TamperData is essentially a packet sniffer designed just for firefox and is available as an extension. https://addons.mozilla.org/en-US/firefox/addon/966 You can open it under Tools>Tamper Data TamerData will list all outbound requests, and will display the: Time Duration Size Url Request Type Status Content Type Load Flags All Header Data Of every request the browser sends, all in an easy to read format. Not only that, but it also allows you to trap and edit any request you want, changing any of the header or POST data, as well as allowing you to spoof as dozens of different browsers (and has a list of the header information for each one) It also contains some tools that appear to be designed for SQL injection and similar. TamperData can do in minutes what Ethereal takes half an hour to do, and the ability to trap requests is invaluable for figuring out how things work. I cannot recommend it enough.