terraform-vpc-dns-filtering-nat-instance

Resources exaplained

VPC

• 1 VPC - 10.193.0.0/16
• 2 public subnets - 10.193.0.0/24, 10.193.1.0/24
• 2 private subnets - 10.193.2.0/24, 10.193.3.0/24
• 1 internet gateway
• 5 route tables - 1 for VPC default, 2 for each public subnets, 2 for each private subnets
• 1 dhcp options set
• 1 Gateway endpoint - To access S3 via PrivateLink

S3

• 1 S3 Bucket
• 1 S3 Bucket Policy - Allow VPC Endpoint access
• 1 S3 Bucket acl block - Block public access

EC2

• 2 Instances on each Public subnet : Working as a proxy for private subnet instnace to access Public internet(Also working as a SSH bastion to access private subnet instance. I added for testing purpose)
• • Configured Squid for proxy feature.
• • Perform domain whitelisting. Only allow access to https://*.google.com from Private instance.
• • For example, http://google.com will denied by Squid. But https://google.com will work.
• • I wanted Squid to perform redirect http request to https but currently not working as I intended.
• • (Need more research for Squid)
• 2 Instances on each Private subnet : Each instance can only access https://google.com
• • Caution : google.com will not work.

References

AWS Blog (Originally implemented with AWS CloudFormation) - How to add DNS filtering to your NAT instance with Squid