How to Set Up CloudFront IP Whitelist with AWS WAF

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In enterprise applications and API protection, AWS CloudFront provides high-performance content delivery. But how do you ensure only authorized IPs can access your resources? This guide explains how to configure a CloudFront IP whitelist using AWS WAF to enhance security and prevent unauthorized access.

Why Do You Need a CloudFront IP Whitelist?

Common Use Cases:

  • Internal Enterprise APIs: Allow only company fixed IPs to access internal system APIs
  • Partner Integration: Restrict API calls to specific partner IP addresses
  • Test Environment Protection: Prevent test environments from external scanning or attacks
  • DDoS Risk Mitigation: Limit source IP ranges to reduce distributed attack surface

Technical Considerations:

  • CloudFront itself doesn’t have built-in IP whitelist functionality; you must use AWS WAF
  • WAF rules execute at CloudFront edge locations without affecting cache performance
  • Suitable for applications requiring an additional security layer, but adds management overhead

Step 1: Query CloudFront Source IPs

Method 1: Using nslookup to Resolve Domain

First, query the IP addresses resolved by CloudFront:

nslookup example.com

Method 2: Using dig to Resolve Domain

dig +short example.com

Sample Output:

example.com canonical name = dxxxxxxxxxx.cloudfront.net.
Name: dxxxxxxxxxx.cloudfront.net
Address: 13.35.185.65
Address: 13.35.185.104
Address: 13.35.185.53
Address: 13.35.185.46

This indicates CloudFront uses dxxxxxxxxxx.cloudfront.net as a CNAME, mapping to Amazon CloudFront IP addresses.

Important Notes:

  • CloudFront IPs change dynamically; don’t whitelist these IPs directly
  • Configure whitelist based on client source IPs (IPs accessing CloudFront), not CloudFront’s IPs
  • To restrict communication between CloudFront and Origin, use CloudFront custom headers or Origin Access Identity (OAI)

Step 2: Configure AWS WAF to Restrict IP Access to CloudFront

AWS WAF controls which IPs can access CloudFront through Web ACL.

Create AWS WAF Web ACL

  1. Open AWS WAF Console → AWS WAF
  2. Create Web ACL
    • Click 「Create web ACL」
    • Select Resource Type → Choose CloudFront (CloudFront is a global resource, so WAF must be deployed in Global (CloudFront) region)
    • Enter Web ACL Name (e.g., CloudFront-IP-Whitelist)
    • Click Next

Create IP Whitelist Rule

  1. Add Rule
    • Click 「Add rules」 → 「Add my own rules and rule groups」
    • Enter Rule Name (e.g., AllowOnlyMyIP)
    • Rule Type: Select IP set
    • Set Action to Allow
    • Select「Create an IP set」
  2. Create IP Set
    • Click 「Create IP set」
    • Enter IP Set Name (e.g., MyIPWhitelist)
    • Select Region as「Global (CloudFront)」
    • Enter Allowed IPs or IP Ranges
      • Single IP: 203.0.113.5/32
      • IP Range (e.g., company internal IPs): 203.0.113.0/24
    • Click「Create」and Save
  3. Configure Default Action
    • Return to Web ACL configuration page
    • Set Default action to Block (block all IPs not in whitelist)

Rule Logic Explanation:

  • Web ACL first checks if IP is in whitelist (Allow rule)
  • If IP is in whitelist, allow through
  • If IP is not in whitelist, apply default action (Block)

Bind WAF Web ACL to CloudFront

  1. Return to Web ACL Main Page → Click 「Add AWS resources」
  2. Select CloudFront Distribution
  3. Apply Web ACL to CloudFront
  4. Save Configuration

Propagation Time: Typically takes 3-5 minutes for WAF rules to take effect across all edge locations.

Step 3: Verify AWS WAF Is Working

Method 1: Test Using curl

Test with Whitelisted IP

curl -I -X GET https://example.com/

Expected Response

HTTP/2 200 OK

This indicates the request succeeded and the IP is in the whitelist.

Test with Non-Whitelisted IP

curl -I -X GET --interface eth1 https://example.com/

Expected Response

HTTP/2 403 Forbidden

This indicates WAF successfully blocked unauthorized access.

Method 2: Check AWS WAF Logs

  1. Open AWS WAF Console
  2. Select Web ACL → Logging and metrics
  3. Enable CloudWatch Logging
  4. Use CloudWatch to check「blocked requests」, ensuring non-whitelisted IPs are blocked by WAF

Log Contents Include:

  • Request source IP
  • Request timestamp
  • Matched rule
  • Action taken (Allow / Block)

AWS WAF Cost Estimation

AWS WAF Pricing Structure:

  • Web ACL (Web Access Control List): $5.00 per Web ACL per month
  • Rules: $1.00 per rule per month
  • Requests: $0.60 per million requests

Cost Estimation Example:

Assuming you use one Web ACL with one IP whitelist rule, processing 10 million requests per month, the cost would be:

  • Web ACL: $5.00/month
  • Rule: $1.00/month
  • Requests: $0.60 × 10 = $6.00/month

Total: Approximately $12.00/month

Note: Pricing may change according to AWS pricing policies. Please refer to official pricing for the latest estimates.

Common Issues and Solutions

Issue 1: Whitelisted IP Still Blocked

Possible Causes:

  • Incorrect IP format in IP Set (not using CIDR format like /32)
  • WAF rule priority misconfigured (Block rule has higher priority than Allow)
  • WAF changes not yet propagated to all edge locations (wait 3-5 minutes)

Solutions:

  • Verify IP Set format: single IP uses x.x.x.x/32, IP range uses x.x.x.0/24
  • Check rule order: Allow rules should be before Block rules
  • Wait 5 minutes and retest

Issue 2: WAF Logs Not Showing Block Records

Possible Causes:

  • WAF logging not enabled
  • CloudWatch Logs permission issues

Solutions:

  • Enable「Logging」in Web ACL settings
  • Verify CloudWatch Logs resource policy allows WAF to write logs

Issue 3: How to Configure Whitelist for Dynamic IP Environments?

Solutions:

  • Use AWS Lambda to periodically update IP Set (automatic updates via API)
  • Consider using VPN with fixed IP
  • Use alternative authentication methods (like API Key, JWT Token)

Conclusion

Through this guide, you have completed:

  • Queried CloudFront source IPs and understood the difference between CloudFront and client IPs
  • Configured AWS WAF to restrict IP access to CloudFront using Web ACL + IP Set for security
  • Verified WAF rules are working, ensuring non-whitelisted IPs receive 403 Forbidden
  • Understood AWS WAF cost structure to predict usage costs
  • Learned common issues and solutions to avoid configuration errors

Security Reminders:

  • Regularly review and update whitelist IPs, removing unused IPs
  • Combine with other security measures (like SSL/TLS, API authentication) to build multi-layered protection
  • Monitor WAF logs to detect abnormal access attempts promptly

Related Articles

Related posts:

  1. 如何使用 AWS WAF 設定 CloudFront IP 白名單
  2. 利用 CloudFront 訪問 S3 的私有內容
  3. AWS VPC Public 與 Private Subnet 設計與配置指南
  4. AWS VPC Public and Private Subnet Design and Configuration Guide

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