The communication between remote computers connected in your LAN or within Internet realized by this ports. Each port have a number and most important ports have names. Think for this ports like small doors. Through this doors any software program perform communication over TCP/IP networks.

Each computer connected to some TCP/IP network have several opened ports. But more client PCs will not set and they have many opened ports, which are not using and only can open some hackers doors for the security. To close ports, go to Start > Settings > Control Panel > Network Connections > Your_Network_Connection_Name > Properties.

In appeared window go to Internet Protocol (TCP/IP) > Advanced > Options > Properties. Check Enable TCP/IP Filtering (All adapters) and check the radio buttons Permit Only for TCP Ports and for IP Protocols, without adding anything from Add buttons.

Don't set UDP ports. They are different and lets keep Permit All option for him.

Click OK button on all opened windows. With this, you will filter almost all ports, without interrupting any application which are using this ports.
For example: If you don't add 5190 port in TCP ports, will no produce any conflict with ICQ communication.

In some computer configurations, TCP/IP filtering can make some problems like Internet interruption or stop working of some internet applications. If you see some problems like described, its better to stop TCP/IP filtering.

Please note, that if you are using some router or wireless access point probably this settings for port filtering have to be made from router control panel. Or if you are in office network may be your system administrator has been already done this.