Opening Firewall Ports on Windows

What is a port?

A port is an opening into your computer through which information can flow. For example, if you are exchanging instant messages with someone who wants to send you a file, such as a photo, your firewall program (e.g., Windows Firewall) will ask you if you want to unblock the request so that the photo can reach your computer. Or, if you want to play a multiplayer network game with friends (either over the Internet or over your local area network), you must open a port so that the firewall can allow game information to be sent to your computer.

How ports work

Each port has a number, which is like an address. Many programs and services have a “permanent address” that is, they have predefined port numbers. You can find the correct port number for a program or service in the manufacturer’s documentation or on their Web site. Some programs (many games, for example) do not have predefined port numbers, but rather open ports automatically as needed.

Risks of opening ports

Each time that you allow a program to communicate through your firewall, your computer is made more vulnerable. Opening a port is like poking a hole through the firewall. If there are too many holes, there is not much wall left in your firewall. Unknown intruders often use software that scans the Internet looking for computers with unprotected connections. If you have many open ports, your computer can become a victim of these intruders.

To help decrease your security risks:

  • Only open a port when you really need it.
  • Never open a port for a program that you do not recognize.
  • Close a port when you no longer need it.

Opening ports in Windows Firewall

To help protect the security of your computer, you should keep Windows Firewall (or another firewall of your choice) turned on, so that unsolicited requests to connect to your computer are blocked.

To allow a type of connection, you must create an exception or open a port for the specific program or service. Performing a search should yield many resources that will help you manage your firewall and network communications.