Fortinet FortiGate FortiGate-100A - Transparent Mode

Configuring the FortiGate unit Planning the FortiGate configuration
FortiGate-60 series and FortiGate-100A FortiOS 3.0 MR4 Install Guide
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Figure 5: FortiGate-100A NAT/Route multiple internet connection configuration
Transparent mode
In Transparent mode, the FortiGate unit is invisible to the network. Similar to a
network bridge, all FortiGate interfaces must be on the same subnet. You only
need to configure a management IP address to make configuration changes. The
management IP address is also used for antivirus and attack definition updates.
You typically use the FortiGate unit in Transparent mode on a private network
behind an existing firewall or behind a router. The FortiGate unit performs firewall
functions, IPSec VPN, virus scanning, IPS web content filtering, and Spam
filtering.
You can connect up to four network segments to the FortiGate unit to control
traffic between these network segments.
Internet
Router
Internal
network
DMZ network
Web Server
Mail Server
MODEM
Internal
DMZ1
WAN1
WAN2
Hub
or switch
Table 7: Transparent mode network segments
FortiGate Unit Internal Interface External Interface Other
FortiGate-60
FortiGate-60ADSL
FortiGate-60B
Internal WAN1 WAN2
DMZ
FortiGate-60M Internal WAN1
WAN2
DMZ
FortiWiFi-60
FortiWiFi-60B
Internal WLAN DMZ
WAN1
WAN2
FortiGate-100A Internal WAN1 WAN2
DMZ1
DMZ2
Note: In Transparent mode, the modem interface is not available on the FortiGate-60M.