No traffic at all!

Running on Mac OS X 10.9

I'm a beginner trying to teach myself some networking. I've just installed wireshark, but can't detect any traffic. In the interfaces dialogue box, it claims there's no packets or traffic anywhere, and when I start a capture, nothing is detected. Which to me seems impossible, as I'm browsing the internet right now. It seems related to a mystery that's sprung up on terminal - since about a week ago, whenever I enter 'ifconfig' into the mac terminal, all the interfaces claim to be 'inactive' and give no IP address (except lo0, of course, which has the usual IP address). Again, how can that be as I'm surfing the net? I'm using an o2 usb dongle, which HAS shown an active en1 connection on ifconfig in the past.

Completely confused.