In this lab, we use Packet Tracer in order to learn how to configure PAT such that many devices on a given network can communicate with a web server using a single public IP address.

• Cisco Packet Tracer
• Lab Packet Tracer File

The completed lab environment should look similar to below:

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Pre-Req: Ensure that routing has been configured and the NAT "inside" + "outside" interfaces have been defined. (**Additional config info --> Here)

# Creating an Address Pool containing the IP addresses that the internal clients can use
# (pool only contains 1 address)
R1(config)> ip nat pool <Pool-Name-Here> <Public-IP> <Public-IP-Again> netmask <Subnet-Mask-Here>

# Creating an access-list used to define which Internal IPs can use the specified Public IP Pool from above
R1(config)> access-list 1 permit <Internal-IP-Network-Address> <Reverse-Subnet-Mask-Notation>

# Assign the newly created Address Pool and Access List to the inside/internal interface using NAT 
# - (Note: Overload = Public IP can be used by up to 64,000 clients)
R1(config)> ip nat inside source list 1 pool <Pool-Name-Here> overload

In order to verify if PAT is working correctly, you can use the following command below to view the router's current NAT Table:

• R1#show ip nat translations

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Figure 1: Screenshot of the IP NAT Table on my Router 1 CLI Interface showing the internal PCs successfully connecting to the web server (20.0.0.2) using a single IP via PAT.