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Apache2 Virtual Host Configurations

Apache's virtual host configurations allow you to serve multiple websites on a single server, each with its own configuration. The <VirtualHost> directive is used to define the settings for each website.

Basic Syntax​

<VirtualHost *:80>
    DocumentRoot /var/www/html
    ServerName www.example.com
    ServerAlias example.com
    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>

Key Directives for Virtual Hosts​

1. <VirtualHost>​

Defines the virtual host. The *:80 indicates that this virtual host is listening on port 80 (HTTP). You can change the port as needed (e.g., *:443 for HTTPS).

  • Syntax: <VirtualHost [IP_address|*]:port>

2. DocumentRoot​

Specifies the directory where the website’s files are stored.

  • Example: DocumentRoot /var/www/example

3. ServerName​

Specifies the primary domain name for this virtual host.

  • Example: ServerName www.example.com

4. ServerAlias​

Specifies additional domain names that should be handled by this virtual host (e.g., www and non-www versions, or alternate domain names).

  • Example: ServerAlias example.com *.example.com

5. ErrorLog​

Specifies the file where error logs are written for this virtual host.

  • Example: ErrorLog /var/log/apache2/example_error.log

6. CustomLog​

Specifies the file for the access logs and the log format.

  • Example: CustomLog /var/log/apache2/example_access.log combined

7. <Directory>​

Specifies directory-level options for the virtual host, such as permissions, directory indexing, and overrides.

  • Example:
<Directory /var/www/example>
    AllowOverride All
    Options Indexes FollowSymLinks
    Require all granted
</Directory>

8. Listen​

Specifies the IP address and port on which Apache should listen. This can be configured in the main Apache config or within a virtual host block.

  • Example: Listen 80

9. DirectoryIndex​

Specifies the default file that will be served if no file is requested (e.g., index.html, index.php).

  • Example: DirectoryIndex index.php index.html

10. SSLEngine (for HTTPS)​

If you’re using HTTPS, you need to enable SSL in the virtual host for secure communication.

  • Enable SSL Module
sudo a2enmod ssl
sudo systemctl restart apache2
  • Generate a Self-Signed SSL Certificate
sudo mkdir -p /etc/apache2/ssl
sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 \
  -keyout /etc/apache2/ssl/apache-selfsigned.key \
  -out /etc/apache2/ssl/apache-selfsigned.crt

  • Example:
<VirtualHost *:443>
    DocumentRoot /var/www/example
    ServerName www.example.com
    SSLEngine on
    SSLCertificateFile /etc/apache2/ssl/apache-selfsigned.crt
    SSLCertificateKeyFile /etc/apache2/ssl/apache-selfsigned.key
</VirtualHost>

11. RewriteEngine​

Enables URL rewriting, often used for redirects and clean URLs.

  • Example:
<VirtualHost *:80>
    DocumentRoot /var/www/example
    ServerName www.example.com
    RewriteEngine On
    RewriteRule ^/old-page$ /new-page [R=301,L]
</VirtualHost>

12. ProxyPass and ProxyPassReverse​

Used to configure reverse proxies.

  • Example:
<VirtualHost *:80>
    DocumentRoot /var/www/example
    ServerName www.example.com
    ProxyPass /app http://127.0.0.1:8080/
    ProxyPassReverse /app http://127.0.0.1:8080/
</VirtualHost>

13. SetEnv​

Used to set environment variables for the virtual host.

  • Example: SetEnv APP_ENV production

14. php_admin_value and php_value​

Used to configure PHP settings for this virtual host.

  • Example:
<VirtualHost *:80>
    DocumentRoot /var/www/example
    php_admin_value upload_max_filesize 10M
    php_value memory_limit 128M
</VirtualHost>

15. LogFormat and CustomLog​

Defines the log format for access logs.

  • Example:
LogFormat "%h %l %u %t "%r" %>s %b" common
CustomLog /var/log/apache2/example_access.log common

16. AllowOverride​

Specifies whether .htaccess files can override configuration settings for a directory.

  • Example: AllowOverride All

17. Require​

Defines access control for the virtual host or directory.

  • Example: Require all granted (to allow all access)

18. Timeout​

Sets the maximum time (in seconds) Apache will wait for certain operations.

  • Example: Timeout 300

19. KeepAlive​

Determines whether persistent connections are allowed.

  • Example: KeepAlive On

Example Configurations​

1. Basic HTTP Virtual Host​

<VirtualHost *:80>
    DocumentRoot /var/www/example
    ServerName www.example.com
    ServerAlias example.com
    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined

    <Directory /var/www/example>
        AllowOverride All
        Options Indexes FollowSymLinks
        Require all granted
    </Directory>
</VirtualHost>

2. SSL Virtual Host (HTTPS)​

<VirtualHost *:443>
    DocumentRoot /var/www/example
    ServerName www.example.com
    SSLEngine on
    SSLCertificateFile /etc/ssl/certs/example_com.crt
    SSLCertificateKeyFile /etc/ssl/private/example_com.key
    SSLCertificateChainFile /etc/ssl/certs/example_com_chain.crt
    ErrorLog ${APACHE_LOG_DIR}/ssl_error.log
    CustomLog ${APACHE_LOG_DIR}/ssl_access.log combined
</VirtualHost>

3. Redirect Non-WWW to WWW (or vice versa)​

<VirtualHost *:80>
    ServerName example.com
    Redirect permanent / https://www.example.com/
</VirtualHost>

<VirtualHost *:443>
    ServerName www.example.com
    DocumentRoot /var/www/example
    SSLEngine on
    SSLCertificateFile /etc/ssl/certs/example_com.crt
    SSLCertificateKeyFile /etc/ssl/private/example_com.key
    ErrorLog ${APACHE_LOG_DIR}/ssl_error.log
    CustomLog ${APACHE_LOG_DIR}/ssl_access.log combined
</VirtualHost>

4. Proxy Pass Example (for reverse proxy)​

<VirtualHost *:80>
    ServerName www.example.com
    DocumentRoot /var/www/example
    ProxyPass /api http://127.0.0.1:5000/
    ProxyPassReverse /api http://127.0.0.1:5000/
</VirtualHost>

5. Prevent Host Header Injection Attacks​

Set up a default virtual host to handle unexpected Host headers. This ensures no sensitive application is served for unknown hosts.

Example:

<VirtualHost *:80>
    ServerName default
    <Location />
        Require all denied
    </Location>
</VirtualHost>

<VirtualHost *:443>
    ServerName default
    <Location />
        Require all denied
    </Location>
</VirtualHost>

Including Virtual Hosts​

To include multiple virtual host configurations in Apache, you can use the Include directive in the main Apache configuration file (httpd.conf or apache2.conf).

Example:

Include sites-enabled/*.conf

This allows you to separate each virtual host configuration into its own file under the sites-available or sites-enabled directory, a convention commonly used in Debian/Ubuntu systems.

Enabling a Site (Debian/Ubuntu)​

After creating a configuration file for a site in /etc/apache2/sites-available/, enable it with:

sudo a2ensite example.com.conf

To disable a site, use:

sudo a2dissite example.com.conf

Then reload Apache:

sudo systemctl reload apache2

Conclusion​

This guide should give you a comprehensive understanding of Apache2 virtual host configurations and how to set up and manage multiple websites on a single Apache server.

Apache .htaccess Rules and Examples​

Overview​

The .htaccess file is used to configure settings for Apache web servers at the directory level. Below are common examples and explanations of .htaccess rules.

1. Redirects​

Redirect all HTTP traffic to HTTPS:

RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Redirect to a specific domain:

RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.example\.com$ [NC]
RewriteRule ^(.*)$ https://www.example.com/$1 [L,R=301]

2. Directory Index​

Set a custom directory index:

DirectoryIndex custom_index.html

3. Access Control​

Block access by IP address:

Order Deny,Allow
Deny from 192.168.1.100

Allow access only from a specific IP address:

Order Deny,Allow
Deny from all
Allow from 192.168.1.101

4. Password Protection​

Protect a directory with a password:

  1. Create a .htpasswd file: 
    htpasswd -c /path/to/.htpasswd username
  2. Add the following to .htaccess: 
    AuthType Basic
    AuthName "Restricted Area"
    AuthUserFile /path/to/.htpasswd
    Require valid-user

5. Custom Error Pages​

Set up custom error pages:

ErrorDocument 404 /404.html
ErrorDocument 500 /500.html

6. Cache Control​

Enable browser caching:

<IfModule mod_expires.c>
    ExpiresActive On
    ExpiresByType image/jpg "access plus 1 year"
    ExpiresByType image/jpeg "access plus 1 year"
    ExpiresByType image/gif "access plus 1 year"
    ExpiresByType image/png "access plus 1 year"
    ExpiresByType text/css "access plus 1 month"
    ExpiresByType text/javascript "access plus 1 month"
</IfModule>

7. Gzip Compression​

Enable Gzip compression:

<IfModule mod_deflate.c>
    AddOutputFilterByType DEFLATE text/html text/plain text/xml
    AddOutputFilterByType DEFLATE text/css text/javascript
    AddOutputFilterByType DEFLATE application/javascript
    AddOutputFilterByType DEFLATE application/x-javascript
    AddOutputFilterByType DEFLATE application/xml
</IfModule>

8. Prevent Hotlinking​

Deny hotlinking of images:

RewriteEngine On
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^https://(www\.)?example\.com/ [NC]
RewriteRule \.(jpg|jpeg|png|gif)$ - [F]

9. Deny Directory Listing​

Prevent users from seeing a list of files in a directory:

Options -Indexes

10. CORS (Cross-Origin Resource Sharing)​

Allow cross-origin requests:

<IfModule mod_headers.c>
    Header set Access-Control-Allow-Origin "*"
</IfModule>

Notes​

  • Ensure the .htaccess file is placed in the appropriate directory.
  • Some rules may require enabling specific Apache modules (e.g., mod_rewrite, mod_headers).