quick network engineering review question

I want to sniff all traffic on the upstream link at my installation. I have a wire that comes into my cisco router from the CSU/DSU. The question is, is this wire a normal ethernet wire, so that I could plug it into a hub and plug the hub into the Cisco, that is, put a hub in line with it, or is it something else? I already have the crossover cable for the new connection, if plugging the CSU/DSU wire into a hub is in fact copasetic. Please reply on or off list as appropriate -- David L Nicol Twinkies and Wonderbread are mainstream Americana