_ gtk:
       
       GTK+ is a multi-platform toolkit for creating graphical user interfaces.
                                     
     _ gnu

       The GNU Project was launched in 1984 to develop a complete Unix-like 
       operating system which is free software: the GNU system. 

     _ freshmeat

       freshmeat is the first stop for Linux users hunting for the software 
       they need for work or play. 

     _ sourceforge

       SourceForge.net provides free services to Open Source developers.

     _ iptables

        The netfilter/iptables project is the Linux 2.4.x / 2.5.x firewalling 
        subsystem.

     _ linux

       Linux is the kernel of the GNU/Linux operating system.