What you will learn
- Walk the network stack methodically
- Use traceroute and mtr
- Capture packets with tcpdump
New to this? Start here
The basics, in plain English
When something cannot connect, you do not guess randomly. You check each step of the path in order: is my machine online, is there a route to the target, is the port open, does the name resolve. These tools help you find where it breaks.
- ping
- A command that checks if another machine is reachable and how fast it replies.
- traceroute
- A command that shows every hop your data takes to reach a destination.
- Packet
- A small chunk of data sent over the network; big messages are split into many packets.
- Latency
- The delay, in milliseconds, for data to travel there and back.
- Work the layers
- A method: start at your own machine and move outward, testing one thing at each step.
01
A method
Start local and move outward: interface, route, firewall, DNS, remote service. tcpdump and mtr reveal where packets stop.
Try it yourself
bash
$mtr example.com↳Live, continuously updating traceroute plus packet loss per hop.$traceroute example.com↳Show each network hop between you and the destination.$tcpdump -i any port 443↳Capture HTTPS packets on every interface for inspection.$ss -s↳Print a summary of socket statistics.↳ lines explain what each command does — only the commands get copied
Finished this topic?
Mark it done to earn 100 XP and keep your streak alive.