User Documentation

Version 1.2 / August 2020 Page 45 / 102

Network → 1:1 NAT

Configuration → Network → 1:1 NAT

Function

With 1:1 NAT you can map a private subnet to the public subnet defined in the IP configura-

tion. This allows you to resolve conflicts between identical networks. E.g. if all LAN ports in

extended IP routing mode are connected to equal subnets, they can be accessed uniquely

via the public subnet without the need for changing any configuration of the private subnets.

1:1 NAT can be configured for all active (physical and virtual) interfaces.

Note: While the private subnets may be equal they must not conflict with the public IP sub-

nets.

For more detailed information about using 1:1 NAT please refer to application notes

in appendix A.

Enable 1:1 NAT

Enable 1:1 NAT for this interface.

Note: 1:1 NAT only can be activated if NAT (masquering) is not ena-

bled for this interface

Public IP address

This is the public interface IP address and subnet mask as defined in

menu ‘IP Configuration’, e.g. 192.168.1.110/24. If DHCP is enabled,

you must define a network to which the IP addresses received via

DHCP will be mapped.

Private IP ad-

dress

The definition of the private subnet is the private device IP with the

subnet mask appended. E.g. 192.168.0.110/24 means, that the device

itself is reachable as 192.168.0.110 from the private subnet

192.168.0.0/24

Enable double

sided network

mapping

With this extension, (private) IP address conflicts can be solved if pub-

lic hosts use IP addresses from the same subnet as the 1:1 NAT pri-

vate subnet. Where possible, you should not use such a subnet for 1:1

NAT private subnet, but sometimes the private subnet is already de-

fined through the according network components. This conflict will be

solved by using a further subnet that is not used anywhere else, nei-

ther on public nor on private subnets.

Substitute with IP

address/subnet

mask

A subnet, preferably of the same size as the according private 1:1 NAT

subnet. Will be used for translating private IP addresses on public in-

terfaces to a subnet of IP addresses that is otherwise not used. There-

fore, only IP source address for packets going to the according private

subnet will be changed. This option is not necessary if the private sub-

net is not used on public interfaces.