Nat/Route Mode With Multiple External Network Connections - Fortinet FortiGate FortiGate-1000 Install Manual

Planning the FortiGate configuration

NAT/Route mode with multiple external network connections

FortiGate-200, FortiGate-300, FortiGate-400, FortiGate-500 and FortiGate-1000 FortiOS 3.0 MR4 Install Guide
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You can add firewall policies to control whether communications through the
FortiGate unit operate in NAT or Route mode. Firewall policies control the flow of
traffic based on the source address, destination address, and service of each
packet. In NAT mode, the FortiGate unit performs network address translation
before it sends the packet to the destination network. In Route mode, there is no
address translation.
You typically use NAT/Route mode when the FortiGate unit is operating as a
gateway between private and public networks. In this configuration, you would
create NAT mode firewall policies to control traffic flowing between the internal,
private network and the external, public network (usually the Internet).
Note: If you have multiple internal networks, such as a DMZ network in addition to the
internal, private network, you could create route mode firewall policies for traffic flowing
between them.
Figure 9: NAT/Route mode network configuration for a FortiGate-200.
Internet
In NAT/Route mode, you can 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)
• Internal is the interface to the internal network
• DMZ/HA is the redundant interface to the external network
You must configure routing to support redundant Internet connections. Routing
can automatically redirect connections from an interface if its connection to the
external network fails.
Otherwise, security policy configurations is similar to a NAT/Route mode
configuration with a single Internet connection. You would create NAT mode
firewall policies to control traffic following between the internal, private network
and the external, public network (usually the Internet).
FortiGate-200 unit
in NAT/Route mode
Internal
192.168.1.99
External
204.23.1.5
DMZ
10.10.10.1
NAT policies controlling
traffic between internal
and external networks.
Configuring the FortiGate unit
Internal
network
192.168.1.3
Policies controlling
traffic between
Internal networks.
DMZ
network
10.10.10.2
01-30004-0267-20070215