Help needed from networking experts
I have DSL Connection 2MB.
I connected my DSL modem to the Network switch
and given connection to some of my friend
but i think one of my friends have installed a switch there and shared network to others.
how can i detect it?
how can i block others?
remember that i m not using any server.
i have connected switch through straight cable

Thread moved to proper section..

You cant detect or control it, unless you can setup your router to control ip address / mac address which pc can use internet. But this is router dependent. Not all routers have this configuration.

i only want to check that how many pcs are connected to our network?

Yes it can be but again not all routers have that feature.

Check your user manual