Ports

Problem

Your computer has one IP address: 10.0.0.20 But Chrome, Teams, SSH and hundreds of other processes may communicate simultaneously. An incoming packet reaches the computer. Which application should receive it?

Solution — Ports

Transport protocols identify endpoints using port numbers.

10.0.0.20:22    → SSH
10.0.0.20:443   → HTTPS server
10.0.0.20:53021 → client connection

Core idea: IP identifies the host; ports help identify the communication endpoint/application.