Tool to monitor home network traffic & stats?

I have a home network with several users, using both LAN & Wifi. I have a Billion 7800N router which is also my ADSl2 modem. Is there a tool or something I can use that monitors all traffic going through the router, including capturing packets? Some features im looking for is broadband usage per user/ip, packet inspection (not required but handy) and other general network stats. I was looking at Netuse network monitor from AppStore as it also uses the SNMP data on the router, but with no trial version im not willing to buy just yet. Thanks