Despite being accessible through the private network, why is it not possible to access an EC2 server via the public network?

Have you ever encountered a situation with an AWS EC2 instance where the server is running and accessible through a private network, but not accessible through the public network? If you are unable to access your EC2 server using its public IP address, there could be several reasons for this.

The reason why you cannot access an EC2 server via the public network, even though it is accessible through the private network, is due to the default security settings in Amazon Web Services (AWS).

By default, EC2 instances in AWS are launched within a Virtual Private Cloud (VPC), which acts as a private network isolated from the public internet. These instances are assigned private IP addresses that can only be reached within the VPC.

To make an EC2 instance accessible from the public internet, you need to configure the appropriate networking settings. This includes assigning a public IP address to the instance and configuring security groups and network access control lists (ACLs) to allow inbound traffic from the internet.

Check your firewall settings to ensure that the specified ports, such as 80 or 443, are allowed.

The first possible reason is that your server's firewall configuration may not be allowing traffic on these ports. By allowing this traffic, you may be able to access the server.

Allocate and associate an Elastic IP address with your EC2 instance.

This will provide a static public IP address that can be used to access the instance.

Check the security groups to ensure that they allow traffic on the specified ports.

One possible reason for this issue is that your security group settings may not be properly configured. By allowing traffic on these ports in the security group settings, you can access the EC2 server via the internet's public network.

Ensure that the Network ACL associated with the subnet of your VPC allows the necessary inbound and outbound traffic to and from the EC2 instance.

By default, all inbound and outbound traffic is allowed in the Network ACL, but you may have customized rules that need to be adjusted.