title: How can I attach a private IP from a different subnet to an EC2 instance?
body: <p>First of all, I know enough about VPN setup just to be dangerous, so hopefully I can explain my problem clear enough.</p>
  
  <p>We have a server in our AWS VPC that a client will need to access via a VPN connection. The client wants to access the server as though it's a specific IP address on their internal network. That IP address is not within the subnet we use, nor even the VPC, so I'm wondering if/how I can map it to our server. It seems like I want something like an EIP, only a private one I can select. Is that possible?</p>
  
  <p>Here are some values from the AWS side:</p>
  
  <pre><code>vpc: 10.0.0.0/16
  subnet: 10.0.1.0/24
  instance: 10.0.1.140
  </code></pre>
  
  <p>The desired IP address from the client's perspective is 10.128.13.25. I'd like to configure the AWS side so that requests to 10.128.13.25 route to 10.0.1.140.</p>
  
  <p>I've done something similar outside of AWS. In that case the server was multi-homed, and configured one interface as 10.128.13.25. I'm not sure how to do that within AWS, though. Any suggestions on how I can do it?</p>
  
  <p><strong>UPDATE:</strong></p>
  
  <p>I tried to add an ENI with the desired IP address, but that address is not just in a different subnet, it's outside the 10.0.0.0/16 range of our VPC. I've seen a little about peer-to-peer VPCs. Do I need to create a second VPC, then set them up as peers?</p>