I have a Debian box and a Windows XP box on the network connected like this:
SIU---router~~wireless link~~access point---switch--PCs
where SIU is the wireless service interface unit, equivalent to a DSL modem.
I am assuming that the traffic I need to monitor is coming from one of my PCs and not the router so I want to install a traffic monitoring program on the Debian box.
There seem to be lots of them available so can anyone suggest one that would be suitable for this application? Ideally it would have minimal configuration requirements.
Because you have a switched network, your debian box will not be able to see traffic corresponding to the other machines on your local network. You can run the software on the debian box, but you'll need to get it to collect information from the router directly, normally via SNMP. I haven't tried to do this with a linksys WRT, so I'm not sure what information, if any, is presented via SNMP. You may find you have to install openwrt instead and use SNMP on that, or something that creates netflow records. If SNMP is good enough, you can use cacti to graph traffic and so on. it's a web-based application that polls SNMP (and other) hosts for traffic and so on. In fact, you could install the SNMP services on your windows and linux machines, and use cacti to poll all of them directly for their traffic statistics.