Adding an SNAT Rule

After a public NAT gateway is created, add an SNAT rule, so that servers in a VPC subnet or servers that are connected to a VPC through Direct Connect can access the Internet by sharing an EIP.

One SNAT rule takes effect for only one subnet. If there are multiple subnets in a VPC, add multiple SNAT rules to allow servers in the subnets to share an EIP.

• Only one SNAT rule can be added for each VPC subnet.
• If an SNAT rule is added for a Direct Connect connection, the custom CIDR block must be the CIDR block of a Direct Connect connection and cannot overlap with that of the NAT gateway's VPC.
• There is no limit on the number of SNAT rules that can be added on a 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. 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 displayed page, click the name of the public NAT gateway on which you need to add an SNAT rule.
5. On the SNAT Rules tab, click Add SNAT Rule.

6. Configure required parameters. For details, see Table 1.

   Table 1 Descriptions of SNAT rule parameters

   Parameter	Description
   Scenario	The scenarios where the SNAT rule is used Select VPC if your servers in a VPC need to access the Internet. Select Direct Connect if servers in your on-premises data center need to access the Internet.
   CIDR Block	In a VPC scenario, specify a VPC subnet to enable servers in that subnet to access the Internet using the SNAT rule. In a Direct Connect scenario, specify a CIDR block of your data center to enable your servers to access the Internet using the SNAT rule.
   Public IP Address Type	The EIP used for accessing the Internet You can select an EIP that either has not been bound, has been bound to a DNAT rule of the current public NAT gateway with Port Type set to Specific port, or has been bound to an SNAT rule of the current public NAT gateway. You can select up to 20 EIPs for an SNAT rule. If you have selected multiple EIPs for an SNAT rule, one EIP will be chosen randomly.
   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	Provides supplementary information about the SNAT rule. Enter up to 255 characters. Angle brackets (<>) are not allowed.

7. Click OK.