Configuring a Security Group Rule

Context

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.

Scenarios

When you attempt to connect to an RDS DB instance through a private network, check whether the ECS and 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. Connect to the DB instance by referring to .
• If they are in different security groups, 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 group 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.

Constraints

The default security group rule allows all outgoing data packets. ECSs and RDS DB instances can access each other if they are 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 100 security groups in your cloud account.
• By default, you can add up to 50 security group rules to a security group.
• One RDS instance can be associated only with one security group, but one security group can be associated with multiple RDS instances.
• Too many security group rules will increase the first packet latency. You are advised to create no more than 50 rules for a security group.
• To enable access to 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.

The default value of Source is 0.0.0.0/0, indicating that RDS DB instances in the security group can be accessed from any IP address.

Procedure

1. Log in to the management console.
2. Click in the upper left corner of the page and choose Databases > Relational Database Service.
3. On the Instances page, click the DB instance name.
4. In the navigation pane on the left, choose Connectivity & Security. In the Security Group Rules area, view security group rules.
5. Click Add Inbound Rule or Allow All IP to configure security group rules.

   To add more inbound rules, click .

   

   Allow All IP allows all IP addresses to access RDS DB instances in the security group, which poses high security risks. Exercise caution when performing this operation.

   Table 1 Inbound rule parameter description

   Parameter	Description	Example Value
   Protocol & Port	Protocol: network protocol. Available options: All ports, Custom TCP, Custom UDP, ICMP, or GRE.	Custom TCP
   	Port: the port over which the traffic can reach your DB instance. RDS for MariaDB instances can use database ports 1024 to 65535, excluding 12017 and 33071, which are reserved for RDS system use.	3306
   Type	Supported source IP address type. Its value can be: IPv4 IPv6	IPv4
   Source	The source in an inbound rule is used to match the IP address or address range of an external request. The source can be: Single IP address: 192.168.10.10/32 (IPv4 address) IP address segment: 192.168.1.0/24 (IPv4 address segment) All IP addresses: 0.0.0.0/0 (any IPv4 address) Security group: sg-abc IP address group: ipGroup-test	0.0.0.0/0
   Description	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 (>).	N/A

6. Click OK.