One of the most common tasks for a router nowadays is connecting many workstations in a LAN to the mother of all networks, the Internet. Everyone should, if possible, have direct access to the Internet for the latest work-related information.
"IP masquerading" is used as a means of concealing intranet clients so that individual computers and their IP addresses are not visible from the Internet. IP masquerading places two conflicting demands on the router: Whereas each computer needs a valid intranet IP address in order to be reachable from the LAN, it also needs a valid, public IP address (either fixed or assigned dynamically by the provider).
As a matter of principle these two addresses cannot co-exist in a single logical network, so the router must have two IP addresses:
- The intranet IP address for communication with the clients in the LAN
- The public IP address for communication with remote devices in the Internet
The computers in the LAN use the router as a gateway and are not visible individually. The router separates the Internet from the intranet.
In addition to the options "simple masquerading" and "port forwarding" listed below, LCOS also supports WAN policy-based NAT, which allows masquerading via firewall rules.
