Chapter 3 – NAT

3-1 Source NAT

Learning Objectives

  • Configure a NAT policy in FortiGate
  • Identify source NAT

 

Scenario: We are going to enable Source NAT(SNAT) to reach the Internet from Kali. That means that all traffic from the local network to the Internet should be allowed.

 

Source NAT main scenario
Figure 3-1: main scenario

Source NAT

Table 3-1: Devices configuration
Device IP address Access
Kali DHCP Client –
WordPress/Kali DHCP Client –
Ethernet Switch – –
FortiGate Port 2 – ( 192.168.1.1/24) – DHCP Server ( 192.168.1.10-192.168.1.20)

Port 3 – DHCP Client

Port 4 – 10.10.10.1/24

 ICMP-HTTP-HTTPS
WebTerm 10.10.10.2/24 –

Basic Configuration

1- Port configuration in the firewall as follows:

Port configuration in the firewall
Figure 3-2: Ports configuration in the firewall

2- Set a DHCP server on interface port2 (Range of IP address should be: 192.168.1.10- 192.168.1.20, DNS: 4.2.2.4)

Set a DHCP server on interface port2
Figure 3-3: DHCP Server configuration

3- Set port3 as a DHCP client and connect to the NAT.

Set port3 as a DHCP client and connect to the NAT
Figure 3-4: DHCP client configuration

4- Set a static route in the firewall to reach to NAT object.

Set static route in the firewall to reach to NAT object
Figure 3-5: Set a static route

5- Go to Policy & Objects > Firewall Policy section, click Create New to add a new firewall policy ,and configure the following settings:

      • Name: LocalToInternet
      • From inside to outside (port2 to port3)
      • Source: Create an address for the local network (Subnet: 192.168.1.0/24)
      • Destination: all
      • Schedule: Always
      • Service: Only HTTP, HTTPS, and DNS
      • Action: Accept
Configure Firewall Policy and enable NAT
Figure 3-6: Configure Firewall Policy and enable Source NAT

6- Open the browser in Kali, you should be able to access the internet.

you should be able to access the internet.
Figure 3-7: Verify your configuration

License

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FortiGate Firewall: Practical Guidance and Hands-On Labs by Hamid Talebi is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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