Creating a Public NAT Gateway

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

• Rules on a public NAT gateway can use the same EIP, but rules on different NAT gateways must use different EIPs.
• Each VPC can be associated with multiple public NAT gateways.
• Only one NAT gateway can be created for a subnet.
• SNAT and DNAT rules can use the same EIP to save resources. However, when Port Type of a DNAT rule is set to All ports, the resources configured for the DNAT rule will preferentially use all ports of the EIP. So an SNAT rule cannot share an EIP with such a DNAT rule.
• 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. Do not use the ports in the table below.

  Protocol	Port
  TCP	42, 135, 137, 138, 139, 444, 445, 593, 1025, 1068, 1434, 3127, 3128, 3129, 3130, 4444, 4789, 4790, 5554, 5800, 5900, and 9996
  UDP	135 to 139, 1026, 1027, 1028, 1068, 1433, 1434, 4789, 4790, 5554, and 9996

• 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 route table already has a route with the destination of 0.0.0.0/0, the default route that points to the public NAT gateway will fail to be added. In this case, manually add a route that points to the gateway or create a custom route table and add a route with the destination of 0.0.0.0/0 pointing to the gateway to the new route table.

1. Log in to the management console.
2. Click in the upper left corner and select the desired region and project.
3. In the upper left corner of the page, click to expand the service list and choose Network > NAT Gateway.

   The Public NAT Gateways page is displayed.

4. On the Public NAT Gateways page, click Create Public NAT Gateway.
5. 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.
   Specifications	The specifications of the public NAT gateway. The value can be Small, Medium, Large, or Extra-large. You can click Learn more on the page to view details of each specification.
   Name	The name of the public NAT gateway. Enter up to 64 characters. Only letters, digits, underscores (_), hyphens (-), and periods (.) are allowed.
   VPC	The VPC that the public NAT gateway belongs to. The selected VPC cannot be changed after the public NAT gateway is created. 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 route table already has a route with the destination of 0.0.0.0/0, the default route that points to the public NAT gateway will fail to be added. In this case, manually add a route that points to the gateway or create a custom route table and add a route with the destination of 0.0.0.0/0 pointing to the gateway to the new route 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 the public NAT gateway is created. 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.
   Enterprise Project	The enterprise project that the public NAT gateway belongs to. If an enterprise project has been configured, select the enterprise project. If you have not configured any enterprise project, select the default enterprise project.
   Advanced Settings (Optional)	Click the drop-down arrow to configure advanced parameters of the public NAT gateway, such as Description.
   Advanced Settings > Description	Supplementary information about the public NAT gateway. Enter up to 255 characters. Angle brackets (<>) are not allowed.
   Advanced Settings > Tag	The identifier of the public NAT gateway. A tag is a key-value pair. The tag key and value must meet the requirements listed in Table 2.

   Table 2 Tag requirements

   Parameter	Requirement
   Key	Cannot be left blank. Must be unique for each NAT gateway. Can contain a maximum of 128 characters.
   Value	Can contain a maximum of 255 characters.

6. Click Create Now. On the page displayed, confirm the public NAT gateway specifications.
7. Click Submit.

   The creation takes 1 to 5 minutes to complete.

8. In the public NAT gateway list, you can see the gateway status.