Understanding Nginx Reverse Proxy: Concepts and Configuration Examples

Before understanding reverse proxy, you need to know what a forward proxy is.

A forward proxy sits between a client and the target server, forwarding client requests. For example, if you cannot access Google directly, you can use an overseas forward proxy to reach it.

Reverse proxy works in the opposite direction: it sits in front of one or more backend servers and forwards client requests to those servers.

Large websites such as Taobao or JD.com use reverse proxy to handle high‑concurrency traffic.

When a user requests www.taobao.com, the request first reaches the Nginx reverse proxy, which then distributes the request to multiple real application servers according to a load‑balancing strategy.

Configuration example (Nginx):

server {
    listen 80;
    server_name www.taobao.com;
    location / {
        proxy_pass http://backend_upstream;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

All client requests are sent to the reverse proxy, which forwards them to the real backend servers. The client only knows the proxy address and not the actual IP addresses of the backend servers, thereby distributing load and ensuring stable operation of the website.