How To Configure Port Forwarding On A Cisco Router?

How To Configure Port Forwarding On A Cisco Router?

How To Configure Port Forwarding On A Cisco Router?

Port forwarding is a technique to direct incoming requests from one port to another. Port forwarding can be used for many purposes, such as rerouting traffic from an insecure public network to a secure private network or redirecting traffic from the internet onto an internal computer running firewall software. This article discusses how to configure Port Forwarding on Cisco Routers.

How To Configure Port Forwarding On A Cisco Router?

First, you will need access and authorization credentials for your Cisco Router’s configuration mode.

Steps To Follow:

  • Login into the Cisco router using the IP address (e.g., by using any tool like putty or cmd.
  • Enter the “enable” command and enter your password if prompted for it, then click the OK button on the login prompt window after successfully entering the correct password/username combination.
  • Type “IP nat inside source static TCP ” Port number “101 interface Dialer 0 overload”, where Port number is any port that you want to redirect traffic from outside of the network(internet). For example, Port 21 can be used for FTP protocol or Port 22 can be used for SSH connection, etc., And Port 101 is just an example Port number to demonstrate Port Forwarding. 
  • Port Forwarding should be configured.
  • Save the configuration and reboot Cisco Router for Port forwarding settings to take effect in your network.

Are There Any Other Ways To Configure Port Forwarding?

Yes, you can use the GUI interface of the Cisco router instead of the command-line instructions provided above. Still, it requires more time as compared with configuring Port Forwarding using CLI on the Cisco router.

Configure Port Forwarding Using GUI Interface Of Cisco Router

Go to a web browser and login into the Cisco router using an IP address (e.g.,

Go to the Port Forwarding section of Cisco Router by the following path: Applications & Gaming > Port Range Forwarding, or you can use the shortcut which is available at the top right corner of the webpage under the Configuration tab when the GUI interface opens up on the browser screen; either way will get you the same Port forwarding page with a different name but similar content where configuration settings are required to be done next step onwards.

Steps To Follow:

  • Select Port Range (for example, 21-22).
  • Click Add New button above the Port Ranges section on the Port forwarding page. A new configuration window will open up where you can enter the Source IP address(outside of your network) and Destination port number that needs to be redirected or forwarded. (e.g – Port Number 2100). You should also select Protocol type, which is TCP protocol by default, so leave it as TCP unless specifically required otherwise.)
  • Finally, click the Submit button after entering the correct Port forwarding configuration settings. The Port Forwarding rule should be configured successfully. The browser screen saves all current configuration updates done to the device.
  • Reboot Cisco Router for new port forwarding rules to take effect, if not already done, before making any changes through this article about how to configure port forwarding on a Cisco router.

Port Forwarding Rules

Yes, you can create Port forwarding rules for many purposes like Port number 21 can be used for FTP protocol, Port 22 can be used for SSH connection, etc. You should know what protocols and Port numbers are already in use before creating the Port Forwarding rule on the Cisco router, or else it may conflict with other existing Port Forwarding settings on your network if there is any which will end up breaking the current configuration setup of your network even though this scenario does not happen very commonly but still we need to make sure that above-given points while configuring port forwarding on Cisco routers.

Is Port Forwarding The Same As Opening A Port?

Port Forwarding is different from opening a port on Firewall software running on your computer. Port forwarding redirects traffic from an insecure public network to a private, secure LAN. In contrast, Port Opening sends the request directly to target PC/servers connected with the firewall. Still, no change in incoming or outgoing IP address occurs, so security experts do not recommend opening ports for public access because that makes you vulnerable.


Port forwarding is very useful for redirecting traffic from public networks to private, secure LANs. Port forwarding is done on Router/Gateway, between the insecure public network and private, secure LAN. This article about how to configure port forwarding on a Cisco router was written here with the help of the above-given information and configuration steps that are easy enough for anyone who knows basic networking knowledge like Port numbers, Protocol types, etc.

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