What a proxy and a reverse proxy are and what they are for

You may have heard the word proxy in connection with privacy, security and servers. In reality there are two different kinds that are often confused. Let us explain what a proxy is, what a reverse proxy is and what they are for.

What a proxy server is

A proxy is an intermediary between you and the internet. When you set up a proxy, your requests do not go directly to the target website, but first to the proxy server, which forwards them on. The website then sees the proxy, not you directly. This is also called a forward proxy.

What a proxy is for

• Privacy and anonymity. The website does not see your real IP address, but the proxy’s address. This relates to the public IP address.
• Content filtering. Companies and schools use a proxy to block unsuitable pages.
• Speedup via cache. A proxy can store frequently visited content and deliver it faster.
• Bypassing restrictions. Access to content blocked on a given network.

What a reverse proxy is

A reverse proxy stands on the opposite side, at the server. It is an intermediary that receives requests from visitors and distributes them to the servers in the background. The visitor communicates with the reverse proxy and has no idea which server actually answers.

What a reverse proxy is for

• Load balancing. It distributes visitors among several servers so none is overloaded.
• Security. It hides the real servers and protects them from a direct attack, similar to a firewall.
• Encryption (HTTPS). The SSL certificate for the whole website is often handled here.
• Speedup via cache, similar to a CDN.

What a reverse proxy is built with

In practice the most common reverse proxies are Nginx, HAProxy, Caddy or Apache. Nginx and Caddy can, alongside proxying, also serve the website and certificates directly, while HAProxy focuses mainly on load balancing. Cloud services like Cloudflare in principle also work as large reverse proxies in front of your server.

Proxy versus VPN

They are often confused, but they are not the same thing:

• A proxy usually redirects just one application (for example the browser) and often does not encrypt the whole connection.
• A VPN creates an encrypted tunnel for the whole device and protects all traffic, not just the browser.

So for privacy and a secure connection on someone else’s wifi a VPN is more suitable. A proxy is better for targeted tasks like corporate filtering or caching.

The main difference

A simple aid:

• A proxy protects and represents the user, the website does not see you.
• A reverse proxy protects and represents the server, you do not know which server answers.

Where you meet them

A reverse proxy is the foundation of almost every larger website and we use it too when managing servers and hosting. A proxy, in turn, helps with corporate filtering and privacy, although for privacy protection a VPN is more commonly used today.

This article is part of our Computer networks overview.