www.company2.com) 。 虚拟主机可以“基于 IP”，即每个 IP 一个站点； 或者“基于名称”， 即每个 IP 多个站点。这些站点运行在同一物理服务器上的事实不会明显的透漏给最终用户。
Apache 是第一个支持基于 IP 的虚拟主机的服务器。 Apache 版本 1.1 和更新的版本同时支持基于 IP 和基于名称的虚拟主机。 基于名称的虚拟主机有时候称为基于主机或非 IP 的虚拟主机.
以下是在 Apache 1.3 以及更新版本中，解释支持虚拟主机的所有详细信息的文档页面列表。
- 基于名称的虚拟主机 (每个 IP 多个站点)
- 基于 IP 的虚拟主机 (每个 IP 一个站点)
- 文件句柄限制 (或者日志文件太多)
如果你要调试虚拟主机配置，你会发现 Apache 的命令行参数
这个命令将会显示 Apache 是如何解析配置文件的。仔细检查 IP 地址与服务器名称可能会帮助你发现配置错误 (参见
Name-based Virtual Host Support
This document describes when and how to use name-based virtual hosts.
Name-based vs. IP-based Virtual Hosts
IP-based virtual hosts use the IP address of the connection to determine the correct virtual host to serve. Therefore you need to have a separate IP address for each host. With name-based virtual hosting, the server relies on the client to report the hostname as part of the HTTP headers. Using this technique, many different hosts can share the same IP address.
Name-based virtual hosting is usually simpler, since you need only configure your DNS server to map each hostname to the correct IP address and then configure the Apache HTTP Server to recognize the different hostnames. Name-based virtual hosting also eases the demand for scarce IP addresses. Therefore you should use name-based virtual hosting unless you are using equipment that explicitly demands IP-based hosting. Historical reasons for IP-based virtual hosting based on client support are no longer applicable to a general-purpose web server, unless you are using a
mod_ssl version without SNI support (standard in Apache releases since 2.2.12).
Using Name-based Virtual Hosts
|Related Modules||Related Directives|
To use name-based virtual hosting, you must designate the IP address (and possibly port) on the server that will be accepting requests for the hosts. This is configured using the
NameVirtualHost directive. In the normal case where any and all IP addresses on the server should be used, you can use
* as the argument to
NameVirtualHost. If you're planning to use multiple ports (e.g. running SSL) you should add a Port to the argument, such as
*:80. Note that mentioning an IP address in a
NameVirtualHost directive does not automatically make the server listen to that IP address. See Setting which addresses and ports Apache uses for more details. In addition, any IP address specified here must be associated with a network interface on the server.
The next step is to create a
block for each different host that you would like to serve. The argument to the
directive must match a defined
NameVirtualHost directive. (In this usual case, this will be "*:80"). Inside each
block, you will need at minimum a
ServerName directive to designate which host is served and a
DocumentRoot directive to show where in the filesystem the content for that host lives.
Main host goes away
If you are adding virtual hosts to an existing web server, you must also create a
block for the existing host. The
DocumentRoot included in this virtual host should be the same as the global
DocumentRoot. List this virtual host first in the configuration file so that it will act as the default host.
For example, suppose that you are serving the domain
www.domain.tld and you wish to add the virtual host
www.otherdomain.tld, which points at the same IP address. Then you simply add the following to
ServerAlias domain.tld *.domain.tld
You can alternatively specify an explicit IP address in place of the
* in both the
directives. For example, you might want to do this in order to run some name-based virtual hosts on one IP address, and either IP-based, or another set of name-based virtual hosts on another address.
Many servers want to be accessible by more than one name. This is possible with the
ServerAlias directive, placed inside the
section. For example in the first
block above, the
ServerAlias directive indicates that the listed names are other names which people can use to see that same web site:
ServerAlias domain.tld *.domain.tld
then requests for all hosts in the
domain.tld domain will be served by the
www.domain.tld virtual host. The wildcard characters
? can be used to match names. Of course, you can't just make up names and place them in
ServerAlias. You must first have your DNS server properly configured to map those names to an IP address associated with your server.
The complete list of names in the
VirtualHost directive are treated just like a (non wildcard)
Finally, you can fine-tune the configuration of the virtual hosts by placing other directives inside the
containers. Most directives can be placed in these containers and will then change the configuration only of the relevant virtual host. To find out if a particular directive is allowed, check the Context of the directive. Configuration directives set in the main server context (outside any
container) will be used only if they are not overridden by the virtual host settings.
Now when a request arrives, the server will first check if it is using an IP address that matches the
NameVirtualHost. If it is, then it will look at each
section with a matching IP address and try to find one where the
ServerAlias matches the requested hostname. If it finds one, then it uses the configuration for that server. If no matching virtual host is found, then the first listed virtual host that matches the IP address will be used.
As a consequence, the first listed virtual host is the default virtual host. The
DocumentRoot from the main server will never be used when an IP address matches the
NameVirtualHost directive. If you would like to have a special configuration for requests that do not match any particular virtual host, simply put that configuration in a
container and list it first in the configuration file.
Compatibility with Older Browsers
As mentioned earlier, there are some clients who do not send the required data for the name-based virtual hosts to work properly. These clients will always be sent the pages from the first virtual host listed for that IP address (the primary name-based virtual host).
How much older?
Please note that when we say older, we really do mean older. You are very unlikely to encounter one of these browsers in use today. All current versions of any browser send the
Host header as required for name-based virtual hosts.
There is a possible workaround with the
ServerPath directive, albeit a slightly cumbersome one:
What does this mean? It means that a request for any URI beginning with "
/domain" will be served from the virtual host
www.domain.tld. This means that the pages can be accessed as
http://www.domain.tld/domain/ for all clients, although clients sending a
Host: header can also access it as
In order to make this work, put a link on your primary virtual host's page to
http://www.domain.tld/domain/. Then, in the virtual host's pages, be sure to use either purely relative links (e.g., "
file.html" or "
../icons/image.gif") or links containing the prefacing
/domain/ (e.g., "
http://www.domain.tld/domain/misc/file.html" or "
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.