Tracking Wireless Network Usage

Question

How do you determine the overall bandwidth usage for each computer connected to a wireless network?

I manage a small wireless network consisting of a couple of cheap Cisco/Linksys wifi routers. Unfortunately, these routers seem to have little built-in logging ability, and no way to tell which clients are using a lot of bandwidth. This is a problem because several dozen people use the wireless, and occasionally the network speed will get extremely slow (ping google.com takes several seconds/minutes).

I'm suspecting someone's downloading movies/torrents, which I wouldn't mind so much, but it's interfering with other people doing their jobs. I've already manually caught a couple interns downloading torrents, but I want to be more pro-active about it, and walking around the office to see what everyone's doing isn't practical.

Is there any way for a computer connected to a wireless network to monitor usage associated with MAC/IP addresses? I've looked into software like Wireshark, but it seems insanely complex to configure it to monitor any usage other than your own.

I don't care what sites people are going to, only the overall amount of bandwidth they're using. What's the easiest way to find this out?

Answer 1

I strongly advise spending the money for a router which has decent traffic monitoring and Quality of Service (or "QoS") which will allow you to not just see what and who is using bandwidth, but mark certain types of traffic as high-priority (skype, online multiplayer games, email, webbrowsing, streaming audio/video) or low-priority (http downloads, torrenting, ftp). Most medium / high-end ($70-$120) consumer routers support this, especially if you get one which can run DD-WRT as a replacement firmware.

You mention interns, which suggests a work environment; The solution might be as simple as informing the employees that bandwidth is limited and that they should avoid and minimize high-bandwidth activities, and that you'll be monitoring the network for overall health. (Note, the definitions of 'high-priority' and 'low-priority' in the first paragraph might also be different, and you might want to outright block certain types of traffic or ports or websites)

Answer 2

Less on the topic of monitoring but if you believe people are using high-bandwidth applications you could just block the ports for them on your firewall. the ports for bit torrent traffic are TCP 6881-6889, 6969 and 8080 and to insure blocking it make sure that UDP 1024-65534 are also blocked. (source: http://www.imfirewall.com/en/protocols/Bittorrent.htm) if you follow a similar approach with all other strenuous applications (skype, gaming etc) you should notice improved network performance.