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. In my case, the document roots for http and https are specified in the files </etc/apache2/sites-available/default> and </etc/apache2/sites-available/default-ssl>.

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 (important)

Main configuration file

/etc/apache2/httpd.conf

By default, this file is empty

/etc/apache2/ports.conf (important)

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/ (important)

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-available/default

This is the place to set up the document root for http port 80.

<VirtualHost *:80>
	ServerAdmin webmaster@localhost
        ServerName taichimd.us
	DocumentRoot /var/www/
	<Directory />
		Options FollowSymLinks
		AllowOverride None
	</Directory>
	<Directory /var/www/>
		Options Indexes FollowSymLinks MultiViews
		AllowOverride None
		Order allow,deny
		allow from all
	</Directory>
...
</VirtualHost>

/etc/apache2/sites-available/default-ssl

This is the place to set up the document root for https port 443.

<IfModule mod_ssl.c>
<VirtualHost _default_:443>
        ServerAdmin webmaster@localhost
        ServerName taichimd.us
        DocumentRoot /var/www
        <Directory />
                Options FollowSymLinks
                AllowOverride None
        </Directory>
        <Directory /var/www/>
                Options Indexes FollowSymLinks MultiViews
                AllowOverride None
                Order allow,deny
                allow from all
        </Directory>
...
        #   SSL Engine Switch:
        #   Enable/Disable SSL for this virtual host.
        SSLEngine on
        SSLCertificateFile    /FullPathTo/CAName.crt
        SSLCertificateKeyFile /FullPathTo/KeyName.key
        SSLCACertificateFile "/FullPathTo/bundle.crt"
...
</VirtualHost>

/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

Misc

Running different sites on different ports

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

.htaccess file

https://www.digitalocean.com/community/tutorials/how-to-use-the-htaccess-file

Set Up Mod_Rewrite

• https://www.digitalocean.com/community/tutorials/how-to-set-up-mod_rewrite-page-2 It contains an example to add www to a url.
• http://xmodulo.com/how-to-enable-mod_rewrite-in-apache2-on-debian-ubuntu.html

Error. Could not determine the server’s fully qualified domain name

http://tuxtweaks.com/2009/07/how-to-configure-apache-linux/

echo "ServerName localhost" | sudo tee /etc/apache2/conf.d/fqdn
sudo service apache2 reload

How to set up a secure Apache webserver on Ubuntu

http://xmodulo.com/secure-apache-webserver-ubuntu.html

• Update TimeZone and Check Correct Time
• Disable AppArmor Conflicts
• Stop DDoS Attacks
• Stop Slowloris Attacks
• Stop DNS Injection Attacks
• Turn off Server Signature

How To Enable And Run Multiple Websites Using Apache2

https://www.liberiangeek.net/2015/07/how-to-enable-and-run-multiple-websites-using-apache2-on-ubuntu-15-04/

we’re going to be using example.com and myexample.com domain names on a single Ubuntu server assigned IP address 192.168.20.1.

Note: As you can see from this exercise, it is perfectly OK to have multiple hostnames associated with the same IP4 address.

sudo apt-get install apache2
sudo mkdir -p /var/www/html/example.com/public_html
sudo mkdir -p /var/www/html/myexample.com/public_html

sudo vi /var/www/html/example.com/public_html/index.html
sudo vi /var/www/html/myexample.com/public_html/index.html
sudo chown www-data:www-data /var/www/html
sudo chmod -R 755 /var/www/html

sudo cp /etc/apache2/sites-available/000-default.conf /etc/apache2/sites-available/example.com.conf
sudo cp /etc/apache2/sites-available/000-default.conf /etc/apache2/sites-available/myexample.com.conf

# Change ServerName, ServerAlias and DocumentRoot entries
sudo vi /etc/apache2/sites-available/example.com.conf
sudo vi /etc/apache2/sites-available/myexample.com.conf

sudo a2dissite 000-default.conf
sudo a2ensite example.com.conf
sudo a2ensite myexample.com.conf
sudo service restart apache2

sudo nano /etc/hosts
# 192.168.20.1    example.com
# 192.168.20.1    myexample.com

How to create multiple virtual hosts

• http://codingpad.maryspad.com/2012/03/14/how-to-create-multiple-virtual-hosts-in-ubuntu/
• http://httpd.apache.org/docs/2.2/vhosts/examples.html Virtual host examples for different scenarios
• http://www.tecmint.com/apache-ip-based-and-name-based-virtual-hosting/
• https://www.digitalocean.com/community/tutorials/how-to-set-up-multiple-wordpress-sites-on-a-single-ubuntu-vps
• http://www.unixmen.com/setup-virtual-hosts-apache-ubuntu-14-04-lts/

25 Apache Interview Questions for Beginners and Intermediates

http://www.tecmint.com/apache-interview-questions/

Add www to your domain name for your website

https://www.linux.com/learn/tutorials/464510:weekend-project-create-virtual-hosts-with-apache Using ServerAlias or creating multiple virtualhost.

Disable directory browsing

• http://www.linuxscrew.com/2008/06/03/faq-how-to-disable-directory-browsing-in-apachehttpd/

Remove word Indexes from the following line in the file </etc/apache2/sites-available/default> & </etc/apache2/sites-available/default-ssl>

Options Includes Indexes FollowSymLinks MultiViews

Or try the following commands

sudo a2dismod autoindex
sudo service apache2 restart

List of all virtual hosts

apache2ctl -S

Diable a website through virtual host

• http://manpages.ubuntu.com/manpages/hardy/man8/a2ensite.8.html

sudo a2dissite 000-default

Show all loaded modules

apache2ctl -M

/usr/sbin/apache2ctl: 87: ulimit: error setting limit (Operation not permitted)
Loaded Modules:
 core_module (static)
 log_config_module (static)
 logio_module (static)
 mpm_prefork_module (static)
 http_module (static)
 so_module (static)
 alias_module (shared)
 auth_basic_module (shared)
 authn_file_module (shared)
 authz_default_module (shared)
 authz_groupfile_module (shared)
 authz_host_module (shared)
 authz_user_module (shared)
 autoindex_module (shared)
 cgi_module (shared)
 deflate_module (shared)
 dir_module (shared)
 env_module (shared)
 mime_module (shared)
 negotiation_module (shared)
 php5_module (shared)
 reqtimeout_module (shared)
 setenvif_module (shared)
 ssl_module (shared)
 status_module (shared)
Syntax OK