Help Center> Cloud Firewall> Best Practices> Using CFW to Protect SNAT> Configuring a NAT Gateway
Updated on 2024-04-09 GMT+08:00
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Configuring a NAT Gateway

Prerequisites

If VPC-NAT is associated with the NAT gateway, a route will be added to the default route table by default. (The destination address is 0.0.0.0/0, and the Next Hop Type is NAT gateway.) This route diverts the traffic destined for VPC-NAT to the NAT gateway. Do not delete it.

Step 1: Configure an SNAT Rule

  1. In the service list, click NAT Gateway under Networking. The Public NAT Gateway page is displayed.
  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 1.

    Table 1 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:

      When 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.

Step 2: Configure a 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 2.

    Table 2 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.