One of my friends asked if there an alternative to Visio few days ago. I suggested her to try Draw.io or Dia and she eventually chose Draw.io. I once tried this tool. It's pretty cool. But still, Dia I think is the best option when it comes to desktop-based diagramming tool for Linux.
Nice share, Ricardo. I used use this tool before I knew Wireshark. This makes me want to make a nostalgic with Tdpdump