การส่งต่อส่วนหัวและ IP ของไคลเอนต์

When Nginx acts as a reverse proxy, the upstream server only sees a connection coming from Nginx, not the real client. Without extra configuration, the backend loses the visitor's original IP, host, and protocol.

To keep this information, Nginx must forward headers describing the original request.

By default Nginx may pass the upstream server's address as the Host header. Many apps rely on the original host for routing or building absolute URLs.

Set it explicitly so the backend sees what the client requested:

The X-Real-IP header carries the original client's address so the backend can log or rate-limit by real visitor.

• $remote_addr holds the connecting client's IP

X-Forwarded-For is a comma-separated chain of every proxy a request passed through. The variable $proxy_add_x_forwarded_for appends the current client to any existing value.

If TLS terminates at Nginx, the backend speaks plain HTTP and cannot tell the original scheme. Send X-Forwarded-Proto so it can build correct https URLs and set secure cookies.

A standard reverse-proxy block bundles all four headers. This is the baseline you will reuse across nearly every project.

Repeating the same headers in every location is error prone. Put them in an include file and pull it in wherever needed.

Clients can spoof X-Forwarded-For. Only trust it from known proxies. Use the real_ip module to set the true client IP from trusted upstreams.

You can strip a header by setting it to an empty string. This is useful to hide internal headers from upstream or to prevent leaking server identity.

You can inject your own headers to give the backend extra context, such as a tag identifying which gateway handled the request.

Test from a backend that echoes headers (or use an inspector endpoint). You should see X-Real-IP matching your machine and X-Forwarded-Proto matching the scheme you used.

You learned how Nginx rewrites requests and how to keep client context intact:

• Host preserves the requested domain
• X-Real-IP and X-Forwarded-For carry the client IP
• X-Forwarded-Proto reports the original scheme
• Use real_ip and trusted ranges to avoid spoofing

These headers are the foundation of a transparent, secure reverse proxy.