NOTE1: Be careful, since the xt_ACCOUNT module seems not to be loaded, if
you have shorewall, you'll need to put this module in shorewalls
modules.xtables file.

NOTE2: if you're using shorewall, you can put the following in the
/etc/shorewall/accounting file:

SECTION PREROUTING
ACCOUNT(down,0.0.0.0/0)		-	eth0	-
ACCOUNT(local,192.168.0.0/24)	-	eth1	-
SECTION POSTROUTING
ACCOUNT(up,0.0.0.0/0)		-	-	eth0
ACCOUNT(local,192.168.0.0/24)	-	-	eth1

(assuming you have a LAN 192.168.0.0/24 on eth1 and internet on eth0)

[]# iptables -l down (will show your total downstream traffic in the src)
[]# iptables -l up (will show your total upstream traffic in the src section)
[]# iptables -l local (will show your up/downstream traffic per ip address)

(special case 0.0.0.0/0 will have all traffic always in src)