How to connect to a private server from AWS Lambda with AWS site to site VPN connection?

Question

I am trying to connect to a private server running on a windows machine from my AWS Lambda. The goal is to get some data from that server in the Lambda and work with it.

I've created a site-to-site VPN connection with that private server and the tunnels are up. I've put my lambda on the VPC that is connected to the site-to-site VPN. But still I can't connect to the server.

Can anyone please give me any resource or suggest the steps on how I should actually do it?

I've followed the following steps:

1. Created a VPC with a CIDR.
2. Created a private subnet from that VPC (let's say it's named subnet-1)
3. Added a site-to-site VPN, connected it to the private server and attached the VPC to the VPN connection.
4. Created a Lambda within the subnet-1.
5. Tried to ping the private server, but failed.

I'm not providing any code or any screenshot as this might make this question too long

Update: The issue is solved. I had a wrong configuration in the router table. After fixing that, it worked.

Answer 1

There are several things that can cause the connectivity to fail:

• Are there NACLs that prevents the traffic from flowing outside of the subnet?
• Is the lambda armed with a security group that allows passage towards the windows server?
• Is the VPN fully working at the time of testing?
• Are there any network firewalls on the on-premise network that prevents the traffic from the lambda to flow?
• Do the CIDRs of the VPC collide with the CIDRs of the on-premise network?
  • I would usually assign compatible subnets between my VPC and on-premise site to make this work.
• UPDATE: As per question's author, he faced router table related issue that prevents propagation of traffic between on-premise and AWS-based network.

These are the questions that I tend to ask when running into this problems but there could be other things that can cause your issue. Hope these checks help.