Apache Core Features

These are just a few parameters control the core Apache features.

Directives

BindAddress
DocumentRoot
Listen
NameVirtualHost
ServerAdmin
ServerAlias
ServerName
ServerPath
ServerRoot
<VirtualHost>

BindAddress directive

Syntax: BindAddress *|IP-address|domain-name
Default: BindAddress *
Context: server config
Status: core
Compatibility: BindAddress is deprecated and will be eliminated in Apache 2.0.

A Unix® http server can either listen for connections to every IP address of the server machine, or just one IP address of the server machine. If the argument to this directive is *, then the server will listen for connections on every IP address. Otherwise, the server can listen to only a specific IP-address or a fully-qualified Internet domain-name.

For example:

BindAddress 192.168.15.48

Only one BindAddress directive can be used.

This directive is deprecated and will be eliminated in Apache 2.0. Equivalent functionality and more control over the address and ports Apache listens to is available using the Listen directive.

BindAddress can be used as an alternative method for supporting virtual hosts using multiple independent servers, instead of using <VirtualHost> sections.

DocumentRoot directive

Syntax: DocumentRoot directory-path
Default: DocumentRoot /usr/local/apache/htdocs
Context: server config, virtual host
Status: core

This directive sets the directory from which httpd will serve files. Unless matched by a directive like Alias, the server appends the path from the requested URL to the document root to make the path to the document. Example:

DocumentRoot /usr/web

then an access to http://www.my.host.com/index.html refers to /usr/web/index.html.

There appears to be a bug in mod_dir which causes problems when the DocumentRoot has a trailing slash (i.e., "DocumentRoot /usr/web/") so please avoid that.

Listen directive

Syntax: Listen [IP-address:]port
Context: server config
Status: core
Compatibility: Listen is only available in Apache 1.1 and later.

The Listen directive instructs Apache to listen to more than one IP address or port; by default it responds to requests on all IP interfaces, but only on the port given by the Port directive.

Listen can be used instead of BindAddress and Port. It tells the server to accept incoming requests on the specified port or address-and-port combination. If the first format is used, with a port number only, the server listens to the given port on all interfaces, instead of the port given by the Port directive. If an IP address is given as well as a port, the server will listen on the given port and interface.

Note that you may still require a Port directive so that URLs that Apache generates that point to your server still work.

Multiple Listen directives may be used to specify a number of addresses and ports to listen to. The server will respond to requests from any of the listed addresses and ports.

For example, to make the server accept connections on both port 80 and port 8000, use:

  Listen 80
   Listen 8000

To make the server accept connections on two specified interfaces and port numbers, use
  Listen 192.170.2.1:80
   Listen 192.170.2.5:8000

 NameVirtualHost directive
 Syntax: NameVirtualHost addr[:port]
 Context: server config
 Status: core
 Compatibility: NameVirtualHost is only available in Apache 1.3 and later
The NameVirtualHost directive is a required directive if you want to configure name-based virtual hosts.
 Although addr can be hostname it is recommended that you always use an IP address or wildcard, e.g.
 NameVirtualHost 111.22.33.44 
With the NameVirtualHost directive you specify the IP address on which the server will receive requests for the name-based virtual hosts. This will usually be the address to which your name-based virtual host names resolve. In cases where a firewall or other proxy receives the requests and forwards them on a different IP address to the server, you must specify the IP address of the physical interface on the machine which will be servicing the requests. If you have multiple name-based hosts on multiple addresses, repeat the directive for each address.
Note: the "main server" and any _default_ servers will never be served for a request to a NameVirtualHost IP Address (unless for some reason you specify NameVirtualHost but then don't define any VirtualHosts for that address).
 Optionally you can specify a port number on which the name-based virtual hosts should be used, e.g.
 NameVirtualHost 111.22.33.44:8080 
In Apache 1.3.13 and greater you can specify a * for the addr. This creates a wildcard NameVirtualHost which will match connections to any address that isn't configured with a more specific NameVirtualHost directive or <VirtualHost> section. This is useful if you want only name-based virtual hosts and you don't want to hard-code the server's IP address into the configuration file.
 ServerAdmin directive
 Syntax: ServerAdmin email-address
 Context: server config, virtual host
 Status: core
The ServerAdmin sets the e-mail address that the server includes in any error messages it returns to the client.
 It may be worth setting up a dedicated address for this, e.g.
 ServerAdmin www-admin@foo.bar.com 
as users do not always mention that they are talking about the server!
 ServerAlias directive
 Syntax: ServerAlias hostname [hostname] ...
 Context: virtual host
 Status: core
 Compatibility: ServerAlias is only available in Apache 1.1 and later.
The ServerAlias directive sets the alternate names for a host, for use with name-based virtual hosts.
 Example:
  <VirtualHost *>
    ServerName server.domain.com
    ServerAlias server server2.domain.com server2
    ...
    </VirtualHost> 
 ServerName directive
 Syntax: ServerName fully-qualified-domain-name 
 Context: server config, virtual host
 Status: core
The ServerName directive sets the hostname of the server; this is used when creating redirection URLs. If it is not specified, then the server attempts to deduce it from its own IP address; however this may not work reliably, or may not return the preferred hostname. For example:
 ServerName www.example.com 
would be used if the canonical (main) name of the actual machine were simple.example.com.
If you are using name-based virtual hosts, the ServerName inside a <VirtualHost> section specifies what hostname must appear in the request's Host: header to match this virtual host.
 
 ServerPath directive
 Syntax: ServerPath directory-path
 Context: virtual host
 Status: core
 Compatibility: ServerPath is only available in Apache 1.1 and later.
The ServerPath directive sets the legacy URL pathname for a host, for use with name-based virtual hosts.
 
 ServerRoot directive
 Syntax: ServerRoot directory-path
 Default: ServerRoot /usr/local/apache
 Context: server config
 Status: core
The ServerRoot directive sets the directory in which the server lives. Typically it will contain the subdirectories conf/ and logs/. Relative paths for other configuration files are taken as relative to this directory.
 
 <VirtualHost> directive
 Syntax: <VirtualHost addr[:port] [addr[:port]] ...> ... </VirtualHost> 
 Context: server config
 Status: Core.
 Compatibility: Non-IP address-based Virtual Hosting only available in Apache 1.1 and later.
 Compatibility: Multiple address support only available in Apache 1.2 and later.
<VirtualHost> and </VirtualHost> are used to enclose a group of directives which will apply only to a particular virtual host. Any directive which is allowed in a virtual host context may be used. When the server receives a request for a document on a particular virtual host, it uses the configuration directives enclosed in the <VirtualHost> section. Addr can be
  The IP address of the virtual host
  
A fully qualified domain name for the IP address of the virtual host. 
 
Example:
<VirtualHost 10.1.2.3>

  ServerAdmin webmaster@host.foo.com

  DocumentRoot /www/docs/host.foo.com

  ServerName host.foo.com

  ErrorLog logs/host.foo.com-error_log

  TransferLog logs/host.foo.com-access_log

</VirtualHost> 
Each VirtualHost must correspond to a different IP address, different port number or a different host name for the server, in the former case the server machine must be configured to accept IP packets for multiple addresses. (If the machine does not have multiple network interfaces, then this can be accomplished with the ifconfig alias command (if your OS supports it), or with kernel patches like VIF (for SunOS(TM) 4.1.x)).
You can specify more than one IP address. This is useful if a machine responds to the same name on two different interfaces. For example, if you have a VirtualHost that is available to hosts on an internal (intranet) as well as external (internet) network. Example:
 <VirtualHost 192.168.1.2 204.255.176.199>

  DocumentRoot /www/docs/host.foo.com

  ServerName host.foo.com

  ServerAlias host

</VirtualHost> 
The special name _default_ can be specified in which case this virtual host will match any IP address that is not explicitly listed in another virtual host. In the absence of any _default_ virtual host the "main" server config, consisting of all those definitions outside any VirtualHost section, is used when no match occurs.
You can specify a :port to change the port that is matched. If unspecified then it defaults to the same port as the most recent Port statement of the main server. You may also specify :* to match all ports on that address. (This is recommended when used with _default_.)