Firewall rules define a range of IP addresses that are allowed to connect to the cluster. You can configure your firewall rules on a per cluster basis. This applies to your primary cluster as well as any read replicas associated with that cluster. By default your cluster is configured with rules that allow for all traffic into it:
In order to restrict your database, you can delete the defaults and create new rules within the Networking tab of your cluster. All network rules are in CIDR notation. For a single IP, please add
/32 to the end of the IP.
Firewall rules cannot overlap. For example, if you do not delete the default of
0.0.0.0/0, you will not be able to add any new IPv4 rules as they will overlap with the default.