Blocking Ports on Your Router to Stop File Sharing

by Louis Kroeck Google

There are a variety of reasons you may want to block ports on your router in order to stop file sharing. Whether you are worried that individuals on your computer network are using file sharing to engage in copyright infringement or if you are looking to stop file sharing to free network resources, port blocking is one potential solution.

Definition of Ports

Ports are essentially virtual connections on a router that allow Internet traffic in or out of a computer network. Blocking a port is like closing a door that's a certain shape to keep objects of that shape from passing in or out of a structure. Similarly, any Internet traffic that's the specific nature the port admits will not be able to enter or exit your computer network. In order to close ports your router will need to be equipped with a firewall or other port-blocking device.

Limiting File Sharing

Stopping file sharing on your network through port blocking can be a very difficult task. Not only do most-file sharing applications use different ports for operation, but also many of those applications allow those ports to be changed in order to circumvent firewalls. In order to attempt to stop file sharing through port blocking you will need to identify what ports your network user's file sharing programs use. Common file-sharing ports include 21 for FTP, 6346 to 6347 for Limewire, 411 and 1025 to 32000 for DC++ and 3689 for iTunes.


If you attempt to block all ports, or block too many ports in an attempt to prevent file sharing, you may severely limit the functionality of your router and your computer network. Different applications commonly operate on the same ports, so it is possible to block the functionality of a program other than a file-sharing program as a consequence of overreaching in your attempt to block file-sharing ports.

Other Methods to Stop File Sharing

There are a variety of other methods network administrators can use in addition to blocking ports in order to stop file sharing over their networks. Network administrators should start by creating an acceptable use policy informing network users that file sharing is not appropriate on the computer network. Limiting network users' ability to install applications used for file sharing will also help stop file sharing.

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