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What Information Does a Laptop Leak on a Wireless Network?


What identifying signatures are given off by my laptop when I’m connected to a wireless network? I’m sure that my WiFi card, hard drive, Windows ID, and other identifying information is broadcast, but what is it? Would I guess that a traffic sniffer would show the make and model of my computer? Or does it go deeper than that?

Actually, it doesn’t go that deep at all. In general, it’s not as much information as you list… as long as you’re doing things right.

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Doing it right

Let’s start with a secure connection to a wireless hotspot that requires a WPA or WPA2 encryption key. All of the data that gets transmitted between your laptop and the hotspot is encrypted, so sniffing, seeing, or understanding anything interesting in it is basically off the table.

The MAC address is actually visible. That’s a hardware serial number that’s used by your wireless network card. It’s actually how the wireless access point says that “this packet” is destined for “that machine.” It identifies “that machine” by the MAC address. In most cases, you might be able to determine the manufacturer and the model number of the wireless card from the MAC address. That’s just a side effect of how MAC addresses are assigned.

Knowing that, someone sniffing can figure a few things out. They might realize that that card only works in these PCs, or that the wireless interface is actually in a mobile phone, or those kinds of things. Certainly nothing that is specific to your particular computer.

And that’s about it. I really can’t think of anything else that would actually be exposed in a properly secured wireless connection.

That’s why a secure wireless connection is so important… because it’s secure.

Open hotspots

Someone's Peeking!Now, what about that open WiFi hotspot where there is no WPA or WPA2 key?

Most of what you list is actually not automatically sent out. I can’t see how or why information about your hard drive or your Windows ID would automatically be transmitted anywhere.

Now, it is important to note that any information that you cause to be transmitted over an open network could, of course,  be seen.

That could include what you described and probably more, depending exactly on what it is that you’re doing or how it is that you’re using that network connection. But by default, it’s still not very much.

On an open WiFi connection,  things like the machine name might be visible. If you have file sharing turned on in Windows, then the names of the shares that you make available could be visible. Again, if you don’t have the firewall turned on and no security on those shares, then it’s possible that the very contents of those shares could be visible.

But I have a hard time coming up with much more than that, especially if the Windows firewall has been turned on.

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