How can I tell what type of computers are in a coffee shop?

Question

This is more a thought experiment than anything.

I'm wondering what it would take to detect everything I legally can about the laptops in a hotspot. My first thought was to grab every MAC address I can and extract the maker from the first 24bit.

The question is would this be illegal and what else could I legally scavenge, preferably passively?

P.S. This constitutes a pattern-recognition problem so it IS programming... I think.

Answer 1

For the brain dead answer: Quit typing and look around for a few minutes :-D

Answer 2

nmap can do a reasonable job of guessing the operating system by the way the target system responds to various probes

Answer 3

IIRC there are ways to detect what TCP/IP stack is being used by sniffing choices in port usage and sequence numbers.

Answer 4

I guess the obvious one would be to sniff the user-agent out of their HTTP requests.

Answer 5

Why does it matter, 90% of them will be apples ;-)

Answer 6

GFI Languard gives a lot of info like this. Check it out.

Answer 7

The people wearing black turtle necks will be using Macs, the rest will be using PC's and Windows (except for that one guy with long pony tail who is using Linux).

Answer 8

Packet sniffing is illegal without the network owners consent. At least that's the generally followed precedent. There has been very few tests of this in court. But your idea of how to do it, using the mac addresses, would work well. Wireshark is a good packet sniffer if you're looking.