What is a reverse proxy?

A reverse proxy is a server that acts as an intermediary between clients and one or more web servers. When you visit a website, your web browser (the client) usually sends a request directly to the web server that hosts that website. With a reverse proxy, your request goes to the reverse proxy server first. The reverse proxy then forwards your request to the appropriate web server.

This setup allows the reverse proxy to perform several important tasks, such as:

• Distributing traffic: If there are multiple web servers, the reverse proxy can spread the incoming requests across them, preventing any single server from being overloaded.
• Filtering requests: The reverse proxy can analyze incoming requests and block any that seem malicious or suspicious, protecting the web servers from attacks.
• Caching content: The reverse proxy can store copies of frequently accessed content, like images or web pages, so it can deliver them quickly to clients without having to contact the web server each time.

A reverse proxy acts as a protective buffer and efficiency booster for web servers, improving their performance, security, and reliability.

How do reverse proxies work?

When a client (like a web browser) sends a request to a website, the reverse proxy intercepts that request before it reaches the origin server. This allows the reverse proxy to perform several important functions, improving the overall efficiency and security of the website.

Here’s a simplified breakdown of a reverse proxy’s process:

1. You send a request to access a website or web application using your web browser or another client application.
2. The reverse proxy intercepts the client’s request before it reaches the origin server. This allows the reverse proxy to analyze the request and perform various actions based on its configuration.
3. The reverse proxy can modify the client's request before forwarding it to the origin server. This might involve adding or removing headers, encrypting or decrypting data, or redirecting the request to a different server based on load balancing rules.
4. The reverse proxy forwards the modified or original request to the appropriate origin server. The origin server processes the request and generates a response.
5. The reverse proxy intercepts the response from the origin server before it reaches the client.
6. The reverse proxy can modify the server's response before sending it back to the client. This might involve compressing the response data, adding or removing headers, or caching the response for future requests.
7. The reverse proxy forwards the modified or original response back to the client. The client receives the response and displays the requested content.

Throughout this process, the client interacts directly with the reverse proxy, unaware of the underlying origin server(s). This separation of concerns allows the reverse proxy to perform its functions without affecting the client's experience or requiring any changes to the client's configuration.

What are reverse proxies used for?

Reverse proxies enhance various aspects of web server functionality. They can improve security by protecting against attacks and hiding the origin server's identity. They can also boost performance by distributing traffic across multiple servers and caching content. Additionally, reverse proxies can simplify management tasks like SSL encryption/decryption and centralized authentication.

Security

Reverse proxies act as a first line of defense for web servers, filtering out malicious traffic and preventing attacks like DDoS (Distributed Denial of Service) from reaching them. By hiding the origin server's IP address, reverse proxies make it harder for attackers to target the server directly, adding an extra layer of protection.

Load balancing

When a website experiences high traffic, a single server might struggle to handle all the requests, leading to slow loading times or even crashes for the people trying to visit the site. Reverse proxies can distribute incoming traffic across multiple servers, ensuring no single server becomes overloaded. This improves website performance, prevents downtime, and provides a better user experience.

Example: A popular online store experiences a surge in traffic during a holiday sale. Without a reverse proxy, the high traffic might overwhelm the origin server, leading to slow loading times and potential crashes. A reverse proxy can distribute the traffic across multiple servers, ensuring that the website remains responsive and available even under heavy load.

Caching

Serving static content like images, CSS files, and JavaScript files can consume significant server resources. Reverse proxies can cache this content, storing copies of it so they can deliver it quickly to users without needing to contact the origin server each time. This reduces the load on the origin server, speeds up content delivery, and improves website performance.

SSL encryption/decryption

Handling SSL encryption and decryption for every client request can be computationally expensive for a web server. Reverse proxies can offload this task, handling the encryption and decryption of data between the client and the server. This frees up resources on the origin server, allowing it to focus on other tasks and improving overall website performance.

Centralized authentication

Managing user authentication and authorization for multiple web applications can be complex. Reverse proxies can centralize this process, acting as a single point of authentication for all applications behind it. This simplifies user management, improves security, and provides a more consistent user experience across different applications.

Reverse proxy benefits

• Improved security: Reverse proxies act as a first line of defense, filtering malicious traffic and preventing attacks like DDoS (Distributed Denial of Service) from reaching the origin server. By hiding the origin server's IP address, reverse proxies make it harder for attackers to target the server directly.
• Increased performance and reliability: Distributing traffic across multiple servers ensures that no single server becomes overloaded, improving website performance and preventing downtime. Caching frequently accessed content reduces the load on the origin server and speeds up content delivery to users.
• Simplified management: Reverse proxies can centralize configuration for multiple web servers, making it easier to manage security policies, SSL certificates, and other settings. Adding or removing web servers becomes easier with a reverse proxy, allowing for flexible scaling based on website traffic demands.

Reverse proxy disadvantages

While reverse proxies offer lots of benefits, you should also be aware of some pitfalls they can cause:

• Setting up and maintaining a reverse proxy can be more complex than managing a single web server.
• If the reverse proxy fails, it can affect access to all the web servers behind it.
• Deploying a reverse proxy requires additional server resources and infrastructure, which can increase costs.