A sniffer is a software program used by IT administrators to monitor network usage, investigate network problems, investigate network misuse and abuse, identify configuration issues and determine the state of a network’s security. Sniffers ultimately decode the data so it is readable in words, numbers and computer code.
Note that last part: “determine the state of a network’s security.” That is a big one. This is because while good-guy IT security professionals use sniffers to determine the security of a network, bad guys also use them to see your data as it travels from your device to the router communicating the wireless internet signal.
Unsecured, unprotected, unencrypted and sometimes shared wireless internet communications over Wi-Fi in your home, office or any publicly connected Wi-Fi (such as at a coffee shop, airport or hotel) are vulnerable to sniffers. A sniffer employed by a criminal can be used to spy on anything you communicate wirelessly. Criminals can steal your data, get your usernames and passwords, and potentially hijack your device…and your life.
The kind of data that is most vulnerable to sniffers is that which is unencrypted; this can include something as simple as files being copied and pasted or shared from one device to another. Any information coming through your browser that isn’t coming from or going to a website employing encryption designated HTTPS—the S means secure—is also vulnerable.
On wireless connections that aren’t properly secured—such as those public ones I mentioned earlier—your best line of defense is to use a virtual private network software that protects your identity by ensuring that all web transactions (shopping, filling out forms, downloads) are secured through HTTPS. Hotspot Shield VPN is a good one to use. It’s secure, free to you (supported by ads) and available for PC, Mac, iPhone and Android.
Robert Siciliano on Google+