Stage 1 · Lesson 4 of 7
Ports, TCP and UDP
An IP address finds the machine; a number finds the program on it. TCP (Transmission Control Protocol) opens a connection and delivers data reliably and in order. UDP (User Datagram Protocol) sends independent packets with no guarantee, which suits lookups and video calls.
Learn the ports you will meet constantly: 22 for , 80 for , 443 for HTTPS, 5432 for PostgreSQL and 3306 for MySQL. Every cloud you write is a list of protocols, ports and allowed sources, so knowing what your app actually listens on is the first step to opening only that.
Common trapopening a database port or SSH to the whole internet to make a connection error go away.
A question to check yourself, an AI practice session and 1 cheat sheet entry come with the full roadmap. Unlock
Resources for this stage
Start with· follow one of these
- CourseFreeLinux Upskill Challenge
Linux Upskill Challenge · Beginner
Free, one task a day on a real cloud server: the shell skills this roadmap assumes
- VideoFreeComputer Networking: A Top-Down Approach (Video Lectures)
Jim Kurose and Keith Ross · Intermediate
Free lectures: watch the chapters on the application, transport and network layers for IP, TCP, UDP and DNS