Originally posted here by Somefilename
Actualy all port scanners are the same.
I cant say I agree. There is a substantial difference between some port scanners and their functionality. Most are just simple try and connect, if yes, good, if not, continue. some of the better port scanners employ much stronger techniques that include stealth scanning, and that allow you to gain some information whether or not there is a firewall filtering requests. see nmap, im not about to list all the features it has beyond the whole basic connection attempt on each port.