Zenmap - Ever wondered how to do a portscan or understand the ports exposed by a computer?

Simple answer is download Zenmap from http://nmap.org/download.html. Install the software, then key in the ip you want to discover about, Click Scan.... After few minute you get the entire information about that ip address. You can do lot of stuff with this... Don't use it for illegal purposes.  If everything is working you should see some thing like this. Handle it with care, don't use it in office or networks you don't own.