How Do I Configure a Security Group to Enable Access to RDS DB Instances?

When you attempt to connect to a DB instance through a private network, check whether the ECS and RDS DB instance are in the same security group.
- If the ECS and RDS DB instance are in the same security group, they can communicate with each other by default. No security group rules need to be configured.
- If the ECS and RDS DB instance are in different security groups, you need to configure security group rules for them, separately.
  - RDS DB instance: Configure an inbound rule for the security group with which the DB instance is associated.
  - ECS: The default security group rule allows all outgoing data packets. In this case, you do not need to configure a security rule for the ECS. If not all outbound traffic is allowed in the security group, you need to configure an outbound rule for the ECS.
When you attempt to connect to a DB instance through an EIP, you need to configure an inbound rule for the security group associated with the DB instance.