EDR-G9010 Series User Manual
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9.
NAT (Network Address Translation)
NAT Concept
NAT (Network Address Translation) is a common security function for changing the IP address during
Ethernet packet transmission. When the user wants to hide the internal IP address (LAN) from the external
network (WAN), the NAT function will translate the internal IP address to a specific IP address, or an
internal IP address range to one external IP address. The benefits of using NAT include:
•
The N-1 or port forwarding NAT function to hide the internal IP address of a critical network or device to
increase the level of security of industrial network applications.
•
The Industrial Secure Router uses the same private IP address for different, but identical, groups of
Ethernet devices. For example, 1-to-1 NAT makes it easy to duplicate or extend identical production
lines.
NOTE
The NAT function will check if incoming or outgoing packets match the policy. It starts by checking the
packet against the first policy (Index=1); if the packet matches this policy, the Industrial Secure Router
will translate the address immediately and then start checking the next packet. If the packet does not
match this policy, it will check with the next policy.
NOTE
The Industrial Secure Router supports a maximum of 512 NAT policies.
1-to-1 NAT Overview
If the internal device and external device need to communicate with each other, choose 1-to-1 NAT, which
offers bi-directional communication (N-to-1 and Port forwarding are both single-directional communication
NAT functions).
1-to-1 NAT is usually used when you have a group of internal servers with private IP addresses that must
connect to the external network. You can use 1-to-1 NAT to map the internal servers to public IP addresses.
The IP address of the internal device will not change. 1-to-1 NAT will also create a corresponding secondary
IP address (10.10.10.1) if the device is in the same subnet as the incoming interface.
