Adding a DNAT Rule

Scenarios

After a NAT gateway is created, you can add DNAT rules to allow servers in your VPC to provide services accessible from the Internet.

You can configure a DNAT rule for each port of a server. If multiple servers need to provide services accessible from the Internet, you need to create multiple DNAT rules.

Prerequisites

A NAT gateway has been created.

Procedure

1. Log in to the management console.
2. Under Network, click NAT Gateway.
3. On the displayed page, click the name of the NAT gateway for which you want to add the DNAT rule.
4. On the NAT gateway details page, click the DNAT Rules tab.
5. Click Add DNAT Rule.
   Figure 1 Add DNAT Rule
   
   

   You need to add security group rules to allow inbound or outbound traffic after you add a DNAT rule. Otherwise, the DNAT rule does not take effect.

6. Set the parameters as prompted. For details, see Table 1.

   Table 1 Parameter description

   Parameter	Description
   Scenario	VPC: indicates that the servers in a VPC can share one EIP to provide services accessible from the Internet through the DNAT rule. Direct Connect: indicates that servers in your data center that are connected to a VPC using Direct Connect or VPN can provide services accessible from the Internet through the DNAT rule.
   Port Type	Specifies the port type, including All ports and Specific port. All ports: indicates the IP mapping method. This method is equivalent to assigning an EIP to a server. Any requests on the EIP will be forwarded by the NAT gateway to your server based on IP address mapping. Specific port: indicates the port mapping method. The NAT gateway forwards the requests with specific protocol and port on the EIP to the corresponding port of the target server.
   Protocol	The protocol can be TCP or UDP. This parameter is available if you select Specific port for Port Type. If you select All ports, the value of this parameter will be All by default.
   EIP	Specifies the EIP that will be used by the server to provide services accessible from the Internet. You can only select an EIP that has not been bound, has been bound to a DNAT rule with Port Type set to Specific port of the current NAT gateway, or has been bound to an SNAT rule of the current NAT gateway.
   Outside Port	Specifies the port of the EIP. This parameter is available if you select Specific port for Port Type. The value ranges from 1 to 65535. The value can be a single port number or a port range, for example, 80 or 80-100.
   Private IP Address	In the VPC scenario, set this parameter to the IP address of the server in a VPC. This IP address is used by the server to provide services accessible from the Internet through DNAT. In the Direct Connect scenario, set this parameter to IP address of the server in the local data center or the user's private IP address. This IP address is used by local servers that are connected to a VPC through Direct Connect or VPN to provide services accessible from the Internet through DNAT. Configure the port of Private IP Address if you select Specific port for Port Type.
   Inside Port	Specifies the port of the server that provides services for the Internet through the DNAT rule. This parameter is available if you select Specific port for Port Type. The value ranges from 1 to 65535. The value can be a single port number or a port range, for example, 80 or 80-100.
   Description	Provides supplementary information about the DNAT rule. The description can contain a maximum of 255 characters.

7. After the configuration is complete, click OK. Once the rule is created, its status changes to Running.