Nat/Route Mode With Multiple External Network Connections; Transparent Mode - Fortinet FortiGate FortiGate-50A Installation Manual

Planning the FortiGate configuration

NAT/Route mode with multiple external network connections

Transparent mode

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Figure 6: Example NAT/Route mode network configuration
204.23.1.5
Internet
In NAT/Route mode, you can use the modem interface to configure the FortiGate unit
with multiple redundant connections to the external network (usually the Internet). For
example, you could create the following configuration:
• External is the default interface to the external network (usually the Internet).
• Modem is the redundant interface to the external network.
• Internal is the interface to the internal network.
You must configure routing to support redundant Internet connections. Routing can be
used to automatically redirect connections from an interface if its connection to the
external network fails.
Otherwise, security policy configuration is similar to a NAT/Route mode configuration
with a single Internet connection. You would create NAT mode firewall policies to
control traffic flowing between the internal, private network and the external, public
network (usually the Internet).
Figure 7: Example NAT/Route multiple internet connection configuration
External
204.23.1.5
Internet
Modem
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 have to
configure a management IP address so that you can 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.
01-28008-0017-20050128
FortiGate-50A Unit
in NAT/Route mode
External
POWER
PWR STATUS
INTERNAL
A LINK 100
NAT mode policies controlling
traffic between internal and
external networks.
FortiGate-50A Unit
in NAT/Route mode
PWR STATUS
INTERNAL EXTERNAL
A
LINK 100 LINK 100
192.168.1.1
NAT mode policies controlling
traffic between internal and
external networks.
Internal
192.168.1.99
Internal network
EXTERNAL
LINK 100
Internal network
Internal
Getting started
192.168.1.3
192.168.1.3
Fortinet Inc.