Enabling NAT Gateway Traffic Protection

Prerequisites

• Traffic diversion depends on the enterprise router
• A firewall has been created. For details, see Creating a VPC Border Firewall.

Constraints

• Only the professional edition supports NAT gateway traffic protection.
• By default, CFW supports standard private network CIDR blocks. To enable non-standard CIDR block communication, submit a service ticket.
• To let the DNAT gateway divert east-west traffic to the CFW cluster and configure DNAT rules, submit a service ticket to ask service O&M personnel to upgrade CFW. The old version does not support DNAT functions and may cause traffic loss.

Enabling NAT Gateway Traffic Protection

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

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

   

   Two connections need to be added. Set their Attached Resource to VPC1 and VPC-NAT, respectively.

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.

      Click the Route Tables tab. Click Create Route Table. For more information, see Table 1.

      Table 1 Route table parameters

      Parameter	Description
      Name	Route table name. It must meet the following requirements: Must contain 1 to 64 characters. Can contain letters, digits, underscores (_), hyphens (-), and periods (.).
      Description	Route table description
      Tag	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.

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. For more information, see Table 2.

      Table 2 Association parameters

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

      

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

   2. Add a static route to the firewall. Click the Routes tab and click Create Route. For more information, see Table 3.
      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 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. Create a propagation for VPC1. On the route table setting page, click the Propagations tab and click Create Propagation. For more information, see Table 4.
      Figure 2 Creating a propagation
      

      Table 4 Propagation parameters

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

   2. Add a static route to VPC-NAT. Click the Routes tab and click Create Route. For more information, see Table 5.

      Table 5 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

1. Add an SNAT rule.
   1. Return to the Enterprise Router page. In the navigation pane of Network Console, choose NAT Gateway > Public NAT Gateways.
   2. Click the name of a public network NAT gateway. The Basic Information tab is displayed. Click the SNAT Rules tab.
   3. Click Add SNAT Rule. For more information, see Table 6.

      Table 6 Adding an SNAT rule

      Parameter	Description
      Scenario	Scenario where the SNAT rule is used. Select VPC.
      CIDR Block	Select Custom to enable servers in this subnet to use the SNAT rule to access the Internet. Custom: Customize a CIDR block or enter the IP address of a VPC. NOTE: If you select Custom, you can enter 0.0.0.0/0. Only a 32-bit server IP address is supported.
      EIP	EIP used for accessing the Internet. You can select only an EIP that is not bound to any resource, an EIP that is bound to a DNAT rule whose Port Type is not set to All ports in the current public NAT gateway, or an EIP that is bound to an SNAT rule of the current public NAT gateway. You can select multiple EIPs at once. Up to 20 EIPs can be selected for each SNAT rule. If you have selected multiple EIPs for an SNAT rule, one EIP will be chosen randomly.
      Monitoring	Monitoring of the number of SNAT connections. You can set alarm rules to monitor your SNAT connections and keep informed of any changes in a timely manner.
      Description	Supplementary information about the SNAT rule. Enter up to 255 characters.

2. Configure the VPC-NAT route table.
   1. In the service list, click Virtual Private Cloud under Networking. In the navigation pane, choose Route Tables.
   2. In the Name column, click the route table name of a VPC. The Summary page is displayed.
   3. Click Add Route. For more information, see Table 7.

      Table 7 Route parameters

      Parameter	Description
      Destination Type	Select IP address.
      Destination	Destination CIDR block. Enter the IP address of VPC1. NOTE: The value cannot conflict with existing routes or subnet CIDR blocks in the VPC.
      Next Hop Type	Select Enterprise Router from the drop-down list.
      Next Hop	Select a resource for the next hop. The enterprise routers you created are displayed in the drop-down list.
      Description	(Optional) Supplementary information about the route. NOTE: Enter up to 255 characters. Angle brackets (< or >) are not allowed.

Step 3: Configure a route table for VPC1

1. On the Route Tables page, in the Name column, click the route table name of VPC1. The Summary page is displayed.
2. Click Add Route. For more information, see Table 8.

   Table 8 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 enterprise routers you created are displayed in the drop-down list.
   Description	(Optional) Supplementary information about the route. NOTE: Enter up to 255 characters. Angle brackets (< or >) are not allowed.

Step 4: Enable a VPC Border Firewall

1. In the navigation pane, choose Assets > Inter-VPC Border Firewalls.
2. Click Enable Protection to the right of Firewall Status.
3. Click OK.

Follow-up Operations

• Fine-grained protection for private IP addresses: Configure NAT protection rules. For details, see Adding a NAT Traffic Protection Rule.
• Interception of network attacks: Configure intrusion prevention. For details, see Blocking Network Attacks.