Adding a Security Group Rule

Scenarios

A security group consists of inbound and outbound rules. You can add security group rules to allow or deny the traffic to reach and leave the instances (such as ECSs) in the security group.

Precautions

Before configuring security group rules, you need to plan access policies for instances in the security group. For details about common security group rules, see Security Group Configuration Examples.
Add as fewer rules as possible. Security Group Constraints lists the constraints on the number of rules in a security group.

By default, instances in the same security group can communicate with each other. If instances in the same security group cannot communicate with each other, possible causes are as follows:

The inbound rules for communications between these instances are deleted. Table 1 shows the inbound rules.

**Table 1** Inbound rules for communication between instances
Direction	Protocol & Port	Source/Destination
Inbound	All	Source: current security group (Sg-A)

Different VPCs cannot communicate with each other. The instances belong to the same security group but different VPCs.
You can use VPC peering connections to connect VPCs in different regions.

Adding Rules to a Security Group

Log in to the management console.
Click in the upper left corner and choose Network > Virtual Private Cloud.
The Virtual Private Cloud page is displayed.
In the navigation pane on the left, choose Access Control > Security Groups.
The security group list is displayed.
Locate the row that contains the target security group, and click Manage Rule in the Operation column.
The page for configuring security group rules is displayed.
On the Inbound Rules tab, click Add Rule.
The Add Inbound Rule dialog box is displayed.

Configure required parameters.

You can click + to add more inbound rules.

**Table 2** Inbound rule parameter description
Parameter	Description	Example Value
Protocol & Port	The network protocol used to match traffic in a security group rule. The value can be All, TCP, UDP, GRE, and ICMP.	TCP
Protocol & Port	Destination port used to match traffic in a security group rule. The value can be from 1 to 65535. Inbound rules control incoming traffic over specific ports to instances in the security group.	22, or 22-30
Source	Source of the security group rule. The value can be an IP address or a security group to allow access from IP addresses or instances in the security group. IPv4 address: xxx.xxx.xxx.xxx/32 Subnet: xxx.xxx.xxx.0/24 Any IP address: 0.0.0.0/0 If the source is a security group, this rule will apply to all instances associated with the selected security group.	0.0.0.0/0
Description	Supplementary information about the security group rule. This parameter is optional. The security group rule description can contain a maximum of 255 characters and cannot contain angle brackets (< or >).	N/A

Click OK.
The inbound rule list is displayed.
On the Outbound Rules tab, click Add Rule.
The Add Outbound Rule dialog box is displayed.

Configure required parameters.

You can click + to add more outbound rules.

**Table 3** Outbound rule parameter description
Parameter	Description	Example Value
Protocol/Application	The network protocol. Currently, the value can be All, TCP, UDP, ICMP, or more.	TCP
Port & Destination	Port: The port or port range over which the traffic can leave your ECS. The value ranges from 1 to 65535.	22, or 22-30
Port & Destination	Destination: The destination of the security group rule. The value can be a single IP address or a security group to allow access to IP addresses or instances in the security group. For example: xxx.xxx.xxx.xxx/32 (IPv4 address) xxx.xxx.xxx.0/24 (IP address range) 0.0.0.0/0 (all IP addresses) sg-abc (security group)	0.0.0.0/0
Description	Supplementary information about the security group rule. This parameter is optional. The security group rule description can contain a maximum of 255 characters and cannot contain angle brackets (< or >).	N/A