Using Name-based Virtual Hosts

Doc sau giúp:

- ĐN name-based.

- Virtual host

- Default Virtual host -> tạo Dummy host

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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. (NameVirtualHost * will work only in version 1.3.13 and later.) 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 <VirtualHost> block for each different host that you would like to serve. The argument to the <VirtualHost> directive should be the same as the argument to the NameVirtualHost directive (ie, an IP address, or * for all addresses). Inside each <VirtualHost> 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.

If you are adding virtual hosts to an existing web server, you must also create a <VirtualHost> block for the existing host. The ServerName and DocumentRoot included in this virtual host should be the same as the global ServerName and 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 httpd.conf:

    NameVirtualHost *

    <VirtualHost *>
    ServerName www.domain.tld
    DocumentRoot /www/domain
    </VirtualHost>

    <VirtualHost *>
    ServerName www.otherdomain.tld
    DocumentRoot /www/otherdomain
    </VirtualHost>

You can alternatively specify an explicit IP address in place of the * in both the NameVirtualHost and <VirtualHost> directives. The IP address is required in version 1.3.12 and earlier.

Many servers want to be accessible by more than one name. This is possible with the ServerAlias directive, placed inside the <VirtualHost> section. For example if you add this to the first <VirtualHost> block above

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 * and ? can be used to match names. Of course, you can’t just make up names and place them in ServerName or ServerAlias. You must first have your DNS server properly configured to map those names to an IP address associated with your server.

Finally, you can fine-tune the configuration of the virtual hosts by placing other directives inside the <VirtualHost> 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 <VirtualHost> container) will be used only if they are not overriden 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 <VirtualHost> section with a matching IP address and try to find one where the ServerName or 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 <VirtualHost> container and list it first in the configuration file.

http://httpd.apache.org/docs/1.3/vhosts/name-based.html

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