Port Forwarding and NAT on Cisco Routers - Accessing private network from the internet

This article demonstrates on how to access your private network from outside- the internet, using port forwarding or static nat on cisco routers.

Port forwarding is redirecting a request from one ip address and port number combination to another by a gateway or router. So, Port forwarding allows remote computers (for example, computers on the internet to connect to a specific computer or service within a private local-area network (LAN).

LAB

In our scenario, we have used cisco router 887va, dialer 1 is the outside interface of the cisco router which is connected to the internet (ISP), and vlan 1 is the inside interface of the cisco router which is connected to the local network.

Looking at the above diagram, we need accessing the pc 192.168.50.11 from the internet, as you see in the diagram, the pc (My Pc) is connected to the internet using dsl modem in Germany, and the pc 192.168.50.11 is connected to the internet using cisco router 887VA in Palestine. The pc (My PC) from the internet in Germany will request the public ip of the cisco router and remote desktop port 3389, the router will forward or redirect this packet to the LAN PC 192.168.50.11 on port 3389, This represents the port forwarding.

Port forwarding is a part of network address translation (NAT).

Configuratiion Steps:

1- Configure redirecting the request of the public ip address or the outside interface of the cisco 887va and port number 3389 to the private ip 192.168.50.11

R(config)#ip nat inside source static tcp 192.168.5.11 3389 interface dialer 1 3389

2- Specify the inside interface and outside interface of the router

R(config)#int vlan 1

R(config)#ip nat inside

R(config)#int dialer 1

R(config)#ip nat outside

For more details and explanation , watch this video on youtube

https://youtu.be/8WVWoW86Uhw

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