If you’ve done everything else we’ve suggested, but still are uber-paranoid that some sort of hacker, government or otherwise, is leeching data from your computer, there’s one way to find out for sure: packet sniffing.

Packet sniffers, also known as protocol analyzers, record and identify all traffic travelling through a network interface, such as your wireless card. When traffic leaves your computer, it is broken up into chunks called “packets,” and this software will make a list of each packet, its “metadata” (date/time, source, destination, port number, etc.), and optionally, the full contents of the packet. If someone is taking data from your machine, you’ll see it.

There is but one gold standard in packet sniffing, and has been for as long as I can remember: Wireshark (formerly known as Ethereal). It’s cross-platform, free, and awesome.

This is one of a 30-part series, “No Surveillance State Month,” where daily for the month of June I’ll be posting ways to avoid invasion of your privacy in the digital age. The intent of these posts is not to enable one to escape detection while engaging in criminal activity — there’s still the old-fashioned “send a detective to watch you” for which these posts will not help. Rather, this series will help you to opt-out of the en masse collection of data by the government and large corporations that places Americans in databases without their knowing and freely-given consent for indefinite time periods. We all have the right to privacy, and I hope you demand it.