Bastion Server for all AWS instances

Question

i have more than 30 production Windows severs in all AWS regions. I would like to connect all servers from one base bastion host. can any one please let me know which one is good choice? How can i setup one bastion host to communicate all servers which is different regions and different VPC's? Kindly anyone give advice for this?

Answer 1

First of all, I would question what are you trying to achieve with a single bastion design? For example, if all you want is to execute automation commands or patches it would be significantly more efficient (and cheaper) to use AWS System Manager Run Commands or AWS System Manager Patch Manager respectively. With AWS System Manager you are getting a managed service that offers advance management capabilities with highest security principles built-in. Additionally, with SSM almost all access permissions could be regulated via IAM permission policies.

Still, if you need to set-up bastion host for some other purpose not supported by SSM, the answer includes several steps that you need to do. Firstly, since you are dealing with multiple VPCs (across regions), one way to connect them all and access them from you bastion's VPC would be to set-up a Inter-Region Transit Gateway. However, among other, you would need to make sure that your VPC (and Subnet) CIDR ranges are not overlapping. Otherwise, it will be impossible to properly arrange routing tables.

Secondly, you need to arrange that access from your bastion is allowed in the inbound connections of your target's security group. Since, you are dealing with peered VPCs you will need to properly allow your inbound access based on CIDR ranges.

Finally, you need to decide how you will secure access to your Windows Bastion host. Like with almost all use-cases relying on Amazon EC2 instances, I would stress to keep all the instances in private subnets. From private subnets you can always reach the internet via NAT Gateways (or NAT Instances) and stay protected from unauthorized external access attempts. Therefore, if your Bastion is in private subnet you could use the capability of SSM to establish a port-forwarding session to your local machine. In this way, you enable yourself the connection while even your bastion is secured in private subnet.

Overall, this answer to your question involves a lot of complexity and components that will definitely incur charges to your AWS account. So, it would be wise to consider what practical problem are you trying to solve (not shared in the question)? Afterwards, you could evaluate if there is an applicable managed service like SSM that is already provided by AWS. In the end, from a security perspective, granting access to all instances from a single bastion might not be best practice. If you consider scenarios in which you bastion is compromised for whatever reason, you basically compromised all of your instances across all of the regions.

Hope it gives you slightly better understanding of your potential solution.