Adding a Security Group Rule

Scenarios

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 Examples.
• Add as fewer rules as possible. Constraints on Using Security Groups lists the constraints on the number of rules in a security group.
• After allowing traffic over a port in a security group rule, ensure that the port used by the instance is opened. For details, see Verifying Security Group Rules.
• 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	Priority	Action	Type	Protocol & Port	Source/Destination
    Inbound	1	Allow	IPv4	All	Source: current security group (Sg-A)
    Inbound	1	Allow	IPv6	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

1. Log in to the management console.
2. Click in the upper left corner and choose Network > Virtual Private Cloud.

   The Virtual Private Cloud page is displayed.

3. In the navigation pane on the left, choose Access Control > Security Groups.

   The security group list is displayed.

4. Locate the target security group and click Manage Rules in the Operation column.

   The page for configuring security group rules is displayed.

5. On the Inbound Rules tab, click Add Rule.

   The Add Inbound Rule dialog box is displayed.

6. Configure required parameters.

   You can click to add more inbound rules.

   Table 2 Inbound rule parameter description

   Parameter	Description	Example Value
   Priority	The security group rule priority. The priority value ranges from 1 to 100. The default value is 1 and has the highest priority. The security group rule with a smaller value has a higher priority.	1
   Action	The value can be Allow or Deny. If the Action is set to Allow, traffic is allowed to access the cloud servers in the security group over specified ports. If the Action is set to Deny, traffic is denied to access the cloud servers in the security group over specified ports.	Allow
   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 protocol can be All, TCP, UDP, GRE, or ICMP.	TCP
   	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, 22-30
   Source	Source of the security group rule. The value can be an IP address, a security group, or an IP address group, to allow access from the IP addresses or the 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) IP address group: ipGroup-A If the source is a security group, this rule will apply to all instances associated with the selected security group.	192.168.0.0/24
   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

7. Click OK.

   The inbound rule list is displayed.

8. On the Outbound Rules tab, click Add Rule.

   The Add Outbound Rule dialog box is displayed.

9. Configure required parameters.

   You can click to add more outbound rules.

   Table 3 Outbound rule parameter description

   Parameter	Description	Example Value
   Priority	The security group rule priority. The priority value ranges from 1 to 100. The default value is 1 and has the highest priority. The security group rule with a smaller value has a higher priority.	1
   Action	The value can be Allow or Deny. If the Action is set to Allow, access from ECSs in the security group is allowed to the destination over specified ports. If the Action is set to Deny, access from ECSs in the security group is denied to the destination over specified ports.	Allow
   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 protocol can be All, TCP, UDP, GRE, or ICMP.	TCP
   	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, 22-30
   Destination	Destination of the security group rule. The value can be an IP address, a security group, or an IP address group, to allow access to the IP address or the 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) IP address group: ipGroup-A	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

10. Click OK.

    The outbound rule list is displayed.

Verifying Security Group Rules

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 4 shows the rule.

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

1. 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

        
        
2. 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.