To change the security group associated with an ECS network interface, perform the operations described in this section.
in the upper left corner and select a region and project.The Change Security Group panel slides out.

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