<p>This article describes common concepets used in the IGW on Ping An Cloud.</p> <table border="1" cellpadding="0" cellspacing="0" style="width:0px"> <tbody> <tr> <td style="background-color:#ededed; width:156px"> <p><strong>Concept</strong></p> </td> <td style="background-color:#ededed; width:625px"> <p><strong>Description</strong></p> </td> </tr> <tr> <td style="width:156px"> <p>Ethernet Connection Service (ECS)</p> </td> <td style="width:625px"> <p>ECS binds an Internet IP to a cloud host instance and configures security policies for the IP address to realize interconnection between the cloud host and the Internet.</p> </td> </tr> <tr> <td style="width:156px"> <p>Destination NAT (DNAT)</p> </td> <td style="width:625px"> <p>DNAT maps an Internet IP to the IP address of a private network instance (the IP address of intranet ELB service). The specified ELB instance uses the specified Internet IP to provide Internet services.</p> <p>DNAT supports IP mapping and port mapping.</p> </td> </tr> <tr> <td style="width:156px"> <p>IP Mapping</p> </td> <td style="width:625px"> <p>IP mapping maps the intranet IP to the Internet IP and provides service for the Internet via the Internet IP.</p> </td> </tr> <tr> <td style="width:156px"> <p>Port Mapping</p> </td> <td style="width:625px"> <p>Port mapping maps a port of the Internet IP to the ELB instance of the intranet, so that the specified ELB instance provides services to the Internet through the specified Internet IP and the port. Port mapping can maximize the use of a single Internet IP. Port mapping is initiated by an external address, and is mainly used for external publishing of intranet services.</p> </td> </tr> <tr> <td style="width:156px"> <p>Security Policy</p> </td> <td style="width:625px"> <p>Security policy provides secure access control for cloud host that is bound to the ECS. Users can define properties including IN/OUT direction, protocol type, port range, and the authorized IP by creating security policy.</p> </td> </tr> </tbody> </table>