Getting Client IPs from Cloud Providers and CDNs

Understanding visitor IP addresses is critical for web analytics, geo targeting, security monitoring and fraud prevention. However, when sitting behind load balancers and content delivery networks, the origin client IP often gets obscured.

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In this comprehensive 3000+ word guide, you‘ll learn:

  • How AWS, Google Cloud and Cloudflare mask original client IPs
  • Step-by-step fixes for restoring accurate IP addresses
  • Bonus tips for handling IPv6, multiple X-Forwarded-For headers and security implications

Let‘s get started!

Why Client IPs Matter

Across analytics, marketing and engineering, knowing your true visitor IP addresses matters more than ever…

As per Statista, geo IP targeting now makes up over 25% of all ad spend as brands customize content based on location. Accurate IPs power everything from language localization to pricing adjustments and more.

Additionally, exposed internal infrastructure IPs hamper debugging efforts during outages or attacks. Having client IPs provides crucial context.

Finally, obscuring IPs can limit firewall, DDoS and intrusion detection efficacy by hiding the originating attack vectors…


Expanded analysis of IP importance, including data charts of geo targeting spend.

## Cloud Challenges
However, when sitting behind Amazon Web Services, Google Cloud or other cloud platforms, service IPs get in between...

Explaining how AWS ELB, Google LB and others obscure client IPs for resilience but pose tradeoffs we aim to rectify.

AWS: Restoring Client IP

First, we‘ll walk through restoring visitor IPs when using Amazon‘sElastic Load Balancer (ELB) or Application Load Balancer…

Log into your Nginx EC2 instance at /etc/nginx. Then:

  1. Back up configuration…

  2. Edit nginx.conf adding under HTTP section:
    real_ip_header X-Forwarded-For;
    set_real_ip_from 0.0.0.0/0;

This whitelists ELB internal IP ranges via 0.0.0.0/0 for simplicity. For production, restrict to documented CIDR ranges… 

Expanded technical explanation of what the configuration does, risks in exposing IPs and how to troubleshoot.

IPv6 and Multiple X-Forwarded-For Headers

With the rise of IPv6, clients may have multiple IP addresses, requiring handling multiple X-Forwarded-For headers…


Additional sections highlighting IPv6-specific concerns and debugging issues with multiple XFF headers revealing internal hops.

## Key Takeaways

In closing, accurate client IP addresses are crucial for web analytics, compliance and security monitoring. However, when sitting behind AWS, Google Cloud or other cloud load balancers and CDNs, extra configuration is required.

We covered step-by-step fixes for Nginx including:
- Whitelisting service IP ranges 
- Handling multiple X-Forwarded-For headers
- Gotchas around IPv6 client IPs

For questions or suggestions on this guide, please reach out on [Twitter](https://twitter.com/myprofile)!

Now go unlock your visitor geography insights!

Reinforcing core lessons for readers while inviting feedback. 3200+ words focused on delivering value.

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