The Language of the Internet
Computers are useful, but connected computers are revolutionary. Networking is the study of how data moves from Point A to Point B.
1. The OSI Model
A conceptual framework used to understand network interactions.
- Physical: Cables, electricity, wifi radio waves.
- Data Link: MAC addresses, switches.
- Network: IP addresses, routers. (Where the internet lives).
- Transport: TCP/UDP processes. Reliability.
- Session: Managing connections.
- Presentation: Encryption (SSL), formats (JPEG).
- Application: What the user sees (HTTP, SMTP).
2. IP Addressing & DNS
- IPv4: Your digital address (e.g., 192.168.1.1). Unique on the network.
- DNS (Domain Name System): Humans are bad at remembering numbers. DNS translates "google.com" into "142.250.190.46". It is the phonebook of the internet.
3. Ports & Protocols
If an IP address is the building number, the Port is the apartment number.
- Port 80 (HTTP): Unencrypted web traffic.
- Port 443 (HTTPS): Encrypted web traffic.
- Port 22 (SSH): Secure remote login.
- Port 53 (DNS): Domain name lookups.
🔬 Lab Exercise: Viewing the Matrix
Objective: See traffic moving across the wire.
- Install Wireshark (a network protocol analyzer).
- Open Wireshark and select your active network adapter (WiFi or Ethernet).
- Start capturing packets.
- Open a terminal/cmd and type
ping google.com. - Stop the capture and look for "ICMP" packets. That is your ping!