See the overview for ntop
- Analyse IP traffic and sort it according to the source/destination
- Display IP Traffic Subnet matrix (who's talking to who?)
Ntop can show traffic statistics between other PCs and the internet, you just have to make sure the computer running ntop is able to see all the traffic. Modern ethernet switches segregate traffic so the a computer only sees traffic addressed to it. A managed switch will allow you to set up port-mirroring to the computer running ntop.
It seems the Belkin's built-in switch doesn't support Port-mirroring. Maybe you could interpose a suitable inexpensive switch between the Belkin and the four wired PCs.
Old ethernet hubs (not switches) also allow any computer to see all traffic. I have an old Netgear EN104 10-Base-T hub I used to use for this. I see they are available for a few dollars
See ntop blog about this
If the PCs are on the WLAN you'll need a different solution.
There are commercial products that claim to do this. E.g.
If the Belkin F5D7632-4 supported RMON or Netflow, you might be able to use that.