Identifying Wi-Fi Hogs
I'm having increasing problems with poor network performance at public wi-fi hotspots.
I'm particularly susceptible to bandwidth problems, because I do a lot of interactive work on the net. Most people use the net in batch mode: fetch a web page, download an email, and the like. I'm often logged into a remote server, transmitting small packets of information a keystroke at a time.
I have a sneaking suspicion that a lot of times I observe network performance problems, that's because somebody is being a bandwidth hog. They may be doing something like connecting to a streaming music server, which uses a continual and significant part of the network bandwidth.
I have no hard data to support or disprove my theory. So, this afternoon, I did a little research. What I want is a network analysis tool that puts my wireless interface into promiscuous mode (that's a mode where an application can see what everybody is doing on the network), and then accumulates network usage by the various devices on the net.
iftop does for network usage what top(1) does for CPU usage. It listens to network traffic on a named interface and displays a table of current bandwidth usage by pairs of hosts. Handy for answering the question "why is our ADSL link so slow?".
I'll be curious to see whether bandwidth hogging behavior is as prevalent as I fear it may be.