This is the command nstk that can be run in the OnWorks free hosting provider using one of our multiple free online workstations such as Ubuntu Online, Fedora Online, Windows online emulator or MAC OS online emulator
nstk - ns with tk support
ns [ file [ arg arg ... ] ]
nstk is same as ns,but with tk GUI support.
See ns (1) for more details.
Use nstk online using onworks.net services