Viper SC+™ IP Router for Licensed Spectrum PN 001-5008-000 Rev. C | Page 161NAT ON VIPERThe purpose of the NAT (Network Address Translation) protocol is to hide a private IP network from a public network.This mechanism serves first as a firewall and second to save IP address space. In a Viper, it is normally used on the WANside of an IP network to hide local IP addresses from an external IP network.The NAT-enabled device translates the source address of packets transiting from the private network to the publicnetwork. The original IP source address gets replaced by the NAT-enabled IP address (address of the outgoinginterface). The NAT module creates an address creates an address translation table that is used when traffic is comingback from the public network to the private network.The user can select which of two interfaces (Ethernet or RF) will be considered private. The following examplesillustrate how to configure the Vipers. The examples use a private network of 192.168.205.x and a public network of172.31.5.x.ETHERNET INTERFACE PRIVATEThe following figure shows NAT enabled for the Ethernet interface.Figure 82 – NAT Enabled, Ethernet Interface (Private)
