For installing ns 2.35 in ubuntu Linux you have download ns-allinone-2.35.tar.gz (56.7MB) and following steps. 1. Get an active internet connection and connect your computer with internet. 2. Update your computer by using command sudo apt-get update 3. Run command sudo apt-get install build essential autoconf automake libxmu-dev 4. If in step-3 or step-2 command give some error then you have to connect your terminal to internet.For this you can visit url http://askubuntu.com/questions/298177/a-failed-to-fetch-error-occurs-when-apt-get-update-is-run-how-do-i-fix-this 5. The downloaded file is a tar file. You need to untar it. So, run command tar zxvf ns-allinone-2.35. tar.gz . 6. Run four given commands cd ns-allinone-2.35 ./install cd sudo apt-get install ns2 7. If command ...