Network-Traffic (volume in MB) loggen for each Host

Hello, I know - this isn't a new toppic, but I've searched the internet and havn't found anything. So my question: I've got a Router (192.168.0.5), which forewards all incomming traffic to another PC (ip 192.168.0.1). Now there are three hosts, which communicates with the PC (.0.1) over the router. I want to log the volume in MB, which every host is sending or getting over this Router (.0.5). Thanks for tipps, Andreas