How to Configure PAT NAT Overload on Cisco Router in GNS3? – One of the NAT configurations on Cisco Routers is NAT overload and is also known as PAT.
How to Configure PAT NAT Overload on Cisco Router in GNS3?

How to Configure PAT NAT Overload on Cisco Router in GNS3?

PAT configuration on Cisco Router differs from Static NAT and Dynamic NAT. While Static NAT is configured on Cisco Router, the computers on the local network are statically matched to the IP address when accessing the Internet. In Dynamic NAT, this process works with a pool system. The NAT pool consists of IP addresses assigned by the Internet Service Provider.

In the Cisco Router Dynamic NAT process, the private IP addresses of the computers on the local network are matched with the unused IP addresses in the NAT pool.

The NAT Overload (PAT) configuration on Cisco Router is the ideal method for most home users and small businesses. Since there is only one Global IP address assigned by the ISP, all devices on the network will be able to access the Internet through the PAT method.

For Static NAT configuration on Cisco Router, you can read the topic called “How to Configure Static NAT on Cisco Router?“.

 

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How to Configure NAT Overload (PAT) in GNS3?

PAT configuration on Cisco Router is very similar to Dynamic NAT. And since it is a single global IP address that is purchased by the ISP, there is no need to define a NAT pool.

Follow the steps below to configure PAT on Cisco Router using GNS3 and VMware virtual machines.

   Step 1

First, open the GNS3 program and create a new project. Next, add the Router, Cloud, Switch and two Host to the GNS3 workspace. Afterward, create the topology as shown below.

How to Configure PAT NAT Overload on Cisco Router in GNS3?

   Step 2

After opening Cloud settings, select the physical Ethernet of your computer and click the add button.

How to Configure PAT NAT Overload on Cisco Router in GNS3?

   Step 3

In the GNS3 program, some problems may occur when two computers add to a Switch. You can solve this problem by changing the port numbers as shown in the following image.

How to Configure PAT NAT Overload on Cisco Router in GNS3?

   Step 4

Add VMnet3 in the Virtual Network Editor program of VMware Workstation. After setting the IP address block, select VMnet3 from the Ethernet tab in the settings of the computers on the GNS3 workspace and save the settings.

How to Configure PAT NAT Overload on Cisco Router in GNS3?

   Step 5

Double-click on Cisco Router and open the CLI command prompt. Next, execute the following commands to configure PAT (NAT Overload) on Cisco Router.

R1# conf t
R1(config)# interface fastethernet 0/0
R1(config)# ip address 192.168.8.1 255.255.255.0
R1(config-if)# ip nat inside
R1(config-if)# no shutdown
R1(config-if)# exit
R1(config)# interface fastethernet 0/1
R1(config-if)# ip address dhcp
R1(config-if)# ip nat outside
R1(config-if)# no shutdown
R1(config-if)# exit
R1(config)# access-list 1 permit 192.168.8.0 0.0.0.255
R1(config)# ip nat inside source list 1 interface fastethernet 0/1 overload
R1(config)#exit
R1# copy running-config startup-config

 
How to Configure PAT NAT Overload on Cisco Router in GNS3?

   Step 6

After configuring PAT on Cisco Router, check the network connection by pinging the Google DNS server through the VMware Windows 8.1 virtual machine.

As you can see in the image below, Ping will be successful!

How to Configure PAT NAT Overload on Cisco Router in GNS3?

   Step 7

Likewise, ping the Google DNS server from the VMware Windows 10 virtual machine and review the results.

How to Configure PAT NAT Overload on Cisco Router in GNS3?

   Step 8

When you execute the show ip nat translations command in the privileged configuration mode of Cisco Router, you can see that the IP addresses and port numbers convert as follows.

How to Configure PAT NAT Overload on Cisco Router in GNS3?

   Step 9

You can examine the entries of NAT when you execute the show ip nat statistics command on Cisco Router.

How to Configure PAT NAT Overload on Cisco Router in GNS3?

   Step 10

After configuring NAT Overload on Cisco Router, you can remove the NAT entries on the Router with the clear ip nat translations * command.

How to Configure PAT NAT Overload on Cisco Router in GNS3?

Show Commands Related to How to Configure PAT NAT Overload on Cisco Router in GNS3

R1#show running-configR1# show ip nat translationsR1# show ip nat translations
R1#show running-config
Building configuration...

Current configuration : 1095 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R1
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
ip cef
!
!
no ip domain lookup
ip auth-proxy max-nodata-conns 3
ip admission max-nodata-conns 3
!
!
ip tcp synwait-time 5
!
!
interface FastEthernet0/0
ip address 192.168.8.1 255.255.255.0
ip nat inside
ip virtual-reassembly
duplex auto
speed auto
!
interface FastEthernet0/1
ip address dhcp
ip nat outside
ip virtual-reassembly
duplex auto
speed auto
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
ip nat inside source list 1 interface FastEthernet0/1 overload
!
access-list 1 permit 192.168.8.0 0.0.0.255
no cdp log mismatch duplex
!
!
control-plane
!
!
gatekeeper
shutdown
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
R1#
R1# show ip nat translations
Pro Inside global Inside local Outside local Outside global
icmp 192.168.1.102:1 192.168.8.5:1 8.8.8.8:1 8.8.8.8:1
tcp 192.168.1.102:49193 192.168.8.5:49193 2.17.20.139:80 2.17.20.139:80
tcp 192.168.1.102:49194 192.168.8.5:49194 2.17.20.139:80 2.17.20.139:80
tcp 192.168.1.102:49195 192.168.8.5:49195 2.22.109.171:80 2.22.109.171:80
icmp 192.168.1.102:0 192.168.8.10:1 8.8.8.8:1 8.8.8.8:0
tcp 192.168.1.102:49706 192.168.8.10:49706 23.62.98.64:80 23.62.98.64:80
tcp 192.168.1.102:49730 192.168.8.10:49730 23.62.98.64:80 23.62.98.64:80
tcp 192.168.1.102:49731 192.168.8.10:49731 23.62.98.8:80 23.62.98.8:80
tcp 192.168.1.102:49736 192.168.8.10:49736 23.62.98.8:80 23.62.98.8:80
tcp 192.168.1.102:49809 192.168.8.10:49809 173.223.11.177:80 173.223.11.177:80
tcp 192.168.1.102:49854 192.168.8.10:49854 13.107.4.50:80 13.107.4.50:80
tcp 192.168.1.102:49858 192.168.8.10:49858 23.62.98.8:80 23.62.98.8:80
tcp 192.168.1.102:49895 192.168.8.10:49895 13.107.4.50:80 13.107.4.50:80
tcp 192.168.1.102:49897 192.168.8.10:49897 13.107.4.50:80 13.107.4.50:80
tcp 192.168.1.102:49908 192.168.8.10:49908 40.77.229.91:443 40.77.229.91:443
tcp 192.168.1.102:49909 192.168.8.10:49909 40.77.229.17:443 40.77.229.17:443
tcp 192.168.1.102:49914 192.168.8.10:49914 40.77.229.10:443 40.77.229.10:443
tcp 192.168.1.102:49916 192.168.8.10:49916 40.77.226.250:443 40.77.226.250:443
tcp 192.168.1.102:49917 192.168.8.10:49917 92.123.166.179:443 92.123.166.179:443
udp 192.168.1.102:59225 192.168.8.10:59225 192.168.1.1:53 192.168.1.1:53
R1# show ip nat translations
Pro Inside global Inside local Outside local Outside global
tcp 192.168.1.102:49212 192.168.8.5:49212 151.101.194.49:80 151.101.194.49:80
R1# show ip nat statistics
Total active translations: 1 (0 static, 1 dynamic; 1 extended)
Outside interfaces:
FastEthernet0/1
Inside interfaces:
FastEthernet0/0
Hits: 180715 Misses: 431
CEF Translated packets: 179908, CEF Punted packets: 2474
Expired translations: 635
Dynamic mappings:
-- Inside Source
[Id: 1] access-list 1 interface FastEthernet0/1 refcount 1
Appl doors: 0
Normal doors: 0
Queued Packets: 0
R1#

How to Configure PAT NAT Overload on Cisco Router in GNS3? ⇒ Video

To configure PAT (NAT Overload) on GNS3, you can watch the following video, and you can also subscribe to our YouTube channel to support us.

  Final Word

How to Configure PAT NAT Overload on Cisco Router in GNS3?  – In this article, we have configured the PAT on Cisco Router using the GNS3 network simulator program. Thanks for following us!

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