Step 4: Add 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.

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 1** Inbound rule parameter description
Parameter	Description	Example Value
Type	Source IP address version. You can select: IPv4 IPv6	IPv4
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. IP address: Single IP address: 192.168.10.10/32 (IPv4); 2002:50::44/128 (IPv6) All IP addresses: 0.0.0.0/0 (IPv4); ::/0 (IPv6) IP address range: 192.168.1.0/24 (IPv4); 2407:c080:802:469::/64 (IPv6) 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 2** Outbound rule parameter description
Parameter	Description	Example Value
Type	Destination IP address version. You can select: IPv4 IPv6	IPv4
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. Outbound rules control outgoing traffic over specific ports from instances in the security group.	22, or 22-30
Destination	Destination of the security group rule. The value can be an IP address or a security group to allow access to IP addresses or instances in the security group. For example: IP address: Single IP address: 192.168.10.10/32 (IPv4); 2002:50::44/128 (IPv6) All IP addresses: 0.0.0.0/0 (IPv4); ::/0 (IPv6) IP address range: 192.168.1.0/24 (IPv4); 2407:c080:802:469::/64 (IPv6)	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 outbound rule list is displayed.

Verifying Security Group Rules

After allowing traffic over a port in a security group rule, you need to ensure that the port used by the instance is also opened.

For example, if you have deployed a website on an ECS and want users to access your website through HTTP (80), you need to add an inbound rule to the ECS security group to allow access over the port. Table 3 shows the rule.

**Table 3** Security group rule
Direction	Protocol & Port	Source
Inbound	TCP: 80	IP address: 0.0.0.0/0

After adding the security group rule, perform the following operations to check whether the ECS port is opened and whether the rule is applied:

Log in to the ECS and check whether the ECS port is opened.
- Checking the port of a Linux server
  Run the following command to check whether TCP port 80 is being listened on:
  
  netstat -an | grep 80
  
  If the following figure is displayed, TCP port 80 is enabled.
  
  Figure 1 Command output for the Linux ECS
- Checking the port of a Windows server
  1. Choose Start > Run. Type cmd to open the Command Prompt.
  2. Run the following command to check whether TCP port 80 is being listened on:
    netstat -an | findstr 80
    
    If the following figure is displayed, TCP port 80 is enabled.
    
    Figure 2 Command output for the Windows ECS
Enter http://ECS EIP in the address box of the browser and press Enter.
If the requested page can be accessed, the security group rule has taken effect.