NAT Gateway is a network cloud service that supports IP address translation, and can provide Network Address Translation for computing instances in a VPC (Virtual Private Cloud). It is divided into two functions of SNAT and DNAT. Through SNAT, multiple ECSs can share EIP to access the Internet. Through DNAT, multiple ECSs can provide Internet services. The NAT Gateway is the ingress and egress of the Internet traffic in the VPC, which protects the private network information from being directly exposed on the Internet.

Related Concepts

Public IP Address

also the Internet protocol address, being an address that can be routed on the Internet. If the cloud resource intends to provide external services, the Internet IP information corresponding to the cloud resource needs to be published.

NAT (Network Address Translation)

The cloud resources in the VPC are assigned with private IPs, which cannot be routed on the Internet. If the cloud resources in the VPC wish to interconnect with the Internet or provide services to the Internet, it is necessary to convert the private IP of the cloud resources into the Internet IP that can be routed and publish it externally.

DNAT (Destination Network Address Translation)

Definition: Convert the destination address in the IP message through IP mapping or port mapping.

Bind NAT Gateway and the EIP and enable DNAT, so that multiple ECS resources in the VPC can share the EIP to provide external services.

SNAT (Source Network Address Translation)

Definition: Convert the source address and source port of the IP message.

Bind the NAT Gateway and the EIP, enable SNAT, and convert the private IP of the ECS to the Internet IP, so that resources without Internet IP in the VPC can directly access the Internet and resources of multiple ECSs in the VPC can share the EIP to actively access the Internet.