}
Figure 5-5 Port Forwarding Settings - Example Three
5.1.1.5 NAT Rule
5.1.1.6 Introduction to NAT
The NAT (Network Address Translation) is an Internet standard that is used to map
one IP address space (i.e., Intranet) to another IP address space (i.e., Internet). The
NAT is designed to alleviate the shortage of IP addresses, that is, it allows all the LAN
hosts to share a single or a small group of IP addresses: On the Internet, there is only
a single device using a single or a small group of public IP addresses; but the LAN
hosts can use any range of private IP addresses, and these IP addresses are not
visible from the Internet. As the internal network can be effectively isolated from the
outside world, the NAT can also provide the benefit of network security assurance.
The Device provides flexible NAT features, and the following sections will describe
them in detail.
NAT Address Space Definitions
To ensure that NAT operates properly, the Device uses and maintains two address
spaces:
●
Internal IP address:
It indicates the IP address that is assigned to a LAN host by
the administrator. It is usually a private IP address.
●
External IP address:
It indicates the IP address that is assigned to the Device
’s
Internet connection by the ISP. It is a legal public IP address that can represent
one or more internal IP addresses to the outside world.
5.1.1.8 NAT Types
The Device provides two types of NAT:
One2One
and
EasyIP
.
