Passive FTP (File Transferring Protocol) virtual server mode is extensively use to solve the issue of the client firewall blocking the FTP server data connection.
Virtual Server setting is a platform to configure virtual server on the router to change due to the router with default configuration does not allow computers fron Internet access LAN computer trhough the firewall.
Special Application is defined when the firewall found a ‘Trigger Port’ to be opened by a computer, it allow the connections from Internet to pass through the corresponding external port to be established.
DMZ (Demiliterized Zone) is a physical or logical subnetwork that contains and exposes an organization’s external-facing services to a larger and untrusted network, usually the Internet. The purpose of a DMZ is to add an additional layer of security to an organization’s Local Area Network (LAN).
One-to-One NAT (Network Address Translation) is a way tp make systems behind a firewall and configured with private IP addresses appear to have public IP addresses.