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A reverse proxy, the inverse of a forward proxy, works instead by sitting in front of one or more web servers. The reverse proxy intercepts all incoming requests before they reach the destination. Reverse proxies perform various vital functions such as load balancing, filtering, and caching- all of which can improve both the reliability and security of web servers.

Reverse proxies

A reverse proxy gets its name from the inverse action of the former. A reverse proxy acts as the middleman between the web server and the client. When you make a request using a reverse proxy, the request is first sent to the reverse proxy server instead of directly reaching the web server. Here’s a diagram to help you understand the process:

How reverse proxies work

Reverse proxies play a crucial role in the management of traffic and the security of servers. The process of how this works is fairly simple; here’s a step-by-step breakdown:

1. You (the client) make a request to access a website or resource online.
2. The request is passed to the reverse proxy instead of the web server.
3. The reverse proxy intervenes and performs any necessary actions, such as load balancing for example.
4. The request is continued and lands at the back end web server to be processed.
5. Once processed, the request is forwarded back to the reverse proxy.
6. The reverse proxy then returns the response back to the client.

During the above process, a client never interacts directly with the end server, which offers multiple advantages. A reverse proxy essentially acts as the security guard, inspecting and managing incoming requests before they reach the backend servers. By doing so, it can filter out malicious traffic, block unwanted requests, and mitigate potential threats such as Distributed Denial-of-Service (DDoS) attacks. This additional layer of protection ensures the backend servers remain secure and operational even under heavy traffic or targeted attacks, essential for critical systems.

Types of reverse proxies

Equally as important as they are versatile, there are many different types of reverse proxies such as:

• NGNIX
• Squid
• AWS global accelerator

NGNIX (Engine X)

NGINX is one of the most popular and well known reverse proxies, famed for its high performance and versatility. It can handle a variety of protocols (HTTP, HTTPS, TCP, and UDP), making it an great choice for an all-round solution for web applications, APIs, and load balancing. NGINX is particularly valued for its ability to efficiently manage high traffic volumes and its robust support for caching, SSL/TLS termination, and URL rewriting. Its open-source nature and active community make it a popular choice for developers and system administrators across the industry.

Squid

Squid is a reverse proxy that specialises in caching and optimising web traffic. It is often used to cache frequently accessed content, such as images or API responses, reducing server load and improving response times. Squid is also known for its content filtering capabilities, allowing administrators to enforce access controls or block certain content. While Squid is less versatile than NGINX in handling multiple protocols, it excels in environments where caching is a priority, such as enterprise networks or content delivery setups.

AWS global accelerator

AWS Global Accelerator is a reverse proxy solution designed for global traffic distribution (GSLB). It uses AWS's significant global network to route user requests to the nearest or most available server, significantly reducing latency and improving response times by shortening the travel time for requests. This type of reverse proxy is ideal for applications that serve users across multiple regions, such as e-commerce websites or SaaS platforms. AWS Global Accelerator also provides features such as health checks and automatic failover, ensuring high availability and reliability for critical services.

Use cases

Reverse proxies are often deployed as an extra layer of protection for the back end servers of critical infrastructure. Here’s a variety of applications of a reverse proxy:

Load balancing

Load balancng spreads the number of a request a single site receives across multiple back end servers. This is essential for sites that receive heavy traffic, preventing a single back end server from taking the entire burden. A reverse proxy can distribube requests to prevent oerloading, which could result in slower response time or even total downtime.

In addition to this, load balancing can be stretched globally. Global server load balancing (GSLB) can distribute traffic to servers closer to the geographical location of the user; allowing faster response times by decreasing the travel distance between client and server with requests.

Caching

Caching with a reverse proxy works by temporarily storing frequently accessed content, such as static assets or API responses, on the proxy server itself. When a client makes a request for cached content, the reverse proxy serves it directly without needing to contact the backend server, significantly reducing latency and server load.

Caching is an important part of optimising response time, essentially saving certain content for later, allowing it to be accessed quicker. Think of this in computer hardware terms: if a PC had to retrieve data stored from a mechanical disk every time it needed to be accessed as opposed to the RAM, the entire process would be significantly slower. Just like RAM, cache keeps frequently accessed data at hand.

SSL/TLS encryption

SSL/TLS (Secure socket layer, transport layer security) encryption is critical for ensuring secure communication between clients and servers. A reverse proxy can play a significant role in managing SSL/TLS encryption by acting as a termination point for encrypted connections. When a client connects to a website using HTTPS, the reverse proxy handles the encryption and decryption of the data, meaning the backend servers don’t need to handle this resource-intensive process themselves.

Conclusion

Reverse proxies are an essential tool in modern web infrastructure, offering a wide range of benefits, from improving performance and security to ensuring scalability and reliability. By sitting between clients and backend servers, reverse proxies handle tasks like load balancing, caching, SSL/TLS termination, and global traffic distribution. These capabilities not only enhance the efficiency of web applications but also provide robust protection against potential threats, such as DDoS attacks and malicious traffic.