Acme Web Hosting is replacing one of their firewalls with a FortiGate. It must be able to apply port forwarding to their back-end web servers while blocking virus uploads and TCP SYN floods from…

NAT/route mode (or NAT mode) allows the FortiGate to function as a Layer 3 gateway, enabling Network Address Translation (NAT) for port forwarding and providing full access to advanced security features like antivirus and IPS for robust threat protection.

NAT mode with an interface in one-arm sniffer mode is primarily for monitoring network traffic passively and does not support active blocking, port forwarding, or acting as a security enforcement point.

Transparent mode (or Bridge mode) operates at Layer 2, acting as a 'bump in the wire' without performing NAT or port forwarding, thus not meeting the requirement for port forwarding.

NAT/route mode perfectly suits the requirements for port forwarding and advanced threat protection.