1. From Home|Network|Interfaces, click on the pencil icon next to the network interface where you want OUTBOUND traffic to be translated (more than likely, this will be your external interface).
2. Check the box that says "Enable IP Network Address Translation (NAT)".
3. Click on STORE to store your changes.
4. Click on COMMIT and then COMMIT again to commit the changes.

NAT does OUTBOUND traffic translation on forwarded (routed) IP packets.

You will only be able to enable NAT on one interface, and it will automatically do NAT for multiple internal networks (each with it's own gateway interface on the NetMAX)

If you need to do NAT on more than one outbound interface, then you will not want to use the check box above, as it will not suit your needs. Instead, you'll need to create some custom FORWARD firewall rules with IPMASQ enabled. More information on this is available in the here.
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