When you run Nmap and see a list of open ports, each one represents a service – a program listening for connections. Understanding what these services do and how they work is essential, because you can’t attack (or defend) what you don’t understand.

Let’s walk through the services you’ll encounter most often.

FTP (Port 21) – File Transfer Protocol. Used for transferring files between systems. FTP sends everything including usernames and passwords in plain text. Anyone sniffing the network can see your credentials. SFTP is the secure alternative.

SSH (Port 22)

Part of the free Intro to Cyber course by Cover6 Solutions.