Apache

Apache2 Structure

/etc/apache2/
|-- apache2.conf
|-- envvars
|-- httpd.conf
|-- magic
|-- ports.conf
|-- conf-enabled
|       `-- *.conf
|-- mods-available
|       |-- *.load
|       `-- *.conf
|-- mods-enabled
|       |-- *.load
|       `-- *.conf
|-- sites-available
|       default, default-ssl
|-- sites-enabled
|       |-- 000-default  # points to ../sites-available/default
|       `-- default-ssl  # points to ../sites-available/default-ssl
|-- ssl
|       *.crt, *.key

• apache2.conf is the main configuration file. It puts the pieces together by including all remaining configuration files when starting up the web server.
• ports.conf is always included from the main configuration file. It is used to determine the listening ports for incoming connections, and this file can be customized anytime.
• Configuration files in the mods-enabled/, conf-enabled/ and sites-enabled/ directories contain particular configuration snippets which manage modules, global configuration fragments, or virtual host configurations, respectively.
• They are activated by symlinking available configuration files from their respective *-available/ counterparts. These should be managed by using our helpers a2enmod, a2dismod, a2ensite, a2dissite, and a2enconf, a2disconf . See their respective man pages for detailed information.
• The binary is called apache2. Due to the use of environment variables, in the default configuration, apache2 needs to be started/stopped with /etc/init.d/apache2 or apache2ctl. Calling /usr/bin/apache2 directly will not work with the default configuration.

By default, Ubuntu does not allow access through the web browser to any file apart of those located in /var/www, public_html directories (when enabled) and /usr/share (for web applications). If your site is using a web document root located elsewhere (such as in /srv) you may need to whitelist your document root directory in /etc/apache2/apache2.conf.

The default Ubuntu document root is /var/www/html (Ubuntu 14.04) or /var/www (Ubuntu 12.04). You can make your own virtual hosts under /var/www. This is different to previous releases which provides better security out of the box.

Important files

• http://www.basicconfig.com/linuxnetwork/ubuntu_web_server_setup Good cover
• http://www.htpcbeginner.com/how-to-setup-apache-web-server-on-ubuntu/2/. It includes how to set up DNS, running multiple websites
• How To Set Up Apache Virtual Hosts on Ubuntu 12.04 LTS from digitalocean.com. It teaches how to create a new virtual host file (instead of using the default one).

/etc/apache2/apache2.conf

Main configuration file

/etc/apache2/httpd.conf

By default, this file is empty

/etc/apache2/ports.conf

NameVirtualHost *:80
Listen 80

<IfModule mod_ssl.c>
    # If you add NameVirtualHost *:443 here, you will also have to change
    # the VirtualHost statement in /etc/apache2/sites-available/default-ssl
    # to <VirtualHost *:443>
    # Server Name Indication for SSL named virtual hosts is currently not
    # supported by MSIE on Windows XP.
    Listen 443
</IfModule>

<IfModule mod_gnutls.c>
    Listen 443
</IfModule>

/etc/apache2/mods-available/

Contains all the modules installed for your server.

/etc/apache2/mods-enabled/

Symbolic link in this directory that refers to the module file in /mods-available above to enable it.

/etc/apache2/sites-available/

Stores all the configuration files for the web sites serviced by Apache server. By default, only one file available, a default virtual host configuration file.

/etc/apache2/sites-enabled/

Create a symbolic link to enable sites in /etc/apache2/sites-available.

Commands

sudo a2ensite default      # activate the default site /etc/apache2/sites-available/default 
sudo a2ensite domain2.com  # activate each virtual host
sudo service apache2 reload

service apache2 status     # check if apache2 is running 
sudo service apache2 start # run this if apache2 is not running

Running different sites on different ports

http://httpd.apache.org/docs/2.2/vhosts/examples.html#port