is allowed
by default.  Any client which does not match a <code>Deny</code>
directive or does match an <code>Allow</code> directive will be
allowed access to the server.</dd>

<DT>Allow,Deny</dt> <DD>The <CODE>Allow</CODE> directives are
evaluated before the <CODE>Deny</CODE> directives.  Access is
denied by default.  Any client which does not match
an <code>Allow</code> directive or does match a <code>Deny</code>
directive will be denied access to the server.</dd>

<DT>Mutual-failure</dt> <DD>Only those hosts which appear on the
<CODE>Allow</CODE> list and do not appear on the <CODE>Deny</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; no whitespace is allowed
between them.  Note that in all cases every <CODE>Allow</CODE>
and <CODE>Deny</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>

<BLOCKQUOTE><CODE>
    Order Deny,Allow<BR>
    Deny from all<BR>
    Allow from apache.org<BR>
</CODE></BLOCKQUOTE>

<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>

<blockquote><code>
    Order Allow,Deny<br>
    Allow from apache.org<br>
    Deny from foo.apache.org<br>
</code></blockquote>

<p>On the other hand, if the <code>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 <em>allow</em>.</p>

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

<blockquote><code>
&lt;Directory /www&gt;<br>
&nbsp;&nbsp;Order Allow,Deny<br>
&lt;/Directory&gt;
</code></blockquote>

<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 <code>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>Allow</code> or <code>Deny</code> directive occurring
in a &lt;Location&gt; section will always be evaluated after
an <code>Allow</code> or <code>Deny</code> directive occurring
in a &lt;Directory&gt; section or <code>.htaccess</code> file,
regardless of the setting of the <code>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>

<P>See also: <A HREF="#deny">Deny</A> and <A HREF="#allow">Allow</A>.
<!--#include virtual="footer.html" -->
</BODY>
</HTML>