Can networks destinguish users not using the network?

Say you had a home network set up where everyone logged onto a pc in your home with a set up user name and you were the admin,


Is there a way you cant tell if someone brings their own laptop with ought using the network and logs onto your networks internet?

Can networks destinguish users not using the network?
If they brought a laptop, there are 2 ways to log into your network. (1) directly hooking up to the modem (or router) with an ethernet cable and (2) wirelessly. They can hook up easily with the ethernet cable attached. If they choose to do it wirelessly, they'll need your passphrase to get in, unless you removed it for some reason.





AT%26amp;T DSL provides an online page that is called "System Summary". Here you can click on "System at a Glance" and view the "Home Network". It will show the number of computers on the network, both wireless connections and ethernet connections. If those numbers total more than the number of computers you know you have, someone else is on your network. If you are using AT%26amp;T DSL and can't find this page, call customer support and ask for the link. If you are using another ISP, try the following:


Click on start, control panel, network %26amp; internet, network %26amp; sharing, network discovery ... turn on network discovery and you will be able to see the other comps in the network and they will be able to see you too.