Default Security Group and Its Rules

If you have not created any security groups yet, the system automatically creates a default security group for you and associates it with the instance (such as an ECS) when you create it. A default security group has the following rules:

  • Inbound rules control incoming traffic to instances in a security group. Only instances in the same security group can communicate with each other, and all inbound requests are denied.

  • Outbound rules allow all outbound traffic and response traffic to the outbound requests.

**Figure 1** Default security group

Figure 1 Default security group

Note

  • You cannot delete the default security group, but you can modify existing rules or add rules to the group.

  • The default security group is automatically created to simplify the process of creating an instance for the first time. The default security group denies all external requests. To log in to an instance, add a security group rule by referring to Remotely Logging In to an ECS from a Local Server.

Table 1 describes the default rules for the default security group.

Table 1 Default security group rules

Direction

Protocol

Port/Range

Source/Destination

Description

Outbound

All

All

Destination: 0.0.0.0/0

Allows all outbound traffic.

Inbound

All

All

Source: the current security group (for example, sg-xxxxx)

Allows communications among ECSs within the security group and denies all inbound traffic (incoming data packets).