Fun way to learn about networking protocols

[eyefragment]

Step 1)   Install Wireshark
Step 2)   Choose an interface to analyze
Step 3)   If you see a protocol that you don't recognize, go read the wikipedia article and/or the RFCs and figure out what it's being used for.
Step 4)   Out of protocols?  Change your interface!  You won't get many differences, but there might be a few.

Comments

[hahafaha]

Indeed, that's very fun! Though, I'd mention that you should probably have a fairly good idea as to what protocols are running on your system simply from the fact that they tend to come from applications that you are running :P

[hahafaha]

Well, right, but if you approach the question from the point of view of applications, you can look up what protocols a given application uses and then read the specs on them. There's no need to actually look at the network traffic.