Whenever an application wants to make itself accessible over the network, it claims a TCP/IP port, which means that port can’t be used by anything else. So how do you check open ports to see what application is already using it?
So you have an antivirus program guarding your system, your firewall is up, your browser is updated, and you’re not missing any security patches. But how can be sure your defenses are actually working as well as you think they are?