Configuring a Security Group Rule

Scenarios

A security group is a collection of access control rules for ECSs and RDS DB instances that have the same security protection requirements and are mutually trusted in a VPC.

This section describes how to create a security group to enable specific IP addresses and ports to access RDS.

• When you attempt to connect to an RDS DB instance through an EIP, you need to configure an inbound rule for the security group associated with the DB instance.
• Check whether the ECS and RDS DB instance are in the same security group.
  • If the ECS and RDS DB instance are in the same security group, they can communicate with each other by default. No security group rule needs to be configured.
  • If the ECS and RDS DB instance are in different security groups, you need to configure security group rules for them, separately.
    • RDS DB instance: Configure an inbound rule for the security group with which the RDS DB instance is associated.
    • ECS: The default security group rule allows all outgoing data packets. In this case, you do not need to configure a security rule for the ECS. If not all outbound traffic is allowed in the security group, you need to configure an outbound rule for the ECS.

Precautions

The default security group rule allows all outgoing data packets. ECSs and RDS DB instances can access each other if they are deployed in the same security group. After a security group is created, you can configure security group rules to control access from and to the DB instances in the security group.

• By default, you can create a maximum of 500 security group rules.
• One security group can be associated with only one RDS DB instance.
• Too many security group rules will increase the first packet latency. You are advised to create a maximum of 50 rules for each security group.
• To access an RDS DB instance from resources outside the security group, you need to configure an inbound rule for the security group associated with the RDS DB instance.

If you use 0.0.0.0/0, you enable all IP addresses to access RDS DB instances in the security group.

Procedure

1. Log in to the management console.
2. Click in the upper left corner and select a region and a project.
3. Click Service List. Under Database, click Relational Database Service. The RDS console is displayed.
4. On the Instance Management page, click the target DB instance.
5. Configure security group rules.
   • In the Connection Information area on the Basic Information page, click the security group.
     Figure 1 Connection information
     

6. On the inbound rule tab, click Add Rule. In the displayed dialog box, set required parameters to add an inbound rule.
   You can click + to add more inbound rules.

   Figure 2 Adding an inbound rule
   

   Table 1 Inbound rule parameter description

   Parameter	Description	Example Value
   Protocol & Port	Specifies the network protocol. Currently, the value can be All, TCP, UDP, ICMP, GRE, or others.	Custom TCP
   	Port: specifies the port or port range over which the traffic can reach your ECS.	When connecting to the DB instance through a private network, enter the port of the target DB instance.
   Source	Specifies the source of the security group rule. The value can be another security group or a single IP address. For example: xxx.xxx.xxx.xxx/32 (IPv4 address) xxx.xxx.xxx.0/24 (subnet) 0.0.0.0/0 (any IP address)	0.0.0.0/0
   Description	Provides supplementary information about the security group rule. This parameter is optional. The description can contain a maximum of 255 characters and cannot contain angle brackets (<) or (>).	-