Help Center/ NAT Gateway/ User Guide (Paris Region) / Public NAT Gateways/ Managing Public NAT Gateways/ Creating a Public NAT Gateway
Updated on 2024-03-30 GMT+08:00
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Creating a Public NAT Gateway

Scenarios

Create a public NAT gateway to enable your servers to access the Internet or provide services accessible from the Internet.

Constraints and Limitations

  • Rules on one public NAT gateway can use the same EIP, but rules on different NAT gateways must use different EIPs.
  • Each VPC can have only one NAT gateway.
  • Each VPC can be associated with multiple public NAT gateways.
  • SNAT and DNAT rules cannot use the same EIP.
  • If both an EIP and a public NAT gateway are configured for a server, data will be forwarded through the EIP.
  • Some carriers will block the following ports for security reasons. It is recommended that you do not use the following ports.

    Protocol

    Port

    TCP

    42 135 137 138 139 444 445 593 1025 1068 1434 3127 3128 3129 3130 4444 4789 4790 5554 5800 5900 9996

    UDP

    135~139 1026 1027 1028 1068 1433 1434 4789 4790 5554 9996

Prerequisites

  • The VPC and subnet where your public NAT gateway will be deployed are available.
  • To allow traffic to pass through the public NAT gateway, a route to the public NAT gateway in the VPC is required. When you create a public NAT gateway, a default route 0.0.0.0/0 to the public NAT gateway is automatically added to the default route table of the VPC. If the default route 0.0.0.0/0 already exists in the default route table of the VPC before you create the public NAT gateway, the default route that points to the public NAT gateway will fail to be added automatically. In this case, perform the following operations after the public NAT gateway is successfully created: Manually add a different route that points to the gateway or create a default route 0.0.0.0/0 pointing to the gateway in the new routing table.

Procedure

  1. Log in to the management console.
  2. Click Service List in the upper left corner. Under Network, select NAT Gateway.

    The Public NAT Gateway page is displayed.

  3. On the displayed page, click Create NAT Gateway.
  4. Configure required parameters. For details, see Table 1.
    Table 1 Descriptions of public NAT gateway parameters

    Parameter

    Description

    Region

    The region where the public NAT gateway is located

    Name

    The name of the public NAT gateway

    Enter up to 64 characters. Only digits, letters, underscores (_), and hyphens (-) are allowed.

    VPC

    The VPC that the public NAT gateway belongs to

    The selected VPC cannot be changed after you create the public NAT gateway.

    NOTE:

    To allow traffic to pass through the public NAT gateway, a route to the public NAT gateway in the VPC is required. When you create a public NAT gateway, a default route 0.0.0.0/0 to the public NAT gateway is automatically added to the default route table of the VPC. If the default route 0.0.0.0/0 already exists in the default route table of the VPC before you create the public NAT gateway, the default route that points to the public NAT gateway will fail to be added automatically. In this case, perform the following operations after the public NAT gateway is successfully created: Manually add a different route that points to the gateway or create a default route 0.0.0.0/0 pointing to the gateway in the new routing table.

    Subnet

    The subnet that the public NAT gateway belongs to

    The subnet must have at least one available IP address.

    The selected subnet cannot be changed after you create the public NAT gateway.

    The NAT gateway will be deployed in the selected subnet. The NAT gateway works for the entire VPC where it is deployed. To enable communications over the Internet, add SNAT or DNAT rules.

    Specifications

    The specifications of the public NAT gateway

    The value can be Extra-large, Large, Medium, or Small. To view more details about specifications, click Learn more on the page.

    Description

    Supplementary information about the public NAT gateway

    Enter up to 255 characters. Angle brackets (<>) are not allowed.
  5. Click Create Now. On the page displayed, confirm the public NAT gateway specifications.
  6. Click Submit to create a public NAT gateway.

    It takes 1 to 6 minutes to create a public NAT gateway.

  7. In the list, view the status of the public NAT gateway.

After the public NAT gateway is created, check whether a default route (0.0.0.0/0) that points to the public NAT gateway exists in the default route table of the VPC where the public NAT gateway is. If no, add a route pointing to the public NAT gateway to the default route table, alternatively, create a custom route table and add the default route 0.0.0.0/0 pointing to the public NAT gateway to the table. The following describes how to add a route to a custom route table.

Adding a Default Route Pointing to the Public NAT Gateway

  1. Log in to the management console.
  2. Under Network, select Virtual Private Cloud.
  3. In the navigation pane on the left, choose Route Tables.
  4. On the Route Tables page, click Create Route Table in the upper right corner.

    VPC: Select the VPC to which the public NAT gateway belongs.

  5. After the custom route table is created, click its name.

    The Summary page is displayed.

  6. Click Add Route and configure parameters as follows:

    Destination: Set it to 0.0.0.0/0.

    Next Hop Type: Select NAT gateway.

    Next Hop: Select the created NAT gateway.

  7. Click OK.