How to set up HTTPS for link click tracking

This tutorial will cover how to configure HSTS-compatible click tracking, meaning links.[YOUR_DOMAIN].com go through SSL/TLS. https://links.[YOUR_TOP_LEVEL_DOMAIN].com needs to reroute to https://links.iterable.com, where we set cookies on the URL for tracking purposes before redirecting back to your domain.

The reason for this setup is that links.iterable.com lives behind an AWS ELB. Currently the only way to support SSL on ELB is via a custom CloudFront Distribution, because it supports SNI and is able to proxy dynamic content to any origin server. Another option might be a server-less API Gateway + Lambda setup, but that won't be explored in this tutorial.

# Setup

# Generate an SSL certificate

1. Generate an SSL certificate for the domain (i.e. links.YOUR_DOMAIN.com) which you want to CNAME to links.iterable.com. We recommend doing this through AWS Certificate Manager due to the convenience, but you can use another service as well. You can learn about how to do that in Amazon's documentation.

2. Continue to the next step once you've approved the certificate.

# Create a new CloudFront distribution

1. Go to https://console.aws.amazon.com/cloudfront/ and click Create Distribution

2. Select Web as your delivery method

3. Origin Settings

   • Origin Domain Name: links.iterable.com
   • Origin Path: leave blank
   • Origin ID: ELB-linkslb-1505033010
   • Origin SSL Protocols: check only TLS1.2
   • Origin Protocol Policy: HTTPS Only
   • HTTP Port: 80 (default)
   • HTTPS Port: 443 (default)

4. Default Cache Behavior

   NOTE

   If using Iterable's unsubscribe page, allow POST as well (otherwise resubscribe requests from the page will fail)

   • Viewer Protocol Policy: HTTP and HTTPS (default)
   • Allowed HTTP Methods: GET, HEAD, OPTIONS, PUT, POST, DELETE
   • Cache Based on Selected Request Headers: All
   • Minimum TTL: 0 (default)
   • Maximum TTL: 31536000 (default)
   • Default TTL: 86400
   • Forward Cookies: All
   • Query String Forwarding and Caching: Forward all, cache based on all
   • Smooth Streaming: No (default)
   • Restrict Viewer Access: No (default)
   • Lambda Function Associations: leave blank

5. Distribution Settings

   • Choose the certificate that you created through ACM or through another service
   • Price Class: Use All Edge Locations (default)
   • AWS WAF Web ACL: None (default)
   • Alternate Domain Names (CNAMEs): links.[YOUR_DOMAIN].com
     • For example: links.mysite.com
   • SSL Certificate: Custom SSL Certificate
   • Custom SSL Client Support: Only Clients that Support Server Name Indication (SNI)
   • Security Policy: TLSv1.2
   • Supported HTTP Versions: HTTP/2, HTTP/1.1, HTTP/1.0 (default)
   • Default Root Object: leave blank
   • Logging: Off (default)
   • Bucket for Logs: leave blank
   • Log Prefix: leave blank
   • Cookie Logging: Off (default)
   • Enable IPv6: Enable
   • Distribution State: Enabled (default)
   • Click Create Distribution once everything looks good.

# Wrap up

1. On the CloudFront Distributions page, you should see your distribution in an In Progress status with a spinning arrow.

2. Once that changes to Deployed, copy the URL of your CloudFront distribution from Domain Name under the General tab of your distribution. You will need this for the Deploy step.

3. Navigate to Settings > Mail Domains in Iterable and add links.[YOUR_DOMAIN].com as a tracking domain. Set that tracking domain as default.

4. Also be sure to contact support@iterable.com to toggle on Use HTTPS.

# Confirm correct configuration

• Use the openssl command line tool to confirm correct configuration
  • openssl s_client -servername [CNAME] -connect [CLOUDFRONT_DISTRO_URL]:443
  • If you don't see an output that contains your certificate, double-check your CloudFront Distribution settings.

# Deploy

• Set a CNAME record in your DNS settings
  • links.[YOUR_DOMAIN].com CNAME [YOUR_CF_URL]
    • For example: links.mysite.com CNAME d49jhgak555.cloudfront.net