Angry Ip Scanner is a small open source application that lets you scan IP addresses and ports, you can even specifiy the range of the scan by yourself. After pinging the target IP it is able to resolve other data like hostname, MAC address and open ports.
It also has additional features, like NetBIOS information (computer name, workgroup name, and currently logged in Windows user), favorite IP address ranges, customizable openers, etc.
The tool is mainly useful for system administrators who want to take a quick look at their network and see whats going on. Plugins enhance the tool tremendously, for instance there are plugins that detect ftp servers, windows shares and more. Pretty handy tool if you ask me.

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