Virtual Host Directives

NameVirtualHost

Description Nominates an IP address as using name based virtual hosting
Synopsis NameVirtualHost IPaddr[:port]
Context Default Server
Example NameVirtualHost 206.148.97.56
<VirtualHost 206.148.97.56>
...
</VirtualHost>
Notes

The NameVirtualHost directive specifies that an IP address will be used for name based virtual hosting. Appweb provides two virtual hosting mechanisms:

  • IP based
  • Name based

IP based virtual hosting uses a dedicated IP address for each virtual host on a server. Name based hosting uses one IP address for a set of virtual hosts that are distinguished from each other by a "Host" HTTP header.

The IPAddress argument may be "*" in which case addresses on which Appweb is listening will use name based virtual hosting.

Example of Name Based Virtual Hosting

This example shows two virtual hosts with independent document webs. Both share the same IP address and use the "Host" HTTP header to select the appropriate virtual host.

NameVirtualHost 206.148.97.56
<VirtualHost 206.148.97.56>
    ServerName www.acme.com
    DocumentRoot /var/www/acme
    ...
</VirtualHost>
<VirtualHost 206.148.97.56>
    ServerName www.coyote.com
    DocumentRoot /var/www/coyote
    ...
</VirtualHost>

Example of IP Based Virtual Hosting

This example shows two virtual hosts with independent document webs. Each has a dedicated IP address.

<VirtualHost 206.148.97.56>
    ServerName www.acme.com
    DocumentRoot /var/www/acme
    ...
</VirtualHost>
<VirtualHost 206.148.97.57>
    ServerName www.coyote.com
    DocumentRoot /var/www/coyote
    ...
</VirtualHost>

You can use both IP based and name based hosting on one server.

Security

You should only ever use an IP address for the argument to the directive. Using a host name will cause a DNS lookup which makes the availability of your web server dependent on the DNS server.

VirtualHost

Description Create a new directive block that applies to a specific IP address. The VirtualHost block inherits the existing configuration at the point of the opening VirtualHost directive.
Synopsis <VirtualHost IPaddress[:port] [, IPaddress[:port]]...>
...
</VirtualHost>
Context Default Server
Example
<VirtualHost 206.148.97.56:443>
    ServerName www.acme.com
    DocumentRoot /var/www/acme
    SSLEngine on
    ....
</VirtualHost>
Notes

The VirutalHost directive defines a block of directives that will apply to the nominated IP addresses. The IPaddresses specifies the set of IP addresses for this VirtualHost. Note: this does not cause Appweb to listen on these addresses. You will still need an appropriate Listen directive for each IP address. The IPaddress can be set to "*" in which case the VirtualHost will listen on all interfaces.

If the IPaddress is also specified in a NameVirtualHost directive, the virtual host will use name based hosting. This requires the browser (as nearly all modern browsers do), to include the domain portion of the URL in the HTTP host header. Appweb examines this header and routes the request to the Virtual Host that has a corresponding ServerName

NOTE: Unlike Apache, only one IPaddress may be specified per VirtualHost directive.

The ServerName may being with a "*" which means match any hosts that contains the following host name. For example "*.embedthis.com" will then match blog.embedthis.com and www.embedthis.com.

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