(Originally posted on SuperUser, not sure if it might be better suited here)

I have in my home a standard Comcast cable internet connection. I have it going from the wall to a cable modem, and from the modem to a late-series Linksys router, which provides wired and wireless networking. The vast majority of the users are wireless connections. For day-to-day tasks, this connection is fully sufficient for all my needs.

However, on regular occassions, we have social gatherings that involve many people bringing laptops and other PCs and using the network and internet simultaneously, frequently for gaming. I have no administrative oversight over these machines; they have been known to be riddled with spyware and/or bloatware or be running torrents, legal or otherwise. The only reason I care is that on a regular basis, one of the machines will flatline my internet bandwith, and consume it all in order to upload/download/spam people/whatever. When this happens, the latency of the connections for gaming and the like becomes unacceptable, and everyone suffers.

My question is: Is there a system I can set up whereby I can easily monitor the various systems connected to my wireless connection, see how much bandwith each one is using, and for what ends? That way, at a glance, I can spot the offending machine and kick it from the connection, without having to go from machine to machine, checking each one's "bandwith used" properties manually, and dealing with the owner's indignant protests all the while. I understand this will likely involve 3rd-party software and/or hardware; my issue is I don't even know where to begin.