Network Troubleshooting for Beginners: The Swiss Army Knives of Diagnostics

Introduction

Up to this point, we’ve used simple utilities for specific tasks:

• ping checked connectivity,
• traceroute showed the path,
• ipconfig and arp helped with the local network,
• telnet and nc tested ports.

That’s like having a separate hammer, screwdriver, and wrench. But sometimes you need a multi-purpose tool. Today we’ll look at three such “all-in-one” tools:

• mtr — ping + traceroute on steroids,
• nmap — universal network scanner,
• curl — a command-line browser.

mtr — Real-Time Traceroute 🚀

What does it do?

Combines the features of ping and traceroute. In real time, it shows latency and packet loss percentage for each hop along the path.

Installation

Linux:

sudo apt install mtr

macOS (Homebrew):

brew install mtr

Usage

mtr google.com

Example output

Host                     Loss%   Snt   Last   Avg  Best  Wrst StDev
1. _gateway               0.0%    50    0.4   0.4   0.3   0.5   0.0
2. 10.0.0.1.provider.net  0.0%    50    1.2   1.5   1.1   5.2   0.5
3. some-router.msk.ru    10.0%    50   15.1  14.8  14.5  16.0   0.4
4. ...

• Loss% — packet loss.
• If loss appears and persists until the end of the route — the issue is at that node.

👉 Conclusion: mtr is invaluable for detecting intermittent problems that a plain traceroute won’t show.

nmap — Scanning All the Doors at Once 🔍

What does it do?

Scans ports and shows which ones are open, closed, or filtered. It can even detect which services are running behind them.

Usage

nmap scanme.nmap.org

Example output

Nmap scan report for scanme.nmap.org (45.33.32.156)
Host is up (0.16s latency).
Not shown: 996 closed ports
PORT      STATE  SERVICE
22/tcp    open   ssh
80/tcp    open   http
9929/tcp  open   nping-echo
31337/tcp open   Elite

👉 Conclusion: nmap is the best way to get a map of open ports and see which services are actually available.

curl — Looking at a Site Through a Machine’s Eyes 🤖

What does it do?

Sends HTTP(S) requests and shows the server’s raw response. Helps you see what’s happening “under the hood” of the browser.

Key modes

• Headers (-I):

  curl -I https://google.com
  

  HTTP/2 301
  location: https://www.google.com/
  

  Shows the response code (301 Moved Permanently) and the redirect target.

• Verbose (-v):

  curl -v https://google.com
  

  Displays: DNS query, TCP/SSL handshake, and header exchange.

👉 Conclusion: curl shows the exact reaction of a web server without the “decorations” of a browser.

Conclusion

Now your toolkit includes three multipurpose utilities:

• mtr — diagnosing unstable connections,
• nmap — scanning ports and services,
• curl — checking web services.

These tools cover most scenarios where basic commands fall short.

What’s Next?

We’ve covered nearly the whole path. But what if even these tools don’t help? For the trickiest cases, one last method remains — packet analysis.

In the next article, we’ll get to know tcpdump — a tool for capturing and analyzing network traffic.

Resources

• mtr (Linux man page)
• nmap.org
• curl documentation