Security Group
Security group is composed of a series of rules used to control inbound and outbound traffic of network interfaces. It is a stateful packet filtering virtual firewall that can be used for network access control of single or multiple cloud servers and is an important means of network security isolation. Security group is designed based on the whitelist principle, and it rejects inbound/outbound traffic of network interfaces by default. You can add security group rules as needed to allow traffic to pass.