is there a way to geo block China from connecting my GCP VMs?
I see this item in my billing:
Network Internet Egress from Americas to China
Can I block the whole lot?
Is there a way to investigate what kind of IPs are connecting? (I know you can add logging rules to the GCP firewall but I am fuzzy on the details)..
If none of the above possible - is there a public list of rules for Linux firewalls (CentOS 8) to block IPs by countries?
There are several ways to achieve your use case. With GCP product, you can use Cloud Armor for a location-based traffic filtering through its Web Application Firewall.
Here are several threads that can also help you on your use case: