A system and method for gathering data for detecting fraudulent transactions includes, in one embodiment, a web page that contains a fraud data gathering script and causes a client device to download a fraud detection applet. The fraud data gathering script causes the client device to collect information from the client device that is usable to identify the client device. The fraud detection applet causes the client device to connect to an identification echo service server to obtain the actual IP address of the client device. The fraud detection data, including the identifying information and the actual IP address, are then sent to a web server and/or a fraud data gathering server for further processing and to determine whether a transaction with the client device is likely to be fraudulent.