seanmoffett.info

Sean Moffett

IT pro who builds things on the side.

I work in IT. When something I need to understand refuses to stick, I build a small tool that makes it stick, then put it here in case it helps someone else. Everything below is real, live, and free to use.

Projects

01 · 2026
Trunk Line, level 3: two switches joined by a trunk, with the frame inspector below showing an 802.1Q tag of VLAN 10 on the frame and the hop-by-hop trace.

Trunk Line

A game that teaches VLANs, tagging and firewall rules one frame at a time.

You configure switch ports and firewall rules, run a set of test flows, then watch a single Ethernet frame travel hop by hop across the diagram. The frame inspector shows the 802.1Q tag going on at a trunk port and coming off at the far access port. Every failed test names the exact port that dropped the frame and why.

Ten levels, from access ports through native VLANs, voice VLANs and router-on-a-stick to a DMZ and a troubleshooting finale. Every port panel shows the same config in Cisco, UniFi and HP/Aruba terms, because half the confusion is vocabulary.

Status
Live
Built with
One HTML file. No framework, no build step, no dependencies.
Why
I was struggling to learn this. Now I am not.
Play Trunk Line Source

Now

Currently learning networking properly: VLANs, 802.1Q, native VLAN traps, firewall policy. Trunk Line is the study guide I could not find, so I made it. More to come as the list of things that will not stick gets shorter.