[FIX] Amazon EC2 gateway NAT doesn't work?

gistfile1.txt

# Had this crazy networking problem when trying to use an EC2 instance as a NAT gateway.
#
# Here's a fix I found buried in documentation here:
# http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_NAT_Instance.html
#

Disabling Source/Destination Checks

Each EC2 instance performs source/destination checks by default. This means that the instance must be the source or destination of any traffic it sends or receives. However, a NAT instance must be able to send and receive traffic when the source or destination is not itself. Therefore, you must disable source/destination checks on the NAT instance.

Use the following procedure to disable the SrcDestCheck attribute for a NAT instance that's either running or stopped.

To disable source/destination checking on a NAT instance

    Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.

    Click Instances in the navigation pane.

    Right-click the NAT instance, and then select Change Source / Dest Check.

    For a NAT instance, this attribute should be disabled. Click Yes, Disable.

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