What is a reverse proxy? Proxy servers explained: What Is a Reverse Proxy and How Does It Work? A reverse proxy protects web servers from attacks and can provide performance and reliability benefits. Learn more about forward and reverse proxies.
Website traffic is not constant. For instance, the traffic on content streaming services like Netflix goes through the roof when new episodes of popular series are released.
So how do websites scale instantaneously when the traffic they receive increases exponentially? Well, they use reverse proxies to balance the traffic on their website—but what is a reverse proxy, and how do reverse proxies work?
What’s a proxy server?
A forward proxy, often called a proxy, proxy server, or web proxy is a server that sits in front of a group of client machines. When those computers make requests to sites and services on the Internet, the proxy server intercepts those requests and then communicates with web servers on behalf of those clients, like a middleman.
Why would anyone add this extra middleman to their Internet activity? There are a few reasons one might want to use a forward proxy:
- To avoid state or institutional browsing restrictions – Some governments, schools, and other organizations use firewalls to give their users access to a limited version of the Internet. A forward proxy can be used to get around these restrictions, as they let the user connect to the proxy rather than directly to the sites they are visiting.
- To block access to certain content – Conversely, proxies can also be set up to block a group of users from accessing certain sites. For example, a school network might be configured to connect to the web through a proxy which enables content filtering rules, refusing to forward responses from Facebook and other social media sites.
- To protect their identity online – In some cases, regular Internet users simply desire increased anonymity online, but in other cases, Internet users live in places where the government can impose serious consequences on political dissidents. Criticizing the government in a web forum or on social media can lead to fines or imprisonment for these users. If one of these dissidents uses a forward proxy to connect to a website where they post politically sensitive comments, the IP address used to post the comments will be harder to trace back to the dissident. Only the IP address of the proxy server will be visible.
How is a reverse proxy different?
A reverse proxy is a server that sits in front of one or more web servers, intercepting requests from clients. This is different from a forward proxy, where the proxy sits in front of the clients. With a reverse proxy, when clients send requests to the origin server of a website, those requests are intercepted at the network edge by the reverse proxy server. The reverse proxy server will then send requests to and receive responses from the origin server.
The difference between a forward and reverse proxy is subtle but important. A simplified way to sum it up would be to say that a forward proxy sits in front of a client and ensures that no origin server ever communicates directly with that specific client. On the other hand, a reverse proxy sits in front of an origin server and ensures that no client ever communicates directly with that origin server.
What Is a Reverse Proxy, and How Does It Work?
Just like forward proxies, reverse proxies also solve a problem. However, this problem relates to servers. In short, reverse proxies work in the exact opposite manner when compared to a forward proxy.
Essentially, a reverse proxy collects all the requests made to the server. Once intercepted, the reverse proxy sends the requests to the server with the data you are looking for. Due to this, the reverse proxy can manage the traffic landing on a website.
This design architecture solves a big problem when it comes to distributing content. You see, if a server receives an overwhelming number of requests in a short duration, it can’t process them, and clients cannot access the website they are looking for.
A reverse proxy solves this problem by monitoring the number of requests being made to the server and trying to balance them between different servers.
Benefits of Using a Reverse Proxy
Besides the above use case, reverse proxies also grant many other benefits. The section below discusses some of their major advantages.
Load Balancing
A single origin server cannot handle all the incoming traffic for a website with millions of daily unique visitors. In these cases, you can distribute the traffic smartly among a pool of many servers. Usually, all the servers will host the same content to eliminate a single point of failure, making the website more reliable.
A reverse proxy is a great way to set this up as it can receive the incoming traffic before it reaches the origin server. If the origin server is overloaded or fails completely, it can distribute the traffic to other servers without affecting the site functionality.
Reverse proxies can also direct incoming requests to several servers, with each server performing a specific function it’s optimized for. The reverse proxy can then gather responses from all the servers and deliver them to the client.
Since we use most of the popular reverse proxies primarily for load balancing, they’re also referred to as Load Balancers.
Global Server Load Balancing (GSLB)
GSLB is an advanced load balancing method for distributing website traffic among many servers placed strategically around the world. It’s typically done via the anycast routing technique, where the reverse proxy picks the server node based on the fastest travel time between the client and the server.
Not only does GSLB increase the site’s reliability and security considerations, it also reduces latency and load times, thereby enhancing user experience. You can use GSLB with other network optimization techniques such as Spoon Feeding to free up the origin servers’ computational resources even more.
Though you can set up Global Server Load Balancing manually on your server, it’s usually taken care of by dedicated CDNs such as Cloudflare and KeyCDN (which also powers Kinsta CDN). Kinsta serves all the websites hosted with it through a Load Balancer powered by Google Cloud Platform.
Enhanced Security
Reverse proxies can cloak the IP address and other characteristics of origin servers. Thus, your website’s origin server can maintain its anonymity better, increasing its security significantly.
Since the reverse proxy will receive all the traffic before it reaches the main server, any attackers or hackers will find it harder to target your website with security threats such as DDoS attacks.
You can use a strict firewall to harden the reverse proxy with tighter security against common cyber attacks. Without a reverse proxy installed, it is difficult to remove malware or start takedowns.
Info
Kinsta uses reverse proxies in its backend architecture and offers free WordPress hack fixes to all the websites it hosts.
A reverse proxy like HAProxy can add basic HTTP access authentication to a web server that doesn’t have it enabled. You can also use a reverse proxy to add centralized authentication for various types of requests.
Powerful Caching
You can use a reverse proxy for web acceleration purposes by caching both static and dynamic content. This can reduce the load on the origin server, resulting in a faster website.
For instance, if your origin server is in the USA and a user from Europe visits your website, then you can serve a cached version of your site from a reverse proxy server in Europe. Since the reverse proxy is closer to the user than the origin server, the website will take less time to load, making it perform superbly.
Varnish and Nginx FastCGI are prominent examples of reverse proxies that are used for caching web content. If your site is hosted with Kinsta, you don’t have to worry about caching as Kinsta takes care of all the caching legwork for you.
Superior Compression
Server responses use up a lot of bandwidth. Compressing server responses (e.g. with gzip) before sending them to the client can reduce the amount of bandwidth required, speeding up server responses over the network.
A reverse proxy is ideal to compress server responses as it sits in between the origin servers and the client.
Optimized SSL Encryption
Encrypting and decrypting SSL/TLS requests for each client can be highly taxing for the origin server. A reverse proxy can take up this task to free up the origin server’s resources for other important tasks, like serving content.
Another advantage of offloading SSL/TSL encryption and decryption is to reduce latency for clients that are geographically distant from the origin server.
You can also opt for a reverse proxy with specialized SSL/TLS acceleration hardware to optimize this task even further. Such a reverse proxy is called an SSL/TLS termination proxy. Some servers like Varnish do not support SSL/TSL protocols, so an SSL/TSL termination reverse proxy can help secure the traffic passing through them.
Better A/B Testing
Most A/B testing tools require you to use external JavaScript libraries to load their functions. However, loading third-party scripts can slow down your page load times and create a choppy experience for users.
Instead, you can use a reverse proxy to create two separate flows at the server level itself. For example, you can use Nginx’s split_clients
or sticky route
methods to control traffic redirection.
You can refer to tutorials on Nginx and freeCodeCamp to learn more about performing A/B testing with a reverse proxy.
Monitoring and Logging Traffic
A reverse proxy captures any requests that go through it. Hence, you can use them as a central hub to monitor and log traffic. Even if you use multiple web servers to host all your website’s components, using a reverse proxy will make it easier to monitor all the incoming and outgoing data from your site.
How to implement a reverse proxy
Some companies build their own reverse proxies, but this requires intensive software and hardware engineering resources, as well as a significant investment in physical hardware. One of the easiest and most cost-effective ways to reap all the benefits of a reverse proxy is by signing up for a CDN service.
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