summaryrefslogtreecommitdiff
path: root/usr.sbin/httpd
diff options
context:
space:
mode:
Diffstat (limited to 'usr.sbin/httpd')
-rw-r--r--usr.sbin/httpd/htdocs/manual/host.html185
-rw-r--r--usr.sbin/httpd/htdocs/manual/vhosts-in-depth.html398
-rw-r--r--usr.sbin/httpd/htdocs/manual/virtual-host.html216
3 files changed, 0 insertions, 799 deletions
diff --git a/usr.sbin/httpd/htdocs/manual/host.html b/usr.sbin/httpd/htdocs/manual/host.html
deleted file mode 100644
index 74639a5b5fb..00000000000
--- a/usr.sbin/httpd/htdocs/manual/host.html
+++ /dev/null
@@ -1,185 +0,0 @@
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
-<html><head>
-<title>Apache non-IP Virtual Hosts</title>
-</head>
-
-<!-- Background white, links blue (unvisited), navy (visited), red (active) -->
-<BODY
- BGCOLOR="#FFFFFF"
- TEXT="#000000"
- LINK="#0000FF"
- VLINK="#000080"
- ALINK="#FF0000"
->
-<DIV ALIGN="CENTER">
- <IMG SRC="images/sub.gif" ALT="[APACHE DOCUMENTATION]">
- <H3>
- Apache HTTP Server Version 1.2
- </H3>
-</DIV>
-
-<h1 ALIGN="CENTER">Apache non-IP Virtual Hosts</h1>
-
-<strong>See Also:</strong>
-<a href="virtual-host.html">Virtual Host Support</a>
-
-<hr>
-
-<h2>What is a Virtual Host</h2>
-
-<p>The "Virtual Host" refers to the practice of maintaining more than
-one server on one machine, as differentiated by their apparent
-hostname. For example, it is often desirable for companies sharing a
-web server to have their own domains, with web servers accessible as
-<code>www.company1.com</code> and <code>www.company2.com</code>,
-without requiring the user to know any extra path information.</p>
-
-<p>Apache was one of the first servers to support virtual hosts right
-out of the box, but since the base <code>HTTP</code> (HyperText
-Transport Protocol) standard does not allow any method for the server
-to determine the hostname it is being addressed as, Apache's virtual
-host support has required a separate IP address for each
-server. Documentation on using this approach (which still works very
-well) <a href="virtual-host.html">is available</a>.
-
-<p>While the approach described above works, with the available IP
-address space growing smaller, and the number of domains increasing,
-it is not the most elegant solution, and is hard to implement on some
-machines. The <code>HTTP/1.1</code> protocol contains a method for the
-server to identify what name it is being addressed as. Apache 1.1 and
-later support this approach as well as the traditional
-IP-address-per-hostname method.</p>
-
-<p>The benefits of using the new virtual host support is a practically
-unlimited number of servers, ease of configuration and use, and
-requires no additional hardware or software. The main disadvantage is
-that the user's browser must support this part of the protocol. The
-latest versions of many browsers (including Netscape Navigator 2.0 and
-later) do, but many browsers, especially older ones, do not. This can
-cause problems, although a possible solution is addressed below.</p>
-
-<h2>Using non-IP Virtual Hosts</h2>
-
-<p>Using the new virtual hosts is quite easy, and superficially looks
-like the old method. You simply add to one of the Apache configuration
-files (most likely <code>httpd.conf</code> or <code>srm.conf</code>)
-code similar to the following:</p>
-<pre>
- &lt;VirtualHost www.apache.org&gt;
- ServerName www.apache.org
- DocumentRoot /usr/web/apache
- &lt;/VirtualHost&gt;
-</pre>
-
-<p>Of course, any additional directives can (and should) be placed
-into the <code>&lt;VirtualHost&gt;</code> section. To make this work,
-all that is needed is to make sure that the <code>www.apache.org</code>
-DNS entry points to the same IP address as the main
-server. Optionally, you could simply use that IP address in the
-&lt;VirtualHost&gt; entry.</p>
-
-<p>Additionally, many servers may wish to be accessible by more than
-one name. For example, the Apache server might want to be accessible
-as <code>apache.org</code>, or <code>ftp.apache.org</code>, assuming
-the IP addresses pointed to the same server. In fact, one might want it
-so that all addresses at <code>apache.org</code> were picked up by the
-server. This is possible with the <code>ServerAlias</code>
-directive, placed inside the &lt;VirtualHost&gt; section. For
-example:</p>
-
-<pre>
- ServerAlias apache.org *.apache.org
-</pre>
-
-<p>Note that you can use <code>*</code> and <code>?</code> as wild-card
-characters.</p>
-
-<p>You also might need ServerAlias if you are serving local users who
-do not always include the domain name. For example, if local users are
-familiar with typing "www" or "www.physics" then you will need to add
-<code>ServerAlias www www.physics</code>. It isn't possible for the
-server to know what domain the client uses for their name resolution
-because the client doesn't provide that information in the request.</p>
-
-<h2>Security Considerations</h2>
-
-Apache allows all virtual hosts to be made accessible via the
-<code>Host:</code> header through all IP interfaces, even those which
-are configured to use different IP interfaces. For example, if the
-configuration for <code>www.foo.com</code> contained a virtual host
-section for <code>www.bar.com</code>, and <code>www.bar.com</code> was
-a separate IP interface, such that
-non-<code>Host:</code>-header-supporting browsers can use it, as
-before with Apache 1.0. If a request is made to
-<code>www.foo.com</code> and the request includes the header
-<code>Host: www.bar.com</code>, a page from <code>www.bar.com</code>
-will be sent.
-
-<P>
-
-This is a security concern if you are controlling access to a
-particular server based on IP-layer controls, such as from within a
-firewall or router. Let's say <code>www.bar.com</code> in the above
-example was instead an intra-net server called
-<code>private.foo.com</code>, and the router used by foo.com only let
-internal users access <code>private.foo.com</code>. Obviously,
-<code>Host:</code> header functionality now allows someone who has
-access to <code>www.foo.com</code> to get
-<code>private.foo.com</code>, if they send a <code>Host:
-private.foo.com</code> header. It is important to note that this
-condition exists only if you only implement this policy at the IP
-layer - all security controls used by Apache (i.e., <A
-HREF="mod/mod_access.html">allow, deny from,</A> etc.) are consistently
-respected.
-
-<h2>Compatibility with Older Browsers</h2>
-
-<p>As mentioned earlier, a majority of browsers do not send the
-required data for the new virtual hosts to work properly. These
-browsers will always be sent to the main server's pages. There is a
-workaround, albeit a slightly cumbersome one:</p>
-
-<p>To continue the <code>www.apache.org</code> example (Note: Apache's
-web server does not actually function in this manner), we might use the
-new <code>ServerPath</code> directive in the <code>www.apache.org</code> virtual host,
-for example:
-
-<pre>
- ServerPath /apache
-</pre>
-<p>What does this mean? It means that a request for any file beginning
-with "<code>/apache</code>" will be looked for in the Apache
-docs. This means that the pages can be accessed as
-<code>http://www.apache.org/apache/</code> for all browsers, although
-new browsers can also access it as
-<code>http://www.apache.org/</code>.</p>
-
-<p>In order to make this work, put a link on your main server's page
-to <code>http://www.apache.org/apache/</code> (Note: Do not use
-<code>http://www.apache.org/</code> - this would create an endless
-loop). Then, in the virtual host's pages, be sure to use either purely
-relative links (e.g. "<code>file.html</code>" or
-"<code>../icons/image.gif</code>" or links containing the prefacing
-<code>/apache/</code>
-(e.g. "<code>http://www.apache.org/apache/file.html</code>" or
-"<code>/apache/docs/1.1/index.html</code>").</p>
-
-<p>This requires a bit of
-discipline, but adherence to these guidelines will, for the most part,
-ensure that your pages will work with all browsers, new and old. When
-a new browser contacts <code>http://www.apache.org/</code>, they will
-be directly taken to the Apache pages. Older browsers will be able to
-click on the link from the main server, go to
-<code>http://www.apache.org/apache/</code>, and then access the
-pages.</p>
-
-<HR>
-<H3 ALIGN="CENTER">
- Apache HTTP Server Version 1.2
-</H3>
-
-<A HREF="./"><IMG SRC="images/index.gif" ALT="Index"></A>
-
-</BODY>
-</HTML>
-
diff --git a/usr.sbin/httpd/htdocs/manual/vhosts-in-depth.html b/usr.sbin/httpd/htdocs/manual/vhosts-in-depth.html
deleted file mode 100644
index 0f87f775ed6..00000000000
--- a/usr.sbin/httpd/htdocs/manual/vhosts-in-depth.html
+++ /dev/null
@@ -1,398 +0,0 @@
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
-<html><head>
-<title>An In-Depth Discussion of VirtualHost Matching</title>
-</head>
-
-<!-- Background white, links blue (unvisited), navy (visited), red (active) -->
-<BODY
- BGCOLOR="#FFFFFF"
- TEXT="#000000"
- LINK="#0000FF"
- VLINK="#000080"
- ALINK="#FF0000"
->
-<DIV ALIGN="CENTER">
- <IMG SRC="images/sub.gif" ALT="[APACHE DOCUMENTATION]">
- <H3>
- Apache HTTP Server Version 1.2
- </H3>
-</DIV>
-
-<h1 ALIGN="CENTER">An In-Depth Discussion of VirtualHost Matching</h1>
-
-<p>This is a very rough document that was probably out of date the moment
-it was written. It attempts to explain exactly what the code does when
-deciding what virtual host to serve a hit from. It's provided on the
-assumption that something is better than nothing. The server version
-under discussion is Apache 1.2.
-
-<p>If you just want to &quot;make it work&quot; without understanding
-how, there's a <a href="#whatworks">What Works</a> section at the bottom.
-
-<h3>Config File Parsing</h3>
-
-<p>There is a main_server which consists of all the definitions appearing
-outside of <CODE>VirtualHost</CODE> sections. There are virtual servers,
-called <EM>vhosts</EM>, which are defined by
-<A
- HREF="mod/core.html#virtualhost"
-><SAMP>VirtualHost</SAMP></A>
-sections.
-
-<p>The directives
-<A
- HREF="mod/core.html#port"
-><SAMP>Port</SAMP></A>,
-<A
- HREF="mod/core.html#servername"
-><SAMP>ServerName</SAMP></A>,
-<A
- HREF="mod/core.html#serverpath"
-><SAMP>ServerPath</SAMP></A>,
-and
-<A
- HREF="mod/core.html#serveralias"
-><SAMP>ServerAlias</SAMP></A>
-can appear anywhere within the definition of
-a server. However, each appearance overrides the previous appearance
-(within that server).
-
-<p>The default value of the <code>Port</code> field for main_server
-is 80. The main_server has no default <code>ServerName</code>,
-<code>ServerPath</code>, or <code>ServerAlias</code>.
-
-<p>In the absence of any
-<A
- HREF="mod/core.html#listen"
-><SAMP>Listen</SAMP></A>
-directives, the (final if there
-are multiple) <code>Port</code> directive in the main_server indicates
-which port httpd will listen on.
-
-<p> The <code>Port</code> and <code>ServerName</code> directives for
-any server main or virtual are used when generating URLs such as during
-redirects.
-
-<p> Each address appearing in the <code>VirtualHost</code> directive
-can have an optional port. If the port is unspecified it defaults to
-the value of the main_server's most recent <code>Port</code> statement.
-The special port <SAMP>*</SAMP> indicates a wildcard that matches any port.
-Collectively the entire set of addresses (including multiple
-<SAMP>A</SAMP> record
-results from DNS lookups) are called the vhost's <EM>address set</EM>.
-
-<p> The magic <code>_default_</code> address has significance during
-the matching algorithm. It essentially matches any unspecified address.
-
-<p> After parsing the <code>VirtualHost</code> directive, the vhost server
-is given a default <code>Port</code> equal to the port assigned to the
-first name in its <code>VirtualHost</code> directive. The complete
-list of names in the <code>VirtualHost</code> directive are treated
-just like a <code>ServerAlias</code> (but are not overridden by any
-<code>ServerAlias</code> statement). Note that subsequent <code>Port</code>
-statements for this vhost will not affect the ports assigned in the
-address set.
-
-<p>
-All vhosts are stored in a list which is in the reverse order that
-they appeared in the config file. For example, if the config file is:
-
-<blockquote><pre>
- &lt;VirtualHost A&gt;
- ...
- &lt;/VirtualHost&gt;
-
- &lt;VirtualHost B&gt;
- ...
- &lt;/VirtualHost&gt;
-
- &lt;VirtualHost C&gt;
- ...
- &lt;/VirtualHost&gt;
-</pre></blockquote>
-
-Then the list will be ordered: main_server, C, B, A. Keep this in mind.
-
-<p>
-After parsing has completed, the list of servers is scanned, and various
-merges and default values are set. In particular:
-
-<ol>
-<li>If a vhost has no
- <A
- HREF="mod/core.html#serveradmin"
- ><code>ServerAdmin</code></A>,
- <A
- HREF="mod/core.html#resourceconfig"
- ><code>ResourceConfig</code></A>,
- <A
- HREF="mod/core.html#accessconfig"
- ><code>AccessConfig</code></A>,
- <A
- HREF="mod/core.html#timeout"
- ><code>Timeout</code></A>,
- <A
- HREF="mod/core.html#keepalivetimeout"
- ><code>KeepAliveTimeout</code></A>,
- <A
- HREF="mod/core.html#keepalive"
- ><code>KeepAlive</code></A>,
- <A
- HREF="mod/core.html#maxkeepaliverequests"
- ><code>MaxKeepAliveRequests</code></A>,
- or
- <A
- HREF="mod/core.html#sendbuffersize"
- ><code>SendBufferSize</code></A>
- directive then the respective value is
- inherited from the main_server. (That is, inherited from whatever
- the final setting of that value is in the main_server.)
-
-<li>The &quot;lookup defaults&quot; that define the default directory
- permissions
- for a vhost are merged with those of the main server. This includes
- any per-directory configuration information for any module.
-
-<li>The per-server configs for each module from the main_server are
- merged into the vhost server.
-</ol>
-
-Essentially, the main_server is treated as &quot;defaults&quot; or a
-&quot;base&quot; on
-which to build each vhost. But the positioning of these main_server
-definitions in the config file is largely irrelevant -- the entire
-config of the main_server has been parsed when this final merging occurs.
-So even if a main_server definition appears after a vhost definition
-it might affect the vhost definition.
-
-<p> If the main_server has no <code>ServerName</code> at this point,
-then the hostname of the machine that httpd is running on is used
-instead. We will call the <EM>main_server address set</EM> those IP
-addresses returned by a DNS lookup on the <code>ServerName</code> of
-the main_server.
-
-<p> Now a pass is made through the vhosts to fill in any missing
-<code>ServerName</code> fields and to classify the vhost as either
-an <EM>IP-based</EM> vhost or a <EM>name-based</EM> vhost. A vhost is
-considered a name-based vhost if any of its address set overlaps the
-main_server (the port associated with each address must match the
-main_server's <code>Port</code>). Otherwise it is considered an IP-based
-vhost.
-
-<p> For any undefined <code>ServerName</code> fields, a name-based vhost
-defaults to the address given first in the <code>VirtualHost</code>
-statement defining the vhost. Any vhost that includes the magic
-<SAMP>_default_</SAMP> wildcard is given the same <code>ServerName</code> as
-the main_server. Otherwise the vhost (which is necessarily an IP-based
-vhost) is given a <code>ServerName</code> based on the result of a reverse
-DNS lookup on the first address given in the <code>VirtualHost</code>
-statement.
-
-<p>
-
-<h3>Vhost Matching</h3>
-
-<p>
-The server determines which vhost to use for a request as follows:
-
-<p> <code>find_virtual_server</code>: When the connection is first made
-by the client, the local IP address (the IP address to which the client
-connected) is looked up in the server list. A vhost is matched if it
-is an IP-based vhost, the IP address matches and the port matches
-(taking into account wildcards).
-
-<p> If no vhosts are matched then the last occurrence, if it appears,
-of a <SAMP>_default_</SAMP> address (which if you recall the ordering of the
-server list mentioned above means that this would be the first occurrence
-of <SAMP>_default_</SAMP> in the config file) is matched.
-
-<p> In any event, if nothing above has matched, then the main_server is
-matched.
-
-<p> The vhost resulting from the above search is stored with data
-about the connection. We'll call this the <EM>connection vhost</EM>.
-The connection vhost is constant over all requests in a particular TCP/IP
-session -- that is, over all requests in a KeepAlive/persistent session.
-
-<p> For each request made on the connection the following sequence of
-events further determines the actual vhost that will be used to serve
-the request.
-
-<p> <code>check_fulluri</code>: If the requestURI is an absoluteURI, that
-is it includes <code>http://hostname/</code>, then an attempt is made to
-determine if the hostname's address (and optional port) match that of
-the connection vhost. If it does then the hostname portion of the URI
-is saved as the <EM>request_hostname</EM>. If it does not match, then the
-URI remains untouched. <STRONG>Note</STRONG>: to achieve this address
-comparison,
-the hostname supplied goes through a DNS lookup unless it matches the
-<code>ServerName</code> or the local IP address of the client's socket.
-
-<p> <code>parse_uri</code>: If the URI begins with a protocol
-(<EM>i.e.</EM>, <code>http:</code>, <code>ftp:</code>) then the request is
-considered a proxy request. Note that even though we may have stripped
-an <code>http://hostname/</code> in the previous step, this could still
-be a proxy request.
-
-<p> <code>read_request</code>: If the request does not have a hostname
-from the earlier step, then any <code>Host:</code> header sent by the
-client is used as the request hostname.
-
-<p> <code>check_hostalias</code>: If the request now has a hostname,
-then an attempt is made to match for this hostname. The first step
-of this match is to compare any port, if one was given in the request,
-against the <code>Port</code> field of the connection vhost. If there's
-a mismatch then the vhost used for the request is the connection vhost.
-(This is a bug, see observations.)
-
-<p>
-If the port matches, then httpd scans the list of vhosts starting with
-the next server <STRONG>after</STRONG> the connection vhost. This scan does not
-stop if there are any matches, it goes through all possible vhosts,
-and in the end uses the last match it found. The comparisons performed
-are as follows:
-
-<ul>
-<li>Compare the request hostname:port with the vhost
- <code>ServerName</code> and <code>Port</code>.
-
-<li>Compare the request hostname against any and all addresses given in
- the <code>VirtualHost</code> directive for this vhost.
-
-<li>Compare the request hostname against the <code>ServerAlias</code>
- given for the vhost.
-</ul>
-
-<p>
-<code>check_serverpath</code>: If the request has no hostname
-(back up a few paragraphs) then a scan similar to the one
-in <code>check_hostalias</code> is performed to match any
-<code>ServerPath</code> directives given in the vhosts. Note that the
-<STRONG>last match</STRONG> is used regardless (again consider the ordering of
-the virtual hosts).
-
-<h3>Observations</h3>
-
-<ul>
-
-<li>It is difficult to define an IP-based vhost for the machine's
- &quot;main IP address&quot;. You essentially have to create a bogus
- <code>ServerName</code> for the main_server that does not match the
- machine's IPs.
-
-<li>During the scans in both <code>check_hostalias</code> and
- <code>check_serverpath</code> no check is made that the vhost being
- scanned is actually a name-based vhost. This means, for example, that
- it's possible to match an IP-based vhost through another address. But
- because the scan starts in the vhost list at the first vhost that
- matched the local IP address of the connection, not all IP-based vhosts
- can be matched.
-
- <p>Consider the config file above with three vhosts A, B, C. Suppose
- that B is a named-based vhost, and A and C are IP-based vhosts. If
- a request comes in on B or C's address containing a header
- &quot;<SAMP>Host: A</SAMP>&quot; then
- it will be served from A's config. If a request comes in on A's
- address then it will always be served from A's config regardless of
- any Host: header.
- </p>
-
-<li>Unless you have a <SAMP>_default_</SAMP> vhost,
- it doesn't matter if you mix name-based vhosts in amongst IP-based
- vhosts. During the <code>find_virtual_server</code> phase above no
- named-based vhost will be matched, so the main_server will remain the
- connection vhost. Then scans will cover all vhosts in the vhost list.
-
- <p>If you do have a <SAMP>_default_</SAMP> vhost, then you cannot place
- named-based vhosts after it in the config. This is because on any
- connection to the main server IPs the connection vhost will always be
- the <SAMP>_default_</SAMP> vhost since none of the name-based are
- considered during <code>find_virtual_server</code>.
- </p>
-
-<li>You should never specify DNS names in <code>VirtualHost</code>
- directives because it will force your server to rely on DNS to boot.
- Furthermore it poses a security threat if you do not control the
- DNS for all the domains listed.
- <a href="dns-caveats.html">
- There's more information
- available on this and the next two topics</a>.</p>
-
-<li><code>ServerName</code> should always be set for each vhost. Otherwise
- A DNS lookup is required for each vhost.</p>
-
-<li>A DNS lookup is always required for the main_server's
- <code>ServerName</code> (or to generate that if it isn't specified
- in the config).</p>
-
-<li>If a <code>ServerPath</code> directive exists which is a prefix of
- another <code>ServerPath</code> directive that appears later in
- the configuration file, then the former will always be matched
- and the latter will never be matched. (That is assuming that no
- Host header was available to disambiguate the two.)</p>
-
-<li>If a vhost that would otherwise be a name-vhost includes a
- <code>Port</code> statement that doesn't match the main_server
- <code>Port</code> then it will be considered an IP-based vhost.
- Then <code>find_virtual_server</code> will match it (because
- the ports associated with each address in the address set default
- to the port of the main_server) as the connection vhost. Then
- <code>check_hostalias</code> will refuse to check any other name-based
- vhost because of the port mismatch. The result is that the vhost
- will steal all hits going to the main_server address.</p>
-
-<li>If two IP-based vhosts have an address in common, the vhost appearing
- later in the file is always matched. Such a thing might happen
- inadvertently. If the config has name-based vhosts and for some reason
- the main_server <code>ServerName</code> resolves to the wrong address
- then all the name-based vhosts will be parsed as ip-based vhosts.
- Then the last of them will steal all the hits.</P>
-
-<li>The last name-based vhost in the config is always matched for any hit
- which doesn't match one of the other name-based vhosts.</p>
-
-</ul>
-
-<h3><a name="whatworks">What Works</a></h3>
-
-<p>In addition to the tips on the <a href="dns-caveats.html#tips">DNS
-Issues</a> page, here are some further tips:
-
-<ul>
-
-<li>Place all main_server definitions before any VirtualHost definitions.
-(This is to aid the readability of the configuration -- the post-config
-merging process makes it non-obvious that definitions mixed in around
-virtualhosts might affect all virtualhosts.)
-<p>
-
-<li>Arrange your VirtualHosts such
-that all name-based virtual hosts come first, followed by IP-based
-virtual hosts, followed by any <SAMP>_default_</SAMP> virtual host
-<p>
-
-<li>Avoid <code>ServerPaths</code> which are prefixes of other
-<code>ServerPaths</code>. If you cannot avoid this then you have to
-ensure that the longer (more specific) prefix vhost appears earlier in
-the configuration file than the shorter (less specific) prefix
-(<EM>i.e.</EM>, &quot;ServerPath /abc&quot; should appear after
-&quot;ServerPath /abcdef&quot;).
-<p>
-
-<li>Do not use <i>port-based</i> vhosts in the same server as
-name-based vhosts. A loose definition for port-based is a vhost which
-is determined by the port on the server (<em>i.e.</em> one server with
-ports 8000, 8080, and 80 all of which have different configurations).
-<p>
-
-</ul>
-
-<HR>
-<H3 ALIGN="CENTER">
- Apache HTTP Server Version 1.2
-</H3>
-
-<A HREF="./"><IMG SRC="images/index.gif" ALT="Index"></A>
-
-</BODY>
-</HTML>
diff --git a/usr.sbin/httpd/htdocs/manual/virtual-host.html b/usr.sbin/httpd/htdocs/manual/virtual-host.html
deleted file mode 100644
index d21ac708fd8..00000000000
--- a/usr.sbin/httpd/htdocs/manual/virtual-host.html
+++ /dev/null
@@ -1,216 +0,0 @@
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
-<html>
-<head>
-<title>Apache Server Virtual Host Support</title>
-</head>
-
-<!-- Background white, links blue (unvisited), navy (visited), red (active) -->
-<BODY
- BGCOLOR="#FFFFFF"
- TEXT="#000000"
- LINK="#0000FF"
- VLINK="#000080"
- ALINK="#FF0000"
->
-<DIV ALIGN="CENTER">
- <IMG SRC="images/sub.gif" ALT="[APACHE DOCUMENTATION]">
- <H3>
- Apache HTTP Server Version 1.2
- </H3>
-</DIV>
-
-<h1 ALIGN="CENTER">Virtual Host Support</h1>
-
-<strong>See Also:</strong>
-<a href="host.html">Non-IP based virtual hosts</a>
-
-<h2>What are virtual hosts?</h2>
-This is the ability of a single machine to be a web server for multiple
-domains. For example, an Internet service provider might have a machine
-called <code>www.serve.com</code> which provides Web space for several
-organizations including, say, <em>smallco</em> and <em>baygroup</em>.
-Ordinarily, these groups would be given parts of the Web tree on www.serve.com.
-So smallco's home page would have the URL
-<blockquote>
-http://www.serve.com/smallco/
-</blockquote>
-and baygroup's home page would have the URL
-<blockquote>
-http://www.serve.com/baygroup/
-</blockquote>
-<p>
-For esthetic reasons, however, both organizations would rather their home
-pages appeared under their own names rather than that of the service
-provider's; but they do not want to set up their own Internet links and
-servers.
-<p>
-Virtual hosts are the solution to this problem. smallco and baygroup would
-have their own Internet name registrations, <code>www.smallco.com</code> and
-<code>www.baygroup.org</code> respectively. These hostnames would both
-correspond to the service provider's machine (www.serve.com). Thus
-smallco's home page would now have the URL
-<blockquote>
-http://www.smallco.com/
-</blockquote>
-and baygroup's home page would would have the URL
-<blockquote>
-http://www.baygroup.org/
-</blockquote>
-
-<h2>System requirements</h2>
-Due to limitations in the HTTP/1.0 protocol, the web server <strong>must have a
-different IP address for each virtual host</strong>. This can be achieved
-by the machine having several physical network connections, or by use
-of a <a href="misc/vif-info.html">virtual interface</a> on some operating systems.
-
-<h2>How to set up Apache</h2>
-There are two ways of configuring apache to support multiple hosts.
-Either by running a separate httpd daemon for each hostname, or by running a
-single daemon which supports all the virtual hosts.
-<p>
-Use multiple daemons when:
-<ul>
-<li>The different virtual hosts need very different httpd configurations, such
- as different values for: <A HREF="mod/core.html#servertype">ServerType</A>,
- <A HREF="mod/core.html#user">User</A>,
- <A HREF="mod/core.html#group">Group</A>,
- <A HREF="mod/mod_mime.html#typesconfig">TypesConfig</A> or
- <A HREF="mod/core.html#serverroot">ServerRoot</A>.
-<li>The machine does not process a very high request rate.
-</ul>
-Use a single daemon when:
-<ul>
-<li>Sharing of the httpd configuration between virtual hosts is acceptable.
-<li>The machine services a large number of requests, and so the performance
- loss in running separate daemons may be significant.
-</ul>
-
-<h2>Setting up multiple daemons</h2>
-Create a separate httpd installation for each virtual host.
-For each installation, use the
-<A HREF="mod/core.html#bindaddress">BindAddress</A> directive in the configuration
-file to select which IP address (or virtual host) that daemon services.
-e.g.
-<blockquote><code>BindAddress www.smallco.com</code></blockquote>
-This hostname can also be given as an IP address.
-
-<h2>Setting up a single daemon</h2>
-For this case, a single httpd will service requests for all the virtual hosts.
-The <A HREF="mod/core.html#virtualhost">VirtualHost</A> directive in the
- configuration file is used to set the values of
-<A HREF="mod/core.html#serveradmin">ServerAdmin</A>,
-<A HREF="mod/core.html#servername">ServerName</A>,
-<A HREF="mod/core.html#documentroot">DocumentRoot</A>,
-<A HREF="mod/core.html#errorlog">ErrorLog</A> and
-<A HREF="mod/mod_log_common.html#transferlog">TransferLog</A> configuration
-directives to different values for each virtual host.
-e.g.
-<blockquote><code>
-&lt;VirtualHost www.smallco.com&gt;<br>
-ServerAdmin webmaster@mail.smallco.com<br>
-DocumentRoot /groups/smallco/www<br>
-ServerName www.smallco.com<br>
-ErrorLog /groups/smallco/logs/error_log<br>
-TransferLog /groups/smallco/logs/access_log<br>
-&lt;/VirtualHost&gt;<br>
-<br>
-&lt;VirtualHost www.baygroup.org&gt;<br>
-ServerAdmin webmaster@mail.baygroup.org<br>
-DocumentRoot /groups/baygroup/www<br>
-ServerName www.baygroup.org<br>
-ErrorLog /groups/baygroup/logs/error_log<br>
-TransferLog /groups/baygroup/logs/access_log<br>
-&lt;/VirtualHost&gt;<br>
-</code></blockquote>
-
-This VirtualHost hostnames can also be given as IP addresses.
-
-<P>
-
-Almost <strong>ANY</strong> configuration directive can be put
-in the VirtualHost directive, with the exception of
-<A HREF="mod/core.html#servertype">ServerType</A>,
-<A HREF="mod/core.html#user">User</A>,
-<A HREF="mod/core.html#group">Group</A>,
-<A HREF="mod/core.html#startservers">StartServers</A>,
-<A HREF="mod/core.html#maxspareservers">MaxSpareServers</A>,
-<A HREF="mod/core.html#minspareservers">MinSpareServers</A>,
-<A HREF="mod/core.html#maxrequestsperchild">MaxRequestsPerChild</A>,
-<A HREF="mod/core.html#bindaddress">BindAddress</A>,
-<A HREF="mod/core.html#pidfile">PidFile</A>,
-<A HREF="mod/mod_mime.html#typesconfig">TypesConfig</A>, and
-<A HREF="mod/core.html#serverroot">ServerRoot</A>.
-
-<P>
-
-<EM>SECURITY:</EM> When specifying where to write log files, be aware
-of some security risks which are present if anyone other than the
-user that starts Apache has write access to the directory where they
-are written. See the <A HREF="misc/security_tips.html">security
-tips</A> document for details.
-
-<P>
-
-<H2>File Handle/Resource Limits:</H2>
-When using a large number of Virtual Hosts, Apache may run out of available
-file descriptors if each Virtual Host specifies different log files.
-The total number of file descriptors used by Apache is one for each distinct
-error log file, one for every other log file directive, plus 10-20 for
-internal use. Unix operating systems limit the number of file descriptors that
-may be used by a process; the limit is typically 64, and may usually be
-increased up to a large hard-limit.
-<p>
-Although Apache attempts to increase the limit as required, this
-may not work if:
-<ol>
-<li>Your system does not provide the setrlimit() system call.
-<li>The setrlimit(RLIMIT_NOFILE) call does not function on your system
- (such as Solaris 2.3)
-<li>The number of file descriptors required exceeds the hard limit.
-<li>Your system imposes other limits on file descriptors, such as a limit
-on stdio streams only using file descriptors below 256. (Solaris 2)
-</ol>
-
-In the event of problems you can:
-<ul>
-<li>Reduce the number of log files; don't specify log files in the VirtualHost
-sections, but only log to the main log files.
-<li>If you system falls into 1 or 2 (above), then increase the file descriptor
-limit before starting Apache, using a script like
-<blockquote><code>
-#!/bin/sh <br>
-ulimit -S -n 100 <br>
-exec httpd</code></blockquote>
-</ul>
-
-The have been reports that Apache may start running out of resources allocated
-for the root process. This will exhibit itself as errors in the error log like
-"unable to fork". There are two ways you can bump this up:
-
-<OL>
-<LI>Have a <code>csh</code> script wrapper around httpd which sets the
-"rlimit" to some large number, like 512.
-<LI>Edit http_main.c to add calls to setrlimit() from main(), along the lines of
-<PRE>
- struct rlimit rlp;
-
- rlp.rlim_cur = rlp.rlim_max = 512;
- if (setrlimit(RLIMIT_NPROC, &rlp)) {
- fprintf(stderr, "setrlimit(RLIMIT_NPROC) failed.\n");
- exit(1);
- }
-</PRE>
-(thanks to "Aaron Gifford &lt;agifford@InfoWest.COM&gt;" for the patch)
-</OL>
-
-The latter will probably manifest itself in a later version of Apache.
-
-<HR>
-<H3 ALIGN="CENTER">
- Apache HTTP Server Version 1.2
-</H3>
-
-<A HREF="./"><IMG SRC="images/index.gif" ALT="Index"></A>
-
-</body></html>
-