Ntop
Ntop monitors ethernet devices. After apt-get install ntop you need to run ntop once first:
ntop -u ntop
Then you need to enter the password. After this has done you can exit ntop and /etc/init.d/ntop start it. Then surf to http://ip.of.host:3000/ to see the statistics.
In ETCH
you run
ntop --set-admin-password
first