Firewall protects your computer from intrusion by filtering incoming and outgoing traffic. It can be implemented as software or hardware. A hardware firewall is usually a box sitting next to your physical network connection (like DSL or cable modem) and local network computers are connected to it directly or though router or switch.
Internet Connection Firewall (ICF) that is built into Windows is software firewall. This means that it is a software application that runs on your computer and filters network traffic. First you need to enable it and set it up.
Enabling Internet Connection Firewall (ICF) in Windows
1. Open “Control Panel” ([How to open Control Panel->how-to-access-control-panel-in-windows])
2. Click on “Network and Internet Connections”
3. Click on “Network Connections”
4. List with all your Internet connection will appear. Find your connection icon and right click on it and select “Properties”.
5. In “Connection properties” window click on “Advanced” tab
6. To enable firewall, check box next to “Protect my computer and network by limiting or preventing access to this computer from the Internet”
7. Click “OK”. If that connection was active, you will need to disconnect and connect again to enable firewall.
Opening ports in firewall
Ports are used to exchange data between computers on the Internet. Each packet of data sent through network contains in its header, source and destination port. By default firewall will block almost all ports. Some applications like P2P, chat, irc might need to have specific port open in firewall to function properly. Usually you can find port number and type (TCP or UDP) your application is using, in the help file or in the application options.
How to open port in Internet Connection Firewall (ICF) in Windows
1. Repeat previous steps 1-5 to get to “Advanced” tab
2. Click “Settings” button at the bottom of the window
3. Some ports might be already in the list
4. To open new port click “Add” button
5. In the “Service settings” window enter description e.g. “My application port”
6. In the “Name or IP address..” box enter 127.0.0.1
7. Enter port number in “External” and “Internal”
8. Select “TCP” or “UDP”
9. Click “OK” on all dialogs