25.3.5. About Routing in EC2

All Amazon EC2 servers have a source/destination checking routing feature activated by default. This feature drops any packets being sent to the server which have a destination different from the machine's IP address. If the VPN solution selected for connecting agents to the JON server includes a router, this feature needs to be turned off for the server or servers acting as routers or VPN gateways. This configuration setting can be accessed via the Amazon AWS console. Disabled source/destination checking is also required in a Virtual Private Cloud (VPC).
Some VPN configurations route general Internet traffic through the corporate VPN by default. It is recommended that you avoid this as it may be a slower and less efficient configuration for your particular needs.
While the use of a proper addressing schema is not a concern specific to JON, poor schemas can affect it. Amazon EC2 assigns IP addresses from the network. Instances usually have a public IP address also, but only network traffic on the internal IP address within the same availability zone is free. To avoid using the network in private addressing, there are a few things to consider.
  • When creating a VPC, avoid allocating addresses already in use in the private network to avoid connectivity problems.
  • If an instance needs access to availability zone local resources, make sure Amazon EC2 private addresses are used and traffic is not routed through the VPN.
  • If an Amazon EC2 instance will access a small subset of corporate private network addresses (for example only JON servers), only these addresses should be routed through the VPN. This increases security and lowers the chance of Amazon EC2 or private network address space collisions.