Ports (software)

Unlike the hardware ports which you use to connect different devices to your computer (for example, a USB port for your MP3 player or Ethernet port for wired LAN), software ports are virtual connectors that link software together. Ports are also used to funnel data over the network (or the Internet) between a server application and a client application (for example, your web browser accessing the FaceBook contents residing on the remote server over the HTTP port 80). Ports can change dynamically and their numbers can by quite random. Malicious programs can use either common (139 for NetBIOS or 110 for Incoming POP3 account) or unconventional ports to send or receive data. It is essential that ports are monitored and data that is transmitted through them is analyzed. This task is accomplished by a firewall.