What is netstat?

netstat (short for “network statistics”) is a command‑line tool that shows you information about the network connections on a computer. It lists things like which programs are talking to other computers, what ports they’re using, and how much data is being sent or received.

Let's break it down

  • Command: You type netstat in a terminal (Windows, macOS, Linux).
  • Output: A table that includes columns such as Protocol (TCP/UDP), Local Address (your computer’s IP and port), Foreign Address (the remote computer’s IP and port), State (e.g., LISTENING, ESTABLISHED), and PID/Program name (which app opened the connection).
  • Options: Adding flags changes the view, e.g., -a shows all connections, -n shows numbers instead of names, -p shows the owning process, -r displays the routing table.

Why does it matter?

Knowing what’s happening on your network helps you:

  • Detect unwanted or suspicious connections (possible malware).
  • Troubleshoot why a program can’t reach the internet or a server.
  • Verify that a service (like a web server) is actually listening on the correct port.
  • Understand bandwidth usage and performance bottlenecks.

Where is it used?

  • System administrators checking server health or security.
  • Developers debugging network code or confirming that a local service started correctly.
  • Security analysts scanning for rogue connections during incident response.
  • Home users who want to see which apps are accessing the internet.

Good things about it

  • Built‑in on most operating systems, no extra installation needed.
  • Works with both IPv4 and IPv6.
  • Provides real‑time snapshot of all network activity.
  • Simple text output can be piped into other tools for further analysis.
  • Helpful for both quick checks and detailed investigations.

Not-so-good things

  • Output can be overwhelming on busy machines; you may need to filter with options or additional tools.
  • Lacks a graphical interface, which can be less intuitive for beginners.
  • Some modern OS versions limit the detail shown (e.g., Windows may hide PID without admin rights).
  • Does not continuously monitor; you must run it repeatedly or use other tools for live tracking.