Using a Public NAT Gateway to Enable Servers to Share One or More EIPs to Access the Internet

Scenarios

If servers without EIPs need to access the Internet, they can share one or more EIPs to access the Internet through a public NAT gateway. This helps save EIP resources and protect servers from exposing their IP addresses.

Operation Process

Preparations

Before using NAT gateways, sign up for a HUAWEI ID, enable Huawei Cloud services, complete real-name authentication, and top up your account.

• Create a HUAWEI ID and enable Huawei Cloud services.
• Complete real-name authentication.
• Top up your account.

Step 1: Buy an EIP

1. Go to the Buy EIP page.
2. On the Buy EIP page, set the EIP name to EIP-A.

   You can configure other EIP parameters as required. For details, see Buying an EIP.

3. Click Next.

   Return to the EIP list to view EIP-A you have assigned.

Step 2: Buy a Public NAT Gateway

1. Go to the Buy Public NAT Gateway page.
2. On the Buy Public NAT Gateway page, configure required parameters.

   Table 1 Descriptions of public NAT gateway parameters

   Parameter	Example	Description
   Region	CN North-Beijing4	The region where the public NAT gateway is located.
   Billing Mode	Pay-per-use	The billing mode of the public NAT gateway.
   Specifications	Small	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.
   Name	public-nat-01	The name of the public NAT gateway. Enter up to 64 characters. Only letters, digits, underscores (_), hyphens (-), and periods (.) are allowed.
   VPC	vpc-A	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	Subnet-A01	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.
   Advanced Settings (Optional)	-	Click the drop-down arrow to configure advanced parameters of the public NAT gateway.
   SNAT Connection TCP Timeout (s)	900	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: 40 to 7200
   SNAT Connection UDP Timeout (s)	300	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: 40 to 7200
   SNAT Connection ICMP Timeout (s)	10	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: 10 to 7200
   TCP TIME_WAIT (s)	5	How long the side that actively closed the TCP connection is in the TIME_WAIT state. Value range: 0 to 1800
   Description	Not required	Supplementary information about the public NAT gateway. Enter up to 255 characters. Angle brackets (<>) are not allowed.
   Tag	Not required	The identifier of the public NAT gateway. A tag is a key-value pair. You can add up to 20 tags to each public NAT gateway.

3. Click Next. On the page displayed, confirm the public NAT gateway specifications.
4. If you do not need to modify the information, click Submit.

   On the Public NAT Gateways page, you can view the created public NAT gateway in the list.

Step 3: Add an SNAT Rule

1. On the displayed page, click the name of the public NAT gateway on which you need to add an SNAT rule.
2. On the SNAT Rules tab, click Add SNAT Rule.
3. Configure required parameters. Table 2 describes the parameters.

   Table 2 Descriptions of SNAT rule parameters

   Parameter	Example	Description
   Scenario	VPC	Select VPC if your servers in a VPC will use the SNAT rule to access the Internet. Different servers in a VPC can share the same EIP to access the Internet.
   CIDR Block	Existing	The CIDR block is a subset of the NAT gateway's VPC subnets. Servers whose IP addresses in the CIDR block can access the Internet through the SNAT rule. Select a CIDR block from the drop-down list.
   Public IP Address Type	EIP	The EIP used for accessing the Internet.
   Monitoring	-	You can create alarm rules on the Cloud Eye console to monitor your SNAT connections and keep informed of any changes in a timely manner.
   Description	Not required	Supplementary information about the SNAT rule. Enter up to 255 characters. Angle brackets (<>) are not allowed.

4. Click OK.

Step 4: Verify that the SNAT Rule Has Been Added

1. In the SNAT Rules tab, view details of the SNAT rule.
   If Status of the SNAT rule is Running, the SNAT rule has been created.

   Figure 1 Verifying that the SNAT rule has been added
   

Step 5: Verify that Server Can Access the Internet Through the NAT Gateway

1. Go to the ECS list page.
2. Log in to the server to be verified.
3. Verify that the server can access the Internet.
   Figure 2 Verification result