When you run workloads inside a VPC private subnet, outbound-only connectivity sounds easy on paper. In reality, it demands tight control, secure routing, and deployment patterns that don’t slow you down. A good private subnet proxy setup can open outbound traffic while keeping inbound surfaces sealed shut. The trick is deploying it in a way that’s fast, reliable, and repeatable.
The foundation is your routing. Private subnets need a way to send traffic through a proxy in a public subnet, often paired with a NAT gateway or custom proxy instance. This ensures outbound connections reach the internet or other networks while inbound traffic is blocked by design. Using route tables to direct only the required CIDR ranges through the proxy adds precision and reduces exposure.
Security groups and network ACLs must work in lockstep. Everything outbound from the private subnet should pass through the proxy. Nothing from the outside should connect in. Use minimum necessary port ranges and avoid wildcard allowances. TLS termination can be offloaded to the proxy layer, and outbound inspection tools can run at that choke point to ensure compliance.