Secure Mechanism to Connect to Private Subnet in AWS

Correct Answer: D.

In an Amazon Web Services (AWS) context, a bastion host is defined as a server whose purpose is to provide access to a private network from an external network, such as the Internet.

Because of its exposure to potential attack, a bastion host must minimize the chances of penetration.

Option A is incorrect since this would expose the servers to the Internet.

Option B is incorrect since the NAT gateway is used for outward communication from the EC2 Instances only.

Option C is incorrect since the bastion host needs to be in a public subnet.

For more information on the bastion host, please refer to the below URL-

https://en.wikipedia.org/wiki/Bastion_host

To connect to a private subnet in AWS from an external network, you need to implement a secure mechanism. There are a few ways to achieve this, but the most common methods are using a bastion host or a NAT gateway.

A bastion host is a special-purpose instance that is designed to provide secure access to the private subnet. It acts as a jump server, allowing users to connect to it and then access resources within the private subnet. By using a bastion host, you can limit the exposure of your private subnet to the internet, which improves security.

To set up a bastion host, you can create an EC2 instance in a public subnet and configure it to allow SSH or RDP access. You would then create a security group that only allows connections from trusted IP addresses or ranges. Once the bastion host is set up, you can connect to it using SSH or RDP and then use it to access resources within the private subnet.

Option C (Add a bastion host in a private subnet) is incorrect because a bastion host should be deployed in a public subnet to allow external connections. Placing the bastion host in a private subnet would defeat the purpose of creating it.

Option D (Add a bastion host in a public subnet) is the correct answer.

Another option is to use a NAT gateway. A NAT gateway is a managed AWS service that provides internet access to resources in a private subnet. It does this by translating private IP addresses to public IP addresses. This allows resources in the private subnet to access the internet, but it does not allow external users to directly connect to the private subnet.

Option B (Change the Route tables for the subnet to add the NAT gateway) is also a valid answer, but it is not the most secure option because it would allow resources in the private subnet to initiate connections to the internet. If a malicious user gains access to one of these resources, they could potentially use it to launch attacks against other resources in the subnet.

Option A (Change the Route tables for the subnet to add the Internet gateway) is incorrect because it would expose the private subnet directly to the internet, which is not secure.