### Apache HTTP Server Version 1.3

# Virtual Host examples for common setups

## Base configuration

- IP-based vhosts only
- Name-based vhosts only
- Mixed name-/IP-based vhosts
- Port-based vhosts

## Additional features

- Using `_default_` vhosts
- Migrating a named-based vhost to an IP-based vhost
- Using the `ServerPath` directive

### IP-based vhosts only

- Setup 1: The server machine has two IP addresses (`111.22.33.44` and `111.22.33.55`) which resolve to the names `server.domain.tld` and `www.otherdomain.tld` respectively. The hostname `www.domain.tld` is an alias (CNAME) for `server.domain.tld` and will represent the main server.

  Server configuration:

  >         ...
  >         Port 80
  >         DocumentRoot /www/domain
  >         ServerName www.domain.tld

  >         <VirtualHost 111.22.33.55>
  >         DocumentRoot /www/otherdomain
  >         ServerName www.otherdomain.tld
  >         ...
  >         </VirtualHost>

  > `www.otherdomain.tld` can only be reached through the address `111.22.33.55`, while `www.domain.tld` can only be reached through `111.22.33.44` (which represents our main server).

- Setup 2: Same as setup 1, but we don't want to have a dedicated main server.

  Server configuration:

  >         ...
  >         Port 80
  >         ServerName server.domain.tld

  >         <VirtualHost 111.22.33.44>
  >         DocumentRoot /www/domain
  >         ServerName www.domain.tld
  >         ...
  >         </VirtualHost>

  >         <VirtualHost 111.22.33.55>
  >         DocumentRoot /www/otherdomain
  >         ServerName www.otherdomain.tld
  >         ...
  >         </VirtualHost>

  > The main server can never catch a request, because all IP addresses of our machine are in use for IP-based virtual hosts (only `localhost` requests can hit the main server).

- Setup 3: The server machine has two IP addresses (`111.22.33.44` and `111.22.33.55`) which resolve to the names `server.domain.tld` and `www-cache.domain.tld` respectively. The hostname `www.domain.tld` is an alias (CNAME) for `server.domain.tld` and will represent the main server. `www-cache.domain.tld` will become our proxy-cache listening on port 8080, while the web server itself uses the default port 80.

  Server configuration:

  >         ...
  >         Port 80
  >         Listen 111.22.33.44:80
  >         Listen 111.22.33.55:8080
  >         ServerName server.domain.tld

  >         <VirtualHost 111.22.33.44:80>
  >         DocumentRoot /www/domain
  >         ServerName www.domain.tld
  >         ...
  >         </VirtualHost>

  >         <VirtualHost 111.22.33.55:8080>
  >         ServerName www-cache.domain.tld
  >         ...
  >           <Directory proxy:>
  >           order deny,allow
  >           deny from all
  >           allow from 111.22.33
  >           </Directory>
  >         </VirtualHost>

  > The main server can never catch a request, because all IP addresses (apart from `localhost`) of our machine are in use for IP-based virtual hosts. The web server can only be reached on the first address through port 80 and the proxy only on the second address through port 8080.

### Name-based vhosts only

- Setup 1: The server machine has one IP address (`111.22.33.44`) which resolves to the name `server.domain.tld`. There are two aliases (CNAMEs) `www.domain.tld` and `www.sub.domain.tld` for the address `111.22.33.44`.

  Server configuration:

  >         ...
  >         Port 80
  >         ServerName server.domain.tld

  >         NameVirtualHost 111.22.33.44

  >         <VirtualHost 111.22.33.44>
  >         DocumentRoot /www/domain
  >         ServerName www.domain.tld
  >         ...
  >         </VirtualHost>

  >         <VirtualHost 111.22.33.44>
  >         DocumentRoot /www/subdomain
  >         ServerName www.sub.domain.tld
  >         ...
  >         </VirtualHost>

  > Apart from `localhost` there are no unspecified addresses/ports, therefore the main server only serves `localhost` requests. Due to the fact that `www.domain.tld` has the highest priority it can be seen as the default or primary server.

- Setup 2: The server machine has two IP addresses (`111.22.33.44` and `111.22.33.55`) which resolve to the names `server1.domain.tld` and `server2.domain.tld` respectively. The alias `www.domain.tld` should be used for the main server which should also catch any unspecified addresses. We want to use a virtual host for the alias `www.otherdomain.tld` and one virtual host should catch any request to hostnames of the form `*.sub.domain.tld` with `www.sub.domain.tld` as its server name. The address `111.22.33.55` should be used for the virtual hosts.

  Server configuration:

  >         ...
  >         Port 80
  >         ServerName www.domain.tld
  >         DocumentRoot /www/domain

  >         NameVirtualHost 111.22.33.55

  >         <VirtualHost 111.22.33.55>
  >         DocumentRoot /www/otherdomain
  >         ServerName www.otherdomain.tld
  >         ...
  >         </VirtualHost>

  >         <VirtualHost 111.22.33.55>
  >         DocumentRoot /www/subdomain
  >         ServerName www.sub.domain.tld
  >         ServerAlias *.sub.domain.tld
  >         ...
  >         </VirtualHost>

  > Any request to an address other than `111.22.33.55` will be served from the main server. A request to `111.22.33.55` with an unknown or no `Host:` header will be served from `www.otherdomain.tld`.

### Mixed name-/IP-based vhosts

- Setup: The server machine has three IP addresses (`111.22.33.44`, `111.22.33.55` and `111.22.33.66`) which resolve to the names `server.domain.tld`, `www.otherdomain1.tld` and `www.otherdomain2.tld` respectively. The address `111.22.33.44` should we used for a couple of name-based vhosts and the other addresses for IP-based vhosts.

  Server configuration:

  >         ...
  >         Port 80
  >         ServerName server.domain.tld

  >         NameVirtualHost 111.22.33.44

  >         <VirtualHost 111.22.33.44>
  >         DocumentRoot /www/domain
  >         ServerName www.domain.tld
  >         ...
  >         </VirtualHost>

  >         <VirtualHost 111.22.33.44>
  >         DocumentRoot /www/subdomain1
  >         ServerName www.sub1.domain.tld
  >         ...
  >         </VirtualHost>

  >         <VirtualHost 111.22.33.44>
  >         DocumentRoot /www/subdomain2
  >         ServerName www.sub2.domain.tld
  >         ...
  >         </VirtualHost>

  >         <VirtualHost 111.22.33.55>
  >         DocumentRoot /www/otherdomain1
  >         ServerName www.otherdomain1.tld
  >         ...
  >         </VirtualHost>

  >         <VirtualHost 111.22.33.66>
  >         DocumentRoot /www/otherdomain2
  >         ServerName www.otherdomain2.tld
  >         ...
  >         </VirtualHost>

### Port-based vhosts

- Setup: The server machine has one IP address (`111.22.33.44`) which resolves to the name `www.domain.tld`. If we don't have the option to get another address or alias for our server we can use port-based vhosts if we need a virtual host with a different configuration.

  Server configuration:

  >         ...
  >         Listen 80
  >         Listen 8080
  >         ServerName www.domain.tld
  >         DocumentRoot /www/domain

  >         <VirtualHost 111.22.33.44:8080>
  >         DocumentRoot /www/domain2
  >         ...
  >         </VirtualHost>

  > A request to `www.domain.tld` on port 80 is served from the main server and a request to port 8080 is served from the virtual host.

### Using `_default_` vhosts

- Setup 1: Catching every request to any unspecified IP address and port, i.e., an address/port combination that is not used for any other virtual host.

  Server configuration:

  >         ...
  >         <VirtualHost _default_:*>
  >         DocumentRoot /www/default
  >         ...
  >         </VirtualHost>

  > Using such a default vhost with a wildcard port effectively prevents any request going to the main server.
  > A default vhost never serves a request that was sent to an address/port that is used for name-based vhosts. If the request contained an unknown or no `Host:` header it is always served from the primary name-based vhost (the vhost for that address/port appearing first in the configuration file).
  > You can use `AliasMatch` or `RewriteRule` to rewrite any request to a single information page (or script).

- Setup 2: Same as setup 1, but the server listens on several ports and we want to use a second `_default_` vhost for port 80.

  Server configuration:

  >         ...
  >         <VirtualHost _default_:80>
  >         DocumentRoot /www/default80
  >         ...
  >         </VirtualHost>

  >         <VirtualHost _default_:*>
  >         DocumentRoot /www/default
  >         ...
  >         </VirtualHost>

  > The default vhost for port 80 (which must appear before any default vhost with a wildcard port) catches all requests that were sent to an unspecified IP address. The main server is never used to serve a request.

- Setup 3: We want to have a default vhost for port 80, but no other default vhosts.

  Server configuration:

  >         ...
  >         <VirtualHost _default_:80>
  >         DocumentRoot /www/default
  >         ...
  >         </VirtualHost>

  > A request to an unspecified address on port 80 is served from the default vhost any other request to an unspecified address and port is served from the main server.

### Migrating a name-based vhost to an IP-based vhost

- Setup: The name-based vhost with the hostname `www.otherdomain.tld` (from our name-based example, setup 2) should get its own IP address. To avoid problems with name servers or proxies who cached the old IP address for the name-based vhost we want to provide both variants during a migration phase.
  The solution is easy, because we can simply add the new IP address (`111.22.33.66`) to the `VirtualHost` directive.

  Server configuration:

  >         ...
  >         Port 80
  >         ServerName www.domain.tld
  >         DocumentRoot /www/domain

  >         NameVirtualHost 111.22.33.55

  >         <VirtualHost 111.22.33.55 111.22.33.66>
  >         DocumentRoot /www/otherdomain
  >         ServerName www.otherdomain.tld
  >         ...
  >         </VirtualHost>

  >         <VirtualHost 111.22.33.55>
  >         DocumentRoot /www/subdomain
  >         ServerName www.sub.domain.tld
  >         ServerAlias *.sub.domain.tld
  >         ...
  >         </VirtualHost>

  > The vhost can now be accessed through the new address (as an IP-based vhost) and through the old address (as a name-based vhost).

### Using the `ServerPath` directive

- Setup: We have a server with two name-based vhosts. In order to match the correct virtual host a client must send the correct `Host:` header. Old HTTP/1.0 clients do not send such a header and Apache has no clue what vhost the client tried to reach (and serves the request from the primary vhost). To provide as much backward compatibility as possible we create a primary vhost which returns a single page containing links with an URL prefix to the name-based virtual hosts.

  Server configuration:

  >         ...
  >         NameVirtualHost 111.22.33.44

  >         <VirtualHost 111.22.33.44>
  >         # primary vhost
  >         DocumentRoot /www/subdomain
  >         RewriteEngine On
  >         RewriteRule ^/.* /www/subdomain/index.html
  >         ...
  >         </VirtualHost>

  >         <VirtualHost 111.22.33.44>
  >         DocumentRoot /www/subdomain/sub1
  >         ServerName www.sub1.domain.tld
  >         ServerPath /sub1/
  >         RewriteEngine On
  >         RewriteRule ^(/sub1/.*) /www/subdomain$1
  >         ...
  >         </VirtualHost>

  >         <VirtualHost 111.22.33.44>
  >         DocumentRoot /www/subdomain/sub2
  >         ServerName www.sub2.domain.tld
  >         ServerPath /sub2/
  >         RewriteEngine On
  >         RewriteRule ^(/sub2/.*) /www/subdomain$1
  >         ...
  >         </VirtualHost>

  > Due to the `ServerPath` directive a request to the URL `http://www.sub1.domain.tld/sub1/` is always served from the sub1-vhost.
  > A request to the URL `http://www.sub1.domain.tld/` is only served from the sub1-vhost if the client sent a correct `Host:` header. If no `Host:` header is sent the client gets the information page from the primary host.
  > Please note that there is one oddity: A request to `http://www.sub2.domain.tld/sub1/` is also served from the sub1-vhost if the client sent no `Host:` header.
  > The `RewriteRule` directives are used to make sure that a client which sent a correct `Host:` header can use both URL variants, i.e., with or without URL prefix.

### Apache HTTP Server Version 1.3