The main configuration file for Apache is /etc/httpd/conf/httpd.conf. Apache runs as installed, but you can modify configuration directives in this file to customize Apache for your environment. Some of these directives are described in the post below.
Listen [IP address:]port
Tells the server to accept incoming requests on the specified port or IP address and port combination. By default, the server responds to requests on all IP interfaces on port 80. If you specify a port number other than 80, a request to the server must include the port number (as in www.example.com:8080). This is a required directive. Examples are as follows:
Listen 80 Listen 192.168.2.1:8080
ServerName FQDN[:port]
Specifies the fully qualified domain name or IP address of the server and an optional port that Apache listens on. The FQDN must be able to be resolved by DNS. If no FQDN is specified, Apache performs a DNS reverse name lookup on the IP address. If no port is specified, the server uses the port from the incoming request, as shown in the following example:
ServerName www.example.com:80
ServerRoot directory-path
The top of the directory hierarchy under which the Apache server’s configuration, error, and log
files are kept. The default is /etc/httpd. Do not add a slash at the end of directory-path:
ServerRoot /etc/httpd
DocumentRoot directory-path
The top of the directory hierarchy that holds the Apache server content. Do not end the path name with a slash. The apache user needs read access to any files and execute access to the directory and any subdirectories in the hierarchy. The following is the default:
DocumentRoot /var/www/html
UserDir directory-path | disabled | enabled user-list
Allows users identified by the user-list argument to publish content from their home directories. The directory-path is the name of a directory in a user’s home directory from which Apache publishes content. If directory-path is not defined, the default is ~/public_html. The following example enables this feature for user user01. Assuming that the ServerName is www.example.com, browsing to http://www.example.com/~user01 displays the user01 user’s webpage.
UserDir enabled user01
ErrorLog filename | syslog[:facility]
Specifies the name of the file, relative to ServerRoot, that Apache sends error messages to. Alternatively, syslog specifies that Apache must send errors to rsyslogd. The optional facility argument specifies which rsyslogd facility to use. The default facility is local7.
ErrorLog logs/error_log
LoadModule module filename
Apache, like the Linux kernel, uses external modules to extend functionality. These modules are called dynamic shared objects (DSOs). The module argument is the name of the DSO and filename is the path name of the module, relative to ServerRoot. More than 60 modules are included with Apache, and more than 50 of these are loaded by default. An index of all the modules is available at http://httpd.apache.org/docs/2.4/mod/.
LoadModule auth_basic_module modules/mod_auth_basic.so
Allow from All | host [host …]
Specifies which clients can access content. All serves content to any client. Alternatively, you
can list the specific hosts that are allowed access to content.
Deny from All | host [host …]
Specifies which clients are not allowed access to content.
Order deny,allow | allow,deny
Specifies the order in which Allow and Deny directives are evaluated. deny,allow evaluates deny directives first and then allow directives. The following example grants access to clients from the example.com domain only, by first denying access to all and then allowing it from .example.com:
Order deny,allow Deny from all Allow from .example.com
Timeout num
Specifies the number of seconds Apache waits for network operations to finish. The default is 60.