My friend and network security guru Kyle has just recently posted his "Wireshark Crash Course" on Udemy.com. I took the whole course over about an hour and half and even though I'm not completely new to Wireshark, learned a lot.
You should definitely check it out if you have the slightest interest computers or networking, but really, everyone should check it out and here's why:
We live in a world that is infinitely more connected than it once was. Back in the day, to use a computer, you had to understand a computer. These days, everything is done for us which is great, but we are no longer required to understand computers to use them. This opens us up to people trying to take advantage of our lack of knowledge for their own personal gain.
Wireshark is one of the tools that, like the force, in the wrong hands, can be used for evil. It allows a user to view network traffic, see what's being exchanged, read unencrypted data, etc. Used for good, it can foil those who are attempted to spread their evil through the world. Kyle course will take you from the basics including the structure of a data packet, how to install Wireshark and capture your first packets, all the way up through how to strip out HTTP headers and reconstruct the data on your machine, and do basic network analysis.
Kyle decidedly hopes that we use it for good... I think.