Step 2: Buy a Public NAT Gateway

Scenarios

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

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 buy 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 buy 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 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 Networking > NAT Gateway.

   The Public NAT Gateways page is displayed.

4. On the displayed page, click Buy Public NAT Gateway.
5. Configure required parameters. For details, see Table 1.

   Table 1 Descriptions of public NAT gateway parameters

   Parameter	Description
   Billing Mode	Public NAT gateways are billed on a pay-per-use or yearly/monthly basis.
   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 (_), hyphens (-), and periods (.) are allowed.
   VPC	The VPC that the public NAT gateway belongs to The selected VPC cannot be changed after you buy 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 buy 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 buy 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 buy 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.
   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.
   SNAT Connection TCP Timeout (s)	Specifies the timeout period of a TCP connection established using the SNAT rule. If no data is exchanged within this period, the TCP connection will be closed. Value range: 40s to 7,200s
   SNAT Connection UDP Timeout (s)	Specifies the timeout period of a UDP connection established using the SNAT rule. If no data is exchanged within this period, the UDP connection will be closed. Value range: 40s to 7,200s
   SNAT Connection ICMP Timeout (s)	Specifies the timeout period of an ICMP connection established using the SNAT rule. If no data is exchanged within this period, the ICMP connection will be closed. Value range: 10s to 7,200s
   TCP TIME_WAIT (s)	Specifies how long the side that actively closed the TCP connection is in the TIME_WAIT state. Value range: 0s to 1,800s
   Description	Supplementary information about the public NAT gateway Enter up to 255 characters. Angle brackets (<>) are not allowed.
   Tag	Specifies the identifier of the public NAT gateway. A tag is a key-value pair. You can add up to 20 tags to each NAT gateway. If you have configured tag policies for public NAT gateways, you need to add tags to your public NAT gateways based on the tag policies. If you add a tag that does not comply with the tag policies, public NAT gateways may fail to be created. Contact your administrator to learn more about tag policies. 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 36 characters. Cannot contain equal signs (=), asterisks (*), left angle brackets (<), right angle brackets (>), backslashes (\), commas (,), vertical bars (|), and slashes (/), and the first and last characters cannot be spaces.
   Value	Can contain a maximum of 43 characters. Cannot contain equal signs (=), asterisks (*), left angle brackets (<), right angle brackets (>), backslashes (\), commas (,), vertical bars (|), and slashes (/), and the first and last characters cannot be spaces.

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

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

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

Adding a Default Route Pointing to the Public NAT Gateway

1. Log in to the management console.
2. Click in the upper left corner and select the desired region and project.
3. Under Networking, select Virtual Private Cloud.
4. In the navigation pane on the left, choose Route Tables.
5. 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.

   

   If the custom route table quota is insufficient, create a service ticket to increase the route table quota.

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

   The Summary page is displayed.

7. 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.

   Figure 1 Add Route
   
8. Click OK.