Configuring CFW Protection Rules to Protect SNAT Traffic

Step 1: Connect VPC1 and VPC-NAT to an Enterprise Router

This section describes how to connect VPC1 and VPC-NAT to an enterprise router.

1. Add VPC attachments.

   Add two attachments. Set their Attached Resource to VPC1 and VPC-NAT, respectively.

   For details, see Adding VPC Attachments to an Enterprise Router.

2. Create two route tables.
   1. In the upper left corner, click and choose Networking > Enterprise Router. Click Manage Route Table.
   2. Create an association route table and a propagation route table, used for connecting to a protected VPC and a firewall, respectively.

      On the enterprise router details page, click the Route Tables tab. On the route table configuration page, click Create Route Table. In the displayed dialog box, configure parameters.

      Table 1 Route table parameters

      Parameter	Description	Example Value
      Name	Route table name. It must meet the following requirements: Must contain 1 to 64 characters. Can contain letters, numbers, underscores (_), hyphens (-), and periods (.).	er-rtb-01
      AS_Path Route Selection	(Optional) Do not configure: The system compares AS_Path attributes for the routes during load balancing and prefers the route with the shortest AS_Path length. The AS_Path attribute records all AS numbers that a BGP route passes through from the local end to the destination in the vector order. The fewer the AS numbers recorded in the AS_Path attribute, the shorter the AS_Path length. Ignore same length AS_Path: The system skips comparing the AS_Path attributes during load balancing if their lengths are identical. AS_Path prevents BGP loops between ASs. If you select this option, there may be BGP loops.	Do not configure
      Tag	(Optional) During the route table creation, you can tag the route table resources. Tags identify cloud resources for purposes of easy categorization and quick search. For details about tags, see Tag Overview.	Tag key: test Tag value: 01
      Description	(Optional) Route table description.	-

3. Configure the association route table.
   1. Create an association between VPC1 and VPC-NAT. On the route table configuration page, click the Associations tab and click Create Association.

      Two associations need to be added. Set their Attachment to VPC1 and VPC-NAT attachments, respectively.

      Table 2 Association parameters

      Parameter	Description
      Attachment Type	Select VPC.
      Attachment	Select the VPC attachment from the Attachment drop-down list.

   2. Add a static route to the firewall. Click the Routes tab and click Create Route.
      Figure 1 Creating a route
      

      Table 3 Route parameters

      Parameter	Description
      Destination	Set the destination address. If 0.0.0.0/0 is configured, all the traffic (IPv4) of the VPC is protected by CFW. If a CIDR block is configured, the traffic of the CIDR block is protected by CFW.
      Blackhole Route	You are advised to disable this function. If it is enabled, the packets from a route that matches the destination address of the blackhole route will be discarded.
      Attachment Type	Set Attachment Type to CFW instance.
      Next Hop	Select the automatically generated firewall attachment cfw-er-auto-attach.
      Description	(Optional) Description of a route.

4. Configure the propagation route table.
   1. Add an association with the firewall. On the route table configuration page, click the Associations tab and click Create Association.
      Figure 2 Creating an association
      

      Table 4 Association parameters

      Parameter	Description
      Attachment Type	Set Attachment Type to CFW instance.
      Attachment	Select the automatically generated firewall attachment cfw-er-auto-attach.

   2. Configure propagation for VPC1. Click the Propagations tab and click Create Propagation.
      Figure 3 Creating a propagation
      

      Table 5 Propagation parameters

      Parameter	Description
      Attachment Type	Select VPC.
      Attachment	Select the VPC1 attachment from the Attachment drop-down list.

   3. Add a static route to VPC-NAT. Click the Routes tab and click Create Route.

      Table 6 Route parameters

      Parameter	Description
      Destination	Set it to 0.0.0.0/0.
      Blackhole Route	You are advised to disable this function. If it is enabled, the packets from a route that matches the destination address of the blackhole route will be discarded.
      Attachment Type	Select VPC.
      Next Hop	Select the VPC-NAT attachment from the drop-down list.

Step 2: Configure a NAT Gateway

This section describes how to configure a NAT gateway.

Step 3: Configure the Route Table of VPC 1

1. Go to the route table list.
2. In the Name column, click the route table name of VPC1. The Summary page is displayed.
3. Click Add Route and configure parameters.

   Table 9 Route parameters

   Parameter	Description
   Destination Type	Select IP address.
   Destination	Destination CIDR block. Set it to 0.0.0.0/0.
   Next Hop Type	Select Enterprise router from the drop-down list.
   Next Hop	Select a resource for the next hop. The drop-down list displays the enterprise routers you created.
   Description	(Optional) Supplementary information about the route. Enter up to 255 characters. Angle brackets (< or >) are not allowed.

(Optional) Step 4: Test Network Connectivity

Test network connectivity. Use a test server in the service VPC to access the external network. If the access is successful, the NAT configuration is proper.

Step 5: Enable Inter-VPC Firewall Protection

For details, see Enabling the Inter-VPC Firewall.

(Optional) Step 6: Test Network Connectivity Again

Use the test server in the service VPC to test the network connectivity again. If the firewall traffic log contains response records, traffic has been successfully diverted to the firewall. For details about how to query traffic logs, see Traffic Logs.

Step 7: Configure a NAT Protection Rule

After verifying the traffic flow, configure protection rules so that the CFW can allow or block traffic accordingly.

1. Log in to the CFW console.
2. Click in the upper left corner of the management console and select a region.
3. (Optional) Switch to another firewall instance. If there are multiple firewall instances, you can select a desired instance from the drop-down list in the upper left corner of the page.
4. In the navigation pane of the CFW console, choose Protection Policies > Access Control > Internet Border Protection Rules. The Internet Border Protection Rules page is displayed.
5. On the Protection Rules tab page, click the NAT sub-tab, and click Add Rule. On the Add Rule page, configure the key parameters as follows:
   • Rule Type: Select NAT.
   • Direction: Select SNAT.
   • Source: Select IP address. Enter a private IP address.
   • Destination: Select IP address (and enter a public IP address) or Domain name/Domain name group.
   • Application: Select Any.

6. Click OK.

(Optional) Step 8: View Logs

Use the test server to access the IP address or domain name and check whether the access control log contains a log that matches the rule. If it does, the protection rule has taken effect. For more information, see Access Control Logs.

Step 9: Switch Workloads

After the configurations pass the verification, gradually switch workloads from the production-like or live network environment to CFW.