Stop China from connecting to my Google Compute Engine server
Solution 1:
Firewalls have two main choices when receiving unwanted connection attempts.
- REJECT - send a response saying the port/service/etc is closed or
unavailable - DROP - don't respond and just drop the packets
The words REJECT/DROP aren't standard or used across all firewalls but the difference between the concepts behind the two possible actions will be there. You want to do the equivalent of DROP so there is no outbound traffic. As mentioned by others inbound traffic incurs no charges.
Solution 2:
There is no charge for the Google Compute Engine ingress traffic. Take a look at GCE network pricing. If you've been charged for the ingress traffic, you can contact the Cloud billing team to clarify and fix the charge.
Regarding the requests to port 11, as far as this port is blocked in your GCE network's firewall your VM instances should be safe and the requests should not eat up the bandwidth.
I'm curious to know the way in which you monitor these requests.