We have a web/database server on Amazon AWS and I have recently discovered it is getting a ton of attack attempts from various international IPs. After checking a few they mostly seem to reside in China. This is causing performance issues and occasionally web requests are being dropped all together.
The web server services developers and clients in California by they are mobile so we can't nail down their IP addresses.
Since I don't care about any traffic outside of the US how can I best block this? The AWS Security Groups don't really seem to allow that, unless I created inbound rules whitlisting any US IP classes that would fit but that's pretty time consuming.
Is there a table of Class B ranges or something that I could filter out US ranges and cut and paste into a Windows Firewall Inbound Rule?