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FortiGate lab 7 of 25

Destination NAT with virtual IPs

Publish a DMZ web server to the internet with a static NAT VIP and a port-forwarding VIP, let staff reach it by its public address (hairpin), see the VIP's address used for the server's own outbound traffic, and block an attacker with a deny policy that matches VIP traffic.

Run this lab

It needs Lite: its 4 nodes are set to 4 vCPU and 6,144 MB in total. That fits the free demo too.

In your workspace: Shared, then FortiGate NSE 4 guided labs, then 07 - Destination NAT with virtual IPs

Try it free for 30 minutesRun it on Lite from £3 a day

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Level
Intermediate
Time
About 60 minutes
Nodes need
4 vCPU, 6,144 MB
Smallest plan
Lite

The scenario

Harbourside's public web site runs on SRV1 in the DMZ at 10.1.30.10. The ISP has routed 203.0.113.80 and 203.0.113.81 to the firewall's link. The site must be reachable on 203.0.113.80 (HTTP and HTTPS), and a test copy must answer on 203.0.113.81 port 8080. Staff in the office use the same public address. And this morning the security team spotted scanning from 198.51.100.14, which must be blocked from the published server.

DeviceInterfaceAddressConnects to
FGT1port1 (ISP-A)203.0.113.1/24INET 203.0.113.254 (internet clients)
FGT1port2 (LAN)10.1.10.1/24PC1 10.1.10.10
FGT1port3 (DMZ)10.1.30.1/24SRV1 10.1.30.10 (web on 80 and 443)

You test from the "internet" with INET's terminal: curl http://203.0.113.80/whoami. The test site prints the client address it saw and its own address.

What you’ll practise

  • Publish a server with a static NAT virtual IP and an inbound policy
  • Forward one external port to a different internal port, and pick the right policy service
  • Let internal users reach a published server by its public address
  • Explain why outbound traffic from a static-NAT server uses the VIP address
  • Block chosen sources from VIP traffic with match-vip, and read DNAT sessions

The tasks

  1. Start the lab
  2. Publish the web server with a static NAT VIP
  3. A port-forwarding VIP
  4. Hairpin: staff use the public address
  5. The server's own outbound traffic
  6. Block a scanner from the published server

The Lab Tasks pane has the scenario, these tasks, the checks to run, hints and the full solution.

Topology and devices

The network as it opens in EVE-NG, drawn from the lab’s own canvas, and the image each node runs.

Topology of Destination NAT with virtual IPs4 nodes, 3 links. Every link is listed as text below the diagram.FGT1INETPC1SRV1port1eth0port2eth0port3eth0
4 nodes, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • FGT1 port1 to INET eth0
  • FGT1 port2 to PC1 eth0
  • FGT1 port3 to SRV1 eth0
Nodes in Destination NAT with virtual IPs, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
FGT1Fortinet FortiGatefortinet-FGT-v7.0.17.M-build06821 vCPU, 2,048 MB
INETEVE-NG GUI server (Docker)eve-gui-server:latest1 vCPU, 1,024 MB
PC1EVE-NG GUI server (Docker)eve-gui-server:latest1 vCPU, 2,048 MB
SRV1EVE-NG GUI server (Docker)eve-gui-server:latest1 vCPU, 1,024 MB

How to open this lab

  1. Sign in to your workspace at lab.cloudlabbox.com.

  2. In File Manager, open Shared, then the folder FortiGate NSE 4 guided labs.

  3. Open 07 - Destination NAT with virtual IPs and start its nodes, then open Lab Tasks for the scenario and the steps.

The lab is read-only. You can start the nodes and configure the devices, but changes to the topology can’t be saved. To change it, rebuild it in your own folder.

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CloudLabBox is independent of Fortinet. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.