Proxy headers in Nginx - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of proxy headers in nginx?

Proxy headers in nginx pass important client information to the backend server, such as the original IP address and protocol, so the backend knows who made the request.

beginner

Which nginx directive sets the original client IP address in proxy headers?

The directive proxy_set_header X-Real-IP $remote_addr; sets the original client IP address in the X-Real-IP header.

intermediate

What does the X-Forwarded-For header represent?

The X-Forwarded-For header lists the IP addresses of the client and any proxies the request passed through, helping the backend identify the original client IP.

intermediate

How do you pass the original protocol (HTTP or HTTPS) to the backend in nginx proxy headers?

Use proxy_set_header X-Forwarded-Proto $scheme; to send the original protocol (http or https) to the backend server.

beginner

Why is it important to set proxy headers correctly in nginx?

Setting proxy headers correctly ensures the backend server receives accurate client info, which is vital for logging, security checks, and generating correct responses.

Which nginx directive sets the client's original IP address in proxy headers?

A proxy_set_header X-Real-IP $remote_addr;

B proxy_pass http://backend;

C listen 80;

D server_name example.com;

The directive proxy_set_header X-Real-IP $remote_addr; sets the original client IP address in the header.

What does the X-Forwarded-Proto header tell the backend?

A The client's IP address

B The request method (GET, POST)

C The backend server's IP

D The original protocol used (HTTP or HTTPS)

The X-Forwarded-Proto header tells the backend if the original request was HTTP or HTTPS.

Why is the X-Forwarded-For header useful?

A It sets the backend server's IP

B It lists all IPs the request passed through

C It changes the request method

D It sets the server name

The X-Forwarded-For header lists the client and proxy IP addresses for tracking the original client.

Which of these is NOT a typical proxy header set by nginx?

A X-Server-Name

B X-Forwarded-For

C X-Real-IP

D X-Forwarded-Proto

X-Server-Name is not a standard proxy header set by nginx.

What happens if proxy headers are not set correctly in nginx?

A Backend server crashes

B Nginx stops working

C Backend gets wrong client info

D Client IP is hidden from nginx

Without correct proxy headers, the backend server may not know the real client IP or protocol.

Explain why proxy headers like X-Real-IP and X-Forwarded-For are important in nginx proxy setups.

Think about how the backend knows who made the request.

Describe how to configure nginx to pass the original protocol and client IP to the backend server.

Look for directives that set headers with $remote_addr and $scheme.