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openSUSE 11.1 Reference Guide
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28.2 Configuring Apache

Apache in openSUSE can be configured in two different ways: with YaST or manually. Manual configuration offers a higher level of detail, but lacks the convenience of the YaST GUI.

IMPORTANT: Configuration Changes

Changes to most configuration values for Apache only take effect after Apache is restarted or reloaded. This happens automatically when using YaST and finishing the configuration with Enabled checked for the HTTP Service. Manual restart is described in Section 28.3, Starting and Stopping Apache. Most configuration changes only require a reload with rcapache2 reload.

28.2.1 Configuring Apache Manually

Configuring Apache manually involves editing the plain text configuration files as the user root.

Configuration Files

Apache configuration files can be found in two different locations:

  • /etc/sysconfig/apache2

  • /etc/apache2/

/etc/sysconfig/apache2

/etc/sysconfig/apache2 controls some global settings of Apache, like modules to load, additional configuration files to include, flags with which the server should be started, and flags that should be added to the command line. Every configuration option in this file is extensively documented and therefore not mentioned here. For a general-purpose Web server, the settings in /etc/sysconfig/apache2 should be sufficient for any configuration needs.

/etc/apache2/

/etc/apache2/ hosts all configuration files for Apache. In the following, the purpose of each file is explained. Each file includes several configuration options (also referred to as directives). Every configuration option in these files is extensively documented and therefore not mentioned here.

The Apache configuration files are organized as follows:

/etc/apache2/
 |
 |- charset.conv 
 |- conf.d/
 |   |
 |   |- *.conf
 |
 |- default-server.conf
 |- errors.conf
 |- httpd.conf
 |- listen.conf
 |- magic
 |- mime.types
 |- mod_*.conf
 |- server-tuning.conf
 |- ssl.*
 |- ssl-global.conf
 |- sysconfig.d
 |   |
 |   |- global.conf
 |   |- include.conf
 |   |- loadmodule.conf . .
 |
 |- uid.conf
 |- vhosts.d
 |   |- *.conf
Apache Configuration Files in /etc/apache2/
charset.conv

Specifies which character sets to use for different languages. Do not edit.

conf.d/*.conf

Configuration files added by other modules. These configuration files can be included into your virtual host configuration where needed. See vhosts.d/vhost.template for examples. By doing so, you can provide different module sets for different virtual hosts.

default-server.conf

Global configuration for all virtual hosts with reasonable defaults. Instead of changing the values, overwrite them with a virtual host configuration.

errors.conf

Defines how Apache responds to errors. To customize these messages for all virtual hosts, edit this file. Otherwise overwrite these directives in your virtual host configurations.

httpd.conf

The main Apache server configuration file. Avoid changing this file. It mainly contains include statements and global settings. Overwrite global settings in the respective configuration files listed here. Change host-specific settings (such as document root) in your virtual host configuration.

listen.conf

Binds Apache to specific IP addresses and ports. Name-based virtual hosting (see Name-Based Virtual Hosts is also configured here.

magic

Data for the mime_magic module that helps Apache automatically determine the MIME type of an unknown file. Do not change.

mime.types

MIME types known by the system (this actually is a link to /etc/mime.types). Do not edit. If you need to add MIME types not listed here, add them to mod_mime-defaults.conf.

mod_*.conf

Configuration files for the modules that are installed by default. Refer to Section 28.4, Installing, Activating, and Configuring Modules for details. Note that configuration files for optional modules reside in the directory conf.d.

server-tuning.conf

Contains configuration directives for the different MPMs (see Section 28.4.4, Multiprocessing Modules) as well as general configuration options that control Apache's performance. Properly test your Web server when making changes here.

ssl-global.conf and ssl.*

Global SSL configuration and SSL certificate data. Refer to Section 28.6, Setting Up a Secure Web Server with SSL for details.

sysconfig.d/*.conf

Configuration files automatically generated from /etc/sysconfig/apache2. Do not change any of these files—edit /etc/sysconfig/apache2 instead. Put no other configuration files in this directory.

uid.conf

Specifies under which user and group ID Apache runs. Do not change.

vhosts.d/*.conf

Your virtual host configuration should go here.The directory contains template files for virtual hosts with and without SSL. Every file in this directory ending in .conf is automatically included in the Apache configuration. Refer to Virtual Host Configuration for details.

Virtual Host Configuration

The term virtual host refers to Apache's ability to serve multiple URIs (universal resource identifiers) from the same physical machine. This means that several domains, such as www.example.com and www.example.net, are run by a single Web server on one physical machine.

It is common practice to use virtual hosts to save administrative effort (only a single Web server needs to be maintained) and hardware expenses (each domain does not require a dedicated server). Virtual hosts can be name based, IP based, or port based.

To list all existing virtual hosts, use the command httpd2 -S. It outputs a list showing the default server and all virtual hosts together with their IP addresses and listening ports. Furthermore, the list also contains an entry for each virtual host showing its location in the configuration files.

Virtual hosts can be configured via YaST (see Virtual Hosts) or by manually editing a configuration file. By default, Apache in openSUSE is prepared for one configuration file per virtual host in /etc/apache2/vhosts.d/. All files in this directory with the extension .conf are automatically included to the configuration. A basic template for a virtual host is provided in this directory (vhost.template or vhost-ssl.template for a virtual host with SSL support).

HINT: Always Create a Virtual Host Configuration

It is recommended to always create a virtual host configuration file, even if your Web server only hosts one domain. In doing so, you not only have the domain-specific configuration in one file, but you can always fall back to a working basic configuration by simply moving, deleting, or renaming the configuration file for the virtual host. For the same reason, you should also create separate configuration files for each virtual host.

The <VirtualHost></VirtualHost> block holds the information that applies to a particular domain. When Apache receives a client request for a defined virtual host, it uses the directives enclosed in this section. Almost all directives can be used in a virtual host context. See http://httpd.apache.org/docs/2.2/mod/quickreference.html for further information about Apache's configuration directives.

Name-Based Virtual Hosts

With name-based virtual hosts, more than one Web site is served per IP address. Apache uses the host field in the HTTP header sent by the client to connect the request to a matching ServerName entry of one of the virtual host declarations. If no matching ServerName is found, the first specified virtual host is used as a default.

The directive NameVirtualHost tells Apache on which IP address and, optionally, which port to listen for requests by clients containing the domain name in the HTTP header. This option is configured in the configuration file /etc/apache2/listen.conf.

The first argument can be a fully qualified domain name, but it is recommended to use the IP address. The second argument is the port and is optional. By default, port 80 is used and is configured via the Listen directive.

The wild card * can be used for both the IP address and the port number to receive requests on all interfaces. IPv6 addresses must be enclosed in square brackets.

Example 28-1 Variations of Name-Based VirtualHost Entries

# NameVirtualHost IP-address[:Port]
NameVirtualHost 192.168.3.100:80
NameVirtualHost 192.168.3.100
NameVirtualHost *:80
NameVirtualHost *
NameVirtualHost [2002:c0a8:364::]:80

The opening VirtualHost tag takes the IP address (or fully qualified domain name) previously declared with the NameVirtualHost as an argument in a name-based virtual host configuration. A port number previously declared with the NameVirtualHost directive is optional.

The wild card * is also allowed as a substitute for the IP address. This syntax is only valid in combination with the wild card usage in NameVirtualHost * . When using IPv6 addresses, the address must be included in square brackets.

Example 28-2 Name-Based VirtualHost Directives

<VirtualHost 192.168.3.100:80>
  ...
</VirtualHost>

<VirtualHost 192.168.3.100>
  ...
</VirtualHost>

<VirtualHost *:80>
  ...
</VirtualHost>

<VirtualHost *>
  ...
</VirtualHost>

<VirtualHost [2002:c0a8:364::]>
  ...
</VirtualHost>
IP-Based Virtual Hosts

This alternative virtual host configuration requires the setup of multiple IPs for a machine. One instance of Apache hosts several domains, each of which is assigned a different IP.

The physical server must have one IP address for each IP-based virtual host. If the machine does not have multiple network cards, virtual network interfaces (IP aliasing) can also be used.

The following example shows Apache running on a machine with the IP 192.168.3.100, hosting two domains on the additional IPs 192.168.3.101 and 192.168.3.102. A separate VirtualHost block is needed for every virtual server.

Example 28-3 IP-Based VirtualHost Directives

<VirtualHost 192.168.3.101>
  ...
</VirtualHost>

<VirtualHost 192.168.3.102>
  ...
</VirtualHost>

Here, VirtualHost directives are only specified for interfaces other than 192.168.3.100. When a Listen directive is also configured for 192.168.3.100, a separate IP-based virtual host must be created to answer HTTP requests to that interface—otherwise the directives found in the default server configuration (/etc/apache2/default-server.conf) are applied.

Basic Virtual Host Configuration

At least the following directives should be present in each virtual host configuration in order to set up a virtual host. See /etc/apache2/vhosts.d/vhost.template for more options.

ServerName

The fully qualified domain name under which the host should be addressed.

DocumentRoot

Path to the directory from which Apache should serve files for this host. For security reasons, access to the entire file system is forbidden by default, so you must explicitly unlock this directory within a Directory container.

ServerAdmin

E-mail address of the server administrator. This address is, for example, shown on error pages Apache creates.

ErrorLog

The error log file for this virtual host. Although it is not necessary to create separate error log files for each virtual host, it is common practice to do so, because it makes debugging of errors much easier. /var/log/apache2/ is the default directory where Apache's log files should be kept.

CustomLog

The access log file for this virtual host. Although it is not necessary to create separate access log files for each virtual host, it is common practice to do so, because it allows separate analysis of access statistics for each host. /var/log/apache2/ is the default directory where Apache's log files should be kept.

As mentioned above, access to the whole file system is forbidden by default for security reasons. Therefore, explicitly unlock the directories in which you have placed the files Apache should serve—for example the DocumentRoot:

<Directory "/srv/www/www.example.com/htdocs">
  Order allow,deny
  Allow from all
</Directory>

The complete configuration file looks like this:

Example 28-4 Basic VirtualHost Configuration

<VirtualHost 192.168.3.100>
  ServerName www.example.com;
  DocumentRoot /srv/www/www.example.com/htdocs
  ServerAdmin webmaster@example.com
  ErrorLog /var/log/apache2/www.example.com_log
  CustomLog /var/log/apache2/www.example.com-access_log common
  <Directory "/srv/www/www.example.com/htdocs">
    Order allow,deny
    Allow from all
  </Directory>
</VirtualHost>

28.2.2 Configuring Apache with YaST

To configure your Web server with YaST, start YaST and select Network Services > HTTP Server. When starting the module for the first time, the HTTP Server Wizard starts, prompting you to make just a few basic decisions concerning administration of the server. After having finished the wizard, the dialog in HTTP Server Configuration starts every time you call the HTTP Server module.

HTTP Server Wizard

The HTTP Server Wizard consists of five steps. In the last step of the dialog, you are given the opportunity to enter the expert configuration mode to make even more specific settings.

Network Device Selection

Here, specify the network interfaces and ports Apache uses to listen for incoming requests. You can select any combination of existing network interfaces and their respective IP addresses. Ports from all three ranges (well-known ports, registered ports, and dynamic or private ports) that are not reserved by other services can be used. The default setting is to listen on all network interfaces (IP addresses) on port 80.

Check Open Firewall for Selected Ports to open the ports in the firewall that the Web server listens on. This is necessary to make the Web server available on the network, which can be a LAN, WAN, or the public Internet. Keeping the port closed is only useful in test situations where no external access to the Web server is necessary. If you have multiple network interfaces, click on Firewall Details... to specify on which interface(s) the port(s) should be opened.

Click Next to continue with configuration.

Modules

The Modules configuration option allows for the activation or deactivation of the script languages, the Web server should support. For the activation or deactivation of other modules, refer to Server Modules. Click Next to advance to the next dialog.

Default Host

This option pertains to the default Web server. As explained in Virtual Host Configuration, Apache can serve multiple virtual hosts from a single physical machine. The first declared virtual host in the configuration file is commonly referred to as the default host. Each virtual host inherits the default host's configuration.

To edit the host settings (also called directives), choose the appropriate entry in the table then click Edit. To add new directives, click Add. To delete a directive, select it and click Delete.

Figure 28-1 HTTP Server Wizard: Default Host

Here is list of the default settings of the server:

Document Root

Path to the directory from which Apache serves files for this host. /srv/www/htdocs is the default location.

Alias

With the help of Alias directives, URLs can be mapped to physical file system locations. This means that a certain path even outside the Document Root in the file system can be accessed via a URL aliasing that path.

The default openSUSE Alias /icons points to /usr/share/apache2/icons for the Apache icons displayed in the directory index view.

ScriptAlias

Similar to the Alias directive, the ScriptAlias directive maps a URL to a file system location. The difference is that ScriptAlias designates the target directory as a CGI location, meaning that CGI scripts should be executed in that location.

Directory

With the Directory setting, you can enclose a group of configuration options that will only apply to the specified directory.

Access and display options for the directories /usr/share/apache2/icons and /srv/www/cgi-bin are configured here. It should not be necessary to change the defaults.

Include

With include, additional configuration files can be specified. Two Include directives are already preconfigured: /etc/apache2/conf.d/ is the directory containing the configuration files that come with external modules. With this directive, all files in this directory ending in .conf are included. With the second directive, /etc/apache2/conf.d/apache2-manual.conf, the apache2-manual configuration file is included.

Server Name

This specifies the default URL used by clients to contact the Web server. Use a fully qualified domain name (FQDN) to reach the Web server at http://FQDN/ or its IP address. You cannot choose an arbitrary name here—the server must be known under this name.

Server Administrator E-Mail

E-mail address of the server administrator. This address is, for example, shown on error pages Apache creates.

After finishing with the Default Host step, click Next to continue with the configuration.

Virtual Hosts

In this step, the wizard displays a list of already configured virtual hosts (see Virtual Host Configuration). If you have not made manual changes prior to starting the YaST HTTP wizard, no virtual host is present.

To add a host, click Add to open a dialog in which to enter basic information about the host, such as Server Name, Server Contents Root (DocumentRoot), and the Administrator E-Mail. Server Resolution is used to determine how a host is identified (name based or IP based). Specify the name or IP address with Change Virtual Host ID

Clicking Next advances to the second part of the virtual host configuration dialog.

In part two of the virtual host configuration you can specify whether to enable CGI scripts and which directory to use for these scripts. It is also possible to enable SSL. If you do so, you must specify the path to the certificate as well. See Section 28.6.2, Configuring Apache with SSL for details on SSL and certificates. With the Directory Index option, you can specify which file to display when the client requests a directory (by default, index.html). Add one or more filenames (space-separated) if you want to change this. With Enable Public HTML, the content of the users public directories (~user/public_html/) is made available on the server under http://www.example.com/~user.

IMPORTANT: Creating Virtual Hosts

It is not possible to add virtual hosts at will. If using name-based virtual hosts, each hostname must be resolved on the network. If using IP-based virtual hosts, you can assign only one host to each IP address available.

Summary

This is the final step of the wizard. Here, determine how and when the Apache server is started: when booting or manually. Also see a short summary of the configuration made so far. If you are satisfied with your settings, click Finish to complete configuration. If you want to change something, click Back until you have reached the desired dialog. Clicking HTTP Server Expert Configuration opens the dialog described in HTTP Server Configuration.

Figure 28-2 HTTP Server Wizard: Summary

HTTP Server Configuration

The HTTP Server Configuration dialog also lets you make even more adjustments to the configuration than the wizard (which only runs if you configure your Web server for the first time). It consists of four tabs described in the following. No configuration option you change here is effective immediately—you always must confirm your changes with Finish to make them effective. Clicking Abort leaves the configuration module and discards your changes.

Listen Ports and Addresses

In HTTP Service, select whether Apache should be running (Enabled) or stopped (Disabled). In Listen on Ports, Add, Edit, or Delete addresses and ports on which the server should be available. The default is to listen on all interfaces on port 80. You should always check Open Firewall on Selected Ports, because otherwise the Web server is not reachable from the outside. Keeping the port closed is only useful in test situations where no external access to the Web server is necessary. If you have multiple network interfaces, click on Firewall Details... to specify on which interface(s) the port(s) should be opened.

With Log Files, watch either the access log or the error log. This is useful if you want to test your configuration. The log file opens in a separate window from which you can also restart or reload the Web server (see Section 28.3, Starting and Stopping Apache for details). These commands are effective immediately.

Figure 28-3 HTTP Server Configuration: Listen Ports and Addresses

Server Modules

You can change the status (enabled or disabled) of Apache2 modules by clicking Toggle Status. Click Add Module to add a new module that is already installed but not yet listed. Learn more about modules in Section 28.4, Installing, Activating, and Configuring Modules.

Figure 28-4 HTTP Server Configuration: Server Modules

Main Host or Hosts

These dialogs are identical to the ones already described. Refer to Default Host and Virtual Hosts.

openSUSE 11.1 Reference Guide
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