On modern operating systems, ports are numbered addresses for network traffic. Different kinds of services use different ports by default.
image:./nmapscan.png[width=400,float="right"]
For example, normal web traffic uses Port 80, while POP3 email uses Port 110. One of the ways that a firewall works is by allowing or restricting traffic over a particular port.
image:./nmapscan.png[width=400,float="right"]
Because the ports can cause a security risk, it’s critical to know which ports are open and which are blocked.
zeus
3 years ago