Networking (Core 1)

Ports 20 and 21 — port 21 carries control commands, while port 20 carries the actual file data in active mode.

TCP port 22 — SSH provides encrypted remote command-line access.

TCP port 23 — Telnet provides remote command-line access but sends everything, including passwords, in plaintext.

SSH encrypts the entire session, while Telnet transmits credentials and commands in plaintext that anyone on the network can capture.

TCP port 25 — SMTP sends email between mail servers and from clients to servers.

Port 53 — DNS translates domain names into IP addresses, typically over UDP.