ipscan (fast and friendly network scanner)

Angry IP Scanner (or simply ipscan) is an open-source and cross-platform network scanner
designed to be fast and simple to use. It scans IP addresses and ports as well as has many other features. 

It is widely used by network administrators and just curious users around the world
including large and small enterprises, banks, and government agencies. 

It runs on Linux, Windows, and Mac OS X, possibly supporting other platforms as well.

Angry IP scanner simply pings each IP address to check if it’s alive, then optionally it is
resolving its hostname, determines the MAC address, scans ports, etc.
The amount of gathered data about each host can be extended with plugins.

It also has additional features, like NetBIOS information (computer name, workgroup name, and
currently logged in Windows user), favorite IP address ranges, web server detection, customizable openers, etc.

Scanning results can be saved to CSV, TXT, XML or IP-Port list files.
With help of plugins, Angry IP Scanner can gather any information about scanned IPs.
Anybody who can write Java code is able to write plugins and extend functionality of Angry IP Scanner.