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Network+ lab 12 of 27

NAT and PAT with port forwarding at the edge

Connect a private office to the internet. You see why private addresses don't route, share one public address among all hosts with PAT, publish an inside web server with a port forward, and read the NAT table in inside/outside local/global terms.

Run this lab

It needs Lite: its 5 nodes are set to 5 vCPU and 3,072 MB in total. That fits the free demo too.

In your workspace: Shared, then CompTIA Network Plus N10-009 guided labs, then 12 - NAT and PAT with port forwarding at the edge

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Level
Intermediate
Time
About 50 minutes
Nodes need
5 vCPU, 3,072 MB
Smallest plan
Lite

The scenario

Harbour Logistics' depot uses private addresses (10.10.10.0/24) inside. Its provider has given it a small public block, 198.51.100.0/29: R2 (the provider) is .1, R1's outside interface is .2, and .3 to .6 are free. Staff need to reach the internet, and the depot's web server H1 must be reachable from the internet at 198.51.100.3. H2 plays an internet user.

DeviceInterfaceAddressRole
R1Gi0/010.10.10.1/24NAT inside
R1Gi0/1198.51.100.2/29NAT outside, default route to R2
R2Gi0/0 / Gi0/1198.51.100.1/29 / 203.0.113.1/24provider
PC1eth010.10.10.10/24staff PC
H1eth010.10.10.100/24web server (TCP 80)
H2eth0203.0.113.10/24internet user

What you’ll practise

  • Explain why RFC 1918 addresses need translation to reach the internet
  • Mark NAT inside and outside interfaces and configure PAT (overload)
  • Publish an inside server with a static port forward
  • Read a NAT translation table: inside local, inside global, outside local, outside global
  • Compare static NAT, dynamic NAT, PAT and port forwarding

The tasks

  1. Prepare the two Linux hosts
  2. See why private addresses don't reach the internet
  3. Share one public address with PAT
  4. Publish the web server with a port forward
  5. Read the NAT table like the exam does
  6. Choose the right kind of NAT

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 NAT and PAT with port forwarding at the edge5 nodes and 1 network, 5 links. Every link is listed as text below the diagram.R1R2H2PC1H1Inside-LANGi0/0eth0eth0Gi0/1eth0Gi0/1Gi0/0
5 nodes and 1 network, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • R1 Gi0/0 to Inside-LAN (network)
  • PC1 eth0 to Inside-LAN (network)
  • H1 eth0 to Inside-LAN (network)
  • R1 Gi0/1 to R2 Gi0/0
  • R2 Gi0/1 to H2 eth0
Nodes in NAT and PAT with port forwarding at the edge, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
R1Cisco IOSvvios-adventerprisek9-m.SPA.159-3.M61 vCPU, 512 MB
R2Cisco IOSvvios-adventerprisek9-m.SPA.159-3.M61 vCPU, 512 MB
H2Alpine Linuxclbalpinebase-alpine-base-3-20-31 vCPU, 512 MB
PC1VPCS hostBuilt in to EVE-NGCounted as 1 vCPU, 1,024 MB
H1Alpine Linuxclbalpinebase-alpine-base-3-20-31 vCPU, 512 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 CompTIA Network Plus N10-009 guided labs.

  3. Open 12 - NAT and PAT with port forwarding at the edge 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 CompTIA, Cisco and Netgate. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.