What you will learn
- Read interface and route config
- Diagnose open ports
- Test connectivity
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The basics, in plain English
Networking is how one computer talks to another. From the command line you can check your machine’s address, see which doors (ports) are open, and test whether you can reach another computer.
- Network
- Two or more computers connected so they can send data to each other.
- IP address
- A computer’s numeric address on the network, like a house address for data.
- Port
- A numbered doorway on a computer. Different services listen on different ports (web is usually 80 or 443).
- Interface
- The hardware or software connection point your machine uses to reach the network (like Wi-Fi or ethernet).
- curl
- A command that fetches a web address from the terminal, to test if a server responds.
- DNS
- The phonebook of the internet: it turns a name like google.com into an IP address.
01
The tools
ip replaces ifconfig for addresses and routes. ss shows sockets. curl and dig test HTTP and DNS.
02
Debugging
When something cannot connect, walk the stack: is the interface up, is there a route, is the port listening, is DNS resolving.
Try it yourself
bash
$ip addr show↳List network interfaces and their IP addresses.$ss -tulpn↳Show which ports are open and which process owns each one.$dig +short example.com↳Resolve a domain to its IP, output kept brief.$curl -I https://example.com↳Fetch just the response headers to check status and server.↳ lines explain what each command does — only the commands get copied
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