I use Wireshark quite all the time. I was lucky to get a copy of Hacking: The Art of Exploitation when I was a teenager, the book gave me an excellent introduction to using tcpdump to perform network analysis. tcpdump is the first tool I reach for when I wonder where the packets are going, but for anything higher level (breaking down http, checking wlan flags) I use wireshark, I am always impressed.

At 33c3 there was a wireshark introductory self organised session run by kirils. I did not go to this session, but the slides I found look to be an excellent introduction to using wireshark.

Reading: Babylon's Ashes

Aberdeen, Scotland: -3°C, Light rain overnight.