Change the security group associated with an ECS NIC.
in the upper left corner and select your region and project.The Change Security Group dialog box is displayed.

You can select multiple security groups. In such a case, the rules of all the selected security groups will be aggregated to apply on the ECS.
To create a security group, click Create Security Group.
Using multiple security groups may deteriorate ECS network performance. You are suggested to select no more than five security groups.