[SOLVED] How to make use of use internet in one EC2 by another EC2 which has no internet connectivity

How to make use of use internet in one EC2 by another EC2 which has no internet connectivity

I have two AWS EC2 instances namely EC2A and EC2B. Both instances;

runs Amazon Linux 2023
have same subnet
have same VPC
have same availability zone

EC2A has both public IP and private IP, while EC2B has private IP only. I am able to login to EC2A from my desktop but not to EC2B since it doesn't have a public IP, but it is possible to SSH into EC2B from EC2A.

I am able to update and install YUM packages in EC2A, but not in EC2B (since there is no internet). I have whitelisted IP of EC2A for ports 80 and 443 in security group attached to EC2B.

Is there any way to make use of internet in EC2A for installing YUM packages or to access internet in EC2B by making use of internet in EC2A? How can I achieve this?

Solution

With your current architecture, no it would not be possible.

While you could configure your 'public' instance as a NAT instance, that would require the 'private' instance to be in a separate subnet, with a Route Table entry that directs all traffic to the 'public' instance.

The normal setup for a public and private instance would be:

Public instance in a public subnet
Private instance in a private subnet
NAT Gateway (or NAT Instance) in the public subnet
Route table on the private subnet sending Internet-bound traffic to the public instance