to much network activity - how do I pinpoint?
 

So I am looking over a network and the outboudn traffic graph (via mrtg) is running really high. How would you go about pinpointing the machine / service thats raping the bandiwdth?

im currently reading the tcpdump man but was wondering if there were any other console tools that may help me out.

Couple nice utilities:

iptraf - http://cebu.mozcom.com/riker/iptraf/ - LAN station monitor can be useful and also the IP traffic monitor

iftop - http://www.ex-parrot.com/~pdw/iftop/ - is very good - shows all the current connections and the flowing traffic

If you've got an X terminal, etherape (although now unmaintained I believe) gives an excellent graphical overview of the connections.

HTH