how to set same IP for multiple instances when using outgoing restful request?

Question

Hi,
I am trying to use 3rd party services with my EC2 instances.
The 3rd party service has some security rules. one of them is that my instance's IP has to be whitelisted.

I am working with multiple instances that can be scaled over time and I don't want to set Elastic IP for each instance. and I don't want to register new IP every time I'm adding a new instance.

Is there a way to use a service (maybe proxy) that listen to all my instances and forward the outgoing request with the same IP?

I also believe it is more secure to put my outgoing requests behind a proxy.

Can I get an explanation/tutorial for doing that?

Thank you!
Asaf

Answer

This is presented as a [use case for a NAT Gateway](https://docs.aws.amazon.com/vpc/latest/userguide/nat-gateway-scenarios.html#private-nat-allowed-range).

When you create a public NAT Gateway you associate it with an elastic IP which the IP address that outside services would see when it is used by your servers:
> The NAT gateway replaces the source IP address of the instances with the IP address of the NAT gateway. For a public NAT gateway, this is the elastic IP address of the NAT gateway.

how to set same IP for multiple instances when using outgoing restful request?

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