Linuxネットワークの基礎

Ever wondered how machines actually talk to each other? This lesson grounds you in Linux networking — the key terms and how devices connect.

A network is just connected devices sharing data. A node is any device on it; a host is a node with an IP that can send and receive.

Data doesn't travel as one blob — it's split into packets. Each carries a chunk of data plus sender, receiver, and reassembly info.

For devices to understand each other they share rules called protocols — defining how data is formatted, sent, and interpreted. They're the grammar of the network.

Devices connect through a network interface (NIC). In Linux you'll see names like eth0 (wired), wlan0 (Wi-Fi), and lo (loopback).

A MAC address is a unique hardware ID burned into each NIC. It identifies devices within a local segment, operating at the data link layer.

While a MAC names the physical device, an IP address marks its logical location on a network — like a street address that lets it reach across networks.

A switch connects devices within a local network (LAN). It learns which device sits on which port and forwards packets only to the right one.

A router forwards packets between different networks — the internet's traffic cop, directing your data from home out to the right destination.

Devices connect two main ways: Ethernet cables for fast, reliable wired links, and Wi-Fi for flexible wireless connections over radio.

Recap: you covered nodes and hosts, packets and protocols, interfaces, MAC and IP addresses, plus switches and routers. Next — commands to inspect your network.