Creates a new DB security group. DB security groups control access to a DB instance.

A DB security group controls access to EC2-Classic DB instances that are not in a VPC.

EC2-Classic was retired on August 15, 2022. If you haven't migrated from EC2-Classic to a VPC, we recommend that you migrate as soon as possible. For more information, see Migrate from EC2-Classic to a VPC in the Amazon EC2 User Guide, the blog EC2-Classic Networking is Retiring – Here’s How to Prepare, and Moving a DB instance not in a VPC into a VPC in the Amazon RDS User Guide.