Understanding How to Obtain Client-Side Source IP (Global IP) on the WEBAPP side that is Booting on EC2

Learn how to obtain client IP on the server side.

There are many configurations of EC2.
Are you using ALB (ELB), Nginx, or what is the framework of the web application?
I can't say this because it doesn't say that, but I will answer the principle.

The IP address from which it is accessed will arrive in the HTTP header to the final server process, but will be replaced by the address of that server if it is halfway through a load balancer or reverse proxy.Therefore, settings for delivering the original IP address are provided in those intermediate server settings.

See the following values in the HTTP request header:

• REMOTE_ADDR

  • HTTP source address
  • When directly connected, point to the address of the person accessing the browser
  • https://datatracker.ietf.org/doc/html/rfc3875#section-4.1.8

• X-Forwarded-Forwarded

  • Keep the original client IP when going through a proxy server
  • Not retained by proxy settings, etc.
  • https://developer.mozilla.org/ja/docs/Web/HTTP/Headers/X-Forwarded-For

• X-REAL-IP

  • Nginx and other settings, where usage is mentioned all over the Internet but no specifications exist
  • Story behind X-Forwarded-For and X-Real-IP headers-The Matrix has you...

REMOTE_ADDR

• HTTP source address
• When directly connected, point to the address of the person accessing the browser
• https://datatracker.ietf.org/doc/html/rfc3875#section-4.1.8

X-Forwarded-Forwarded

• Keep the original client IP when going through a proxy server
• Not retained by proxy settings, etc.
• https://developer.mozilla.org/ja/docs/Web/HTTP/Headers/X-Forwarded-For

X-REAL-IP

• Nginx and other settings, where usage is mentioned all over the Internet but no specifications exist
• Story behind X-Forwarded-For and X-Real-IP headers-The Matrix has you...

The following articles are helpful.

• remote_addr, x-forwarded-for, x-real-ip, and -Carpe Diem
• python-How do I get user IP address in django?-Stack Overflow
Headers with
• X- are not standardized headers HTTP headers - HTTP|MDN