What is a reverse proxy? Understanding proxy servers

What is a reverse proxy?

A reverse proxy is a server that acts as an intermediary between a web server and a client (for example, your web browser). It sits in front of one or more web servers and forwards client requests to these servers. A reverse proxy can ​​also be called a server-side proxy because it is located on the server’s network.

When a client sends a request to a web service, the reverse proxy server intercepts it. It determines which backend server should handle it based on different factors, including server load, health status, or predefined routing rules.

The reverse proxy then forwards the request to the chosen backend server, which processes it and sends the response back to the proxy. Finally, the proxy forwards the response to the client, making it appear that it came directly from the web server.

This setup spreads out requests evenly and gives web administrators more control over the web servers. By sharing the load among multiple backend servers, the reverse proxy keeps any single server from getting too busy, making everything run faster and more reliably. It also adds security by hiding the details of the origin server and keeping an eye on its health, rerouting traffic as needed to keep things working well.

What is a forward proxy? The difference explained

A proxy server, also known as a forward proxy, web proxy, or simply proxy, serves as an intermediary between clients and the websites they browse.

Instead of connecting directly to a website, the client first connects to the proxy server. The proxy server then forwards their request to the website. When the website responds, it sends the information back to the proxy server, which then sends it to the client. This way, the client’s IP address is hidden from the target server, which provides more security to their browsing activity.

Why would anyone need a forward proxy server? A forward proxy can control and monitor all outgoing traffic from a network. There are a few ways this can benefit you:

• Additional privacy and security. A proxy server masks the user’s IP address when accessing websites. This way, it’s harder to trace activity back to the user, providing an additional layer of privacy while browsing.
• Access control. Forward proxies can block access to specific websites or categories of content, such as adult content or social media sites. Schools or households often use this feature to maintain a safe browsing environment.
• Content filtering. A forward proxy server can filter out harmful content and block suspicious websites to protect users from potential cyber threats.

So what is the difference between a reverse proxy and a forward one? While both forward and reverse proxies serve as intermediaries, they do opposite jobs.

A forward proxy assists clients in securely accessing external servers. A reverse proxy sits in front of servers, managing incoming client requests. Putting it simply – one shields the user, and the other shields the web service.

Their purposes are also different. A forward proxy server is mainly used to enhance privacy and security, whereas a reverse proxy is usually used to manage and optimize server traffic.

What are reverse proxy servers commonly used for?

Why use a reverse proxy server? Because a reverse proxy directs client requests to the correct server, it can speed up access and enhance security. Below are some of the most common uses of reverse proxies.

Load balancing

Load balancing is one of the most common ways to use a reverse proxy server. As incoming traffic increases, it becomes necessary to distribute requests evenly across multiple servers to avoid overloading one single server.

Reverse proxies distribute incoming requests evenly among servers, making the best use of resources and avoiding server overload. They also monitor server health and redirect traffic from down or slow servers. By doing so, reverse proxy servers ensure smooth performance, especially during traffic spikes.

This feature minimizes downtime and bottlenecks and allows for high availability and faster load times. Various content delivery network (CDN) systems often employ reverse proxies to manage incoming traffic across global server locations efficiently and as a failover in case one server fails.

Security

Similar to forward proxy servers, reverse proxies mask the IP addresses of origin servers, protecting them from direct attacks and providing more security.

By acting as an intermediary, the reverse proxy ensures that attackers only interact with the proxy, not the actual backend server. It is especially useful against a DDoS attack because the reverse proxy server can handle the overwhelming traffic intended to disrupt the origin server.

Reverse proxies can also log and monitor traffic. This way, businesses can learn about potential threats and suspicious activity and apply tighter security policies to prevent them.

Caching

A reverse proxy can cache static content on the website, such as images, videos, and HTML files. This will reduce the load on the origin server and improve users' page load times.

By offloading repetitive content requests, reverse proxies minimize latency, help maintain efficient server operations, and optimize bandwidth usage. By doing so, they speed up content delivery and help the backend use resources more efficiently, saving costs.

SSL encryption

Reverse proxies can handle SSL/TLS encryption and decryption to reduce the load on the origin server. By handling SSL termination, the reverse proxy ensures secure communication between clients and the proxy itself while allowing internal traffic to flow without encryption overhead. This improves overall website performance and simplifies the management of SSL certificates across multiple origin servers.

URL rewriting

Reverse proxies can modify URLs before they reach the origin server, making them more user friendly and SEO optimized.

By automatically reformatting URLs, reverse proxies can improve the consistency and readability of web addresses. This will enhance search engine rankings and user experience and help businesses maintain good SEO practices without changing their existing systems.

URL rewriting can also help implement redirection policies, manage content migrations, and ensure that links are consistent and descriptive for better site navigation.

Compression

Reverse proxies can compress outgoing and incoming data sent between clients and servers. This will save bandwidth and speed up content delivery. By reducing data size, reverse proxies lower latency, improve page load speeds, and enhance overall web performance, keeping users engaged and satisfied.

Reverse proxy server implementation

A reverse proxy can significantly enhance the performance, security, and scalability of your web infrastructure. However, setting it up can require some technical know-how. To set up a reverse proxy, follow these steps:

• Choose a reverse proxy software. With many to choose from, you won’t have a hard time finding one that will suit you best. Nginx and Apache are two of the most widely used reverse proxy software solutions.
• Install the software. Install the chosen software on your server using package managers (for example, “apt” for Debian-based systems or “yum” for Red Hat-based systems).
• Configure backend servers. Specify the servers that will handle requests forwarded by a frontend server by editing the configuration file. For example, for Nginx, this involves editing the “nginx.conf” or a site-specific configuration file.
• Set up proxy rules. Configure the proxy rules to forward incoming client requests to the backend servers. For Nginx, use the “proxy_pass” directive within the server block. You can also enable additional features such as load balancing, SSL termination, and caching.
• Restart the server. Restart the server to apply the configuration changes and ensure it correctly forwards requests to the backend servers.

The steps to implement a reverse proxy server can differ based on the specific software and requirements of your infrastructure.