Evaluated two GUI to nmap: Zenmap and Knmap.
Nmap ("Network Mapper") is a utility for network exploration or security auditing. It supports ping scanning (determine which hosts are up), many port scanning techniques, version detection, and TCP/IP fingerprinting.
Zenmap (this was my favourite)
Zenmap is an Nmap frontend. It is meant to be useful for advanced users and to make Nmap easy to use by beginners. It was originally derived from Umit, an Nmap GUI created as part of the Google Summer of Code.
$ sudo apt-get install zenmap
Knmap is a KDE-based interface to the 'nmap' facility available at http://www.insecure.org/nmap.
The main Knmap window provides for the entry of nmap options and the display of nmap-generated output.
$ sudo apt-get install knmap