Fortinet 500A, FORTIGATE, 127 manual NAT/Route mode with multiple external network connections

Getting started NAT/Route mode with multiple external network connections

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).

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 5: Example NAT/Route mode network configuration

Port 2

204.23.1.5

Internet

					Internal network
	FortiGate-500A Unit					192.168.1.3
				Port 1
	in NAT/Route mode
		192.168.1.99
							Route mode policies
	EscEnter						controlling traffic between
	A						internal networks.
			Port 4
						DMZ network
NAT mode policies controlling
		10.10.10.1

traffic between internal and

external networks. 10.10.10.2

NAT/Route mode with multiple external network connections

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:

•LAN is the interface to the internal network.

•Port 1 is the default interface to the external network (usually the Internet).

•Port 2 is the redundant interface to the external 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).

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