Command Center: Apache HTTP Server Version 1.3 Virtual Host examples

Monday, April 12, 2010

Apache HTTP Server Version 1.3 Virtual Host examples

Category: Apache — SkyHi @ Monday, April 12, 2010

Base configuration

Additional features

Simple name-based vhosting

Compatibility: This syntax was added in Apache 1.3.13.
Setup: The server machine has a primary name server.domain.tld. There are two aliases (CNAMEs) www.domain.tld and www.sub.domain.tld for the address server.domain.tld. Server configuration:
```
...
    Port 80
    ServerName server.domain.tld

    NameVirtualHost *:80

    
    DocumentRoot /www/domain
    ServerName www.domain.tld
    ...
    
    
    
    DocumentRoot /www/subdomain
    ServerName www.sub.domain.tld
    ...
     
   
```
The asterisks match all addresses, so the main server serves no requests. Due to the fact that www.domain.tld is first in the configuration file, it has the highest priority and can be seen as the default or primary server.

More complicated name-based vhosts

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 

    
    DocumentRoot /www/domain
    ServerName www.domain.tld
    ...
    
    
    
    DocumentRoot /www/subdomain
    ServerName www.sub.domain.tld
    ...
     
   
```
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 another virtual host, with server name www.sub.domain.tld, should catch any request to hostnames of the form *.sub.domain.tld. 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

    
    DocumentRoot /www/otherdomain
    ServerName www.otherdomain.tld
    ...
    
   
    
    DocumentRoot /www/subdomain
    ServerName www.sub.domain.tld
    ServerAlias *.sub.domain.tld
    ...
     
   
```
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.
Setup 3: The server machine has two IP addresses (192.168.1.1 and 111.22.33.55). The machine is sitting between an internal (intranet) network and an external (internet) network. Outside of the network, the name server1.domain.tld resolves to the external address (111.22.33.55), but inside the network, that same name resolves to the internal address (192.168.1.1). The server can be made to respond to internal and external requests with the same content, with just one VirtualHost section.
Server configuration:
```
...
    NameVirtualHost 192.168.1.1
    NameVirtualHost 111.22.33.55

    
    DocumentRoot /www/server1
    ServerName server1.domain.tld
    ServerAlias server1
    ...
    
   
```
Now requests from both networks will be served from the same VirtualHost

Setup 4: You have multiple domains going to the same IP and also want to serve multiple ports. By defining the ports in the "NameVirtualHost" tag, you can allow this to work. If you try using without the NameVirtualHost name:port or you try to use the Port directive, your configuration will not work. Server configuration:

...   
    NameVirtualHost 111.22.33.44:80
    NameVirtualHost 111.22.33.44:8080

    
    ServerName www.domain.tld
    DocumentRoot /www/domain-80
    

    
    ServerName www.domain.tld
    DocumentRoot /www/domain-8080
    

    
    ServerName www.otherdomain.tld
    DocumentRoot /www/otherdomain-80
    

    
    ServerName www.otherdomain.tld
    DocumentRoot /www/otherdomain-8080

IP-based vhosts

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

    
    DocumentRoot /www/otherdomain
    ServerName www.otherdomain.tld
    ...
    
   
```
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
    
    
    DocumentRoot /www/domain
    ServerName www.domain.tld
    ...
    

    
    DocumentRoot /www/otherdomain
    ServerName www.otherdomain.tld
    ...
    
   
```
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
    
    
    DocumentRoot /www/domain
    ServerName www.domain.tld
    ...
    

    
    ServerName www-cache.domain.tld
    ...
      
      Order Deny,Allow
      Deny from all
      Allow from 111.22.33
      
    
   
```
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.

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 be 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

    
    DocumentRoot /www/domain
    ServerName www.domain.tld
    ...
    
   
    
    DocumentRoot /www/subdomain1
    ServerName www.sub1.domain.tld
    ...
     
    
    
    DocumentRoot /www/subdomain2
    ServerName www.sub2.domain.tld
    ...
     
 
    
    DocumentRoot /www/otherdomain1
    ServerName www.otherdomain1.tld
    ...
     
    
    
    DocumentRoot /www/otherdomain2
    ServerName www.otherdomain2.tld
    ...

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

    
    DocumentRoot /www/domain2
    ...
    
   
```
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:
```
...
    
    DocumentRoot /www/default
    ...
    
   
```
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:
```
...
    
    DocumentRoot /www/default80
    ...
    
    
    
    DocumentRoot /www/default
    ...
        
   
```
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:
```
...
    
    DocumentRoot /www/default
    ...
    
   
```
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

    
    DocumentRoot /www/otherdomain
    ServerName www.otherdomain.tld
    ...
    
   
    
    DocumentRoot /www/subdomain
    ServerName www.sub.domain.tld
    ServerAlias *.sub.domain.tld
    ...
    
   
```
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

    
    # primary vhost
    DocumentRoot /www/subdomain
    RewriteEngine On
    RewriteRule ^/.* /www/subdomain/index.html
    ...
    

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

    
    DocumentRoot /www/subdomain/sub2
    ServerName www.sub2.domain.tld
    ServerPath /sub2/
    RewriteEngine On
    RewriteRule ^(/sub2/.*) /www/subdomain$1 
    ...
    
   
```
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.

REFERENCE
http://httpd.apache.org/docs/1.3/vhosts/examples.html

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