First of all, i hope the network scan is for local use... but heh... I'll leave the ethics up to you...

There's a simple but good scanner, I use from time to time.....

http://www.angryziber.com/ipscan/ , you can dld it , or open it from the weppage

The range has to be following though..... like 172.16.100.1 - 172.16.100.255....

Hope this is what ya mean ,