Access control on an internal firewall between ECS instances

Policy group types

Policy groups are classified into common and enterprise policy groups. The following list describes the scenarios of the two policy groups.

• A common policy group takes effect on the basic security groups of ECS instances. It functions as a virtual firewall to monitor connection status and filter data packets, and can be used to isolate security domains on the cloud. You can configure access control policies to allow or deny inbound and outbound traffic between ECS instances in a common policy group.
• An enterprise policy group takes effect on the advanced security groups of ECS instances. It supports more ECS instances than a common policy group. You can configure access control policies for a large number of private IP addresses. Enterprise policy groups are ideal for enterprises that require efficient O&M on large-scale networks.

Create a policy group

1. Log on to the Cloud Firewall console.
2. In the left-side navigation pane, click Access Control > Access Control.
3. On the Access Control page, click the Internal Firewall tab.
4. In the upper-right corner of the Internal Firewall tab, click Create Policy Group.
5. In the Create Policy Group dialog box, configure the following parameters.

   Parameter	Description
   Policy Group Type	Select a type for the policy group. Valid values: Common Policy Group: suitable for business that requires fine-grained network control on a moderate number of network connections. Enterprise Policy Group: suitable for business that requires efficient O&M.
   Name	Enter a name for the policy group. We recommend that you enter an informative name for easy identification.
   VPC	Select a VPC to which you want to apply the policy group from the VPC drop-down list. Note A policy group can be applied to only one VPC.
   Instance ID	Select one or more ECS instances to which you want to apply the policy group from the Instance ID drop-down list. Note The Instance ID drop-down list only contains ECS instances within the selected VPC.
   Description	Enter a description for the policy group.
   Template	Select a template that you want to use from the Template drop-down list. default-accept-login: allows inbound traffic destined for TCP ports 22 and 3389 and all outbound traffic. default-accept-all: allows all inbound and outbound traffic. default-drop-all: denies all inbound and outbound traffic. Note Enterprise policy groups do not support the default-drop-all template.

6. Click Submit.
   The created policy group is displayed on the Internal Firewall tab. You can perform the following operations on the policy group:

   • Configure Policy: Customize policies to implement fine-grained access control.
   • Publish: Synchronize the access control policies in the policy group to ECS security groups.
   • Modify: Change the ECS instances specified in the policy group and modify the policy group description.
   • Delete: Delete the policy group.
     Warning After you delete a policy group, its access control policies become invalid. Exercise caution when you perform this operation. A deleted policy is retained in the list, but you cannot perform operations on it.
     If you want to delete policy groups that are no longer required, set the policy group source to Custom to obtain all custom policy groups and determine whether to delete them.

Configure a policy in a policy group

After you create a policy group, you must configure a policy for the policy group.

1. Log on to the Cloud Firewall console.
2. In the left-side navigation pane, click Access Control.
3. On the Access Control page, click the Internal Firewall tab.
4. On the Internal Firewall tab, find the required policy group and click Configure Policy in the Actions column.
5. In the upper-right corner of the Configure Policy page, click Create Policy.
6. In the Create Policy dialog box, configure the following parameters.

   Parameter	Description
   Network Type	The default value is Internal and cannot be changed. This value indicates that the policy is applied to ECS instances.
   Direction	The direction of traffic to which the policy applies. Valid values: Inbound: traffic from other ECS instances to the ECS instances specified in the policy group. Outbound: traffic from the ECS instances specified in the policy group to other ECS instances.
   Policy Type	The type of the policy. Valid values: Allow: allows traffic that hits the policy. Deny: denies traffic that hits the policy. If the traffic is denied, data packets are discarded without responses. If two policies have the same configuration but different policy types, the policy whose type is Deny takes effect. Note Enterprise policy groups do not support the Deny policy type.
   Protocol Type	The protocol of traffic to which the policy applies. Valid values: TCP UDP ICMP ANY (If you do not know the traffic protocol, select ANY.)
   Port Range	The destination port of traffic controlled by the policy. Example: 22/22.
   Priority	The priority of the policy. The priority must be an integer within the range of 1 to 100. A smaller value indicates a higher priority. Different policies can have the same priority. If an allow policy and a deny policy have the same priority, the deny policy takes precedence.
   Source Type and Source	The source of traffic. If you set Direction to Inbound, you must specify these parameters. You can specify Source based on the value of Source Type. Valid source types: CIDR Block If you select this type, you must enter a source CIDR block in Source. You can enter only one CIDR block. Policy Group If you select this type, you must select a policy group from the Source drop-down list as the traffic source. Traffic from all ECS instances in the policy group is controlled. Note Enterprise policy groups do not support the Policy Group type.
   Destination	The destination of traffic. If you set Direction to Inbound, you must specify this parameter. Valid values: All ECS Instances: all ECS instances specified in the policy group. CIDR Block: If you select this option, you must enter a destination CIDR block. The ECS instances that correspond to this CIDR block are the destination of traffic.
   Select Source	The type of the traffic source. If you set Direction to Outbound, you must specify this parameter. Valid values: All ECS Instances: all ECS instances specified in the current policy group. CIDR Block: If you select this option, you must enter a destination CIDR block. The ECS instances that correspond to this CIDR block are the source of traffic.
   Destination Type and Destination	The destination type and traffic destination. If you set Direction to Outbound, you must specify these parameters. Valid destination types: CIDR Block If you select this type, you must enter a destination CIDR block. You can enter only one CIDR block. Policy Group If you select this type, you must select a policy group. Traffic destined for all ECS instances in the policy group is controlled. Note Enterprise policy groups do not support the Policy Group type.
   Description	The description for the policy.

7. Click Submit.
   The created policy is displayed in the policy list. You can edit or delete policies.

   Warning After you delete a policy, its access control configuration becomes invalid. Exercise caution when you delete a policy. A deleted policy is retained in the list, but you cannot perform operations on it.

Publish a policy in a policy group

To apply a created policy, you must publish the policy. Then, the policy can control inbound or outbound traffic.

1. Log on to the Cloud Firewall console.
2. In the left-side navigation pane, click Access Control.
3. On the Access Control page, click the Internal Firewall tab, find the required policy group, and then click Publish in the Actions column.
4. In the Publish Policy dialog box, confirm policy changes, set Remarks, and then click OK.
   The policies take effect on ECS security groups only after you publish them. You can log on to the ECS console and choose Network & Security > Security Groups to view the policies you published in the Cloud Firewall console. By default, the policy that you create in the Cloud Firewall console is named Cloud_Firewall_Security_Group.

References

Why does Cloud Firewall provide three types of firewalls?

What are the differences between Cloud Firewall and ECS security groups?