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?“.
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.
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.
After opening Cloud settings, select the physical Ethernet of your computer and click the add button.
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.
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.
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
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!
Likewise, ping the Google DNS server from the VMware Windows 10 virtual machine and review the results.
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.
You can examine the entries of NAT when you execute the show ip nat statistics command on Cisco Router.
After configuring NAT Overload on Cisco Router, you can remove the NAT entries on the Router with the clear ip nat translations * command.
Show Commands Related to How to Configure PAT NAT Overload on Cisco Router in GNS3
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 192.168.1.102:1 192.168.8.5:1 188.8.131.52:1 184.108.40.206:1 tcp 192.168.1.102:49193 192.168.8.5:49193 220.127.116.11:80 18.104.22.168:80 tcp 192.168.1.102:49194 192.168.8.5:49194 22.214.171.124:80 126.96.36.199:80 tcp 192.168.1.102:49195 192.168.8.5:49195 188.8.131.52:80 184.108.40.206:80 icmp 192.168.1.102:0 192.168.8.10:1 220.127.116.11:1 18.104.22.168:0 tcp 192.168.1.102:49706 192.168.8.10:49706 22.214.171.124:80 126.96.36.199:80 tcp 192.168.1.102:49730 192.168.8.10:49730 188.8.131.52:80 184.108.40.206:80 tcp 192.168.1.102:49731 192.168.8.10:49731 220.127.116.11:80 18.104.22.168:80 tcp 192.168.1.102:49736 192.168.8.10:49736 22.214.171.124:80 126.96.36.199:80 tcp 192.168.1.102:49809 192.168.8.10:49809 188.8.131.52:80 184.108.40.206:80 tcp 192.168.1.102:49854 192.168.8.10:49854 220.127.116.11:80 18.104.22.168:80 tcp 192.168.1.102:49858 192.168.8.10:49858 22.214.171.124:80 126.96.36.199:80 tcp 192.168.1.102:49895 192.168.8.10:49895 188.8.131.52:80 184.108.40.206:80 tcp 192.168.1.102:49897 192.168.8.10:49897 220.127.116.11:80 18.104.22.168:80 tcp 192.168.1.102:49908 192.168.8.10:49908 22.214.171.124:443 126.96.36.199:443 tcp 192.168.1.102:49909 192.168.8.10:49909 188.8.131.52:443 184.108.40.206:443 tcp 192.168.1.102:49914 192.168.8.10:49914 220.127.116.11:443 18.104.22.168:443 tcp 192.168.1.102:49916 192.168.8.10:49916 22.214.171.124:443 126.96.36.199:443 tcp 192.168.1.102:49917 192.168.8.10:49917 188.8.131.52:443 184.108.40.206:443 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 220.127.116.11:80 18.104.22.168:80 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.
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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