zNetLaB › Guided labs › Enterprise
Publish an inside server with static NAT and port forwarding
Enterprise Intermediate 4 devices 4 checked tasks 100 points Plan lab
An internal web server must be reachable from the internet at the router’s public address on port 8080. Mark the NAT sides, add a static PAT entry that forwards that port to the server’s private address on port 80, and keep ordinary users’ internet access working with overload. You build it in a browser, type real commands at each device, and every task below is
checked against the running configuration — so you find out it is wrong before anybody else does.
Open this lab in the simulator
The simulator runs in your browser with nothing to install. This lab is part of the full simulator: open it free for 7 days with a new account, then with a plan. It needs an account, which keeps your progress.
The scenario
An internal web server must be reachable from the internet at the router’s public address on port 8080. Mark the NAT sides, add a static PAT entry that forwards that port to the server’s private address on port 80, and keep ordinary users’ internet access working with overload.
Your role: a network engineer on the enterprise team. Level: Intermediate Done when: all 4 goals show as passed (100 points).
Network status
Devices: 1 router, 1 server, 2 PCs, cabled as drawn. No Layer 1 or Layer 2 faults: every link is connected and up. Edge starts with addresses (G0/0 192.168.1.1/24, G0/2 192.168.2.1/24, G0/1 203.0.113.1/24). Web-Inside is a host with 192.168.1.20/24, gateway 192.168.1.1. User is a host with 192.168.1.50/24, gateway 192.168.1.1. Internet-PC is a host with 203.0.113.50/24, gateway 203.0.113.1. Known problems
None: nothing is misconfigured. The network is simply not finished: what the goals list is what you have to build or secure. Goals
Inside and outside interfaces are marked for NAT (25 pts) A static PAT entry forwards public port 8080 to the server’s port 80 (40 pts) Users’ internet access is translated with overload (20 pts) The server is still reachable from the user side (15 pts) The activity, in order
Inside and outside interfaces are marked for NAT Why: NAT needs to know which side is inside; get it backwards and nothing translates. Verify with: show ip nat statistics A static PAT entry forwards public port 8080 to the server’s port 80 Why: This is the task that checks your configuration directly: the line must really be there, not just look right. Verify with: show running-config Users’ internet access is translated with overload Why: PAT lets many private hosts share one public address; the ports tell the replies apart. Verify with: show ip nat translations The server is still reachable from the user side Why: A ping needs a route in BOTH directions. This is the end-to-end proof that everything before it worked. Verify with: ping 192.168.1.1 Tips
Work in the order given: later goals depend on the earlier ones. After every change, run the verify command before moving on; do not guess. Stuck? Read the verify output first. It names the interface, neighbour or route that is wrong. Common mistake: Forwarding to the wrong inside port Common mistake: Static entry on an interface not marked NAT Common mistake: No ACL permitting the forwarded service Why this matters
A server with a private address can be reached from the internet by publishing it: static NAT with port translation maps one public port to the private address and port.
What you will be able to do
Mark NAT inside and outside interfaces
Create a static PAT entry (port forward)
Keep dynamic overload for ordinary users
The network
ISR 2911, Server, PC — 4 devices in all, already cabled.
Gi0/0 192.168.1.1/24 Fa0 Gi0/2 192.168.2.1/24 Fa0 Gi0/1 203.0.113.1/24 Fa0 Edge Web-Inside 192.168.1.20/24 · gw 192.168.1.1 User 192.168.1.50/24 · gw 192.168.1.1 Internet-PC 203.0.113.50/24 · gw 203.0.113.1 Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
Edge ISR 2911 configure it Web-Inside Server 192.168.1.20 / 255.255.255.0 gw 192.168.1.1 User PC 192.168.1.50 / 255.255.255.0 gw 192.168.1.1 Internet-PC PC 203.0.113.50 / 255.255.255.0 gw 203.0.113.1
Cabling
Edge Gi0/0 ↔ Web-Inside Fa0 Edge Gi0/2 ↔ User Fa0 Edge Gi0/1 ↔ Internet-PC Fa0
What is configured at the start
These are already configured when the lab opens — including, where this is a troubleshooting lab, the fault itself:
Edge interface g0/0
ip address 192.168.1.1 255.255.255.0
no shutdown
exit
interface g0/2
ip address 192.168.2.1 255.255.255.0
no shutdown
exit
interface g0/1
ip address 203.0.113.1 255.255.255.0
no shutdown
exit Tasks, and how each one is checked
Every task is decided by reading the live network — a neighbour in FULL, a ping that succeeds, a line in the running configuration — not by looking for a keyword you typed. The same command shows you what the lab sees.
# Task Pts How to verify it yourself
1 Inside and outside interfaces are marked for NAT 25 On Edge: show ip nat statistics — Gi0/0 is inside. and On Edge: show ip nat statistics — Gi0/1 is outside. 2 A static PAT entry forwards public port 8080 to the server’s port 80 40 On Edge: show running-config contains the line(s) matching ip nat inside source static tcp 192\.168\.1\.20 80 (203\.0\.113\.1|interface GigabitEthernet0/1) 8080. 3 Users’ internet access is translated with overload 20 On Edge: show running-config | include nat shows overload . 4 The server is still reachable from the user side 15 On Web-Inside: ping 192.168.1.1 must succeed.
Stuck? Ask the coach
Tell the coach what you see or what you tried. It gives you a hint, not the answer, the way a senior engineer would. Included with a free trial or any plan.
Ask the coach
Common mistakes
Forwarding to the wrong inside port
Static entry on an interface not marked NAT
No ACL permitting the forwarded service
Reference solution
Try it yourself first — the lab checks your work either way. This is one configuration that makes every task pass, device by device:
Edge access-list 1 permit 192.168.1.0 0.0.0.255
interface g0/0
ip nat inside
exit
interface g0/2
ip nat inside
exit
interface g0/1
ip nat outside
exit
ip nat inside source list 1 interface g0/1 overload
ip nat inside source static tcp 192.168.1.20 80 203.0.113.1 8080 Where this is examined
CCNA (NAT), Network+ (NAT, port forwarding).
This lab practises these topics in the zNetLaB certification courses:
Related labs
Where to start
The lessons all guided labs plans
CCNA®, CCNP® and Cisco® are trademarks of Cisco Systems, Inc. zNetLaB is not affiliated with or endorsed by Cisco.