Configuring Security Group Rules

Scenarios

Similar to firewall, a security group is a logical group used to control network access. You can define access rules for a security group to protect the ECSs that are added to this security group.

• Inbound: Inbound rules allow external network traffic to be sent to the ECSs in the security group.
• Outbound: Outbound rules allow network traffic from the ECSs in the security group to be sent out of the security group.

For details about the default security group rules, see Default Security Groups and Security Group Rules. For details about configuration examples for security group rules, see Security Group Configuration Examples.

Procedure

1. Log in to the ECS console.
2. On the Elastic Cloud Server page, click the name of the target ECS.

   The page providing details about the ECS is displayed.

3. Click the Security Groups tab, expand the information of the security group, and view security group rules.
4. Click the security group ID.

   The system automatically switches to the security group details page.

5. Configure required parameters.

   You can click to add more inbound rules.

   Figure 1 Add Inbound Rule
   

   Table 1 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, access from the source is allowed to ECSs in the security group over specified ports. If the Action is set to Deny, access from the source is denied to ECSs in the security group over specified ports. Security group rules are matched by priority and then by action. Deny rules take precedence over allow rules. For more information, see How Traffic Matches Security Group Rules.	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. Specify one of the following: Individual port: Enter a port, such as 22. Consecutive ports: Enter a port range, such as 22-30. Non-consecutive ports: Enter ports and port ranges, such as 22,23-30. You can enter a maximum of 20 ports and port ranges. Each port range must be unique. All ports: Leave it empty or enter 1-65535.	22, or 22-30
   Source	Used to match the IP address or address range of an external request. The source can be: IP address: You can enter multiple IP addresses, separated by commas (,). Each IP address defines a different security group rule. Single IP address: IP address/mask Example IPv4 address: 192.168.10.10/32 Example IPv6 address: 2002:50::44/128 IP address range in CIDR notation: IP address/mask Example IPv4 address range: 192.168.52.0/24 Example IPv6 address range: 2407:c080:802:469::/64 All IP addresses 0.0.0.0/0 represents all IPv4 addresses. ::/0 represents all IPv6 addresses. Security group: The source is from another security group. You can select a security group in the same region from the drop-down list. If there is instance A in security group A and instance B in security group B, and the inbound rule of security group A allows traffic from security group B, traffic is allowed from instance B to instance A. IP address group: An IP address group is a collection of one or more IP addresses. You can select an available IP address group from the drop-down list. An IP address group can help you manage IP address ranges and IP addresses with same security requirements in an easier way. If no IP address groups are available, create one by referring to Creating an IP Address Group.	IP address: 192.168.52.0/24,10.0.0.0/24
   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

6. Configure required parameters.

   You can click to add more outbound rules.

   Figure 2 Add Outbound Rule
   

   Table 2 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. Security group rules are matched by priority and then by action. Deny rules take precedence over allow rules. For more information, see How Traffic Matches Security Group Rules.	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. Specify one of the following: Individual port: Enter a port, such as 22. Consecutive ports: Enter a port range, such as 22-30. Non-consecutive ports: Enter ports and port ranges, such as 22,23-30. You can enter a maximum of 20 ports and port ranges. Each port range must be unique. All ports: Leave it empty or enter 1-65535.	22, or 22-30
   Destination	Used to match the destination address of an internal request. The destination can be: IP address: You can enter multiple IP addresses, separated by commas (,). Each IP address defines a different security group rule. Single IP address: IP address/mask Example IPv4 address: 192.168.10.10/32 Example IPv6 address: 2002:50::44/128 IP address range in CIDR notation: IP address/mask Example IPv4 address range: 192.168.52.0/24 Example IPv6 address range: 2407:c080:802:469::/64 All IP addresses 0.0.0.0/0 represents all IPv4 addresses. ::/0 represents all IPv6 addresses. Security group: The destination is from another security group. You can select a security group in the same region under the current account from the drop-down list. If there is instance A in security group A and instance B in security group B, and the outbound rule of security group A allows traffic to security group B, traffic is allowed from instance A to instance B. IP address group: An IP address group is a collection of one or more IP addresses. You can select an available IP address group from the drop-down list. An IP address group can help you manage IP address ranges and IP addresses with same security requirements in an easier way. If no IP address groups are available, create one by referring to Creating an IP Address Group.	IP address: 192.168.52.0/24,10.0.0.0/24
   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 to complete the security rule configuration.

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.