Can it be traced that I connected to wifi after I have disconnected?

Question

Yesterday I connected to the wifi at a friends house through my cellphone. After I have disconnected, can it ever be traced that I used the wifi?

Answer 1

Yes, potentially. When you connect to the wifi, all your traffic passes through the wifi router. That router can then, theoretically, log anything.

However, in practice, ordinary home wifi routers usually don't keep a history of who was connected. And if it did, you could probably only see something like your phones MAC adress, which wouldn't be so easy to tie to you.

So while it is possible that your friend could find out you connected to the wifi, it is not likely.

Answer 2

Yes. Especially if they know what they're doing.

Even on simple home routers, one thing that Anders forgot, is that your phone's DHCP name, and lease times are also frequently saved to the Router's log, in addition to your phone's MAC address.

Android devices tend to have randomish DHCP names, so that would be harder to track, but many, many iPhones will come up in my personal logs as something like "Dave's iPhone"

Furthermore, even if your phone's name doesn't give you away, if your friend knew you were there, he'd know what time you were there, and the lease time would match. I can't tell you how often I personally have seen android devices, with the lease time, and thought, "Oh that must have been John's phone"

On the other hand, most people don't check their logs, and default home routers won't keep information around very long (Probably only as long as the DHCP lease you were given), as they don't have much space to store it.