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What is a Reverse Proxy? How It Works and Why You Need It

Proxy servers are a well-known technology among IT professionals and other experts working closely with the World Wide Web data. You may have also heard of a reverse proxy server, which takes care of several essential tasks, handling incoming client requests and forwarding them to backend servers.

Unlike forward proxies, which often require a client-side application and configuration, reverse proxy is usually invisible and manages incoming traffic automatically. Businesses primarily use them for load balancing, security, and traffic optimization. In this article, I'll shed some light on a reverse proxy place in a modern internet structure, its benefits, and its exact use cases.

What Is a Reverse Proxy?

A reverse proxy server, or reverse proxy, is a type of proxy that accepts client requests and sends them to backend servers. Without reverse proxies, a client (usually a web browser used for surfing online) sends data requests (for example, to display a video) to the origin server that hosts websites. The origin server interprets a client request and responds with relevant data.

Reverse proxy operation scheme

In this scenario, a reverse proxy is placed in front of the origin server to intercept client requests before they reach the target destination. In fact, you will encounter a reverse proxy server more often than not, but its placement is hidden from the client's view. Before we go into more details, let's get a few confusing details out of the way.

Reverse Proxies vs. Forward Proxies

Forward proxies are popular among all kinds of consumers. Workplace network administrators use them to restrict access to forbidden websites, like torrenting or browser game portals. Simultaneously, data analysts utilize such proxies for web scraping, and casual internet users enjoy bypassing geographical restrictions for more content, like foreign Netflix libraries. Residential proxies are a type of forward proxy because it stands in front of the client and forwards its requests to servers.

Confusing reverse proxies with forward is easy because both types manage online traffic. However, a reverse proxy manages incoming traffic, while forward proxies control outgoing traffic. Similar in design, these two proxy types serve entirely different goals.

Reverse proxy servers protect backend servers from direct access, overloading, and cyberattacks like DDoS. They can be used to host a firewall, encrypt data, and authenticate SSL certificates. They also simplify backend server management because a single reverse proxy server can redistribute traffic through the whole network depending on its configuration.

Forward proxy and reverse proxy comparison

How Does a Reverse Proxy Work?

Understanding reverse proxies is straightforward, but the underlying technology is sophisticated. Because reverse proxy servers function as a single point of entry to the origin server, they must meet strict cybersecurity standards. Here's how reverse proxies manage incoming traffic.

  1. A client sends a request to a web server. This request is first routed to a reverse proxy server.
  2. Reverse proxy accepts the request and analyzes required information, like the target URL, headers, HTTP method, etc.
  3. Reverse proxy forwards the request to a backend server according to its configuration, like load balancing rules. At this point, it can also modify the request, like compressing the data to minimize data consumption.
  4. The origin server accepts and interprets the request and generates an answer.
  5. The response is sent to the reverse proxy server.
  6. A second modification can occur here. Reverse proxy can once again compress the data, cache images, fonts, or other information, manipulate headers, etc.
  7. The reverse proxy sends the final response to the client's device.

Finally, the whole exchange looks like pictured in the image below.

Communication via reverse proxy scheme

This is a straightforward communication via a reverse proxy scheme. If there are additional additional configurations, like traffic encryption or SSL authentication, then numerous additional steps appear in between.

Why Use a Reverse Proxy?

Reverse proxies are essential for efficient World Wide Web maintenance, but in this article let's focus on consumer benefits. Businesses that compete in the digital marketplace may quickly require reverse proxies if their website attracts increasingly more traffic. Simultaneously, enterprises that handle personally identifiable information (PII) need to adhere to data security regulations, which is another reverse proxy benefit.

Load Balancing

Load balancing is one of the most straightforward and common reverse proxy use cases. Imagine your website attracts a hundred thousand visitors daily. Most are visitors from the US who browse your website after work. So, during the day, it handles low-to-average traffic, but it increases greatly after working hours.

Suppose the origin server is not powerful enough to withstand hundreds of users simultaneously. In that case, it will overload, and the website will go down, which is particularly damaging for e-commerce platforms.

Reverse proxy server scheme

Instead, businesses deploy reverse proxies to accept and redistribute client requests between multiple servers. A reverse proxy server redirects client requests to a less overcrowded server, ensuring the whole network uptime. Simultaneously, it can be configured to redirect traffic from distant geographical locations to nearby servers, increasing the data exchange speed.

Caching

Similar to load balancing, reverse proxies can cache specific information to minimize data consumption. For example, when you visit the same website repeatedly, there's no need to fetch the same image from the server over and over again. This repeated task unnecessarily uses the server's resources and sends the same image data back and forth, wasting bandwidth.

In this case, a reverse proxy server stores specified information to send to the client on demand. It will not contact the server for it, so the response comes faster with more optimized bandwidth use. This is a mutually beneficial situation, as the corporate network works more efficiently, and the client receives data faster.

Cybersecurity

According to the IMF, cyberattacks against businesses have increased more than twice since the pandemic. With the current geopolitical tensions, cybercrime is expected to keep growing, so the cybersecurity reverse proxy benefits are as important as ever.

Firstly, reverse proxies obfuscate the backend server IP address. An IP address is like a virtual home address, so exposing your server location on the internet poses security risks. Hackers exploit server IPs to target them with distributed denial-of-service (DDoS) cyberattacks that bombard the server with fake requests. Once the request number reaches a critical mass, it overloads the server to bring the website down.

Reverse proxies can also restrict access to specific server resources. This way, they hide confidential data from unauthorized access. Because reverse proxies work with incoming data, they are an excellent place to host a firewall that will inspect incoming traffic for malicious elements before they infect the backend server. Lastly, reverse proxies can handle SSL encryption, which is essential for data security and online privacy protection.

Geolocation Services

The geolocation optimization uses load balancing and content caching but on a global scale. If you host your website on the US servers but attract thousands of visitors from India, then they may experience slow connection speed due to the huge distance between the servers. You can place a reverse proxy closer to the client's location, which will store cached data and process clients' requests faster.

Common Use Cases for Reverse Proxies

By now, the technological and theoretical aspects of reverse proxies should be apparent. Let's take a look at the most common reverse proxy use cases.

Web Hosting and Application Delivery

Website and application hosting services widely deploy reverse proxies to provide the best services possible. The load balancing and caching ensure that the website or an application loads quickly. Keep in mind that page load speed is particularly important to Google when it ranks websites on its search engine. The quicker your services are displayed for the client, the higher your SERP position.

Simultaneously, hosting companies use reverse proxy SSL termination features, like encryption and certificate authentication. It can also host a firewall, protect from IP-based cyberattacks, and simplify management through a single point of entry.

Content Delivery Networks (CDNs)

A content delivery network (CDN) is at the core of fast online data flows. Because the internet is genuinely global, clients can communicate with servers in any geographical location. However, sending data halfway across the globe is not efficient, especially if hundreds of thousands of clients communicate at the same time.

CND service providers like Cloudflare place reverse proxy servers to optimize online data flows. They redirect user traffic to nearby servers to minimize traveling distance (reducing session latency), cache specific information to reduce server traffic, and compress data to optimize the exchange. CNDs deploy many reverse proxy servers to ensure scalability and worldwide reach.

Caching and Load Balancing in Enterprises

Because we talked about caching and load balancing so much, let's put it into perspective using real-world examples. Amazon is one of the biggest reverse proxy users to distribute its colossal traffic across a vast number of servers. This way, it can serve thousands of consumers worldwide without experiencing downtime.

Netflix is a renowned brand that smartly places reverse proxies to cache popular content. This way, the most watched movies and TV shows reach clients faster and do not waste backend server resources, which are reserved for other users.

How to Set Up a Reverse Proxy

Although setting up and configuring reverse proxies is a lengthy topic for another time, here's a brief example of how it's done on Windows using the Nginx web server.

  1. Download Nginx from its official website and extract it to a selected location.
  2. Locate the nginx.conf file in Nginx installation folder and open it.
  3. Navigate to the server block. You must modify it per your requirements, like in the example below
server {
    listen 80;
    server_name your_domain.com;
    location / {
        proxy_pass http://backend_server:8080;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;  
    }
}
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  1. In the example, the "your_domain.com" part must be filled with your reverse proxy IP address or domain name.
  2. The "http://backend_server:8080" must be replaced with your backend server URL.
  3. Press Windows button and type cmd, and press Enter to open the command prompt.
  4. Type nginx.exe -s start to launch Nginx with the current configuration.

Conclusion

Although unseen to clients, reverse proxy servers are essential to businesses that rely on online data. CND networks and massive e-commerce platforms use them to redistribute massive user traffic without overloading servers. Simultaneously, SSL encryption, IP address obfuscation, and traffic analysis protect backend servers from external threats.

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