Frustrated: 'What is my IP Address' tool keeps showing wrong public IP, need help!

The issue you're describing, where your IP address detection tool returns internal or proxy IPs instead of the true public IP, is a very common challenge, especially in modern web infrastructures involving CDNs, load balancers, and reverse proxies. The core problem usually lies in how your server-side application is interpreting incoming HTTP headers.

When a user accesses your tool directly, their public IP address is typically found in the REMOTE_ADDR server variable (or equivalent in your programming language/framework). However, when a user's request passes through a proxy server, a CDN (like Cloudflare, Akamai, or Sucuri), or even a corporate network's outbound proxy, the REMOTE_ADDR variable will reflect the IP of that intermediate server, not the end-user's actual IP.

To correctly identify the original public IP address, you need to inspect specific HTTP headers that these intermediate services add to the request. The most critical header to check is X-Forwarded-For. This header is designed to carry the originating IP address of a client that connects to a web server through an HTTP proxy or load balancer. It can sometimes contain a comma-separated list of IPs, where the leftmost IP is usually the client's original IP.

Other headers to consider, though less common for the original IP, include X-Real-IP (often used by Nginx) or Via. Your server-side logic needs to be configured to prioritize these headers over REMOTE_ADDR when they are present and trusted. For example, if you're running Apache with a reverse proxy, you might need modules like mod_remoteip. If using Nginx, the real_ip_header directive and set_real_ip_from rules are essential.

Here’s a breakdown of what to check next:

1. Inspect all incoming HTTP Headers: Use a logging tool or temporarily print out all HTTP headers your server receives for a request. Pay close attention to X-Forwarded-For, X-Real-IP, and any similar headers. This will confirm if these headers are even being passed to your application.
2. Order of Precedence: Your application logic should check for X-Forwarded-For first, then X-Real-IP, and only fall back to REMOTE_ADDR if neither of those trusted headers is present. Remember to parse X-Forwarded-For correctly if it's a comma-separated list (typically taking the first IP).
3. Trusting Proxies: If you are using a CDN or a known proxy server, ensure your server is configured to trust IPs from those services. Misconfiguration here can lead to security vulnerabilities if untrusted IPs can spoof X-Forwarded-For. Most web servers and frameworks have mechanisms to define "trusted proxy" IP ranges.
4. Client-Side vs. Server-Side: Confirm your tool is indeed a server-side IP detection tool. Client-side JavaScript can only detect the client's IP as seen by the browser, which might be a local network IP or the IP of a local proxy, not necessarily the public IP from the internet's perspective. For accurate public IP detection, a server-side approach is almost always required.
5. Test with Known Proxy Services: Actively test your tool using publicly available proxy servers or VPNs. This will help you simulate various scenarios and debug the header parsing.

Implementing robust IP detection requires careful handling of these headers. Are you currently using any specific CDN services or reverse proxies in front of your server?