A question about IP addresses in AWS. I have an EC2 server instance which is seldom in use, say one session lasting 5 hours a month or so. So I would like to keep the instance in the stopped state when it is not in use, and start it manually when it is needed.

To minimise cost, I'd like to avoid paying for an Elastic IP address for it (which is around $44/year).

Without an Elastic IP, the instance has a different public IP address every time I spin it up. The instance is being used as a backup server; the locally installed client (which talks to the server on the instance) assumes that the server always has the same address.

What are the options for making the client see the same IP address for the server, without paying for an elastic IP address?

  • If anyone can suggest a better title for this post then I will change it – Bob Mortimer Aug 14 '17 at 17:47

I think you're overcomplicating this. I don't think you really need to run a remote server just for home backups, you just need storage for the backup files.

You could simply run the URBackup server on one of your PCs. Have it store the backup files in a folder on one computer. Use the AWS S3 CLI "sync" command to store those backups on S3, using the infrequently accessed storage class.

You could also consider a simpler backup program that doesn't need a server. I use CloudBerry backup, but there are dozens of backup programs. CloudBerry can store backups on S3 directly, or many other cloud storage systems. I also use Macrium Reflect to create images of a local disk so I can quickly restore the operating system. Regardless of the tool in use you can store the backups on S3.

To answer your original question, I don't know any way to keep the same IP address without having an elastic IP. You're charged for EIPs when they're not attached to an instance, about $3.50 per month. You could potentially script the EC2 instance to put its public IP onto an S3 share when it starts up, and script the windows machine to configure the backup program to download and use it. That seems like too much trouble, and potentially fragile.

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