What is Apache? Apache HTTP Server Complete Overview

Ever wondered how a website loads when you enter a URL in your browser? In the background, web servers serve your requests and send you the content you view. One of the most popular web servers is Apache HTTP Server, commonly referred to as simply Apache. Apache is the top choice for websites and applications worldwide due to its open-source, reliable, secure, and highly customizable.

In this article, we'll explore what Apache is, how it works, its features, installation steps, configurations, security aspects, and comparisons with alternatives like Nginx.

What is Apache HTTP Server?

Apache HTTP Server is an open-source and free web server that is written by the Apache Software Foundation (ASF). It is among the most widely used web servers, serving millions of websites on various platforms such as Linux, Windows, and macOS, and forms an integral part of the LAMP stack (Linux, Apache, MySQL, PHP), which is commonly utilized for web hosting and development.

Uses of Apache Server are:

• It supports cross-platform support as it runs on Linux, Windows, and macOS
• Modular design (Extension support through modules.)
• Dynamic content support (PHP, Python, Perl, etc.)
• Virtual hosting (Hosts many sites in one server)
• Security support (Supports SSL/TLS, authentication, and access control)
• Customizable settings (Makes use of .htaccess files)

Also Read: Web Server and Its Types

Apache Web Application Architecture

Apache is a fundamental part of LAMP (Linux, Apache, MySQL, PHP), the most popular web development stack. It supports easy integration with database management systems such as MySQL and scripting languages such as PHP and Python to develop dynamic web applications.

LAMP stands for:

• Linux: An open-source operating system that manages system resources and executes applications efficiently.
• Apache: A widely used web server that processes HTTP requests and serves web content securely..
• MySQL: A relational database management system (RDBMS) that stores and retrieves structured data efficiently.
• PHP: A server-side scripting language that integrates with Apache to generate dynamic web content.

Apache is the foundation of most CMS (Content Management Systems) such as WordPress, Joomla, and Drupal and thus is a favorite among hosting dynamic websites.

For details refer the article: LAMP Full Form

How Does Apache Work?

Apache uses a client-server model to process the HTTP and HTTPS requests, when the user enter the website address:

1. A user types a website address in their web browser.
2. The browser makes an HTTP request to the web server.
3. Apache executes the request and fetches the requested material (HTML, CSS, images, etc.).
4. Apache returns the response to the user's web browser.
5. The browser renders the web page.

Apache listens for HTTP on port 80 and HTTPS on port 443.

Note: Apache also supports reverse proxy, caching, and compression to improve website speed and performance.

Read: How to Configure an Apache Web Server?

Apache Vs. Nginx: Which is Better?

Apache and Nginx are the two most popular web servers. Here's how they compare:

For more details refer the article Difference between Apache and Nginx

Installing Apache on Different Platforms

Install Apache on Linux (Ubuntu/Debian)

sudo apt update
sudo apt install apache2 -y
sudo systemctl enable apache2
sudo systemctl start apache2\

Check if Apache is running:

sudo systemctl status apache2

Install Apache on Windows

• Download Apache from the Apache Lounge website.
• Extract the files and configure the httpd.conf file.
• Run httpd.exe to start the server.

Install Apache on macOS

Mac users can install Apache using Homebrew:

brew install httpd
sudo apachectl start

For more details refer the article: How to Install Apache Web Server in Linux: Ubuntu, Fedora, RHEL?

Configuring Apache Web Server

Apache configurations are stored in:

• /etc/httpd/httpd.conf (Linux)
• /usr/local/apache2/conf/httpd.conf (macOS)
• C:\Apache24\conf\httpd.conf (Windows)

Common Apache Configurations:

Change the default port:

Listen 8080

Enable virtual hosts to host multiple websites:

<VirtualHost *:80>
    ServerName example.com
    DocumentRoot /var/www/example
</VirtualHost>

Enable URL rewriting:

a2enmod rewrite

For more details refer the article :How to Configure an Apache Web Server?

Apache Security Best Practices

The security of an Apache web server is one of the most important aspects as it is the frontline of defense against cyber attacks such as SQL injection, cross site scripting (XSS) and DDoS. Try these additional steps to help fortify the security of your server:

1. Enable SSL/TLS (HTTPS)

The use of SSL/TLS when encrypting data prevents man in the middle attacks and allows for seamless communication between the web server and the clients.

sudo apt install certbot python3-certbot-apache
sudo certbot --apache -d example.com

Redirect all HTTP traffic to HTTPS by adding this to .htaccess:

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

2. Disable Directory Listing

Apache sometimes allows directory listing in order to ease navigation but it could potentially compromise sensitive documents. To prevent this, open your .htaccess file:

Options -Indexes

3. Restrict Access to Apache Config File

Poorly configured Apache settings can be used by attackers to their advantage. Protect critical files such as .htaccess:

<Files ".htaccess">
    Require all denied
</Files>

4. Limit Request Size

Limiting the request size which prevents buffer overflow attacks:

LimitRequestBody 1048576

5. Block Unauthorized IP Addresses

You can set restrictions to your Apache web server by filtering specific unwanted IP addresses:

<Directory "/var/www/html">
    Order Deny,Allow
    Deny from 192.168.1.100
    Allow from all
</Directory>

6. Keep Apache Updated

Always keep Apache updated which ensures bug fixes, security patches, and performance improvements:

sudo apt update && sudo apt upgrade apache2

7. Prevent Clickjacking Attacks

To prevent clickjacking attacks, add the following to your Apache configuration file:

Header always append X-Frame-Options SAMEORIGIN

Apache Modules: Enhancing Functionality & Performance

Apache modules extend the functionality of the Apache HTTP Server, allowing it to support dynamic content, security features, and performance optimizations.

Enable a module (Ubuntu/Debian):

sudo a2enmod rewrite
sudo systemctl restart apache2

Also Read: How to Use Apache Webserver to Host a Website?

Apache Alternatives

While Apache HTTP Server is one of the most widely used web servers, some alternatives offer better performance, scalability, and security.

When to Choose an Apache Alternative?

• For High-Traffic Websites: Use Nginx for Better load balancing and event-driven architecture
• For WordPress Optimization: Use LiteSpeed for faster PHP execution or if you are using the PHP
• For Automatic HTTPS & Ease of Use: Use the Caddy because they provide built-in SSL/TLS
• For Windows Servers: Use IIS because they provide native Windows integration)

Conclusion

Apache HTTP Server is a powerful web server software that is still open-sourced and widely used across the globe. It is the backbone of millions of applications and websites. It is a crucial part of the LAMP stack (Linux, Apache, MySQL, PHP), which offers great flexibility along with modularity, security, and cross-platform compatibility. Therefore, it is the number one choice for hosting CMS-based dynamic sites like WordPress, Joomla, Drupal and even enterprise applications.

As for the security offered by the software, it has proven to be very robust. Providing secure web access through SSL/TLS (HTTPS) and using powerful Apache modules like mod_rewrite, mod_ssl, and mod_security, Apache guarantees the best performance, security, and scalability.